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Merge branches 'bug.2018.11.12a', 'consolidate.2018.12.01a', 'doc.2018.11.12a', 'fixes.2018.11.12a', 'initrd.2018.11.08b', 'sil.2018.11.12a' and 'srcu.2018.11.27a' into HEAD 

bug.2018.11.12a:  Get rid of BUG_ON() and friends
consolidate.2018.12.01a:  Continued RCU flavor-consolidation cleanup
doc.2018.11.12a:  Documentation updates
fixes.2018.11.12a:  Miscellaneous fixes
initrd.2018.11.08b:  Automate creation of rcutorture initrd
sil.2018.11.12a:  Remove more spin_unlock_wait() calls
This commit is contained in:
Paul E. McKenney 2018-12-01 12:43:16 -08:00
parent f0ad56e876 df56e0f960 97b59370fa 3d709ab5a1 b94ec36896 d4d592a6ee aacb5d91ab
commit eaaf055f27
85 changed files with 3887 additions and 3925 deletions
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@ -23,8 +23,6 @@ to each other.
The <tt>rcu_segcblist</tt> Structure</a>
<li> <a href="#The rcu_data Structure">
The <tt>rcu_data</tt> Structure</a>
<li> <a href="#The rcu_dynticks Structure">
The <tt>rcu_dynticks</tt> Structure</a>
<li> <a href="#The rcu_head Structure">
The <tt>rcu_head</tt> Structure</a>
<li> <a href="#RCU-Specific Fields in the task_struct Structure">
@ -127,9 +125,11 @@ CPUs, RCU would configure the <tt>rcu_node</tt> tree as follows:
</p><p>RCU currently permits up to a four-level tree, which on a 64-bit system
accommodates up to 4,194,304 CPUs, though only a mere 524,288 CPUs for
32-bit systems.
On the other hand, you can set <tt>CONFIG_RCU_FANOUT</tt> to be
as small as 2 if you wish, which would permit only 16 CPUs, which
is useful for testing.
On the other hand, you can set both <tt>CONFIG_RCU_FANOUT</tt> and
<tt>CONFIG_RCU_FANOUT_LEAF</tt> to be as small as 2, which would result
in a 16-CPU test using a 4-level tree.
This can be useful for testing large-system capabilities on small test
machines.
</p><p>This multi-level combining tree allows us to get most of the
performance and scalability
@ -154,44 +154,9 @@ on that root <tt>rcu_node</tt> structure remains acceptably low.
keeping lock contention under control at all tree levels regardless
of the level of loading on the system.
</p><p>The Linux kernel actually supports multiple flavors of RCU
running concurrently, so RCU builds separate data structures for each
flavor.
For example, for <tt>CONFIG_TREE_RCU=y</tt> kernels, RCU provides
rcu_sched and rcu_bh, as shown below:
</p><p><img src="BigTreeClassicRCUBH.svg" alt="BigTreeClassicRCUBH.svg" width="33%">
</p><p>Energy efficiency is increasingly important, and for that
reason the Linux kernel provides <tt>CONFIG_NO_HZ_IDLE</tt>, which
turns off the scheduling-clock interrupts on idle CPUs, which in
turn allows those CPUs to attain deeper sleep states and to consume
less energy.
CPUs whose scheduling-clock interrupts have been turned off are
said to be in <i>dyntick-idle mode</i>.
RCU must handle dyntick-idle CPUs specially
because RCU would otherwise wake up each CPU on every grace period,
which would defeat the whole purpose of <tt>CONFIG_NO_HZ_IDLE</tt>.
RCU uses the <tt>rcu_dynticks</tt> structure to track
which CPUs are in dyntick idle mode, as shown below:
</p><p><img src="BigTreeClassicRCUBHdyntick.svg" alt="BigTreeClassicRCUBHdyntick.svg" width="33%">
</p><p>However, if a CPU is in dyntick-idle mode, it is in that mode
for all flavors of RCU.
Therefore, a single <tt>rcu_dynticks</tt> structure is allocated per
CPU, and all of a given CPU's <tt>rcu_data</tt> structures share
that <tt>rcu_dynticks</tt>, as shown in the figure.
</p><p>Kernels built with <tt>CONFIG_PREEMPT_RCU</tt> support
rcu_preempt in addition to rcu_sched and rcu_bh, as shown below:
</p><p><img src="BigTreePreemptRCUBHdyntick.svg" alt="BigTreePreemptRCUBHdyntick.svg" width="35%">
</p><p>RCU updaters wait for normal grace periods by registering
RCU callbacks, either directly via <tt>call_rcu()</tt> and
friends (namely <tt>call_rcu_bh()</tt> and <tt>call_rcu_sched()</tt>),
there being a separate interface per flavor of RCU)
or indirectly via <tt>synchronize_rcu()</tt> and friends.
RCU callbacks are represented by <tt>rcu_head</tt> structures,
which are queued on <tt>rcu_data</tt> structures while they are
@ -214,9 +179,6 @@ its own synchronization:
<li> Each <tt>rcu_node</tt> structure has a spinlock.
<li> The fields in <tt>rcu_data</tt> are private to the corresponding
CPU, although a few can be read and written by other CPUs.
<li> Similarly, the fields in <tt>rcu_dynticks</tt> are private
to the corresponding CPU, although a few can be read by
other CPUs.
</ol>
<p>It is important to note that different data structures can have
@ -272,11 +234,6 @@ follows:
access to this information from the corresponding CPU.
Finally, this structure records past dyntick-idle state
for the corresponding CPU and also tracks statistics.
<li> <tt>rcu_dynticks</tt>:
This per-CPU structure tracks the current dyntick-idle
state for the corresponding CPU.
Unlike the other three structures, the <tt>rcu_dynticks</tt>
structure is not replicated per RCU flavor.
<li> <tt>rcu_head</tt>:
This structure represents RCU callbacks, and is the
only structure allocated and managed by RCU users.
@ -287,14 +244,14 @@ follows:
<p>If all you wanted from this article was a general notion of how
RCU's data structures are related, you are done.
Otherwise, each of the following sections give more details on
the <tt>rcu_state</tt>, <tt>rcu_node</tt>, <tt>rcu_data</tt>,
and <tt>rcu_dynticks</tt> data structures.
the <tt>rcu_state</tt>, <tt>rcu_node</tt> and <tt>rcu_data</tt> data
structures.
<h3><a name="The rcu_state Structure">
The <tt>rcu_state</tt> Structure</a></h3>
<p>The <tt>rcu_state</tt> structure is the base structure that
represents a flavor of RCU.
represents the state of RCU in the system.
This structure forms the interconnection between the
<tt>rcu_node</tt> and <tt>rcu_data</tt> structures,
tracks grace periods, contains the lock used to
@ -389,7 +346,7 @@ sequence number.
The bottom two bits are the state of the current grace period,
which can be zero for not yet started or one for in progress.
In other words, if the bottom two bits of <tt>-&gt;gp_seq</tt> are
zero, the corresponding flavor of RCU is idle.
zero, then RCU is idle.
Any other value in the bottom two bits indicates that something is broken.
This field is protected by the root <tt>rcu_node</tt> structure's
<tt>-&gt;lock</tt> field.
@ -419,10 +376,10 @@ as follows:
grace period in jiffies.
It is protected by the root <tt>rcu_node</tt>'s <tt>-&gt;lock</tt>.
<p>The <tt>-&gt;name</tt> field points to the name of the RCU flavor
(for example, &ldquo;rcu_sched&rdquo;), and is constant.
The <tt>-&gt;abbr</tt> field contains a one-character abbreviation,
for example, &ldquo;s&rdquo; for RCU-sched.
<p>The <tt>-&gt;name</tt> and <tt>-&gt;abbr</tt> fields distinguish
between preemptible RCU (&ldquo;rcu_preempt&rdquo; and &ldquo;p&rdquo;)
and non-preemptible RCU (&ldquo;rcu_sched&rdquo; and &ldquo;s&rdquo;).
These fields are used for diagnostic and tracing purposes.
<h3><a name="The rcu_node Structure">
The <tt>rcu_node</tt> Structure</a></h3>
@ -971,25 +928,31 @@ this <tt>rcu_segcblist</tt> structure, <i>not</i> the <tt>-&gt;head</tt>
pointer.
The reason for this is that all the ready-to-invoke callbacks
(that is, those in the <tt>RCU_DONE_TAIL</tt> segment) are extracted
all at once at callback-invocation time.
all at once at callback-invocation time (<tt>rcu_do_batch</tt>), due
to which <tt>-&gt;head</tt> may be set to NULL if there are no not-done
callbacks remaining in the <tt>rcu_segcblist</tt>.
If callback invocation must be postponed, for example, because a
high-priority process just woke up on this CPU, then the remaining
callbacks are placed back on the <tt>RCU_DONE_TAIL</tt> segment.
Either way, the <tt>-&gt;len</tt> and <tt>-&gt;len_lazy</tt> counts
are adjusted after the corresponding callbacks have been invoked, and so
again it is the <tt>-&gt;len</tt> count that accurately reflects whether
or not there are callbacks associated with this <tt>rcu_segcblist</tt>
structure.
callbacks are placed back on the <tt>RCU_DONE_TAIL</tt> segment and
<tt>-&gt;head</tt> once again points to the start of the segment.
In short, the head field can briefly be <tt>NULL</tt> even though the
CPU has callbacks present the entire time.
Therefore, it is not appropriate to test the <tt>-&gt;head</tt> pointer
for <tt>NULL</tt>.
<p>In contrast, the <tt>-&gt;len</tt> and <tt>-&gt;len_lazy</tt> counts
are adjusted only after the corresponding callbacks have been invoked.
This means that the <tt>-&gt;len</tt> count is zero only if
the <tt>rcu_segcblist</tt> structure really is devoid of callbacks.
Of course, off-CPU sampling of the <tt>-&gt;len</tt> count requires
the use of appropriate synchronization, for example, memory barriers.
careful use of appropriate synchronization, for example, memory barriers.
This synchronization can be a bit subtle, particularly in the case
of <tt>rcu_barrier()</tt>.
<h3><a name="The rcu_data Structure">
The <tt>rcu_data</tt> Structure</a></h3>
<p>The <tt>rcu_data</tt> maintains the per-CPU state for the
corresponding flavor of RCU.
<p>The <tt>rcu_data</tt> maintains the per-CPU state for the RCU subsystem.
The fields in this structure may be accessed only from the corresponding
CPU (and from tracing) unless otherwise stated.
This structure is the
@ -1015,30 +978,19 @@ as follows:
<pre>
1 int cpu;
2 struct rcu_state *rsp;
3 struct rcu_node *mynode;
4 struct rcu_dynticks *dynticks;
5 unsigned long grpmask;
6 bool beenonline;
2 struct rcu_node *mynode;
3 unsigned long grpmask;
4 bool beenonline;
</pre>
<p>The <tt>-&gt;cpu</tt> field contains the number of the
corresponding CPU, the <tt>-&gt;rsp</tt> pointer references
the corresponding <tt>rcu_state</tt> structure (and is most frequently
used to locate the name of the corresponding flavor of RCU for tracing),
and the <tt>-&gt;mynode</tt> field references the corresponding
<tt>rcu_node</tt> structure.
corresponding CPU and the <tt>-&gt;mynode</tt> field references the
corresponding <tt>rcu_node</tt> structure.
The <tt>-&gt;mynode</tt> is used to propagate quiescent states
up the combining tree.
<p>The <tt>-&gt;dynticks</tt> pointer references the
<tt>rcu_dynticks</tt> structure corresponding to this
CPU.
Recall that a single per-CPU instance of the <tt>rcu_dynticks</tt>
structure is shared among all flavors of RCU.
These first four fields are constant and therefore require not
synchronization.
These two fields are constant and therefore do not require synchronization.
</p><p>The <tt>-&gt;grpmask</tt> field indicates the bit in
<p>The <tt>-&gt;grpmask</tt> field indicates the bit in
the <tt>-&gt;mynode-&gt;qsmask</tt> corresponding to this
<tt>rcu_data</tt> structure, and is also used when propagating
quiescent states.
@ -1057,12 +1009,12 @@ as follows:
3 bool cpu_no_qs;
4 bool core_needs_qs;
5 bool gpwrap;
6 unsigned long rcu_qs_ctr_snap;
</pre>
<p>The <tt>-&gt;gp_seq</tt> and <tt>-&gt;gp_seq_needed</tt>
fields are the counterparts of the fields of the same name
in the <tt>rcu_state</tt> and <tt>rcu_node</tt> structures.
<p>The <tt>-&gt;gp_seq</tt> field is the counterpart of the field of the same
name in the <tt>rcu_state</tt> and <tt>rcu_node</tt> structures. The
<tt>-&gt;gp_seq_needed</tt> field is the counterpart of the field of the same
name in the rcu_node</tt> structure.
They may each lag up to one behind their <tt>rcu_node</tt>
counterparts, but in <tt>CONFIG_NO_HZ_IDLE</tt> and
<tt>CONFIG_NO_HZ_FULL</tt> kernels can lag
@ -1103,10 +1055,6 @@ CPU has remained idle for so long that the
<tt>gp_seq</tt> counter is in danger of overflow, which
will cause the CPU to disregard the values of its counters on
its next exit from idle.
Finally, the <tt>rcu_qs_ctr_snap</tt> field is used to detect
cases where a given operation has resulted in a quiescent state
for all flavors of RCU, for example, <tt>cond_resched()</tt>
when RCU has indicated a need for quiescent states.
<h5>RCU Callback Handling</h5>
@ -1179,26 +1127,22 @@ Finally, the <tt>-&gt;dynticks_fqs</tt> field is used to
count the number of times this CPU is determined to be in
dyntick-idle state, and is used for tracing and debugging purposes.
<h3><a name="The rcu_dynticks Structure">
The <tt>rcu_dynticks</tt> Structure</a></h3>
<p>The <tt>rcu_dynticks</tt> maintains the per-CPU dyntick-idle state
for the corresponding CPU.
Unlike the other structures, <tt>rcu_dynticks</tt> is not
replicated over the different flavors of RCU.
The fields in this structure may be accessed only from the corresponding
CPU (and from tracing) unless otherwise stated.
Its fields are as follows:
<p>
This portion of the rcu_data structure is declared as follows:
<pre>
1 long dynticks_nesting;
2 long dynticks_nmi_nesting;
3 atomic_t dynticks;
4 bool rcu_need_heavy_qs;
5 unsigned long rcu_qs_ctr;
6 bool rcu_urgent_qs;
5 bool rcu_urgent_qs;
</pre>
<p>These fields in the rcu_data structure maintain the per-CPU dyntick-idle
state for the corresponding CPU.
The fields may be accessed only from the corresponding CPU (and from tracing)
unless otherwise stated.
<p>The <tt>-&gt;dynticks_nesting</tt> field counts the
nesting depth of process execution, so that in normal circumstances
this counter has value zero or one.
@ -1240,19 +1184,12 @@ it is willing to call for heavy-weight dyntick-counter operations.
This flag is checked by RCU's context-switch and <tt>cond_resched()</tt>
code, which provide a momentary idle sojourn in response.
</p><p>The <tt>-&gt;rcu_qs_ctr</tt> field is used to record
quiescent states from <tt>cond_resched()</tt>.
Because <tt>cond_resched()</tt> can execute quite frequently, this
must be quite lightweight, as in a non-atomic increment of this
per-CPU field.
</p><p>Finally, the <tt>-&gt;rcu_urgent_qs</tt> field is used to record
the fact that the RCU core code would really like to see a quiescent
state from the corresponding CPU, with the various other fields indicating
just how badly RCU wants this quiescent state.
This flag is checked by RCU's context-switch and <tt>cond_resched()</tt>
code, which, if nothing else, non-atomically increment <tt>-&gt;rcu_qs_ctr</tt>
in response.
the fact that the RCU core code would really like to see a quiescent state from
the corresponding CPU, with the various other fields indicating just how badly
RCU wants this quiescent state.
This flag is checked by RCU's context-switch path
(<tt>rcu_note_context_switch</tt>) and the cond_resched code.
<table>
<tr><th>&nbsp;</th></tr>
@ -1425,11 +1362,11 @@ the last part of the array, thus traversing only the leaf
<h3><a name="Summary">
Summary</a></h3>
So each flavor of RCU is represented by an <tt>rcu_state</tt> structure,
So the state of RCU is represented by an <tt>rcu_state</tt> structure,
which contains a combining tree of <tt>rcu_node</tt> and
<tt>rcu_data</tt> structures.
Finally, in <tt>CONFIG_NO_HZ_IDLE</tt> kernels, each CPU's dyntick-idle
state is tracked by an <tt>rcu_dynticks</tt> structure.
state is tracked by dynticks-related fields in the <tt>rcu_data</tt> structure.
If you made it this far, you are well prepared to read the code
walkthroughs in the other articles in this series.

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@ -160,9 +160,9 @@ was in flight.
If the CPU is idle, then <tt>sync_sched_exp_handler()</tt> reports
the quiescent state.
<p>
Otherwise, the handler invokes <tt>resched_cpu()</tt>, which forces
a future context switch.
<p> Otherwise, the handler forces a future context switch by setting the
NEED_RESCHED flag of the current task's thread flag and the CPU preempt
counter.
At the time of the context switch, the CPU reports the quiescent state.
Should the CPU go offline first, it will report the quiescent state
at that time.

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@ -77,7 +77,7 @@ The key point is that the lock-acquisition functions, including
<tt>smp_mb__after_unlock_lock()</tt> immediately after successful
acquisition of the lock.
<p>Therefore, for any given <tt>rcu_node</tt> struction, any access
<p>Therefore, for any given <tt>rcu_node</tt> structure, any access
happening before one of the above lock-release functions will be seen
by all CPUs as happening before any access happening after a later
one of the above lock-acquisition functions.

206
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@ -900,8 +900,6 @@ Except where otherwise noted, these non-guarantees were premeditated.
Grace Periods Don't Partition Read-Side Critical Sections</a>
<li> <a href="#Read-Side Critical Sections Don't Partition Grace Periods">
Read-Side Critical Sections Don't Partition Grace Periods</a>
<li> <a href="#Disabling Preemption Does Not Block Grace Periods">
Disabling Preemption Does Not Block Grace Periods</a>
</ol>
<h3><a name="Readers Impose Minimal Ordering">Readers Impose Minimal Ordering</a></h3>
@ -1259,54 +1257,6 @@ of RCU grace periods.
<tr><td>&nbsp;</td></tr>
</table>
<h3><a name="Disabling Preemption Does Not Block Grace Periods">
Disabling Preemption Does Not Block Grace Periods</a></h3>
<p>
There was a time when disabling preemption on any given CPU would block
subsequent grace periods.
However, this was an accident of implementation and is not a requirement.
And in the current Linux-kernel implementation, disabling preemption
on a given CPU in fact does not block grace periods, as Oleg Nesterov
<a href="https://lkml.kernel.org/g/20150614193825.GA19582@redhat.com">demonstrated</a>.
<p>
If you need a preempt-disable region to block grace periods, you need to add
<tt>rcu_read_lock()</tt> and <tt>rcu_read_unlock()</tt>, for example
as follows:
<blockquote>
<pre>
1 preempt_disable();
2 rcu_read_lock();
3 do_something();
4 rcu_read_unlock();
5 preempt_enable();
6
7 /* Spinlocks implicitly disable preemption. */
8 spin_lock(&amp;mylock);
9 rcu_read_lock();
10 do_something();
11 rcu_read_unlock();
12 spin_unlock(&amp;mylock);
</pre>
</blockquote>
<p>
In theory, you could enter the RCU read-side critical section first,
but it is more efficient to keep the entire RCU read-side critical
section contained in the preempt-disable region as shown above.
Of course, RCU read-side critical sections that extend outside of
preempt-disable regions will work correctly, but such critical sections
can be preempted, which forces <tt>rcu_read_unlock()</tt> to do
more work.
And no, this is <i>not</i> an invitation to enclose all of your RCU
read-side critical sections within preempt-disable regions, because
doing so would degrade real-time response.
<p>
This non-requirement appeared with preemptible RCU.
<h2><a name="Parallelism Facts of Life">Parallelism Facts of Life</a></h2>
<p>
@ -1381,6 +1331,7 @@ Classes of quality-of-implementation requirements are as follows:
<ol>
<li> <a href="#Specialization">Specialization</a>
<li> <a href="#Performance and Scalability">Performance and Scalability</a>
<li> <a href="#Forward Progress">Forward Progress</a>
<li> <a href="#Composability">Composability</a>
<li> <a href="#Corner Cases">Corner Cases</a>
</ol>
@ -1645,7 +1596,7 @@ used in place of <tt>synchronize_rcu()</tt> as follows:
16 struct foo *p;
17
18 spin_lock(&amp;gp_lock);
19 p = rcu_dereference(gp);
19 p = rcu_access_pointer(gp);
20 if (!p) {
21 spin_unlock(&amp;gp_lock);
22 return false;
@ -1822,6 +1773,106 @@ so it is too early to tell whether they will stand the test of time.
RCU thus provides a range of tools to allow updaters to strike the
required tradeoff between latency, flexibility and CPU overhead.
<h3><a name="Forward Progress">Forward Progress</a></h3>
<p>
In theory, delaying grace-period completion and callback invocation
is harmless.
In practice, not only are memory sizes finite but also callbacks sometimes
do wakeups, and sufficiently deferred wakeups can be difficult
to distinguish from system hangs.
Therefore, RCU must provide a number of mechanisms to promote forward
progress.
<p>
These mechanisms are not foolproof, nor can they be.
For one simple example, an infinite loop in an RCU read-side critical
section must by definition prevent later grace periods from ever completing.
For a more involved example, consider a 64-CPU system built with
<tt>CONFIG_RCU_NOCB_CPU=y</tt> and booted with <tt>rcu_nocbs=1-63</tt>,
where CPUs&nbsp;1 through&nbsp;63 spin in tight loops that invoke
<tt>call_rcu()</tt>.
Even if these tight loops also contain calls to <tt>cond_resched()</tt>
(thus allowing grace periods to complete), CPU&nbsp;0 simply will
not be able to invoke callbacks as fast as the other 63 CPUs can
register them, at least not until the system runs out of memory.
In both of these examples, the Spiderman principle applies: With great
power comes great responsibility.
However, short of this level of abuse, RCU is required to
ensure timely completion of grace periods and timely invocation of
callbacks.
<p>
RCU takes the following steps to encourage timely completion of
grace periods:
<ol>
<li> If a grace period fails to complete within 100&nbsp;milliseconds,
RCU causes future invocations of <tt>cond_resched()</tt> on
the holdout CPUs to provide an RCU quiescent state.
RCU also causes those CPUs' <tt>need_resched()</tt> invocations
to return <tt>true</tt>, but only after the corresponding CPU's
next scheduling-clock.
<li> CPUs mentioned in the <tt>nohz_full</tt> kernel boot parameter
can run indefinitely in the kernel without scheduling-clock
interrupts, which defeats the above <tt>need_resched()</tt>
strategem.
RCU will therefore invoke <tt>resched_cpu()</tt> on any
<tt>nohz_full</tt> CPUs still holding out after
109&nbsp;milliseconds.
<li> In kernels built with <tt>CONFIG_RCU_BOOST=y</tt>, if a given
task that has been preempted within an RCU read-side critical
section is holding out for more than 500&nbsp;milliseconds,
RCU will resort to priority boosting.
<li> If a CPU is still holding out 10&nbsp;seconds into the grace
period, RCU will invoke <tt>resched_cpu()</tt> on it regardless
of its <tt>nohz_full</tt> state.
</ol>
<p>
The above values are defaults for systems running with <tt>HZ=1000</tt>.
They will vary as the value of <tt>HZ</tt> varies, and can also be
changed using the relevant Kconfig options and kernel boot parameters.
RCU currently does not do much sanity checking of these
parameters, so please use caution when changing them.
Note that these forward-progress measures are provided only for RCU,
not for
<a href="#Sleepable RCU">SRCU</a> or
<a href="#Tasks RCU">Tasks RCU</a>.
<p>
RCU takes the following steps in <tt>call_rcu()</tt> to encourage timely
invocation of callbacks when any given non-<tt>rcu_nocbs</tt> CPU has
10,000 callbacks, or has 10,000 more callbacks than it had the last time
encouragement was provided:
<ol>
<li> Starts a grace period, if one is not already in progress.
<li> Forces immediate checking for quiescent states, rather than
waiting for three milliseconds to have elapsed since the
beginning of the grace period.
<li> Immediately tags the CPU's callbacks with their grace period
completion numbers, rather than waiting for the <tt>RCU_SOFTIRQ</tt>
handler to get around to it.
<li> Lifts callback-execution batch limits, which speeds up callback
invocation at the expense of degrading realtime response.
</ol>
<p>
Again, these are default values when running at <tt>HZ=1000</tt>,
and can be overridden.
Again, these forward-progress measures are provided only for RCU,
not for
<a href="#Sleepable RCU">SRCU</a> or
<a href="#Tasks RCU">Tasks RCU</a>.
Even for RCU, callback-invocation forward progress for <tt>rcu_nocbs</tt>
CPUs is much less well-developed, in part because workloads benefiting
from <tt>rcu_nocbs</tt> CPUs tend to invoke <tt>call_rcu()</tt>
relatively infrequently.
If workloads emerge that need both <tt>rcu_nocbs</tt> CPUs and high
<tt>call_rcu()</tt> invocation rates, then additional forward-progress
work will be required.
<h3><a name="Composability">Composability</a></h3>
<p>
@ -2272,7 +2323,7 @@ that meets this requirement.
Furthermore, NMI handlers can be interrupted by what appear to RCU
to be normal interrupts.
One way that this can happen is for code that directly invokes
<tt>rcu_irq_enter()</tt> and </tt>rcu_irq_exit()</tt> to be called
<tt>rcu_irq_enter()</tt> and <tt>rcu_irq_exit()</tt> to be called
from an NMI handler.
This astonishing fact of life prompted the current code structure,
which has <tt>rcu_irq_enter()</tt> invoking <tt>rcu_nmi_enter()</tt>
@ -2294,7 +2345,7 @@ via <tt>del_timer_sync()</tt> or similar.
<p>
Unfortunately, there is no way to cancel an RCU callback;
once you invoke <tt>call_rcu()</tt>, the callback function is
going to eventually be invoked, unless the system goes down first.
eventually going to be invoked, unless the system goes down first.
Because it is normally considered socially irresponsible to crash the system
in response to a module unload request, we need some other way
to deal with in-flight RCU callbacks.
@ -2424,23 +2475,37 @@ for context-switch-heavy <tt>CONFIG_NO_HZ_FULL=y</tt> workloads,
but there is room for further improvement.
<p>
In the past, it was forbidden to disable interrupts across an
<tt>rcu_read_unlock()</tt> unless that interrupt-disabled region
of code also included the matching <tt>rcu_read_lock()</tt>.
Violating this restriction could result in deadlocks involving the
scheduler's runqueue and priority-inheritance spinlocks.
This restriction was lifted when interrupt-disabled calls to
<tt>rcu_read_unlock()</tt> started deferring the reporting of
the resulting RCU-preempt quiescent state until the end of that
It is forbidden to hold any of scheduler's runqueue or priority-inheritance
spinlocks across an <tt>rcu_read_unlock()</tt> unless interrupts have been
disabled across the entire RCU read-side critical section, that is,
up to and including the matching <tt>rcu_read_lock()</tt>.
Violating this restriction can result in deadlocks involving these
scheduler spinlocks.
There was hope that this restriction might be lifted when interrupt-disabled
calls to <tt>rcu_read_unlock()</tt> started deferring the reporting of
the resulting RCU-preempt quiescent state until the end of the corresponding
interrupts-disabled region.
This deferred reporting means that the scheduler's runqueue and
priority-inheritance locks cannot be held while reporting an RCU-preempt
quiescent state, which lifts the earlier restriction, at least from
a deadlock perspective.
Unfortunately, real-time systems using RCU priority boosting may
Unfortunately, timely reporting of the corresponding quiescent state
to expedited grace periods requires a call to <tt>raise_softirq()</tt>,
which can acquire these scheduler spinlocks.
In addition, real-time systems using RCU priority boosting
need this restriction to remain in effect because deferred
quiescent-state reporting also defers deboosting, which in turn
degrades real-time latencies.
quiescent-state reporting would also defer deboosting, which in turn
would degrade real-time latencies.
<p>
In theory, if a given RCU read-side critical section could be
guaranteed to be less than one second in duration, holding a scheduler
spinlock across that critical section's <tt>rcu_read_unlock()</tt>
would require only that preemption be disabled across the entire
RCU read-side critical section, not interrupts.
Unfortunately, given the possibility of vCPU preemption, long-running
interrupts, and so on, it is not possible in practice to guarantee
that a given RCU read-side critical section will complete in less than
one second.
Therefore, as noted above, if scheduler spinlocks are held across
a given call to <tt>rcu_read_unlock()</tt>, interrupts must be
disabled across the entire RCU read-side critical section.
<h3><a name="Tracing and RCU">Tracing and RCU</a></h3>
@ -3233,6 +3298,11 @@ For example, RCU callback overhead might be charged back to the
originating <tt>call_rcu()</tt> instance, though probably not
in production kernels.
<p>
Additional work may be required to provide reasonable forward-progress
guarantees under heavy load for grace periods and for callback
invocation.
<h2><a name="Summary">Summary</a></h2>
<p>

49
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@ -63,7 +63,7 @@ over a rather long period of time, but improvements are always welcome!
pointer must be covered by rcu_read_lock(), rcu_read_lock_bh(),
rcu_read_lock_sched(), or by the appropriate update-side lock.
Disabling of preemption can serve as rcu_read_lock_sched(), but
is less readable.
is less readable and prevents lockdep from detecting locking issues.
Letting RCU-protected pointers "leak" out of an RCU read-side
critical section is every bid as bad as letting them leak out
@ -285,11 +285,7 @@ over a rather long period of time, but improvements are always welcome!
here is that superuser already has lots of ways to crash
the machine.
d. Use call_rcu_bh() rather than call_rcu(), in order to take
advantage of call_rcu_bh()'s faster grace periods. (This
is only a partial solution, though.)
e. Periodically invoke synchronize_rcu(), permitting a limited
d. Periodically invoke synchronize_rcu(), permitting a limited
number of updates per grace period.
The same cautions apply to call_rcu_bh(), call_rcu_sched(),
@ -324,37 +320,14 @@ over a rather long period of time, but improvements are always welcome!
will break Alpha, cause aggressive compilers to generate bad code,
and confuse people trying to read your code.
11. Note that synchronize_rcu() -only- guarantees to wait until
all currently executing rcu_read_lock()-protected RCU read-side
critical sections complete. It does -not- necessarily guarantee
that all currently running interrupts, NMIs, preempt_disable()
code, or idle loops will complete. Therefore, if your
read-side critical sections are protected by something other
than rcu_read_lock(), do -not- use synchronize_rcu().
Similarly, disabling preemption is not an acceptable substitute
for rcu_read_lock(). Code that attempts to use preemption
disabling where it should be using rcu_read_lock() will break
in CONFIG_PREEMPT=y kernel builds.
If you want to wait for interrupt handlers, NMI handlers, and
code under the influence of preempt_disable(), you instead
need to use synchronize_irq() or synchronize_sched().
This same limitation also applies to synchronize_rcu_bh()
and synchronize_srcu(), as well as to the asynchronous and
expedited forms of the three primitives, namely call_rcu(),
call_rcu_bh(), call_srcu(), synchronize_rcu_expedited(),
synchronize_rcu_bh_expedited(), and synchronize_srcu_expedited().
12. Any lock acquired by an RCU callback must be acquired elsewhere
11. Any lock acquired by an RCU callback must be acquired elsewhere
with softirq disabled, e.g., via spin_lock_irqsave(),
spin_lock_bh(), etc. Failing to disable irq on a given
acquisition of that lock will result in deadlock as soon as
the RCU softirq handler happens to run your RCU callback while
interrupting that acquisition's critical section.
13. RCU callbacks can be and are executed in parallel. In many cases,
12. RCU callbacks can be and are executed in parallel. In many cases,
the callback code simply wrappers around kfree(), so that this
is not an issue (or, more accurately, to the extent that it is
an issue, the memory-allocator locking handles it). However,
@ -370,7 +343,7 @@ over a rather long period of time, but improvements are always welcome!
not the case, a self-spawning RCU callback would prevent the
victim CPU from ever going offline.)
14. Unlike other forms of RCU, it -is- permissible to block in an
13. Unlike other forms of RCU, it -is- permissible to block in an
SRCU read-side critical section (demarked by srcu_read_lock()
and srcu_read_unlock()), hence the "SRCU": "sleepable RCU".
Please note that if you don't need to sleep in read-side critical
@ -414,7 +387,7 @@ over a rather long period of time, but improvements are always welcome!
Note that rcu_dereference() and rcu_assign_pointer() relate to
SRCU just as they do to other forms of RCU.
15. The whole point of call_rcu(), synchronize_rcu(), and friends
14. The whole point of call_rcu(), synchronize_rcu(), and friends
is to wait until all pre-existing readers have finished before
carrying out some otherwise-destructive operation. It is
therefore critically important to -first- remove any path
@ -426,13 +399,13 @@ over a rather long period of time, but improvements are always welcome!
is the caller's responsibility to guarantee that any subsequent
readers will execute safely.
16. The various RCU read-side primitives do -not- necessarily contain
15. The various RCU read-side primitives do -not- necessarily contain
memory barriers. You should therefore plan for the CPU
and the compiler to freely reorder code into and out of RCU
read-side critical sections. It is the responsibility of the
RCU update-side primitives to deal with this.
17. Use CONFIG_PROVE_LOCKING, CONFIG_DEBUG_OBJECTS_RCU_HEAD, and the
16. Use CONFIG_PROVE_LOCKING, CONFIG_DEBUG_OBJECTS_RCU_HEAD, and the
__rcu sparse checks to validate your RCU code. These can help
find problems as follows:
@ -455,7 +428,7 @@ over a rather long period of time, but improvements are always welcome!
These debugging aids can help you find problems that are
otherwise extremely difficult to spot.
18. If you register a callback using call_rcu(), call_rcu_bh(),
17. If you register a callback using call_rcu(), call_rcu_bh(),
call_rcu_sched(), or call_srcu(), and pass in a function defined
within a loadable module, then it in necessary to wait for
all pending callbacks to be invoked after the last invocation
@ -469,8 +442,8 @@ over a rather long period of time, but improvements are always welcome!
You instead need to use one of the barrier functions:
o call_rcu() -> rcu_barrier()
o call_rcu_bh() -> rcu_barrier_bh()
o call_rcu_sched() -> rcu_barrier_sched()
o call_rcu_bh() -> rcu_barrier()
o call_rcu_sched() -> rcu_barrier()
o call_srcu() -> srcu_barrier()
However, these barrier functions are absolutely -not- guaranteed

7
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@ -176,9 +176,8 @@ causing stalls, and that the stall was affecting RCU-sched. This message
will normally be followed by stack dumps for each CPU. Please note that
PREEMPT_RCU builds can be stalled by tasks as well as by CPUs, and that
the tasks will be indicated by PID, for example, "P3421". It is even
possible for a rcu_preempt_state stall to be caused by both CPUs -and-
tasks, in which case the offending CPUs and tasks will all be called
out in the list.
possible for an rcu_state stall to be caused by both CPUs -and- tasks,
in which case the offending CPUs and tasks will all be called out in the list.
CPU 2's "(3 GPs behind)" indicates that this CPU has not interacted with
the RCU core for the past three grace periods. In contrast, CPU 16's "(0
@ -206,7 +205,7 @@ handlers are no longer able to execute on this CPU. This can happen if
the stalled CPU is spinning with interrupts are disabled, or, in -rt
kernels, if a high-priority process is starving RCU's softirq handler.
The "fps=" shows the number of force-quiescent-state idle/offline
The "fqs=" shows the number of force-quiescent-state idle/offline
detection passes that the grace-period kthread has made across this
CPU since the last time that this CPU noted the beginning of a grace
period.

70
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@ -266,7 +266,7 @@ rcu_dereference()
unnecessary overhead on Alpha CPUs.
Note that the value returned by rcu_dereference() is valid
only within the enclosing RCU read-side critical section.
only within the enclosing RCU read-side critical section [1].
For example, the following is -not- legal:
rcu_read_lock();
@ -292,6 +292,19 @@ rcu_dereference()
typically used indirectly, via the _rcu list-manipulation
primitives, such as list_for_each_entry_rcu().
[1] The variant rcu_dereference_protected() can be used outside
of an RCU read-side critical section as long as the usage is
protected by locks acquired by the update-side code. This variant
avoids the lockdep warning that would happen when using (for
example) rcu_dereference() without rcu_read_lock() protection.
Using rcu_dereference_protected() also has the advantage
of permitting compiler optimizations that rcu_dereference()
must prohibit. The rcu_dereference_protected() variant takes
a lockdep expression to indicate which locks must be acquired
by the caller. If the indicated protection is not provided,
a lockdep splat is emitted. See RCU/Design/Requirements.html
and the API's code comments for more details and example usage.
The following diagram shows how each API communicates among the
reader, updater, and reclaimer.
@ -322,28 +335,27 @@ to their callers and (2) call_rcu() callbacks may be invoked. Efficient
implementations of the RCU infrastructure make heavy use of batching in
order to amortize their overhead over many uses of the corresponding APIs.
There are no fewer than three RCU mechanisms in the Linux kernel; the
diagram above shows the first one, which is by far the most commonly used.
The rcu_dereference() and rcu_assign_pointer() primitives are used for
all three mechanisms, but different defer and protect primitives are
used as follows:
There are at least three flavors of RCU usage in the Linux kernel. The diagram
above shows the most common one. On the updater side, the rcu_assign_pointer(),
sychronize_rcu() and call_rcu() primitives used are the same for all three
flavors. However for protection (on the reader side), the primitives used vary
depending on the flavor:
Defer Protect
a. rcu_read_lock() / rcu_read_unlock()
rcu_dereference()
a. synchronize_rcu() rcu_read_lock() / rcu_read_unlock()
call_rcu() rcu_dereference()
b. rcu_read_lock_bh() / rcu_read_unlock_bh()
local_bh_disable() / local_bh_enable()
rcu_dereference_bh()
b. synchronize_rcu_bh() rcu_read_lock_bh() / rcu_read_unlock_bh()
call_rcu_bh() rcu_dereference_bh()
c. rcu_read_lock_sched() / rcu_read_unlock_sched()
preempt_disable() / preempt_enable()
local_irq_save() / local_irq_restore()
hardirq enter / hardirq exit
NMI enter / NMI exit
rcu_dereference_sched()
c. synchronize_sched() rcu_read_lock_sched() / rcu_read_unlock_sched()
call_rcu_sched() preempt_disable() / preempt_enable()
local_irq_save() / local_irq_restore()
hardirq enter / hardirq exit
NMI enter / NMI exit
rcu_dereference_sched()
These three mechanisms are used as follows:
These three flavors are used as follows:
a. RCU applied to normal data structures.
@ -867,18 +879,20 @@ RCU: Critical sections Grace period Barrier
bh: Critical sections Grace period Barrier
rcu_read_lock_bh call_rcu_bh rcu_barrier_bh
rcu_read_unlock_bh synchronize_rcu_bh
rcu_dereference_bh synchronize_rcu_bh_expedited
rcu_read_lock_bh call_rcu rcu_barrier
rcu_read_unlock_bh synchronize_rcu
[local_bh_disable] synchronize_rcu_expedited
[and friends]
rcu_dereference_bh
rcu_dereference_bh_check
rcu_dereference_bh_protected
rcu_read_lock_bh_held
sched: Critical sections Grace period Barrier
rcu_read_lock_sched synchronize_sched rcu_barrier_sched
rcu_read_unlock_sched call_rcu_sched
[preempt_disable] synchronize_sched_expedited
rcu_read_lock_sched call_rcu rcu_barrier
rcu_read_unlock_sched synchronize_rcu
[preempt_disable] synchronize_rcu_expedited
[and friends]
rcu_read_lock_sched_notrace
rcu_read_unlock_sched_notrace
@ -890,8 +904,8 @@ sched: Critical sections Grace period Barrier
SRCU: Critical sections Grace period Barrier
srcu_read_lock synchronize_srcu srcu_barrier
srcu_read_unlock call_srcu
srcu_read_lock call_srcu srcu_barrier
srcu_read_unlock synchronize_srcu
srcu_dereference synchronize_srcu_expedited
srcu_dereference_check
srcu_read_lock_held
@ -1034,7 +1048,7 @@ Answer: Just as PREEMPT_RT permits preemption of spinlock
spinlocks blocking while in RCU read-side critical
sections.
Why the apparent inconsistency? Because it is it
Why the apparent inconsistency? Because it is
possible to use priority boosting to keep the RCU
grace periods short if need be (for example, if running
short of memory). In contrast, if blocking waiting

17
Documentation/admin-guide/kernel-parameters.txt
View File

@ -3773,6 +3773,23 @@
Set wait time between force_quiescent_state bursts
in seconds.
rcutorture.fwd_progress= [KNL]
Enable RCU grace-period forward-progress testing
for the types of RCU supporting this notion.
rcutorture.fwd_progress_div= [KNL]
Specify the fraction of a CPU-stall-warning
period to do tight-loop forward-progress testing.
rcutorture.fwd_progress_holdoff= [KNL]
Number of seconds to wait between successive
forward-progress tests.
rcutorture.fwd_progress_need_resched= [KNL]
Enclose cond_resched() calls within checks for
need_resched() during tight-loop forward-progress
testing.
rcutorture.gp_cond= [KNL]
Use conditional/asynchronous update-side
primitives, if available.

73
MAINTAINERS
View File

@ -4033,7 +4033,7 @@ S: Supported
F: drivers/net/ethernet/chelsio/cxgb4vf/
CXL (IBM Coherent Accelerator Processor Interface CAPI) DRIVER
M: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
M: Frederic Barrat <fbarrat@linux.ibm.com>
M: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
L: linuxppc-dev@lists.ozlabs.org
S: Supported
@ -4045,9 +4045,9 @@ F: Documentation/powerpc/cxl.txt
F: Documentation/ABI/testing/sysfs-class-cxl
CXLFLASH (IBM Coherent Accelerator Processor Interface CAPI Flash) SCSI DRIVER
M: Manoj N. Kumar <manoj@linux.vnet.ibm.com>
M: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
M: Uma Krishnan <ukrishn@linux.vnet.ibm.com>
M: Manoj N. Kumar <manoj@linux.ibm.com>
M: Matthew R. Ochs <mrochs@linux.ibm.com>
M: Uma Krishnan <ukrishn@linux.ibm.com>
L: linux-scsi@vger.kernel.org
S: Supported
F: drivers/scsi/cxlflash/
@ -5428,7 +5428,7 @@ S: Orphan
F: fs/efs/
EHEA (IBM pSeries eHEA 10Gb ethernet adapter) DRIVER
M: Douglas Miller <dougmill@linux.vnet.ibm.com>
M: Douglas Miller <dougmill@linux.ibm.com>
L: netdev@vger.kernel.org
S: Maintained
F: drivers/net/ethernet/ibm/ehea/
@ -5565,7 +5565,7 @@ F: Documentation/filesystems/ext4/ext4.rst
F: fs/ext4/
Extended Verification Module (EVM)
M: Mimi Zohar <zohar@linux.vnet.ibm.com>
M: Mimi Zohar <zohar@linux.ibm.com>
L: linux-integrity@vger.kernel.org
S: Supported
F: security/integrity/evm/
@ -5775,7 +5775,7 @@ F: include/linux/firmware.h
FLASH ADAPTER DRIVER (IBM Flash Adapter 900GB Full Height PCI Flash Card)
M: Joshua Morris <josh.h.morris@us.ibm.com>
M: Philip Kelleher <pjk1939@linux.vnet.ibm.com>
M: Philip Kelleher <pjk1939@linux.ibm.com>
S: Maintained
F: drivers/block/rsxx/
@ -6042,7 +6042,7 @@ F: include/linux/fscrypt*.h
F: Documentation/filesystems/fscrypt.rst
FSI-ATTACHED I2C DRIVER
M: Eddie James <eajames@linux.vnet.ibm.com>
M: Eddie James <eajames@linux.ibm.com>
L: linux-i2c@vger.kernel.org
L: openbmc@lists.ozlabs.org (moderated for non-subscribers)
S: Maintained
@ -6218,8 +6218,7 @@ S: Supported
F: drivers/uio/uio_pci_generic.c
GENWQE (IBM Generic Workqueue Card)
M: Frank Haverkamp <haver@linux.vnet.ibm.com>
M: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
M: Frank Haverkamp <haver@linux.ibm.com>
S: Supported
F: drivers/misc/genwqe/
@ -7001,8 +7000,7 @@ F: crypto/842.c
F: lib/842/
IBM Power in-Nest Crypto Acceleration
M: Leonidas S. Barbosa <leosilva@linux.vnet.ibm.com>
M: Paulo Flabiano Smorigo <pfsmorigo@linux.vnet.ibm.com>
M: Paulo Flabiano Smorigo <pfsmorigo@linux.ibm.com>
L: linux-crypto@vger.kernel.org
S: Supported
F: drivers/crypto/nx/Makefile
@ -7019,8 +7017,8 @@ S: Supported
F: drivers/scsi/ipr.*
IBM Power SRIOV Virtual NIC Device Driver
M: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
M: John Allen <jallen@linux.vnet.ibm.com>
M: Thomas Falcon <tlfalcon@linux.ibm.com>
M: John Allen <jallen@linux.ibm.com>
L: netdev@vger.kernel.org
S: Supported
F: drivers/net/ethernet/ibm/ibmvnic.*
@ -7035,41 +7033,38 @@ F: arch/powerpc/include/asm/vas.h
F: arch/powerpc/include/uapi/asm/vas.h
IBM Power Virtual Ethernet Device Driver
M: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
M: Thomas Falcon <tlfalcon@linux.ibm.com>
L: netdev@vger.kernel.org
S: Supported
F: drivers/net/ethernet/ibm/ibmveth.*
IBM Power Virtual FC Device Drivers
M: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
M: Tyrel Datwyler <tyreld@linux.ibm.com>
L: linux-scsi@vger.kernel.org
S: Supported
F: drivers/scsi/ibmvscsi/ibmvfc*
IBM Power Virtual Management Channel Driver
M: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
M: Steven Royer <seroyer@linux.vnet.ibm.com>
M: Steven Royer <seroyer@linux.ibm.com>
S: Supported
F: drivers/misc/ibmvmc.*
IBM Power Virtual SCSI Device Drivers
M: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
M: Tyrel Datwyler <tyreld@linux.ibm.com>
L: linux-scsi@vger.kernel.org
S: Supported
F: drivers/scsi/ibmvscsi/ibmvscsi*
F: include/scsi/viosrp.h
IBM Power Virtual SCSI Device Target Driver
M: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
M: Michael Cyr <mikecyr@linux.vnet.ibm.com>
M: Michael Cyr <mikecyr@linux.ibm.com>
L: linux-scsi@vger.kernel.org
L: target-devel@vger.kernel.org
S: Supported
F: drivers/scsi/ibmvscsi_tgt/
IBM Power VMX Cryptographic instructions
M: Leonidas S. Barbosa <leosilva@linux.vnet.ibm.com>
M: Paulo Flabiano Smorigo <pfsmorigo@linux.vnet.ibm.com>
M: Paulo Flabiano Smorigo <pfsmorigo@linux.ibm.com>
L: linux-crypto@vger.kernel.org
S: Supported
F: drivers/crypto/vmx/Makefile
@ -7346,7 +7341,7 @@ S: Maintained
L: linux-crypto@vger.kernel.org
INTEGRITY MEASUREMENT ARCHITECTURE (IMA)
M: Mimi Zohar <zohar@linux.vnet.ibm.com>
M: Mimi Zohar <zohar@linux.ibm.com>
M: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
L: linux-integrity@vger.kernel.org
T: git git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity.git
@ -7938,9 +7933,8 @@ S: Maintained
F: drivers/media/platform/rcar_jpu.c
JSM Neo PCI based serial card
M: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
L: linux-serial@vger.kernel.org
S: Maintained
S: Orphan
F: drivers/tty/serial/jsm/
K10TEMP HARDWARE MONITORING DRIVER
@ -8170,7 +8164,7 @@ F: include/uapi/linux/kexec.h
F: kernel/kexec*
KEYS-ENCRYPTED
M: Mimi Zohar <zohar@linux.vnet.ibm.com>
M: Mimi Zohar <zohar@linux.ibm.com>
L: linux-integrity@vger.kernel.org
L: keyrings@vger.kernel.org
S: Supported
@ -8179,9 +8173,9 @@ F: include/keys/encrypted-type.h
F: security/keys/encrypted-keys/
KEYS-TRUSTED
M: James Bottomley <jejb@linux.vnet.ibm.com>
M: James Bottomley <jejb@linux.ibm.com>
M: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
M: Mimi Zohar <zohar@linux.vnet.ibm.com>
M: Mimi Zohar <zohar@linuxibm.com>
L: linux-integrity@vger.kernel.org
L: keyrings@vger.kernel.org
S: Supported
@ -8234,7 +8228,7 @@ F: lib/test_kmod.c
F: tools/testing/selftests/kmod/
KPROBES
M: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
M: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
M: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
M: "David S. Miller" <davem@davemloft.net>
M: Masami Hiramatsu <mhiramat@kernel.org>
@ -8590,7 +8584,7 @@ M: Nicholas Piggin <npiggin@gmail.com>
M: David Howells <dhowells@redhat.com>
M: Jade Alglave <j.alglave@ucl.ac.uk>
M: Luc Maranget <luc.maranget@inria.fr>
M: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
M: "Paul E. McKenney" <paulmck@linux.ibm.com>
R: Akira Yokosawa <akiyks@gmail.com>
R: Daniel Lustig <dlustig@nvidia.com>
L: linux-kernel@vger.kernel.org
@ -9548,7 +9542,7 @@ F: drivers/platform/x86/mlx-platform.c
MEMBARRIER SUPPORT
M: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
M: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
M: "Paul E. McKenney" <paulmck@linux.ibm.com>
L: linux-kernel@vger.kernel.org
S: Supported
F: kernel/sched/membarrier.c
@ -10686,7 +10680,7 @@ S: Supported
F: tools/objtool/
OCXL (Open Coherent Accelerator Processor Interface OpenCAPI) DRIVER
M: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
M: Frederic Barrat <fbarrat@linux.ibm.com>
M: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
L: linuxppc-dev@lists.ozlabs.org
S: Supported
@ -12487,7 +12481,7 @@ S: Orphan
F: drivers/net/wireless/ray*
RCUTORTURE TEST FRAMEWORK
M: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
M: "Paul E. McKenney" <paulmck@linux.ibm.com>
M: Josh Triplett <josh@joshtriplett.org>
R: Steven Rostedt <rostedt@goodmis.org>
R: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
@ -12534,11 +12528,12 @@ F: arch/x86/include/asm/intel_rdt_sched.h
F: Documentation/x86/intel_rdt*
READ-COPY UPDATE (RCU)
M: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
M: "Paul E. McKenney" <paulmck@linux.ibm.com>
M: Josh Triplett <josh@joshtriplett.org>
R: Steven Rostedt <rostedt@goodmis.org>
R: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
R: Lai Jiangshan <jiangshanlai@gmail.com>
R: Joel Fernandes <joel@joelfernandes.org>
L: linux-kernel@vger.kernel.org
W: http://www.rdrop.com/users/paulmck/RCU/
S: Supported
@ -12674,7 +12669,7 @@ F: include/linux/reset-controller.h
RESTARTABLE SEQUENCES SUPPORT
M: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
M: Peter Zijlstra <peterz@infradead.org>
M: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
M: "Paul E. McKenney" <paulmck@linux.ibm.com>
M: Boqun Feng <boqun.feng@gmail.com>
L: linux-kernel@vger.kernel.org
S: Supported
@ -13199,7 +13194,7 @@ F: drivers/scsi/sg.c
F: include/scsi/sg.h
SCSI SUBSYSTEM
M: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com>
M: "James E.J. Bottomley" <jejb@linux.ibm.com>
T: git git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi.git
M: "Martin K. Petersen" <martin.petersen@oracle.com>
T: git git://git.kernel.org/pub/scm/linux/kernel/git/mkp/scsi.git
@ -13634,7 +13629,7 @@ F: mm/sl?b*
SLEEPABLE READ-COPY UPDATE (SRCU)
M: Lai Jiangshan <jiangshanlai@gmail.com>
M: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
M: "Paul E. McKenney" <paulmck@linux.ibm.com>
M: Josh Triplett <josh@joshtriplett.org>
R: Steven Rostedt <rostedt@goodmis.org>
R: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
@ -15057,7 +15052,7 @@ F: drivers/platform/x86/topstar-laptop.c
TORTURE-TEST MODULES
M: Davidlohr Bueso <dave@stgolabs.net>
M: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
M: "Paul E. McKenney" <paulmck@linux.ibm.com>
M: Josh Triplett <josh@joshtriplett.org>
L: linux-kernel@vger.kernel.org
S: Supported

2
arch/powerpc/mm/hugetlbpage.c
View File

@ -289,7 +289,7 @@ static void hugepd_free(struct mmu_gather *tlb, void *hugepte)
(*batchp)->ptes[(*batchp)->index++] = hugepte;
if ((*batchp)->index == HUGEPD_FREELIST_SIZE) {
call_rcu_sched(&(*batchp)->rcu, hugepd_free_rcu_callback);
call_rcu(&(*batchp)->rcu, hugepd_free_rcu_callback);
*batchp = NULL;
}
put_cpu_var(hugepd_freelist_cur);

2
arch/s390/mm/pgalloc.c
View File

@ -350,7 +350,7 @@ void tlb_table_flush(struct mmu_gather *tlb)
struct mmu_table_batch **batch = &tlb->batch;
if (*batch) {
call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
call_rcu(&(*batch)->rcu, tlb_remove_table_rcu);
*batch = NULL;
}
}

2
arch/sparc/oprofile/init.c
View File

@ -53,7 +53,7 @@ static void timer_stop(void)
{
nmi_adjust_hz(1);
unregister_die_notifier(&profile_timer_exceptions_nb);
synchronize_sched(); /* Allow already-started NMIs to complete. */
synchronize_rcu(); /* Allow already-started NMIs to complete. */
}
static int op_nmi_timer_init(struct oprofile_operations *ops)

2
arch/x86/pci/i386.c
View File

@ -59,7 +59,7 @@ static struct pcibios_fwaddrmap *pcibios_fwaddrmap_lookup(struct pci_dev *dev)
{
struct pcibios_fwaddrmap *map;
WARN_ON_SMP(!spin_is_locked(&pcibios_fwaddrmap_lock));
lockdep_assert_held(&pcibios_fwaddrmap_lock);
list_for_each_entry(map, &pcibios_fwaddrmappings, list)
if (map->dev == dev)

2
crypto/pcrypt.c
View File

@ -382,7 +382,7 @@ static int pcrypt_cpumask_change_notify(struct notifier_block *self,
cpumask_copy(new_mask->mask, cpumask->cbcpu);
rcu_assign_pointer(pcrypt->cb_cpumask, new_mask);
synchronize_rcu_bh();
synchronize_rcu();
free_cpumask_var(old_mask->mask);
kfree(old_mask);

2
drivers/char/ipmi/ipmi_si_intf.c
View File

@ -2187,7 +2187,7 @@ static void shutdown_smi(void *send_info)
* handlers might have been running before we freed the
* interrupt.
*/
synchronize_sched();
synchronize_rcu();
/*
* Timeouts are stopped, now make sure the interrupts are off

2
drivers/cpufreq/cpufreq_governor.c
View File

@ -346,7 +346,7 @@ static inline void gov_clear_update_util(struct cpufreq_policy *policy)
for_each_cpu(i, policy->cpus)
cpufreq_remove_update_util_hook(i);
synchronize_sched();
synchronize_rcu();
}
static struct policy_dbs_info *alloc_policy_dbs_info(struct cpufreq_policy *policy,

2
drivers/cpufreq/intel_pstate.c
View File

@ -1930,7 +1930,7 @@ static void intel_pstate_clear_update_util_hook(unsigned int cpu)
cpufreq_remove_update_util_hook(cpu);
cpu_data->update_util_set = false;
synchronize_sched();
synchronize_rcu();
}
static int intel_pstate_get_max_freq(struct cpudata *cpu)

2
drivers/net/ethernet/realtek/8139too.c
View File

@ -1661,7 +1661,7 @@ static void rtl8139_tx_timeout_task (struct work_struct *work)
napi_disable(&tp->napi);
netif_stop_queue(dev);
synchronize_sched();
synchronize_rcu();
netdev_dbg(dev, "Transmit timeout, status %02x %04x %04x media %02x\n",
RTL_R8(ChipCmd), RTL_R16(IntrStatus),

4
drivers/net/ethernet/realtek/r8169.c
View File

@ -5866,7 +5866,7 @@ static void rtl_reset_work(struct rtl8169_private *tp)
napi_disable(&tp->napi);
netif_stop_queue(dev);
synchronize_sched();
synchronize_rcu();
rtl8169_hw_reset(tp);
@ -6609,7 +6609,7 @@ static void rtl8169_down(struct net_device *dev)
rtl8169_rx_missed(dev);
/* Give a racing hard_start_xmit a few cycles to complete. */
synchronize_sched();
synchronize_rcu();
rtl8169_tx_clear(tp);

2
drivers/net/ethernet/sfc/efx.c
View File

@ -3167,7 +3167,7 @@ struct hlist_head *efx_rps_hash_bucket(struct efx_nic *efx,
{
u32 hash = efx_filter_spec_hash(spec);
WARN_ON(!spin_is_locked(&efx->rps_hash_lock));
lockdep_assert_held(&efx->rps_hash_lock);
if (!efx->rps_hash_table)
return NULL;
return &efx->rps_hash_table[hash % EFX_ARFS_HASH_TABLE_SIZE];

2
drivers/net/ethernet/sis/sis190.c
View File

@ -1142,7 +1142,7 @@ static void sis190_down(struct net_device *dev)
if (!poll_locked)
poll_locked++;
synchronize_sched();
synchronize_rcu();
} while (SIS_R32(IntrMask));

2
drivers/net/ethernet/smsc/smsc911x.h
View File

@ -67,7 +67,7 @@
#ifdef CONFIG_DEBUG_SPINLOCK
#define SMSC_ASSERT_MAC_LOCK(pdata) \
WARN_ON_SMP(!spin_is_locked(&pdata->mac_lock))
lockdep_assert_held(&pdata->mac_lock)
#else
#define SMSC_ASSERT_MAC_LOCK(pdata) do {} while (0)
#endif /* CONFIG_DEBUG_SPINLOCK */

2
drivers/vhost/net.c
View File

@ -1359,7 +1359,7 @@ static int vhost_net_release(struct inode *inode, struct file *f)
if (rx_sock)
sockfd_put(rx_sock);
/* Make sure no callbacks are outstanding */
synchronize_rcu_bh();
synchronize_rcu();
/* We do an extra flush before freeing memory,
* since jobs can re-queue themselves. */
vhost_net_flush(n);

2
fs/file.c
View File

@ -158,7 +158,7 @@ static int expand_fdtable(struct files_struct *files, unsigned int nr)
* or have finished their rcu_read_lock_sched() section.
*/
if (atomic_read(&files->count) > 1)
synchronize_sched();
synchronize_rcu();
spin_lock(&files->file_lock);
if (!new_fdt)

2
fs/userfaultfd.c
View File

@ -926,7 +926,7 @@ static inline struct userfaultfd_wait_queue *find_userfault_in(
wait_queue_entry_t *wq;
struct userfaultfd_wait_queue *uwq;
VM_BUG_ON(!spin_is_locked(&wqh->lock));
lockdep_assert_held(&wqh->lock);
uwq = NULL;
if (!waitqueue_active(wqh))

2
include/linux/percpu-rwsem.h
View File

@ -41,7 +41,7 @@ static inline void percpu_down_read_preempt_disable(struct percpu_rw_semaphore *
* cannot both change sem->state from readers_fast and start checking
* counters while we are here. So if we see !sem->state, we know that
* the writer won't be checking until we're past the preempt_enable()
* and that one the synchronize_sched() is done, the writer will see
* and that once the synchronize_rcu() is done, the writer will see
* anything we did within this RCU-sched read-size critical section.
*/
__this_cpu_inc(*sem->read_count);

17
include/linux/rcupdate_wait.h
View File

@ -31,21 +31,4 @@ do { \
#define wait_rcu_gp(...) _wait_rcu_gp(false, __VA_ARGS__)
/**
* synchronize_rcu_mult - Wait concurrently for multiple grace periods
* @...: List of call_rcu() functions for different grace periods to wait on
*
* This macro waits concurrently for multiple types of RCU grace periods.
* For example, synchronize_rcu_mult(call_rcu, call_rcu_tasks) would wait
* on concurrent RCU and RCU-tasks grace periods. Waiting on a give SRCU
* domain requires you to write a wrapper function for that SRCU domain's
* call_srcu() function, supplying the corresponding srcu_struct.
*
* If Tiny RCU, tell _wait_rcu_gp() does not bother waiting for RCU,
* given that anywhere synchronize_rcu_mult() can be called is automatically
* a grace period.
*/
#define synchronize_rcu_mult(...) \
_wait_rcu_gp(IS_ENABLED(CONFIG_TINY_RCU), __VA_ARGS__)
#endif /* _LINUX_SCHED_RCUPDATE_WAIT_H */

4
include/linux/sched.h
View File

@ -572,8 +572,10 @@ union rcu_special {
struct {
u8 blocked;
u8 need_qs;
u8 exp_hint; /* Hint for performance. */
u8 pad; /* No garbage from compiler! */
} b; /* Bits. */
u16 s; /* Set of bits. */
u32 s; /* Set of bits. */
};
enum perf_event_task_context {

79
include/linux/srcu.h
View File

@ -38,20 +38,20 @@ struct srcu_struct;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
int __init_srcu_struct(struct srcu_struct *sp, const char *name,
int __init_srcu_struct(struct srcu_struct *ssp, const char *name,
struct lock_class_key *key);
#define init_srcu_struct(sp) \
#define init_srcu_struct(ssp) \
({ \
static struct lock_class_key __srcu_key; \
\
__init_srcu_struct((sp), #sp, &__srcu_key); \
__init_srcu_struct((ssp), #ssp, &__srcu_key); \
})
#define __SRCU_DEP_MAP_INIT(srcu_name) .dep_map = { .name = #srcu_name },
#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
int init_srcu_struct(struct srcu_struct *sp);
int init_srcu_struct(struct srcu_struct *ssp);
#define __SRCU_DEP_MAP_INIT(srcu_name)
#endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
@ -67,28 +67,28 @@ int init_srcu_struct(struct srcu_struct *sp);
struct srcu_struct { };
#endif
void call_srcu(struct srcu_struct *sp, struct rcu_head *head,
void call_srcu(struct srcu_struct *ssp, struct rcu_head *head,
void (*func)(struct rcu_head *head));
void _cleanup_srcu_struct(struct srcu_struct *sp, bool quiesced);
int __srcu_read_lock(struct srcu_struct *sp) __acquires(sp);
void __srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp);
void synchronize_srcu(struct srcu_struct *sp);
void _cleanup_srcu_struct(struct srcu_struct *ssp, bool quiesced);
int __srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp);
void __srcu_read_unlock(struct srcu_struct *ssp, int idx) __releases(ssp);
void synchronize_srcu(struct srcu_struct *ssp);
/**
* cleanup_srcu_struct - deconstruct a sleep-RCU structure
* @sp: structure to clean up.
* @ssp: structure to clean up.
*
* Must invoke this after you are finished using a given srcu_struct that
* was initialized via init_srcu_struct(), else you leak memory.
*/
static inline void cleanup_srcu_struct(struct srcu_struct *sp)
static inline void cleanup_srcu_struct(struct srcu_struct *ssp)
{
_cleanup_srcu_struct(sp, false);
_cleanup_srcu_struct(ssp, false);
}
/**
* cleanup_srcu_struct_quiesced - deconstruct a quiesced sleep-RCU structure
* @sp: structure to clean up.
* @ssp: structure to clean up.
*
* Must invoke this after you are finished using a given srcu_struct that
* was initialized via init_srcu_struct(), else you leak memory. Also,
@ -103,16 +103,16 @@ static inline void cleanup_srcu_struct(struct srcu_struct *sp)
* (with high probability, anyway), and will also cause the srcu_struct
* to be leaked.
*/
static inline void cleanup_srcu_struct_quiesced(struct srcu_struct *sp)
static inline void cleanup_srcu_struct_quiesced(struct srcu_struct *ssp)
{
_cleanup_srcu_struct(sp, true);
_cleanup_srcu_struct(ssp, true);
}
#ifdef CONFIG_DEBUG_LOCK_ALLOC
/**
* srcu_read_lock_held - might we be in SRCU read-side critical section?
* @sp: The srcu_struct structure to check
* @ssp: The srcu_struct structure to check
*
* If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an SRCU
* read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC,
@ -126,16 +126,16 @@ static inline void cleanup_srcu_struct_quiesced(struct srcu_struct *sp)
* relies on normal RCU, it can be called from the CPU which
* is in the idle loop from an RCU point of view or offline.
*/
static inline int srcu_read_lock_held(const struct srcu_struct *sp)
static inline int srcu_read_lock_held(const struct srcu_struct *ssp)
{
if (!debug_lockdep_rcu_enabled())
return 1;
return lock_is_held(&sp->dep_map);
return lock_is_held(&ssp->dep_map);
}
#else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
static inline int srcu_read_lock_held(const struct srcu_struct *sp)
static inline int srcu_read_lock_held(const struct srcu_struct *ssp)
{
return 1;
}
@ -145,7 +145,7 @@ static inline int srcu_read_lock_held(const struct srcu_struct *sp)
/**
* srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing
* @p: the pointer to fetch and protect for later dereferencing
* @sp: pointer to the srcu_struct, which is used to check that we
* @ssp: pointer to the srcu_struct, which is used to check that we
* really are in an SRCU read-side critical section.
* @c: condition to check for update-side use
*
@ -154,29 +154,32 @@ static inline int srcu_read_lock_held(const struct srcu_struct *sp)
* to 1. The @c argument will normally be a logical expression containing
* lockdep_is_held() calls.
*/
#define srcu_dereference_check(p, sp, c) \
__rcu_dereference_check((p), (c) || srcu_read_lock_held(sp), __rcu)
#define srcu_dereference_check(p, ssp, c) \
__rcu_dereference_check((p), (c) || srcu_read_lock_held(ssp), __rcu)
/**
* srcu_dereference - fetch SRCU-protected pointer for later dereferencing
* @p: the pointer to fetch and protect for later dereferencing
* @sp: pointer to the srcu_struct, which is used to check that we
* @ssp: pointer to the srcu_struct, which is used to check that we
* really are in an SRCU read-side critical section.
*
* Makes rcu_dereference_check() do the dirty work. If PROVE_RCU
* is enabled, invoking this outside of an RCU read-side critical
* section will result in an RCU-lockdep splat.
*/
#define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0)
#define srcu_dereference(p, ssp) srcu_dereference_check((p), (ssp), 0)
/**
* srcu_dereference_notrace - no tracing and no lockdep calls from here
* @p: the pointer to fetch and protect for later dereferencing
* @ssp: pointer to the srcu_struct, which is used to check that we
* really are in an SRCU read-side critical section.
*/
#define srcu_dereference_notrace(p, sp) srcu_dereference_check((p), (sp), 1)
#define srcu_dereference_notrace(p, ssp) srcu_dereference_check((p), (ssp), 1)
/**
* srcu_read_lock - register a new reader for an SRCU-protected structure.
* @sp: srcu_struct in which to register the new reader.
* @ssp: srcu_struct in which to register the new reader.
*
* Enter an SRCU read-side critical section. Note that SRCU read-side
* critical sections may be nested. However, it is illegal to
@ -191,44 +194,44 @@ static inline int srcu_read_lock_held(const struct srcu_struct *sp)
* srcu_read_unlock() in an irq handler if the matching srcu_read_lock()
* was invoked in process context.
*/
static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
static inline int srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp)
{
int retval;
retval = __srcu_read_lock(sp);
rcu_lock_acquire(&(sp)->dep_map);
retval = __srcu_read_lock(ssp);
rcu_lock_acquire(&(ssp)->dep_map);
return retval;
}
/* Used by tracing, cannot be traced and cannot invoke lockdep. */
static inline notrace int
srcu_read_lock_notrace(struct srcu_struct *sp) __acquires(sp)
srcu_read_lock_notrace(struct srcu_struct *ssp) __acquires(ssp)
{
int retval;
retval = __srcu_read_lock(sp);
retval = __srcu_read_lock(ssp);
return retval;
}
/**
* srcu_read_unlock - unregister a old reader from an SRCU-protected structure.
* @sp: srcu_struct in which to unregister the old reader.
* @ssp: srcu_struct in which to unregister the old reader.
* @idx: return value from corresponding srcu_read_lock().
*
* Exit an SRCU read-side critical section.
*/
static inline void srcu_read_unlock(struct srcu_struct *sp, int idx)
__releases(sp)
static inline void srcu_read_unlock(struct srcu_struct *ssp, int idx)
__releases(ssp)
{
rcu_lock_release(&(sp)->dep_map);
__srcu_read_unlock(sp, idx);
rcu_lock_release(&(ssp)->dep_map);
__srcu_read_unlock(ssp, idx);
}
/* Used by tracing, cannot be traced and cannot call lockdep. */
static inline notrace void
srcu_read_unlock_notrace(struct srcu_struct *sp, int idx) __releases(sp)
srcu_read_unlock_notrace(struct srcu_struct *ssp, int idx) __releases(ssp)
{
__srcu_read_unlock(sp, idx);
__srcu_read_unlock(ssp, idx);
}
/**

24
include/linux/srcutiny.h
View File

@ -60,7 +60,7 @@ void srcu_drive_gp(struct work_struct *wp);
#define DEFINE_STATIC_SRCU(name) \
static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name)
void synchronize_srcu(struct srcu_struct *sp);
void synchronize_srcu(struct srcu_struct *ssp);
/*
* Counts the new reader in the appropriate per-CPU element of the
@ -68,36 +68,36 @@ void synchronize_srcu(struct srcu_struct *sp);
* __srcu_read_unlock() must be in the same handler instance. Returns an
* index that must be passed to the matching srcu_read_unlock().
*/
static inline int __srcu_read_lock(struct srcu_struct *sp)
static inline int __srcu_read_lock(struct srcu_struct *ssp)
{
int idx;
idx = READ_ONCE(sp->srcu_idx);
WRITE_ONCE(sp->srcu_lock_nesting[idx], sp->srcu_lock_nesting[idx] + 1);
idx = READ_ONCE(ssp->srcu_idx);
WRITE_ONCE(ssp->srcu_lock_nesting[idx], ssp->srcu_lock_nesting[idx] + 1);
return idx;
}
static inline void synchronize_srcu_expedited(struct srcu_struct *sp)
static inline void synchronize_srcu_expedited(struct srcu_struct *ssp)
{
synchronize_srcu(sp);
synchronize_srcu(ssp);
}
static inline void srcu_barrier(struct srcu_struct *sp)
static inline void srcu_barrier(struct srcu_struct *ssp)
{
synchronize_srcu(sp);
synchronize_srcu(ssp);
}
/* Defined here to avoid size increase for non-torture kernels. */
static inline void srcu_torture_stats_print(struct srcu_struct *sp,
static inline void srcu_torture_stats_print(struct srcu_struct *ssp,
char *tt, char *tf)
{
int idx;
idx = READ_ONCE(sp->srcu_idx) & 0x1;
idx = READ_ONCE(ssp->srcu_idx) & 0x1;
pr_alert("%s%s Tiny SRCU per-CPU(idx=%d): (%hd,%hd)\n",
tt, tf, idx,
READ_ONCE(sp->srcu_lock_nesting[!idx]),
READ_ONCE(sp->srcu_lock_nesting[idx]));
READ_ONCE(ssp->srcu_lock_nesting[!idx]),
READ_ONCE(ssp->srcu_lock_nesting[idx]));
}
#endif

8
include/linux/srcutree.h
View File

@ -51,7 +51,7 @@ struct srcu_data {
unsigned long grpmask; /* Mask for leaf srcu_node */
/* ->srcu_data_have_cbs[]. */
int cpu;
struct srcu_struct *sp;
struct srcu_struct *ssp;
};
/*
@ -138,8 +138,8 @@ struct srcu_struct {
#define DEFINE_SRCU(name) __DEFINE_SRCU(name, /* not static */)
#define DEFINE_STATIC_SRCU(name) __DEFINE_SRCU(name, static)
void synchronize_srcu_expedited(struct srcu_struct *sp);
void srcu_barrier(struct srcu_struct *sp);
void srcu_torture_stats_print(struct srcu_struct *sp, char *tt, char *tf);
void synchronize_srcu_expedited(struct srcu_struct *ssp);
void srcu_barrier(struct srcu_struct *ssp);
void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf);
#endif

2
include/linux/tracepoint.h
View File

@ -82,7 +82,7 @@ int unregister_tracepoint_module_notifier(struct notifier_block *nb)
static inline void tracepoint_synchronize_unregister(void)
{
synchronize_srcu(&tracepoint_srcu);
synchronize_sched();
synchronize_rcu();
}
#else
static inline void tracepoint_synchronize_unregister(void)

4
include/linux/types.h
View File

@ -212,8 +212,8 @@ struct ustat {
* weird ABI and we need to ask it explicitly.
*
* The alignment is required to guarantee that bit 0 of @next will be
* clear under normal conditions -- as long as we use call_rcu(),
* call_rcu_bh(), call_rcu_sched(), or call_srcu() to queue callback.
* clear under normal conditions -- as long as we use call_rcu() or
* call_srcu() to queue the callback.
*
* This guarantee is important for few reasons:
* - future call_rcu_lazy() will make use of lower bits in the pointer;

6
init/main.c
View File

@ -1046,12 +1046,12 @@ static void mark_readonly(void)
{
if (rodata_enabled) {
/*
* load_module() results in W+X mappings, which are cleaned up
* with call_rcu_sched(). Let's make sure that queued work is
* load_module() results in W+X mappings, which are cleaned
* up with call_rcu(). Let's make sure that queued work is
* flushed so that we don't hit false positives looking for
* insecure pages which are W+X.
*/
rcu_barrier_sched();
rcu_barrier();
mark_rodata_ro();
rodata_test();
} else

2
kernel/cgroup/cgroup.c
View File

@ -5343,7 +5343,7 @@ int __init cgroup_init(void)
cgroup_rstat_boot();
/*
* The latency of the synchronize_sched() is too high for cgroups,
* The latency of the synchronize_rcu() is too high for cgroups,
* avoid it at the cost of forcing all readers into the slow path.
*/
rcu_sync_enter_start(&cgroup_threadgroup_rwsem.rss);

2
kernel/events/core.c
View File

@ -9918,7 +9918,7 @@ static void account_event(struct perf_event *event)
* call the perf scheduling hooks before proceeding to
* install events that need them.
*/
synchronize_sched();
synchronize_rcu();
}
/*
* Now that we have waited for the sync_sched(), allow further

10
kernel/kprobes.c
View File

@ -229,7 +229,7 @@ static int collect_garbage_slots(struct kprobe_insn_cache *c)
struct kprobe_insn_page *kip, *next;
/* Ensure no-one is interrupted on the garbages */
synchronize_sched();
synchronize_rcu();
list_for_each_entry_safe(kip, next, &c->pages, list) {
int i;
@ -1382,7 +1382,7 @@ out:
if (ret) {
ap->flags |= KPROBE_FLAG_DISABLED;
list_del_rcu(&p->list);
synchronize_sched();
synchronize_rcu();
}
}
}
@ -1597,7 +1597,7 @@ int register_kprobe(struct kprobe *p)
ret = arm_kprobe(p);
if (ret) {
hlist_del_rcu(&p->hlist);
synchronize_sched();
synchronize_rcu();
goto out;
}
}
@ -1776,7 +1776,7 @@ void unregister_kprobes(struct kprobe **kps, int num)
kps[i]->addr = NULL;
mutex_unlock(&kprobe_mutex);
synchronize_sched();
synchronize_rcu();
for (i = 0; i < num; i++)
if (kps[i]->addr)
__unregister_kprobe_bottom(kps[i]);
@ -1966,7 +1966,7 @@ void unregister_kretprobes(struct kretprobe **rps, int num)
rps[i]->kp.addr = NULL;
mutex_unlock(&kprobe_mutex);
synchronize_sched();
synchronize_rcu();
for (i = 0; i < num; i++) {
if (rps[i]->kp.addr) {
__unregister_kprobe_bottom(&rps[i]->kp);

4
kernel/livepatch/patch.c
View File

@ -61,7 +61,7 @@ static void notrace klp_ftrace_handler(unsigned long ip,
ops = container_of(fops, struct klp_ops, fops);
/*
* A variant of synchronize_sched() is used to allow patching functions
* A variant of synchronize_rcu() is used to allow patching functions
* where RCU is not watching, see klp_synchronize_transition().
*/
preempt_disable_notrace();
@ -72,7 +72,7 @@ static void notrace klp_ftrace_handler(unsigned long ip,
/*
* func should never be NULL because preemption should be disabled here
* and unregister_ftrace_function() does the equivalent of a
* synchronize_sched() before the func_stack removal.
* synchronize_rcu() before the func_stack removal.
*/
if (WARN_ON_ONCE(!func))
goto unlock;

4
kernel/livepatch/transition.c
View File

@ -52,7 +52,7 @@ static DECLARE_DELAYED_WORK(klp_transition_work, klp_transition_work_fn);
/*
* This function is just a stub to implement a hard force
* of synchronize_sched(). This requires synchronizing
* of synchronize_rcu(). This requires synchronizing
* tasks even in userspace and idle.
*/
static void klp_sync(struct work_struct *work)
@ -175,7 +175,7 @@ void klp_cancel_transition(void)
void klp_update_patch_state(struct task_struct *task)
{
/*
* A variant of synchronize_sched() is used to allow patching functions
* A variant of synchronize_rcu() is used to allow patching functions
* where RCU is not watching, see klp_synchronize_transition().
*/
preempt_disable_notrace();

2
kernel/locking/lockdep.c
View File

@ -4195,7 +4195,7 @@ void lockdep_free_key_range(void *start, unsigned long size)
*
* sync_sched() is sufficient because the read-side is IRQ disable.
*/
synchronize_sched();
synchronize_rcu();
/*
* XXX at this point we could return the resources to the pool;

4
kernel/locking/mutex-debug.c
View File

@ -36,7 +36,7 @@ void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter)
{
SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
lockdep_assert_held(&lock->wait_lock);
DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list));
DEBUG_LOCKS_WARN_ON(waiter->magic != waiter);
DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list));
@ -51,7 +51,7 @@ void debug_mutex_free_waiter(struct mutex_waiter *waiter)
void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
struct task_struct *task)
{
SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
lockdep_assert_held(&lock->wait_lock);
/* Mark the current thread as blocked on the lock: */
task->blocked_on = waiter;

14
kernel/module.c
View File

@ -2159,7 +2159,7 @@ static void free_module(struct module *mod)
/* Remove this module from bug list, this uses list_del_rcu */
module_bug_cleanup(mod);
/* Wait for RCU-sched synchronizing before releasing mod->list and buglist. */
synchronize_sched();
synchronize_rcu();
mutex_unlock(&module_mutex);
/* This may be empty, but that's OK */
@ -3507,15 +3507,15 @@ static noinline int do_init_module(struct module *mod)
/*
* We want to free module_init, but be aware that kallsyms may be
* walking this with preempt disabled. In all the failure paths, we
* call synchronize_sched(), but we don't want to slow down the success
* call synchronize_rcu(), but we don't want to slow down the success
* path, so use actual RCU here.
* Note that module_alloc() on most architectures creates W+X page
* mappings which won't be cleaned up until do_free_init() runs. Any
* code such as mark_rodata_ro() which depends on those mappings to
* be cleaned up needs to sync with the queued work - ie
* rcu_barrier_sched()
* rcu_barrier()
*/
call_rcu_sched(&freeinit->rcu, do_free_init);
call_rcu(&freeinit->rcu, do_free_init);
mutex_unlock(&module_mutex);
wake_up_all(&module_wq);
@ -3526,7 +3526,7 @@ fail_free_freeinit:
fail:
/* Try to protect us from buggy refcounters. */
mod->state = MODULE_STATE_GOING;
synchronize_sched();
synchronize_rcu();
module_put(mod);
blocking_notifier_call_chain(&module_notify_list,
MODULE_STATE_GOING, mod);
@ -3819,7 +3819,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
ddebug_cleanup:
ftrace_release_mod(mod);
dynamic_debug_remove(mod, info->debug);
synchronize_sched();
synchronize_rcu();
kfree(mod->args);
free_arch_cleanup:
module_arch_cleanup(mod);
@ -3834,7 +3834,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
mod_tree_remove(mod);
wake_up_all(&module_wq);
/* Wait for RCU-sched synchronizing before releasing mod->list. */
synchronize_sched();
synchronize_rcu();
mutex_unlock(&module_mutex);
free_module:
/* Free lock-classes; relies on the preceding sync_rcu() */

120
kernel/rcu/srcutiny.c
View File

@ -37,30 +37,30 @@ int rcu_scheduler_active __read_mostly;
static LIST_HEAD(srcu_boot_list);
static bool srcu_init_done;
static int init_srcu_struct_fields(struct srcu_struct *sp)
static int init_srcu_struct_fields(struct srcu_struct *ssp)
{
sp->srcu_lock_nesting[0] = 0;
sp->srcu_lock_nesting[1] = 0;
init_swait_queue_head(&sp->srcu_wq);
sp->srcu_cb_head = NULL;
sp->srcu_cb_tail = &sp->srcu_cb_head;
sp->srcu_gp_running = false;
sp->srcu_gp_waiting = false;
sp->srcu_idx = 0;
INIT_WORK(&sp->srcu_work, srcu_drive_gp);
INIT_LIST_HEAD(&sp->srcu_work.entry);
ssp->srcu_lock_nesting[0] = 0;
ssp->srcu_lock_nesting[1] = 0;
init_swait_queue_head(&ssp->srcu_wq);
ssp->srcu_cb_head = NULL;
ssp->srcu_cb_tail = &ssp->srcu_cb_head;
ssp->srcu_gp_running = false;
ssp->srcu_gp_waiting = false;
ssp->srcu_idx = 0;
INIT_WORK(&ssp->srcu_work, srcu_drive_gp);
INIT_LIST_HEAD(&ssp->srcu_work.entry);
return 0;
}
#ifdef CONFIG_DEBUG_LOCK_ALLOC
int __init_srcu_struct(struct srcu_struct *sp, const char *name,
int __init_srcu_struct(struct srcu_struct *ssp, const char *name,
struct lock_class_key *key)
{
/* Don't re-initialize a lock while it is held. */
debug_check_no_locks_freed((void *)sp, sizeof(*sp));
lockdep_init_map(&sp->dep_map, name, key, 0);
return init_srcu_struct_fields(sp);
debug_check_no_locks_freed((void *)ssp, sizeof(*ssp));
lockdep_init_map(&ssp->dep_map, name, key, 0);
return init_srcu_struct_fields(ssp);
}
EXPORT_SYMBOL_GPL(__init_srcu_struct);
@ -68,15 +68,15 @@ EXPORT_SYMBOL_GPL(__init_srcu_struct);
/*
* init_srcu_struct - initialize a sleep-RCU structure
* @sp: structure to initialize.
* @ssp: structure to initialize.
*
* Must invoke this on a given srcu_struct before passing that srcu_struct
* to any other function. Each srcu_struct represents a separate domain
* of SRCU protection.
*/
int init_srcu_struct(struct srcu_struct *sp)
int init_srcu_struct(struct srcu_struct *ssp)
{
return init_srcu_struct_fields(sp);
return init_srcu_struct_fields(ssp);
}
EXPORT_SYMBOL_GPL(init_srcu_struct);
@ -84,22 +84,22 @@ EXPORT_SYMBOL_GPL(init_srcu_struct);
/*
* cleanup_srcu_struct - deconstruct a sleep-RCU structure
* @sp: structure to clean up.
* @ssp: structure to clean up.
*
* Must invoke this after you are finished using a given srcu_struct that
* was initialized via init_srcu_struct(), else you leak memory.
*/
void _cleanup_srcu_struct(struct srcu_struct *sp, bool quiesced)
void _cleanup_srcu_struct(struct srcu_struct *ssp, bool quiesced)
{
WARN_ON(sp->srcu_lock_nesting[0] || sp->srcu_lock_nesting[1]);
WARN_ON(ssp->srcu_lock_nesting[0] || ssp->srcu_lock_nesting[1]);
if (quiesced)
WARN_ON(work_pending(&sp->srcu_work));
WARN_ON(work_pending(&ssp->srcu_work));
else
flush_work(&sp->srcu_work);
WARN_ON(sp->srcu_gp_running);
WARN_ON(sp->srcu_gp_waiting);
WARN_ON(sp->srcu_cb_head);
WARN_ON(&sp->srcu_cb_head != sp->srcu_cb_tail);
flush_work(&ssp->srcu_work);
WARN_ON(ssp->srcu_gp_running);
WARN_ON(ssp->srcu_gp_waiting);
WARN_ON(ssp->srcu_cb_head);
WARN_ON(&ssp->srcu_cb_head != ssp->srcu_cb_tail);
}
EXPORT_SYMBOL_GPL(_cleanup_srcu_struct);
@ -107,13 +107,13 @@ EXPORT_SYMBOL_GPL(_cleanup_srcu_struct);
* Removes the count for the old reader from the appropriate element of
* the srcu_struct.
*/
void __srcu_read_unlock(struct srcu_struct *sp, int idx)
void __srcu_read_unlock(struct srcu_struct *ssp, int idx)
{
int newval = sp->srcu_lock_nesting[idx] - 1;
int newval = ssp->srcu_lock_nesting[idx] - 1;
WRITE_ONCE(sp->srcu_lock_nesting[idx], newval);
if (!newval && READ_ONCE(sp->srcu_gp_waiting))
swake_up_one(&sp->srcu_wq);
WRITE_ONCE(ssp->srcu_lock_nesting[idx], newval);
if (!newval && READ_ONCE(ssp->srcu_gp_waiting))
swake_up_one(&ssp->srcu_wq);
}
EXPORT_SYMBOL_GPL(__srcu_read_unlock);
@ -127,24 +127,24 @@ void srcu_drive_gp(struct work_struct *wp)
int idx;
struct rcu_head *lh;
struct rcu_head *rhp;
struct srcu_struct *sp;
struct srcu_struct *ssp;
sp = container_of(wp, struct srcu_struct, srcu_work);
if (sp->srcu_gp_running || !READ_ONCE(sp->srcu_cb_head))
ssp = container_of(wp, struct srcu_struct, srcu_work);
if (ssp->srcu_gp_running || !READ_ONCE(ssp->srcu_cb_head))
return; /* Already running or nothing to do. */
/* Remove recently arrived callbacks and wait for readers. */
WRITE_ONCE(sp->srcu_gp_running, true);
WRITE_ONCE(ssp->srcu_gp_running, true);
local_irq_disable();
lh = sp->srcu_cb_head;
sp->srcu_cb_head = NULL;
sp->srcu_cb_tail = &sp->srcu_cb_head;
lh = ssp->srcu_cb_head;
ssp->srcu_cb_head = NULL;
ssp->srcu_cb_tail = &ssp->srcu_cb_head;
local_irq_enable();
idx = sp->srcu_idx;
WRITE_ONCE(sp->srcu_idx, !sp->srcu_idx);
WRITE_ONCE(sp->srcu_gp_waiting, true); /* srcu_read_unlock() wakes! */
swait_event_exclusive(sp->srcu_wq, !READ_ONCE(sp->srcu_lock_nesting[idx]));
WRITE_ONCE(sp->srcu_gp_waiting, false); /* srcu_read_unlock() cheap. */
idx = ssp->srcu_idx;
WRITE_ONCE(ssp->srcu_idx, !ssp->srcu_idx);
WRITE_ONCE(ssp->srcu_gp_waiting, true); /* srcu_read_unlock() wakes! */
swait_event_exclusive(ssp->srcu_wq, !READ_ONCE(ssp->srcu_lock_nesting[idx]));
WRITE_ONCE(ssp->srcu_gp_waiting, false); /* srcu_read_unlock() cheap. */
/* Invoke the callbacks we removed above. */
while (lh) {
@ -161,9 +161,9 @@ void srcu_drive_gp(struct work_struct *wp)
* at interrupt level, but the ->srcu_gp_running checks will
* straighten that out.
*/
WRITE_ONCE(sp->srcu_gp_running, false);
if (READ_ONCE(sp->srcu_cb_head))
schedule_work(&sp->srcu_work);
WRITE_ONCE(ssp->srcu_gp_running, false);
if (READ_ONCE(ssp->srcu_cb_head))
schedule_work(&ssp->srcu_work);
}
EXPORT_SYMBOL_GPL(srcu_drive_gp);
@ -171,7 +171,7 @@ EXPORT_SYMBOL_GPL(srcu_drive_gp);
* Enqueue an SRCU callback on the specified srcu_struct structure,
* initiating grace-period processing if it is not already running.
*/
void call_srcu(struct srcu_struct *sp, struct rcu_head *rhp,
void call_srcu(struct srcu_struct *ssp, struct rcu_head *rhp,
rcu_callback_t func)
{
unsigned long flags;
@ -179,14 +179,14 @@ void call_srcu(struct srcu_struct *sp, struct rcu_head *rhp,
rhp->func = func;
rhp->next = NULL;
local_irq_save(flags);
*sp->srcu_cb_tail = rhp;
sp->srcu_cb_tail = &rhp->next;
*ssp->srcu_cb_tail = rhp;
ssp->srcu_cb_tail = &rhp->next;
local_irq_restore(flags);
if (!READ_ONCE(sp->srcu_gp_running)) {
if (!READ_ONCE(ssp->srcu_gp_running)) {
if (likely(srcu_init_done))
schedule_work(&sp->srcu_work);
else if (list_empty(&sp->srcu_work.entry))
list_add(&sp->srcu_work.entry, &srcu_boot_list);
schedule_work(&ssp->srcu_work);
else if (list_empty(&ssp->srcu_work.entry))
list_add(&ssp->srcu_work.entry, &srcu_boot_list);
}
}
EXPORT_SYMBOL_GPL(call_srcu);
@ -194,13 +194,13 @@ EXPORT_SYMBOL_GPL(call_srcu);
/*
* synchronize_srcu - wait for prior SRCU read-side critical-section completion
*/
void synchronize_srcu(struct srcu_struct *sp)
void synchronize_srcu(struct srcu_struct *ssp)
{
struct rcu_synchronize rs;
init_rcu_head_on_stack(&rs.head);
init_completion(&rs.completion);
call_srcu(sp, &rs.head, wakeme_after_rcu);
call_srcu(ssp, &rs.head, wakeme_after_rcu);
wait_for_completion(&rs.completion);
destroy_rcu_head_on_stack(&rs.head);
}
@ -219,13 +219,13 @@ void __init rcu_scheduler_starting(void)
*/
void __init srcu_init(void)
{
struct srcu_struct *sp;
struct srcu_struct *ssp;
srcu_init_done = true;
while (!list_empty(&srcu_boot_list)) {
sp = list_first_entry(&srcu_boot_list,
ssp = list_first_entry(&srcu_boot_list,
struct srcu_struct, srcu_work.entry);
list_del_init(&sp->srcu_work.entry);
schedule_work(&sp->srcu_work);
list_del_init(&ssp->srcu_work.entry);
schedule_work(&ssp->srcu_work);
}
}

489
kernel/rcu/srcutree.c
View File

File diff suppressed because it is too large Load Diff

12
kernel/rcu/sync.c
View File

@ -44,15 +44,15 @@ static const struct {
__INIT_HELD(rcu_read_lock_held)
},
[RCU_SCHED_SYNC] = {
.sync = synchronize_sched,
.call = call_rcu_sched,
.wait = rcu_barrier_sched,
.sync = synchronize_rcu,
.call = call_rcu,
.wait = rcu_barrier,
__INIT_HELD(rcu_read_lock_sched_held)
},
[RCU_BH_SYNC] = {
.sync = synchronize_rcu_bh,
.call = call_rcu_bh,
.wait = rcu_barrier_bh,
.sync = synchronize_rcu,
.call = call_rcu,
.wait = rcu_barrier,
__INIT_HELD(rcu_read_lock_bh_held)
},
};

45
kernel/rcu/tree.c
View File

@ -499,17 +499,30 @@ void rcu_force_quiescent_state(void)
}
EXPORT_SYMBOL_GPL(rcu_force_quiescent_state);
/*
* Convert a ->gp_state value to a character string.
*/
static const char *gp_state_getname(short gs)
{
if (gs < 0 || gs >= ARRAY_SIZE(gp_state_names))
return "???";
return gp_state_names[gs];
}
/*
* Show the state of the grace-period kthreads.
*/
void show_rcu_gp_kthreads(void)
{
int cpu;
unsigned long j;
struct rcu_data *rdp;
struct rcu_node *rnp;
pr_info("%s: wait state: %d ->state: %#lx\n", rcu_state.name,
rcu_state.gp_state, rcu_state.gp_kthread->state);
j = jiffies - READ_ONCE(rcu_state.gp_activity);
pr_info("%s: wait state: %s(%d) ->state: %#lx delta ->gp_activity %ld\n",
rcu_state.name, gp_state_getname(rcu_state.gp_state),
rcu_state.gp_state, rcu_state.gp_kthread->state, j);
rcu_for_each_node_breadth_first(rnp) {
if (ULONG_CMP_GE(rcu_state.gp_seq, rnp->gp_seq_needed))
continue;
@ -891,12 +904,12 @@ void rcu_irq_enter_irqson(void)
}
/**
* rcu_is_watching - see if RCU thinks that the current CPU is idle
* rcu_is_watching - see if RCU thinks that the current CPU is not idle
*
* Return true if RCU is watching the running CPU, which means that this
* CPU can safely enter RCU read-side critical sections. In other words,
* if the current CPU is in its idle loop and is neither in an interrupt
* or NMI handler, return true.
* if the current CPU is not in its idle loop or is in an interrupt or
* NMI handler, return true.
*/
bool notrace rcu_is_watching(void)
{
@ -1142,16 +1155,6 @@ static void record_gp_stall_check_time(void)
rcu_state.n_force_qs_gpstart = READ_ONCE(rcu_state.n_force_qs);
}
/*
* Convert a ->gp_state value to a character string.
*/
static const char *gp_state_getname(short gs)
{
if (gs < 0 || gs >= ARRAY_SIZE(gp_state_names))
return "???";
return gp_state_names[gs];
}
/*
* Complain about starvation of grace-period kthread.
*/
@ -2032,9 +2035,9 @@ static void rcu_gp_cleanup(void)
rnp = rcu_get_root();
raw_spin_lock_irq_rcu_node(rnp); /* GP before ->gp_seq update. */
/* Declare grace period done. */
rcu_seq_end(&rcu_state.gp_seq);
/* Declare grace period done, trace first to use old GP number. */
trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("end"));
rcu_seq_end(&rcu_state.gp_seq);
rcu_state.gp_state = RCU_GP_IDLE;
/* Check for GP requests since above loop. */
rdp = this_cpu_ptr(&rcu_data);
@ -2600,10 +2603,10 @@ static void force_quiescent_state(void)
* This function checks for grace-period requests that fail to motivate
* RCU to come out of its idle mode.
*/
static void
rcu_check_gp_start_stall(struct rcu_node *rnp, struct rcu_data *rdp)
void
rcu_check_gp_start_stall(struct rcu_node *rnp, struct rcu_data *rdp,
const unsigned long gpssdelay)
{
const unsigned long gpssdelay = rcu_jiffies_till_stall_check() * HZ;
unsigned long flags;
unsigned long j;
struct rcu_node *rnp_root = rcu_get_root();
@ -2690,7 +2693,7 @@ static __latent_entropy void rcu_process_callbacks(struct softirq_action *unused
local_irq_restore(flags);
}
rcu_check_gp_start_stall(rnp, rdp);
rcu_check_gp_start_stall(rnp, rdp, rcu_jiffies_till_stall_check());
/* If there are callbacks ready, invoke them. */
if (rcu_segcblist_ready_cbs(&rdp->cblist))

15
kernel/rcu/tree.h
View File

@ -57,7 +57,7 @@ struct rcu_node {
/* some rcu_state fields as well as */
/* following. */
unsigned long gp_seq; /* Track rsp->rcu_gp_seq. */
unsigned long gp_seq_needed; /* Track rsp->rcu_gp_seq_needed. */
unsigned long gp_seq_needed; /* Track furthest future GP request. */
unsigned long completedqs; /* All QSes done for this node. */
unsigned long qsmask; /* CPUs or groups that need to switch in */
/* order for current grace period to proceed.*/
@ -163,7 +163,7 @@ union rcu_noqs {
struct rcu_data {
/* 1) quiescent-state and grace-period handling : */
unsigned long gp_seq; /* Track rsp->rcu_gp_seq counter. */
unsigned long gp_seq_needed; /* Track rsp->rcu_gp_seq_needed ctr. */
unsigned long gp_seq_needed; /* Track furthest future GP request. */
union rcu_noqs cpu_no_qs; /* No QSes yet for this CPU. */
bool core_needs_qs; /* Core waits for quiesc state. */
bool beenonline; /* CPU online at least once. */
@ -398,17 +398,6 @@ static const char *tp_rcu_varname __used __tracepoint_string = rcu_name;
#define RCU_NAME rcu_name
#endif /* #else #ifdef CONFIG_TRACING */
/*
* RCU implementation internal declarations:
*/
extern struct rcu_state rcu_sched_state;
extern struct rcu_state rcu_bh_state;
#ifdef CONFIG_PREEMPT_RCU
extern struct rcu_state rcu_preempt_state;
#endif /* #ifdef CONFIG_PREEMPT_RCU */
int rcu_dynticks_snap(struct rcu_data *rdp);
#ifdef CONFIG_RCU_BOOST

10
kernel/rcu/tree_exp.h
View File

@ -450,10 +450,12 @@ static void sync_rcu_exp_select_cpus(smp_call_func_t func)
}
INIT_WORK(&rnp->rew.rew_work, sync_rcu_exp_select_node_cpus);
preempt_disable();
cpu = cpumask_next(rnp->grplo - 1, cpu_online_mask);
cpu = find_next_bit(&rnp->ffmask, BITS_PER_LONG, -1);
/* If all offline, queue the work on an unbound CPU. */
if (unlikely(cpu > rnp->grphi))
if (unlikely(cpu > rnp->grphi - rnp->grplo))
cpu = WORK_CPU_UNBOUND;
else
cpu += rnp->grplo;
queue_work_on(cpu, rcu_par_gp_wq, &rnp->rew.rew_work);
preempt_enable();
rnp->exp_need_flush = true;
@ -690,8 +692,10 @@ static void sync_rcu_exp_handler(void *unused)
*/
if (t->rcu_read_lock_nesting > 0) {
raw_spin_lock_irqsave_rcu_node(rnp, flags);
if (rnp->expmask & rdp->grpmask)
if (rnp->expmask & rdp->grpmask) {
rdp->deferred_qs = true;
WRITE_ONCE(t->rcu_read_unlock_special.b.exp_hint, true);
}
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
}

37
kernel/rcu/tree_plugin.h
View File

@ -397,6 +397,11 @@ static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp)
return rnp->gp_tasks != NULL;
}
/* Bias and limit values for ->rcu_read_lock_nesting. */
#define RCU_NEST_BIAS INT_MAX
#define RCU_NEST_NMAX (-INT_MAX / 2)
#define RCU_NEST_PMAX (INT_MAX / 2)
/*
* Preemptible RCU implementation for rcu_read_lock().
* Just increment ->rcu_read_lock_nesting, shared state will be updated
@ -405,6 +410,8 @@ static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp)
void __rcu_read_lock(void)
{
current->rcu_read_lock_nesting++;
if (IS_ENABLED(CONFIG_PROVE_LOCKING))
WARN_ON_ONCE(current->rcu_read_lock_nesting > RCU_NEST_PMAX);
barrier(); /* critical section after entry code. */
}
EXPORT_SYMBOL_GPL(__rcu_read_lock);
@ -424,20 +431,18 @@ void __rcu_read_unlock(void)
--t->rcu_read_lock_nesting;
} else {
barrier(); /* critical section before exit code. */
t->rcu_read_lock_nesting = INT_MIN;
t->rcu_read_lock_nesting = -RCU_NEST_BIAS;
barrier(); /* assign before ->rcu_read_unlock_special load */
if (unlikely(READ_ONCE(t->rcu_read_unlock_special.s)))
rcu_read_unlock_special(t);
barrier(); /* ->rcu_read_unlock_special load before assign */
t->rcu_read_lock_nesting = 0;
}
#ifdef CONFIG_PROVE_LOCKING
{
int rrln = READ_ONCE(t->rcu_read_lock_nesting);
if (IS_ENABLED(CONFIG_PROVE_LOCKING)) {
int rrln = t->rcu_read_lock_nesting;
WARN_ON_ONCE(rrln < 0 && rrln > INT_MIN / 2);
WARN_ON_ONCE(rrln < 0 && rrln > RCU_NEST_NMAX);
}
#endif /* #ifdef CONFIG_PROVE_LOCKING */
}
EXPORT_SYMBOL_GPL(__rcu_read_unlock);
@ -597,7 +602,7 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags)
*/
static bool rcu_preempt_need_deferred_qs(struct task_struct *t)
{
return (this_cpu_ptr(&rcu_data)->deferred_qs ||
return (__this_cpu_read(rcu_data.deferred_qs) ||
READ_ONCE(t->rcu_read_unlock_special.s)) &&
t->rcu_read_lock_nesting <= 0;
}
@ -617,11 +622,11 @@ static void rcu_preempt_deferred_qs(struct task_struct *t)
if (!rcu_preempt_need_deferred_qs(t))
return;
if (couldrecurse)
t->rcu_read_lock_nesting -= INT_MIN;
t->rcu_read_lock_nesting -= RCU_NEST_BIAS;
local_irq_save(flags);
rcu_preempt_deferred_qs_irqrestore(t, flags);
if (couldrecurse)
t->rcu_read_lock_nesting += INT_MIN;
t->rcu_read_lock_nesting += RCU_NEST_BIAS;
}
/*
@ -642,13 +647,21 @@ static void rcu_read_unlock_special(struct task_struct *t)
local_irq_save(flags);
irqs_were_disabled = irqs_disabled_flags(flags);
if ((preempt_bh_were_disabled || irqs_were_disabled) &&
t->rcu_read_unlock_special.b.blocked) {
if (preempt_bh_were_disabled || irqs_were_disabled) {
WRITE_ONCE(t->rcu_read_unlock_special.b.exp_hint, false);
/* Need to defer quiescent state until everything is enabled. */
raise_softirq_irqoff(RCU_SOFTIRQ);
if (irqs_were_disabled) {
/* Enabling irqs does not reschedule, so... */
raise_softirq_irqoff(RCU_SOFTIRQ);
} else {
/* Enabling BH or preempt does reschedule, so... */
set_tsk_need_resched(current);
set_preempt_need_resched();
}
local_irq_restore(flags);
return;
}
WRITE_ONCE(t->rcu_read_unlock_special.b.exp_hint, false);
rcu_preempt_deferred_qs_irqrestore(t, flags);
}

6
kernel/rcu/update.c
View File

@ -335,8 +335,7 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
/* Initialize and register callbacks for each crcu_array element. */
for (i = 0; i < n; i++) {
if (checktiny &&
(crcu_array[i] == call_rcu ||
crcu_array[i] == call_rcu_bh)) {
(crcu_array[i] == call_rcu)) {
might_sleep();
continue;
}
@ -352,8 +351,7 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
/* Wait for all callbacks to be invoked. */
for (i = 0; i < n; i++) {
if (checktiny &&
(crcu_array[i] == call_rcu ||
crcu_array[i] == call_rcu_bh))
(crcu_array[i] == call_rcu))
continue;
for (j = 0; j < i; j++)
if (crcu_array[j] == crcu_array[i])

2
kernel/sched/core.c
View File

@ -5788,7 +5788,7 @@ int sched_cpu_deactivate(unsigned int cpu)
*
* Do sync before park smpboot threads to take care the rcu boost case.
*/
synchronize_rcu_mult(call_rcu, call_rcu_sched);
synchronize_rcu();
if (!sched_smp_initialized)
return 0;

6
kernel/sched/membarrier.c
View File

@ -210,7 +210,7 @@ static int membarrier_register_global_expedited(void)
* future scheduler executions will observe the new
* thread flag state for this mm.
*/
synchronize_sched();
synchronize_rcu();
}
atomic_or(MEMBARRIER_STATE_GLOBAL_EXPEDITED_READY,
&mm->membarrier_state);
@ -246,7 +246,7 @@ static int membarrier_register_private_expedited(int flags)
* Ensure all future scheduler executions will observe the
* new thread flag state for this process.
*/
synchronize_sched();
synchronize_rcu();
}
atomic_or(state, &mm->membarrier_state);
@ -298,7 +298,7 @@ SYSCALL_DEFINE2(membarrier, int, cmd, int, flags)
if (tick_nohz_full_enabled())
return -EINVAL;
if (num_online_cpus() > 1)
synchronize_sched();
synchronize_rcu();
return 0;
case MEMBARRIER_CMD_GLOBAL_EXPEDITED:
return membarrier_global_expedited();

24
kernel/trace/ftrace.c
View File

@ -173,7 +173,7 @@ static void ftrace_sync(struct work_struct *work)
{
/*
* This function is just a stub to implement a hard force
* of synchronize_sched(). This requires synchronizing
* of synchronize_rcu(). This requires synchronizing
* tasks even in userspace and idle.
*
* Yes, function tracing is rude.
@ -934,7 +934,7 @@ ftrace_profile_write(struct file *filp, const char __user *ubuf,
ftrace_profile_enabled = 0;
/*
* unregister_ftrace_profiler calls stop_machine
* so this acts like an synchronize_sched.
* so this acts like an synchronize_rcu.
*/
unregister_ftrace_profiler();
}
@ -1086,7 +1086,7 @@ struct ftrace_ops *ftrace_ops_trampoline(unsigned long addr)
/*
* Some of the ops may be dynamically allocated,
* they are freed after a synchronize_sched().
* they are freed after a synchronize_rcu().
*/
preempt_disable_notrace();
@ -1286,7 +1286,7 @@ static void free_ftrace_hash_rcu(struct ftrace_hash *hash)
{
if (!hash || hash == EMPTY_HASH)
return;
call_rcu_sched(&hash->rcu, __free_ftrace_hash_rcu);
call_rcu(&hash->rcu, __free_ftrace_hash_rcu);
}
void ftrace_free_filter(struct ftrace_ops *ops)
@ -1501,7 +1501,7 @@ static bool hash_contains_ip(unsigned long ip,
* the ip is not in the ops->notrace_hash.
*
* This needs to be called with preemption disabled as
* the hashes are freed with call_rcu_sched().
* the hashes are freed with call_rcu().
*/
static int
ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs)
@ -4496,7 +4496,7 @@ unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
if (ftrace_enabled && !ftrace_hash_empty(hash))
ftrace_run_modify_code(&probe->ops, FTRACE_UPDATE_CALLS,
&old_hash_ops);
synchronize_sched();
synchronize_rcu();
hlist_for_each_entry_safe(entry, tmp, &hhd, hlist) {
hlist_del(&entry->hlist);
@ -5314,7 +5314,7 @@ ftrace_graph_release(struct inode *inode, struct file *file)
mutex_unlock(&graph_lock);
/* Wait till all users are no longer using the old hash */
synchronize_sched();
synchronize_rcu();
free_ftrace_hash(old_hash);
}
@ -5707,7 +5707,7 @@ void ftrace_release_mod(struct module *mod)
list_for_each_entry_safe(mod_map, n, &ftrace_mod_maps, list) {
if (mod_map->mod == mod) {
list_del_rcu(&mod_map->list);
call_rcu_sched(&mod_map->rcu, ftrace_free_mod_map);
call_rcu(&mod_map->rcu, ftrace_free_mod_map);
break;
}
}
@ -5927,7 +5927,7 @@ ftrace_mod_address_lookup(unsigned long addr, unsigned long *size,
struct ftrace_mod_map *mod_map;
const char *ret = NULL;
/* mod_map is freed via call_rcu_sched() */
/* mod_map is freed via call_rcu() */
preempt_disable();
list_for_each_entry_rcu(mod_map, &ftrace_mod_maps, list) {
ret = ftrace_func_address_lookup(mod_map, addr, size, off, sym);
@ -6262,7 +6262,7 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
/*
* Some of the ops may be dynamically allocated,
* they must be freed after a synchronize_sched().
* they must be freed after a synchronize_rcu().
*/
preempt_disable_notrace();
@ -6433,7 +6433,7 @@ static void clear_ftrace_pids(struct trace_array *tr)
rcu_assign_pointer(tr->function_pids, NULL);
/* Wait till all users are no longer using pid filtering */
synchronize_sched();
synchronize_rcu();
trace_free_pid_list(pid_list);
}
@ -6580,7 +6580,7 @@ ftrace_pid_write(struct file *filp, const char __user *ubuf,
rcu_assign_pointer(tr->function_pids, pid_list);
if (filtered_pids) {
synchronize_sched();
synchronize_rcu();
trace_free_pid_list(filtered_pids);
} else if (pid_list) {
/* Register a probe to set whether to ignore the tracing of a task */

12
kernel/trace/ring_buffer.c
View File

@ -1834,7 +1834,7 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size,
* There could have been a race between checking
* record_disable and incrementing it.
*/
synchronize_sched();
synchronize_rcu();
for_each_buffer_cpu(buffer, cpu) {
cpu_buffer = buffer->buffers[cpu];
rb_check_pages(cpu_buffer);
@ -3151,7 +3151,7 @@ static bool rb_per_cpu_empty(struct ring_buffer_per_cpu *cpu_buffer)
* This prevents all writes to the buffer. Any attempt to write
* to the buffer after this will fail and return NULL.
*
* The caller should call synchronize_sched() after this.
* The caller should call synchronize_rcu() after this.
*/
void ring_buffer_record_disable(struct ring_buffer *buffer)
{
@ -3253,7 +3253,7 @@ bool ring_buffer_record_is_set_on(struct ring_buffer *buffer)
* This prevents all writes to the buffer. Any attempt to write
* to the buffer after this will fail and return NULL.
*
* The caller should call synchronize_sched() after this.
* The caller should call synchronize_rcu() after this.
*/
void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu)
{
@ -4191,7 +4191,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_read_prepare);
void
ring_buffer_read_prepare_sync(void)
{
synchronize_sched();
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(ring_buffer_read_prepare_sync);
@ -4363,7 +4363,7 @@ void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu)
atomic_inc(&cpu_buffer->record_disabled);
/* Make sure all commits have finished */
synchronize_sched();
synchronize_rcu();
raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags);
@ -4496,7 +4496,7 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
goto out;
/*
* We can't do a synchronize_sched here because this
* We can't do a synchronize_rcu here because this
* function can be called in atomic context.
* Normally this will be called from the same CPU as cpu.
* If not it's up to the caller to protect this.

10
kernel/trace/trace.c
View File

@ -1681,7 +1681,7 @@ void tracing_reset(struct trace_buffer *buf, int cpu)
ring_buffer_record_disable(buffer);
/* Make sure all commits have finished */
synchronize_sched();
synchronize_rcu();
ring_buffer_reset_cpu(buffer, cpu);
ring_buffer_record_enable(buffer);
@ -1698,7 +1698,7 @@ void tracing_reset_online_cpus(struct trace_buffer *buf)
ring_buffer_record_disable(buffer);
/* Make sure all commits have finished */
synchronize_sched();
synchronize_rcu();
buf->time_start = buffer_ftrace_now(buf, buf->cpu);
@ -2250,7 +2250,7 @@ void trace_buffered_event_disable(void)
preempt_enable();
/* Wait for all current users to finish */
synchronize_sched();
synchronize_rcu();
for_each_tracing_cpu(cpu) {
free_page((unsigned long)per_cpu(trace_buffered_event, cpu));
@ -5398,7 +5398,7 @@ static int tracing_set_tracer(struct trace_array *tr, const char *buf)
if (tr->current_trace->reset)
tr->current_trace->reset(tr);
/* Current trace needs to be nop_trace before synchronize_sched */
/* Current trace needs to be nop_trace before synchronize_rcu */
tr->current_trace = &nop_trace;
#ifdef CONFIG_TRACER_MAX_TRACE
@ -5412,7 +5412,7 @@ static int tracing_set_tracer(struct trace_array *tr, const char *buf)
* The update_max_tr is called from interrupts disabled
* so a synchronized_sched() is sufficient.
*/
synchronize_sched();
synchronize_rcu();
free_snapshot(tr);
}
#endif

4
kernel/trace/trace_events_filter.c
View File

@ -1614,7 +1614,7 @@ static int process_system_preds(struct trace_subsystem_dir *dir,
/*
* The calls can still be using the old filters.
* Do a synchronize_sched() and to ensure all calls are
* Do a synchronize_rcu() and to ensure all calls are
* done with them before we free them.
*/
tracepoint_synchronize_unregister();
@ -1845,7 +1845,7 @@ int apply_subsystem_event_filter(struct trace_subsystem_dir *dir,
if (filter) {
/*
* No event actually uses the system filter
* we can free it without synchronize_sched().
* we can free it without synchronize_rcu().
*/
__free_filter(system->filter);
system->filter = filter;

2
kernel/trace/trace_kprobe.c
View File

@ -333,7 +333,7 @@ disable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
* event_call related objects, which will be accessed in
* the kprobe_trace_func/kretprobe_trace_func.
*/
synchronize_sched();
synchronize_rcu();
kfree(link); /* Ignored if link == NULL */
}

4
kernel/tracepoint.c
View File

@ -92,7 +92,7 @@ static __init int release_early_probes(void)
while (early_probes) {
tmp = early_probes;
early_probes = tmp->next;
call_rcu_sched(tmp, rcu_free_old_probes);
call_rcu(tmp, rcu_free_old_probes);
}
return 0;
@ -123,7 +123,7 @@ static inline void release_probes(struct tracepoint_func *old)
* cover both cases. So let us chain the SRCU and sched RCU
* callbacks to wait for both grace periods.
*/
call_rcu_sched(&tp_probes->rcu, rcu_free_old_probes);
call_rcu(&tp_probes->rcu, rcu_free_old_probes);
}
}

8
kernel/workqueue.c
View File

@ -3396,7 +3396,7 @@ static void put_unbound_pool(struct worker_pool *pool)
del_timer_sync(&pool->mayday_timer);
/* sched-RCU protected to allow dereferences from get_work_pool() */
call_rcu_sched(&pool->rcu, rcu_free_pool);
call_rcu(&pool->rcu, rcu_free_pool);
}
/**
@ -3503,14 +3503,14 @@ static void pwq_unbound_release_workfn(struct work_struct *work)
put_unbound_pool(pool);
mutex_unlock(&wq_pool_mutex);
call_rcu_sched(&pwq->rcu, rcu_free_pwq);
call_rcu(&pwq->rcu, rcu_free_pwq);
/*
* If we're the last pwq going away, @wq is already dead and no one
* is gonna access it anymore. Schedule RCU free.
*/
if (is_last)
call_rcu_sched(&wq->rcu, rcu_free_wq);
call_rcu(&wq->rcu, rcu_free_wq);
}
/**
@ -4195,7 +4195,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
* The base ref is never dropped on per-cpu pwqs. Directly
* schedule RCU free.
*/
call_rcu_sched(&wq->rcu, rcu_free_wq);
call_rcu(&wq->rcu, rcu_free_wq);
} else {
/*
* We're the sole accessor of @wq at this point. Directly

2
lib/percpu-refcount.c
View File

@ -181,7 +181,7 @@ static void __percpu_ref_switch_to_atomic(struct percpu_ref *ref,
ref->confirm_switch = confirm_switch ?: percpu_ref_noop_confirm_switch;
percpu_ref_get(ref); /* put after confirmation */
call_rcu_sched(&ref->rcu, percpu_ref_switch_to_atomic_rcu);
call_rcu(&ref->rcu, percpu_ref_switch_to_atomic_rcu);
}
static void __percpu_ref_switch_to_percpu(struct percpu_ref *ref)

4
mm/khugepaged.c
View File

@ -1225,7 +1225,7 @@ static void collect_mm_slot(struct mm_slot *mm_slot)
{
struct mm_struct *mm = mm_slot->mm;
VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
lockdep_assert_held(&khugepaged_mm_lock);
if (khugepaged_test_exit(mm)) {
/* free mm_slot */
@ -1631,7 +1631,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
int progress = 0;
VM_BUG_ON(!pages);
VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
lockdep_assert_held(&khugepaged_mm_lock);
if (khugepaged_scan.mm_slot)
mm_slot = khugepaged_scan.mm_slot;

2
mm/mmu_gather.c
View File

@ -199,7 +199,7 @@ void tlb_table_flush(struct mmu_gather *tlb)
if (*batch) {
tlb_table_invalidate(tlb);
call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
call_rcu(&(*batch)->rcu, tlb_remove_table_rcu);
*batch = NULL;
}
}

4
mm/slab.c
View File

@ -962,10 +962,10 @@ static int setup_kmem_cache_node(struct kmem_cache *cachep,
* To protect lockless access to n->shared during irq disabled context.
* If n->shared isn't NULL in irq disabled context, accessing to it is
* guaranteed to be valid until irq is re-enabled, because it will be
* freed after synchronize_sched().
* freed after synchronize_rcu().
*/
if (old_shared && force_change)
synchronize_sched();
synchronize_rcu();
fail:
kfree(old_shared);

6
mm/slab_common.c
View File

@ -724,7 +724,7 @@ void slab_deactivate_memcg_cache_rcu_sched(struct kmem_cache *s,
css_get(&s->memcg_params.memcg->css);
s->memcg_params.deact_fn = deact_fn;
call_rcu_sched(&s->memcg_params.deact_rcu_head, kmemcg_deactivate_rcufn);
call_rcu(&s->memcg_params.deact_rcu_head, kmemcg_deactivate_rcufn);
}
void memcg_deactivate_kmem_caches(struct mem_cgroup *memcg)
@ -839,11 +839,11 @@ static void flush_memcg_workqueue(struct kmem_cache *s)
mutex_unlock(&slab_mutex);
/*
* SLUB deactivates the kmem_caches through call_rcu_sched. Make
* SLUB deactivates the kmem_caches through call_rcu. Make
* sure all registered rcu callbacks have been invoked.
*/
if (IS_ENABLED(CONFIG_SLUB))
rcu_barrier_sched();
rcu_barrier();
/*
* SLAB and SLUB create memcg kmem_caches through workqueue and SLUB

3
mm/swap.c
View File

@ -823,8 +823,7 @@ void lru_add_page_tail(struct page *page, struct page *page_tail,
VM_BUG_ON_PAGE(!PageHead(page), page);
VM_BUG_ON_PAGE(PageCompound(page_tail), page);
VM_BUG_ON_PAGE(PageLRU(page_tail), page);
VM_BUG_ON(NR_CPUS != 1 &&
!spin_is_locked(&lruvec_pgdat(lruvec)->lru_lock));
lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);
if (!list)
SetPageLRU(page_tail);

2
net/bridge/br_mdb.c
View File

@ -728,7 +728,7 @@ static int __br_mdb_del(struct net_bridge *br, struct br_mdb_entry *entry)
rcu_assign_pointer(*pp, p->next);
hlist_del_init(&p->mglist);
del_timer(&p->timer);
call_rcu_bh(&p->rcu, br_multicast_free_pg);
call_rcu(&p->rcu, br_multicast_free_pg);
err = 0;
if (!mp->ports && !mp->host_joined &&

14
net/bridge/br_multicast.c
View File

@ -260,7 +260,7 @@ static void br_multicast_group_expired(struct timer_list *t)
hlist_del_rcu(&mp->hlist[mdb->ver]);
mdb->size--;
call_rcu_bh(&mp->rcu, br_multicast_free_group);
call_rcu(&mp->rcu, br_multicast_free_group);
out:
spin_unlock(&br->multicast_lock);
@ -291,7 +291,7 @@ static void br_multicast_del_pg(struct net_bridge *br,
del_timer(&p->timer);
br_mdb_notify(br->dev, p->port, &pg->addr, RTM_DELMDB,
p->flags);
call_rcu_bh(&p->rcu, br_multicast_free_pg);
call_rcu(&p->rcu, br_multicast_free_pg);
if (!mp->ports && !mp->host_joined &&
netif_running(br->dev))
@ -358,7 +358,7 @@ static int br_mdb_rehash(struct net_bridge_mdb_htable __rcu **mdbp, int max,
}
br_mdb_rehash_seq++;
call_rcu_bh(&mdb->rcu, br_mdb_free);
call_rcu(&mdb->rcu, br_mdb_free);
out:
rcu_assign_pointer(*mdbp, mdb);
@ -1629,7 +1629,7 @@ br_multicast_leave_group(struct net_bridge *br,
rcu_assign_pointer(*pp, p->next);
hlist_del_init(&p->mglist);
del_timer(&p->timer);
call_rcu_bh(&p->rcu, br_multicast_free_pg);
call_rcu(&p->rcu, br_multicast_free_pg);
br_mdb_notify(br->dev, port, group, RTM_DELMDB,
p->flags);
@ -2051,19 +2051,19 @@ void br_multicast_dev_del(struct net_bridge *br)
hlist_for_each_entry_safe(mp, n, &mdb->mhash[i],
hlist[ver]) {
del_timer(&mp->timer);
call_rcu_bh(&mp->rcu, br_multicast_free_group);
call_rcu(&mp->rcu, br_multicast_free_group);
}
}
if (mdb->old) {
spin_unlock_bh(&br->multicast_lock);
rcu_barrier_bh();
rcu_barrier();
spin_lock_bh(&br->multicast_lock);
WARN_ON(mdb->old);
}
mdb->old = mdb;
call_rcu_bh(&mdb->rcu, br_mdb_free);
call_rcu(&mdb->rcu, br_mdb_free);
out:
spin_unlock_bh(&br->multicast_lock);

4
net/core/netpoll.c
View File

@ -800,7 +800,7 @@ void __netpoll_cleanup(struct netpoll *np)
ops->ndo_netpoll_cleanup(np->dev);
RCU_INIT_POINTER(np->dev->npinfo, NULL);
call_rcu_bh(&npinfo->rcu, rcu_cleanup_netpoll_info);
call_rcu(&npinfo->rcu, rcu_cleanup_netpoll_info);
} else
RCU_INIT_POINTER(np->dev->npinfo, NULL);
}
@ -811,7 +811,7 @@ void __netpoll_free(struct netpoll *np)
ASSERT_RTNL();
/* Wait for transmitting packets to finish before freeing. */
synchronize_rcu_bh();
synchronize_rcu();
__netpoll_cleanup(np);
kfree(np);
}

2
net/core/skmsg.c
View File

@ -580,7 +580,7 @@ void sk_psock_drop(struct sock *sk, struct sk_psock *psock)
write_unlock_bh(&sk->sk_callback_lock);
sk_psock_clear_state(psock, SK_PSOCK_TX_ENABLED);
call_rcu_sched(&psock->rcu, sk_psock_destroy);
call_rcu(&psock->rcu, sk_psock_destroy);
}
EXPORT_SYMBOL_GPL(sk_psock_drop);

2
net/decnet/af_decnet.c
View File

@ -2405,7 +2405,7 @@ static void __exit decnet_exit(void)
proto_unregister(&dn_proto);
rcu_barrier_bh(); /* Wait for completion of call_rcu_bh()'s */
rcu_barrier(); /* Wait for completion of call_rcu()'s */
}
module_exit(decnet_exit);
#endif

2
net/sched/sch_api.c
View File

@ -540,7 +540,7 @@ void qdisc_put_stab(struct qdisc_size_table *tab)
if (--tab->refcnt == 0) {
list_del(&tab->list);
call_rcu_bh(&tab->rcu, stab_kfree_rcu);
call_rcu(&tab->rcu, stab_kfree_rcu);
}
}
EXPORT_SYMBOL(qdisc_put_stab);

8
net/sched/sch_generic.c
View File

@ -1372,7 +1372,7 @@ void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
if (!tp_head) {
RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
/* Wait for flying RCU callback before it is freed. */
rcu_barrier_bh();
rcu_barrier();
return;
}
@ -1380,10 +1380,10 @@ void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
&miniqp->miniq1 : &miniqp->miniq2;
/* We need to make sure that readers won't see the miniq
* we are about to modify. So wait until previous call_rcu_bh callback
* we are about to modify. So wait until previous call_rcu callback
* is done.
*/
rcu_barrier_bh();
rcu_barrier();
miniq->filter_list = tp_head;
rcu_assign_pointer(*miniqp->p_miniq, miniq);
@ -1392,7 +1392,7 @@ void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
* block potential new user of miniq_old until all readers
* are not seeing it.
*/
call_rcu_bh(&miniq_old->rcu, mini_qdisc_rcu_func);
call_rcu(&miniq_old->rcu, mini_qdisc_rcu_func);
}
EXPORT_SYMBOL(mini_qdisc_pair_swap);

35
scripts/checkpatch.pl
View File

@ -573,6 +573,27 @@ foreach my $entry (@mode_permission_funcs) {
}
$mode_perms_search = "(?:${mode_perms_search})";
our %deprecated_apis = (
"synchronize_rcu_bh" => "synchronize_rcu",
"synchronize_rcu_bh_expedited" => "synchronize_rcu_expedited",
"call_rcu_bh" => "call_rcu",
"rcu_barrier_bh" => "rcu_barrier",
"synchronize_sched" => "synchronize_rcu",
"synchronize_sched_expedited" => "synchronize_rcu_expedited",
"call_rcu_sched" => "call_rcu",
"rcu_barrier_sched" => "rcu_barrier",
"get_state_synchronize_sched" => "get_state_synchronize_rcu",
"cond_synchronize_sched" => "cond_synchronize_rcu",
);
#Create a search pattern for all these strings to speed up a loop below
our $deprecated_apis_search = "";
foreach my $entry (keys %deprecated_apis) {
$deprecated_apis_search .= '|' if ($deprecated_apis_search ne "");
$deprecated_apis_search .= $entry;
}
$deprecated_apis_search = "(?:${deprecated_apis_search})";
our $mode_perms_world_writable = qr{
S_IWUGO |
S_IWOTH |
@ -6368,6 +6389,20 @@ sub process {
"please use device_initcall() or more appropriate function instead of __initcall() (see include/linux/init.h)\n" . $herecurr);
}
# check for spin_is_locked(), suggest lockdep instead
if ($line =~ /\bspin_is_locked\(/) {
WARN("USE_LOCKDEP",
"Where possible, use lockdep_assert_held instead of assertions based on spin_is_locked\n" . $herecurr);
}
# check for deprecated apis
if ($line =~ /\b($deprecated_apis_search)\b\s*\(/) {
my $deprecated_api = $1;
my $new_api = $deprecated_apis{$deprecated_api};
WARN("DEPRECATED_API",
"Deprecated use of '$deprecated_api', prefer '$new_api' instead\n" . $herecurr);
}
# check for various structs that are normally const (ops, kgdb, device_tree)
# and avoid what seem like struct definitions 'struct foo {'
if ($line !~ /\bconst\b/ &&

2
tools/include/linux/kernel.h
View File

@ -116,6 +116,6 @@ int scnprintf(char * buf, size_t size, const char * fmt, ...);
#define round_down(x, y) ((x) & ~__round_mask(x, y))
#define current_gfp_context(k) 0
#define synchronize_sched()
#define synchronize_rcu()
#endif

8
tools/testing/selftests/rcutorture/bin/kvm.sh
View File

@ -194,6 +194,14 @@ do
shift
done
if test -z "$TORTURE_INITRD" || tools/testing/selftests/rcutorture/bin/mkinitrd.sh
then
:
else
echo No initrd and unable to create one, aborting test >&2
exit 1
fi
CONFIGFRAG=${KVM}/configs/${TORTURE_SUITE}; export CONFIGFRAG
if test -z "$configs"

136
tools/testing/selftests/rcutorture/bin/mkinitrd.sh Executable file
View File

@ -0,0 +1,136 @@
#!/bin/bash
#
# Create an initrd directory if one does not already exist.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, you can access it online at
# http://www.gnu.org/licenses/gpl-2.0.html.
#
# Copyright (C) IBM Corporation, 2013
#
# Author: Connor Shu <Connor.Shu@ibm.com>
D=tools/testing/selftests/rcutorture
# Prerequisite checks
[ -z "$D" ] && echo >&2 "No argument supplied" && exit 1
if [ ! -d "$D" ]; then
echo >&2 "$D does not exist: Malformed kernel source tree?"
exit 1
fi
if [ -s "$D/initrd/init" ]; then
echo "$D/initrd/init already exists, no need to create it"
exit 0
fi
T=${TMPDIR-/tmp}/mkinitrd.sh.$$
trap 'rm -rf $T' 0 2
mkdir $T
cat > $T/init << '__EOF___'
#!/bin/sh
# Run in userspace a few milliseconds every second. This helps to
# exercise the NO_HZ_FULL portions of RCU.
while :
do
q=
for i in \
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
do
q="$q $i"
done
sleep 1
done
__EOF___
# Try using dracut to create initrd
if command -v dracut >/dev/null 2>&1
then
echo Creating $D/initrd using dracut.
# Filesystem creation
dracut --force --no-hostonly --no-hostonly-cmdline --module "base" $T/initramfs.img
cd $D
mkdir -p initrd
cd initrd
zcat $T/initramfs.img | cpio -id
cp $T/init init
chmod +x init
echo Done creating $D/initrd using dracut
exit 0
fi
# No dracut, so create a C-language initrd/init program and statically
# link it. This results in a very small initrd, but might be a bit less
# future-proof than dracut.
echo "Could not find dracut, attempting C initrd"
cd $D
mkdir -p initrd
cd initrd
cat > init.c << '___EOF___'
#ifndef NOLIBC
#include <unistd.h>
#include <sys/time.h>
#endif
volatile unsigned long delaycount;
int main(int argc, int argv[])
{
int i;
struct timeval tv;
struct timeval tvb;
for (;;) {
sleep(1);
/* Need some userspace time. */
if (gettimeofday(&tvb, NULL))
continue;
do {
for (i = 0; i < 1000 * 100; i++)
delaycount = i * i;
if (gettimeofday(&tv, NULL))
break;
tv.tv_sec -= tvb.tv_sec;
if (tv.tv_sec > 1)
break;
tv.tv_usec += tv.tv_sec * 1000 * 1000;
tv.tv_usec -= tvb.tv_usec;
} while (tv.tv_usec < 1000);
}
return 0;
}
___EOF___
# build using nolibc on supported archs (smaller executable) and fall
# back to regular glibc on other ones.
if echo -e "#if __x86_64__||__i386__||__i486__||__i586__||__i686__" \
"||__ARM_EABI__||__aarch64__\nyes\n#endif" \
| ${CROSS_COMPILE}gcc -E -nostdlib -xc - \
| grep -q '^yes'; then
# architecture supported by nolibc
${CROSS_COMPILE}gcc -fno-asynchronous-unwind-tables -fno-ident \
-nostdlib -include ../bin/nolibc.h -lgcc -s -static -Os \
-o init init.c
else
${CROSS_COMPILE}gcc -s -static -Os -o init init.c
fi
rm init.c
echo "Done creating a statically linked C-language initrd"
exit 0

2197
tools/testing/selftests/rcutorture/bin/nolibc.h Normal file
View File

File diff suppressed because it is too large Load Diff

99
tools/testing/selftests/rcutorture/doc/initrd.txt
View File

@ -1,9 +1,12 @@
This document describes one way to create the initrd directory hierarchy
in order to allow an initrd to be built into your kernel. The trick
here is to steal the initrd file used on your Linux laptop, Ubuntu in
this case. There are probably much better ways of doing this.
The rcutorture scripting tools automatically create the needed initrd
directory using dracut. Failing that, this tool will create an initrd
containing a single statically linked binary named "init" that loops
over a very long sleep() call. In both cases, this creation is done
by tools/testing/selftests/rcutorture/bin/mkinitrd.sh.
That said, here are the commands:
However, if you are attempting to run rcutorture on a system that does
not have dracut installed, and if you don't like the notion of static
linking, you might wish to press an existing initrd into service:
------------------------------------------------------------------------
cd tools/testing/selftests/rcutorture
@ -11,22 +14,7 @@ zcat /initrd.img > /tmp/initrd.img.zcat
mkdir initrd
cd initrd
cpio -id < /tmp/initrd.img.zcat
------------------------------------------------------------------------
Another way to create an initramfs image is using "dracut"[1], which is
available on many distros, however the initramfs dracut generates is a cpio
archive with another cpio archive in it, so an extra step is needed to create
the initrd directory hierarchy.
Here are the commands to create a initrd directory for rcutorture using
dracut:
------------------------------------------------------------------------
dracut --no-hostonly --no-hostonly-cmdline --module "base bash shutdown" /tmp/initramfs.img
cd tools/testing/selftests/rcutorture
mkdir initrd
cd initrd
/usr/lib/dracut/skipcpio /tmp/initramfs.img | zcat | cpio -id < /tmp/initramfs.img
# Manually verify that initrd contains needed binaries and libraries.
------------------------------------------------------------------------
Interestingly enough, if you are running rcutorture, you don't really
@ -39,75 +27,12 @@ with 0755 mode.
------------------------------------------------------------------------
#!/bin/sh
[ -d /dev ] || mkdir -m 0755 /dev
[ -d /root ] || mkdir -m 0700 /root
[ -d /sys ] || mkdir /sys
[ -d /proc ] || mkdir /proc
[ -d /tmp ] || mkdir /tmp
mkdir -p /var/lock
mount -t sysfs -o nodev,noexec,nosuid sysfs /sys
mount -t proc -o nodev,noexec,nosuid proc /proc
# Some things don't work properly without /etc/mtab.
ln -sf /proc/mounts /etc/mtab
# Note that this only becomes /dev on the real filesystem if udev's scripts
# are used; which they will be, but it's worth pointing out
if ! mount -t devtmpfs -o mode=0755 udev /dev; then
echo "W: devtmpfs not available, falling back to tmpfs for /dev"
mount -t tmpfs -o mode=0755 udev /dev
[ -e /dev/console ] || mknod --mode=600 /dev/console c 5 1
[ -e /dev/kmsg ] || mknod --mode=644 /dev/kmsg c 1 11
[ -e /dev/null ] || mknod --mode=666 /dev/null c 1 3
fi
mkdir /dev/pts
mount -t devpts -o noexec,nosuid,gid=5,mode=0620 devpts /dev/pts || true
mount -t tmpfs -o "nosuid,size=20%,mode=0755" tmpfs /run
mkdir /run/initramfs
# compatibility symlink for the pre-oneiric locations
ln -s /run/initramfs /dev/.initramfs
# Export relevant variables
export ROOT=
export ROOTDELAY=
export ROOTFLAGS=
export ROOTFSTYPE=
export IP=
export BOOT=
export BOOTIF=
export UBIMTD=
export break=
export init=/sbin/init
export quiet=n
export readonly=y
export rootmnt=/root
export debug=
export panic=
export blacklist=
export resume=
export resume_offset=
export recovery=
for i in /sys/devices/system/cpu/cpu*/online
do
case $i in
'/sys/devices/system/cpu/cpu0/online')
;;
'/sys/devices/system/cpu/cpu*/online')
;;
*)
echo 1 > $i
;;
esac
done
while :
do
sleep 10
done
------------------------------------------------------------------------
References:
[1]: https://dracut.wiki.kernel.org/index.php/Main_Page
[2]: http://blog.elastocloud.org/2015/06/rapid-linux-kernel-devtest-with-qemu.html
[3]: https://www.centos.org/forums/viewtopic.php?t=51621
This approach also allows most of the binaries and libraries in the
initrd filesystem to be dispensed with, which can save significant
space in rcutorture's "res" directory.

4
tools/testing/selftests/rcutorture/formal/srcu-cbmc/include/linux/types.h
View File

@ -131,8 +131,8 @@ struct hlist_node {
* weird ABI and we need to ask it explicitly.
*
* The alignment is required to guarantee that bits 0 and 1 of @next will be
* clear under normal conditions -- as long as we use call_rcu(),
* call_rcu_bh(), call_rcu_sched(), or call_srcu() to queue callback.
* clear under normal conditions -- as long as we use call_rcu() or
* call_srcu() to queue callback.
*
* This guarantee is important for few reasons:
* - future call_rcu_lazy() will make use of lower bits in the pointer;

12
virt/kvm/arm/vgic/vgic.c
View File

@ -196,7 +196,7 @@ void vgic_irq_set_phys_active(struct vgic_irq *irq, bool active)
*/
static struct kvm_vcpu *vgic_target_oracle(struct vgic_irq *irq)
{
DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&irq->irq_lock));
lockdep_assert_held(&irq->irq_lock);
/* If the interrupt is active, it must stay on the current vcpu */
if (irq->active)
@ -273,7 +273,7 @@ static void vgic_sort_ap_list(struct kvm_vcpu *vcpu)
{
struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&vgic_cpu->ap_list_lock));
lockdep_assert_held(&vgic_cpu->ap_list_lock);
list_sort(NULL, &vgic_cpu->ap_list_head, vgic_irq_cmp);
}
@ -311,7 +311,7 @@ bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq,
{
struct kvm_vcpu *vcpu;
DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&irq->irq_lock));
lockdep_assert_held(&irq->irq_lock);
retry:
vcpu = vgic_target_oracle(irq);
@ -702,7 +702,7 @@ static inline void vgic_fold_lr_state(struct kvm_vcpu *vcpu)
static inline void vgic_populate_lr(struct kvm_vcpu *vcpu,
struct vgic_irq *irq, int lr)
{
DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&irq->irq_lock));
lockdep_assert_held(&irq->irq_lock);
if (kvm_vgic_global_state.type == VGIC_V2)
vgic_v2_populate_lr(vcpu, irq, lr);
@ -736,7 +736,7 @@ static int compute_ap_list_depth(struct kvm_vcpu *vcpu,
*multi_sgi = false;
DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&vgic_cpu->ap_list_lock));
lockdep_assert_held(&vgic_cpu->ap_list_lock);
list_for_each_entry(irq, &vgic_cpu->ap_list_head, ap_list) {
int w;
@ -761,7 +761,7 @@ static void vgic_flush_lr_state(struct kvm_vcpu *vcpu)
bool multi_sgi;
u8 prio = 0xff;
DEBUG_SPINLOCK_BUG_ON(!spin_is_locked(&vgic_cpu->ap_list_lock));
lockdep_assert_held(&vgic_cpu->ap_list_lock);
count = compute_ap_list_depth(vcpu, &multi_sgi);
if (count > kvm_vgic_global_state.nr_lr || multi_sgi)