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Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu 

Pull v3.7 RCU commits from Paul E. McKenney:

"
0.	A fix for a latent bug that has been in RCU ever since the
        addition of CPU stall warnings.  This bug results in
        false-positive stall warnings, but thus far only on embedded
        systems with severely cut-down userspace configurations.
        This fix is located on an rcu/urgent branch, with the rest
        of the commits based on top of it.  This commit CCs stable.
        Given that the merge window is coming quite soon and given
        the small number of affected users, I do -not- recommend
        pushing it to 3.6, but the separate branch makes it easy to
        find if someone needs it.

1.	Further reductions in latency spikes for huge systems, along
        with additional boot-time adaptation to the actual hardware.
        This is a large change, as it moves RCU grace-period
        initialization and cleanup, along with quiescent-state forcing,
        from softirq to a kthread.  However, it appears to be in
        quite good shape (famous last words).  Posted to LKML at
        https://lkml.org/lkml/2012/9/20/427.
2.	Updates to documentation and rcutorture, the latter category
        including keeping statistics on CPU-hotplug latencies and
        fixing some initialization-time races.  Posted to LKML at
        https://lkml.org/lkml/2012/8/30/193.

3.	Miscellaneous fixes and improvements, posted to LKML at
        https://lkml.org/lkml/2012/8/30/199.

4.	CPU-hotplug fixes and improvements, posted to LKML at
        https://lkml.org/lkml/2012/8/30/292 for first three and at
        https://lkml.org/lkml/2012/8/3/416.

5.	Idle-loop fixes that were omitted on an earlier submission,
        posted to LKML at https://lkml.org/lkml/2012/8/30/251.
"

Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2012-09-25 09:30:58 +02:00
parent 9b20aa63b8 593d1006cd
commit a9b86fab4b
44 changed files with 1542 additions and 1370 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
Documentation/RCU/checklist.txt
View File

@ -310,6 +310,12 @@ over a rather long period of time, but improvements are always welcome!
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
with softirq disabled, e.g., via spin_lock_irqsave(),
spin_lock_bh(), etc. Failing to disable irq on a given

16
Documentation/RCU/stallwarn.txt
View File

@ -99,7 +99,7 @@ In kernels with CONFIG_RCU_FAST_NO_HZ, even more information is
printed:
INFO: rcu_preempt detected stall on CPU
0: (64628 ticks this GP) idle=dd5/3fffffffffffffff/0 drain=0 . timer=-1
0: (64628 ticks this GP) idle=dd5/3fffffffffffffff/0 drain=0 . timer not pending
(t=65000 jiffies)
The "(64628 ticks this GP)" indicates that this CPU has taken more
@ -116,13 +116,13 @@ number between the two "/"s is the value of the nesting, which will
be a small positive number if in the idle loop and a very large positive
number (as shown above) otherwise.
For CONFIG_RCU_FAST_NO_HZ kernels, the "drain=0" indicates that the
CPU is not in the process of trying to force itself into dyntick-idle
state, the "." indicates that the CPU has not given up forcing RCU
into dyntick-idle mode (it would be "H" otherwise), and the "timer=-1"
indicates that the CPU has not recented forced RCU into dyntick-idle
mode (it would otherwise indicate the number of microseconds remaining
in this forced state).
For CONFIG_RCU_FAST_NO_HZ kernels, the "drain=0" indicates that the CPU is
not in the process of trying to force itself into dyntick-idle state, the
"." indicates that the CPU has not given up forcing RCU into dyntick-idle
mode (it would be "H" otherwise), and the "timer not pending" indicates
that the CPU has not recently forced RCU into dyntick-idle mode (it
would otherwise indicate the number of microseconds remaining in this
forced state).
Multiple Warnings From One Stall

43
Documentation/RCU/trace.txt
View File

@ -333,23 +333,23 @@ o Each element of the form "1/1 0:127 ^0" represents one struct
The output of "cat rcu/rcu_pending" looks as follows:
rcu_sched:
0 np=255892 qsp=53936 rpq=85 cbr=0 cng=14417 gpc=10033 gps=24320 nf=6445 nn=146741
1 np=261224 qsp=54638 rpq=33 cbr=0 cng=25723 gpc=16310 gps=2849 nf=5912 nn=155792
2 np=237496 qsp=49664 rpq=23 cbr=0 cng=2762 gpc=45478 gps=1762 nf=1201 nn=136629
3 np=236249 qsp=48766 rpq=98 cbr=0 cng=286 gpc=48049 gps=1218 nf=207 nn=137723
4 np=221310 qsp=46850 rpq=7 cbr=0 cng=26 gpc=43161 gps=4634 nf=3529 nn=123110
5 np=237332 qsp=48449 rpq=9 cbr=0 cng=54 gpc=47920 gps=3252 nf=201 nn=137456
6 np=219995 qsp=46718 rpq=12 cbr=0 cng=50 gpc=42098 gps=6093 nf=4202 nn=120834
7 np=249893 qsp=49390 rpq=42 cbr=0 cng=72 gpc=38400 gps=17102 nf=41 nn=144888
0 np=255892 qsp=53936 rpq=85 cbr=0 cng=14417 gpc=10033 gps=24320 nn=146741
1 np=261224 qsp=54638 rpq=33 cbr=0 cng=25723 gpc=16310 gps=2849 nn=155792
2 np=237496 qsp=49664 rpq=23 cbr=0 cng=2762 gpc=45478 gps=1762 nn=136629
3 np=236249 qsp=48766 rpq=98 cbr=0 cng=286 gpc=48049 gps=1218 nn=137723
4 np=221310 qsp=46850 rpq=7 cbr=0 cng=26 gpc=43161 gps=4634 nn=123110
5 np=237332 qsp=48449 rpq=9 cbr=0 cng=54 gpc=47920 gps=3252 nn=137456
6 np=219995 qsp=46718 rpq=12 cbr=0 cng=50 gpc=42098 gps=6093 nn=120834
7 np=249893 qsp=49390 rpq=42 cbr=0 cng=72 gpc=38400 gps=17102 nn=144888
rcu_bh:
0 np=146741 qsp=1419 rpq=6 cbr=0 cng=6 gpc=0 gps=0 nf=2 nn=145314
1 np=155792 qsp=12597 rpq=3 cbr=0 cng=0 gpc=4 gps=8 nf=3 nn=143180
2 np=136629 qsp=18680 rpq=1 cbr=0 cng=0 gpc=7 gps=6 nf=0 nn=117936
3 np=137723 qsp=2843 rpq=0 cbr=0 cng=0 gpc=10 gps=7 nf=0 nn=134863
4 np=123110 qsp=12433 rpq=0 cbr=0 cng=0 gpc=4 gps=2 nf=0 nn=110671
5 np=137456 qsp=4210 rpq=1 cbr=0 cng=0 gpc=6 gps=5 nf=0 nn=133235
6 np=120834 qsp=9902 rpq=2 cbr=0 cng=0 gpc=6 gps=3 nf=2 nn=110921
7 np=144888 qsp=26336 rpq=0 cbr=0 cng=0 gpc=8 gps=2 nf=0 nn=118542
0 np=146741 qsp=1419 rpq=6 cbr=0 cng=6 gpc=0 gps=0 nn=145314
1 np=155792 qsp=12597 rpq=3 cbr=0 cng=0 gpc=4 gps=8 nn=143180
2 np=136629 qsp=18680 rpq=1 cbr=0 cng=0 gpc=7 gps=6 nn=117936
3 np=137723 qsp=2843 rpq=0 cbr=0 cng=0 gpc=10 gps=7 nn=134863
4 np=123110 qsp=12433 rpq=0 cbr=0 cng=0 gpc=4 gps=2 nn=110671
5 np=137456 qsp=4210 rpq=1 cbr=0 cng=0 gpc=6 gps=5 nn=133235
6 np=120834 qsp=9902 rpq=2 cbr=0 cng=0 gpc=6 gps=3 nn=110921
7 np=144888 qsp=26336 rpq=0 cbr=0 cng=0 gpc=8 gps=2 nn=118542
As always, this is once again split into "rcu_sched" and "rcu_bh"
portions, with CONFIG_TREE_PREEMPT_RCU kernels having an additional
@ -377,17 +377,6 @@ o "gpc" is the number of times that an old grace period had
o "gps" is the number of times that a new grace period had started,
but this CPU was not yet aware of it.
o "nf" is the number of times that this CPU suspected that the
current grace period had run for too long, and thus needed to
be forced.
Please note that "forcing" consists of sending resched IPIs
to holdout CPUs. If that CPU really still is in an old RCU
read-side critical section, then we really do have to wait for it.
The assumption behing "forcing" is that the CPU is not still in
an old RCU read-side critical section, but has not yet responded
for some other reason.
o "nn" is the number of times that this CPU needed nothing. Alert
readers will note that the rcu "nn" number for a given CPU very
closely matches the rcu_bh "np" number for that same CPU. This

9
Documentation/RCU/whatisRCU.txt
View File

@ -873,7 +873,7 @@ d. Do you need to treat NMI handlers, hardirq handlers,
and code segments with preemption disabled (whether
via preempt_disable(), local_irq_save(), local_bh_disable(),
or some other mechanism) as if they were explicit RCU readers?
If so, you need RCU-sched.
If so, RCU-sched is the only choice that will work for you.
e. Do you need RCU grace periods to complete even in the face
of softirq monopolization of one or more of the CPUs? For
@ -884,7 +884,12 @@ f. Is your workload too update-intensive for normal use of
RCU, but inappropriate for other synchronization mechanisms?
If so, consider SLAB_DESTROY_BY_RCU. But please be careful!
g. Otherwise, use RCU.
g. Do you need read-side critical sections that are respected
even though they are in the middle of the idle loop, during
user-mode execution, or on an offlined CPU? If so, SRCU is the
only choice that will work for you.
h. Otherwise, use RCU.
Of course, this all assumes that you have determined that RCU is in fact
the right tool for your job.

11
Documentation/kernel-parameters.txt
View File

@ -2385,6 +2385,17 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
rcutree.rcu_cpu_stall_timeout= [KNL,BOOT]
Set timeout for RCU CPU stall warning messages.
rcutree.jiffies_till_first_fqs= [KNL,BOOT]
Set delay from grace-period initialization to
first attempt to force quiescent states.
Units are jiffies, minimum value is zero,
and maximum value is HZ.
rcutree.jiffies_till_next_fqs= [KNL,BOOT]
Set delay between subsequent attempts to force
quiescent states. Units are jiffies, minimum
value is one, and maximum value is HZ.
rcutorture.fqs_duration= [KNL,BOOT]
Set duration of force_quiescent_state bursts.

6
arch/alpha/kernel/process.c
View File

@ -28,6 +28,7 @@
#include <linux/tty.h>
#include <linux/console.h>
#include <linux/slab.h>
#include <linux/rcupdate.h>
#include <asm/reg.h>
#include <asm/uaccess.h>
@ -54,9 +55,12 @@ cpu_idle(void)
/* FIXME -- EV6 and LCA45 know how to power down
the CPU. */
rcu_idle_enter();
while (!need_resched())
cpu_relax();
schedule();
rcu_idle_exit();
schedule_preempt_disabled();
}
}

1
arch/alpha/kernel/smp.c
View File

@ -166,6 +166,7 @@ smp_callin(void)
DBGS(("smp_callin: commencing CPU %d current %p active_mm %p\n",
cpuid, current, current->active_mm));
preempt_disable();
/* Do nothing. */
cpu_idle();
}

3
arch/cris/kernel/process.c
View File

@ -25,6 +25,7 @@
#include <linux/elfcore.h>
#include <linux/mqueue.h>
#include <linux/reboot.h>
#include <linux/rcupdate.h>
//#define DEBUG
@ -74,6 +75,7 @@ void cpu_idle (void)
{
/* endless idle loop with no priority at all */
while (1) {
rcu_idle_enter();
while (!need_resched()) {
void (*idle)(void);
/*
@ -86,6 +88,7 @@ void cpu_idle (void)
idle = default_idle;
idle();
}
rcu_idle_exit();
schedule_preempt_disabled();
}
}

3
arch/frv/kernel/process.c
View File

@ -25,6 +25,7 @@
#include <linux/reboot.h>
#include <linux/interrupt.h>
#include <linux/pagemap.h>
#include <linux/rcupdate.h>
#include <asm/asm-offsets.h>
#include <asm/uaccess.h>
@ -69,12 +70,14 @@ void cpu_idle(void)
{
/* endless idle loop with no priority at all */
while (1) {
rcu_idle_enter();
while (!need_resched()) {
check_pgt_cache();
if (!frv_dma_inprogress && idle)
idle();
}
rcu_idle_exit();
schedule_preempt_disabled();
}

3
arch/h8300/kernel/process.c
View File

@ -36,6 +36,7 @@
#include <linux/reboot.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/rcupdate.h>
#include <asm/uaccess.h>
#include <asm/traps.h>
@ -78,8 +79,10 @@ void (*idle)(void) = default_idle;
void cpu_idle(void)
{
while (1) {
rcu_idle_enter();
while (!need_resched())
idle();
rcu_idle_exit();
schedule_preempt_disabled();
}
}

3
arch/ia64/kernel/process.c
View File

@ -29,6 +29,7 @@
#include <linux/kdebug.h>
#include <linux/utsname.h>
#include <linux/tracehook.h>
#include <linux/rcupdate.h>
#include <asm/cpu.h>
#include <asm/delay.h>
@ -279,6 +280,7 @@ cpu_idle (void)
/* endless idle loop with no priority at all */
while (1) {
rcu_idle_enter();
if (can_do_pal_halt) {
current_thread_info()->status &= ~TS_POLLING;
/*
@ -309,6 +311,7 @@ cpu_idle (void)
normal_xtp();
#endif
}
rcu_idle_exit();
schedule_preempt_disabled();
check_pgt_cache();
if (cpu_is_offline(cpu))

3
arch/m32r/kernel/process.c
View File

@ -26,6 +26,7 @@
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/hardirq.h>
#include <linux/rcupdate.h>
#include <asm/io.h>
#include <asm/uaccess.h>
@ -82,6 +83,7 @@ void cpu_idle (void)
{
/* endless idle loop with no priority at all */
while (1) {
rcu_idle_enter();
while (!need_resched()) {
void (*idle)(void) = pm_idle;
@ -90,6 +92,7 @@ void cpu_idle (void)
idle();
}
rcu_idle_exit();
schedule_preempt_disabled();
}
}

3
arch/m68k/kernel/process.c
View File

@ -25,6 +25,7 @@
#include <linux/reboot.h>
#include <linux/init_task.h>
#include <linux/mqueue.h>
#include <linux/rcupdate.h>
#include <asm/uaccess.h>
#include <asm/traps.h>
@ -75,8 +76,10 @@ void cpu_idle(void)
{
/* endless idle loop with no priority at all */
while (1) {
rcu_idle_enter();
while (!need_resched())
idle();
rcu_idle_exit();
schedule_preempt_disabled();
}
}

3
arch/mn10300/kernel/process.c
View File

@ -25,6 +25,7 @@
#include <linux/err.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/rcupdate.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/io.h>
@ -107,6 +108,7 @@ void cpu_idle(void)
{
/* endless idle loop with no priority at all */
for (;;) {
rcu_idle_enter();
while (!need_resched()) {
void (*idle)(void);
@ -121,6 +123,7 @@ void cpu_idle(void)
}
idle();
}
rcu_idle_exit();
schedule_preempt_disabled();
}

3
arch/parisc/kernel/process.c
View File

@ -48,6 +48,7 @@
#include <linux/unistd.h>
#include <linux/kallsyms.h>
#include <linux/uaccess.h>
#include <linux/rcupdate.h>
#include <asm/io.h>
#include <asm/asm-offsets.h>
@ -69,8 +70,10 @@ void cpu_idle(void)
/* endless idle loop with no priority at all */
while (1) {
rcu_idle_enter();
while (!need_resched())
barrier();
rcu_idle_exit();
schedule_preempt_disabled();
check_pgt_cache();
}

4
arch/score/kernel/process.c
View File

@ -27,6 +27,7 @@
#include <linux/reboot.h>
#include <linux/elfcore.h>
#include <linux/pm.h>
#include <linux/rcupdate.h>
void (*pm_power_off)(void);
EXPORT_SYMBOL(pm_power_off);
@ -50,9 +51,10 @@ void __noreturn cpu_idle(void)
{
/* endless idle loop with no priority at all */
while (1) {
rcu_idle_enter();
while (!need_resched())
barrier();
rcu_idle_exit();
schedule_preempt_disabled();
}
}

5
arch/x86/kernel/cpuid.c
View File

@ -199,12 +199,14 @@ static int __init cpuid_init(void)
goto out_chrdev;
}
cpuid_class->devnode = cpuid_devnode;
get_online_cpus();
for_each_online_cpu(i) {
err = cpuid_device_create(i);
if (err != 0)
goto out_class;
}
register_hotcpu_notifier(&cpuid_class_cpu_notifier);
put_online_cpus();
err = 0;
goto out;
@ -214,6 +216,7 @@ out_class:
for_each_online_cpu(i) {
cpuid_device_destroy(i);
}
put_online_cpus();
class_destroy(cpuid_class);
out_chrdev:
__unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid");
@ -225,11 +228,13 @@ static void __exit cpuid_exit(void)
{
int cpu = 0;
get_online_cpus();
for_each_online_cpu(cpu)
cpuid_device_destroy(cpu);
class_destroy(cpuid_class);
__unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid");
unregister_hotcpu_notifier(&cpuid_class_cpu_notifier);
put_online_cpus();
}
module_init(cpuid_init);

5
arch/x86/kernel/msr.c
View File

@ -257,12 +257,14 @@ static int __init msr_init(void)
goto out_chrdev;
}
msr_class->devnode = msr_devnode;
get_online_cpus();
for_each_online_cpu(i) {
err = msr_device_create(i);
if (err != 0)
goto out_class;
}
register_hotcpu_notifier(&msr_class_cpu_notifier);
put_online_cpus();
err = 0;
goto out;
@ -271,6 +273,7 @@ out_class:
i = 0;
for_each_online_cpu(i)
msr_device_destroy(i);
put_online_cpus();
class_destroy(msr_class);
out_chrdev:
__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
@ -281,11 +284,13 @@ out:
static void __exit msr_exit(void)
{
int cpu = 0;
get_online_cpus();
for_each_online_cpu(cpu)
msr_device_destroy(cpu);
class_destroy(msr_class);
__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
unregister_hotcpu_notifier(&msr_class_cpu_notifier);
put_online_cpus();
}
module_init(msr_init);

3
arch/xtensa/kernel/process.c
View File

@ -31,6 +31,7 @@
#include <linux/mqueue.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/rcupdate.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
@ -110,8 +111,10 @@ void cpu_idle(void)
/* endless idle loop with no priority at all */
while (1) {
rcu_idle_enter();
while (!need_resched())
platform_idle();
rcu_idle_exit();
schedule_preempt_disabled();
}
}

266
drivers/infiniband/hw/ehca/ehca_irq.c
View File

@ -42,6 +42,7 @@
*/
#include <linux/slab.h>
#include <linux/smpboot.h>
#include "ehca_classes.h"
#include "ehca_irq.h"
@ -652,7 +653,7 @@ void ehca_tasklet_eq(unsigned long data)
ehca_process_eq((struct ehca_shca*)data, 1);
}
static inline int find_next_online_cpu(struct ehca_comp_pool *pool)
static int find_next_online_cpu(struct ehca_comp_pool *pool)
{
int cpu;
unsigned long flags;
@ -662,17 +663,20 @@ static inline int find_next_online_cpu(struct ehca_comp_pool *pool)
ehca_dmp(cpu_online_mask, cpumask_size(), "");
spin_lock_irqsave(&pool->last_cpu_lock, flags);
cpu = cpumask_next(pool->last_cpu, cpu_online_mask);
if (cpu >= nr_cpu_ids)
cpu = cpumask_first(cpu_online_mask);
pool->last_cpu = cpu;
do {
cpu = cpumask_next(pool->last_cpu, cpu_online_mask);
if (cpu >= nr_cpu_ids)
cpu = cpumask_first(cpu_online_mask);
pool->last_cpu = cpu;
} while (!per_cpu_ptr(pool->cpu_comp_tasks, cpu)->active);
spin_unlock_irqrestore(&pool->last_cpu_lock, flags);
return cpu;
}
static void __queue_comp_task(struct ehca_cq *__cq,
struct ehca_cpu_comp_task *cct)
struct ehca_cpu_comp_task *cct,
struct task_struct *thread)
{
unsigned long flags;
@ -683,7 +687,7 @@ static void __queue_comp_task(struct ehca_cq *__cq,
__cq->nr_callbacks++;
list_add_tail(&__cq->entry, &cct->cq_list);
cct->cq_jobs++;
wake_up(&cct->wait_queue);
wake_up_process(thread);
} else
__cq->nr_callbacks++;
@ -695,6 +699,7 @@ static void queue_comp_task(struct ehca_cq *__cq)
{
int cpu_id;
struct ehca_cpu_comp_task *cct;
struct task_struct *thread;
int cq_jobs;
unsigned long flags;
@ -702,7 +707,8 @@ static void queue_comp_task(struct ehca_cq *__cq)
BUG_ON(!cpu_online(cpu_id));
cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu_id);
BUG_ON(!cct);
thread = *per_cpu_ptr(pool->cpu_comp_threads, cpu_id);
BUG_ON(!cct || !thread);
spin_lock_irqsave(&cct->task_lock, flags);
cq_jobs = cct->cq_jobs;
@ -710,28 +716,25 @@ static void queue_comp_task(struct ehca_cq *__cq)
if (cq_jobs > 0) {
cpu_id = find_next_online_cpu(pool);
cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu_id);
BUG_ON(!cct);
thread = *per_cpu_ptr(pool->cpu_comp_threads, cpu_id);
BUG_ON(!cct || !thread);
}
__queue_comp_task(__cq, cct);
__queue_comp_task(__cq, cct, thread);
}
static void run_comp_task(struct ehca_cpu_comp_task *cct)
{
struct ehca_cq *cq;
unsigned long flags;
spin_lock_irqsave(&cct->task_lock, flags);
while (!list_empty(&cct->cq_list)) {
cq = list_entry(cct->cq_list.next, struct ehca_cq, entry);
spin_unlock_irqrestore(&cct->task_lock, flags);
spin_unlock_irq(&cct->task_lock);
comp_event_callback(cq);
if (atomic_dec_and_test(&cq->nr_events))
wake_up(&cq->wait_completion);
spin_lock_irqsave(&cct->task_lock, flags);
spin_lock_irq(&cct->task_lock);
spin_lock(&cq->task_lock);
cq->nr_callbacks--;
if (!cq->nr_callbacks) {
@ -740,159 +743,76 @@ static void run_comp_task(struct ehca_cpu_comp_task *cct)
}
spin_unlock(&cq->task_lock);
}
spin_unlock_irqrestore(&cct->task_lock, flags);
}
static int comp_task(void *__cct)
{
struct ehca_cpu_comp_task *cct = __cct;
int cql_empty;
DECLARE_WAITQUEUE(wait, current);
set_current_state(TASK_INTERRUPTIBLE);
while (!kthread_should_stop()) {
add_wait_queue(&cct->wait_queue, &wait);
spin_lock_irq(&cct->task_lock);
cql_empty = list_empty(&cct->cq_list);
spin_unlock_irq(&cct->task_lock);
if (cql_empty)
schedule();
else
__set_current_state(TASK_RUNNING);
remove_wait_queue(&cct->wait_queue, &wait);
spin_lock_irq(&cct->task_lock);
cql_empty = list_empty(&cct->cq_list);
spin_unlock_irq(&cct->task_lock);
if (!cql_empty)
run_comp_task(__cct);
set_current_state(TASK_INTERRUPTIBLE);
}
__set_current_state(TASK_RUNNING);
return 0;
}
static struct task_struct *create_comp_task(struct ehca_comp_pool *pool,
int cpu)
{
struct ehca_cpu_comp_task *cct;
cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
spin_lock_init(&cct->task_lock);
INIT_LIST_HEAD(&cct->cq_list);
init_waitqueue_head(&cct->wait_queue);
cct->task = kthread_create_on_node(comp_task, cct, cpu_to_node(cpu),
"ehca_comp/%d", cpu);
return cct->task;
}
static void destroy_comp_task(struct ehca_comp_pool *pool,
int cpu)
{
struct ehca_cpu_comp_task *cct;
struct task_struct *task;
unsigned long flags_cct;
cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
spin_lock_irqsave(&cct->task_lock, flags_cct);
task = cct->task;
cct->task = NULL;
cct->cq_jobs = 0;
spin_unlock_irqrestore(&cct->task_lock, flags_cct);
if (task)
kthread_stop(task);
}
static void __cpuinit take_over_work(struct ehca_comp_pool *pool, int cpu)
static void comp_task_park(unsigned int cpu)
{
struct ehca_cpu_comp_task *cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
struct ehca_cpu_comp_task *target;
struct task_struct *thread;
struct ehca_cq *cq, *tmp;
LIST_HEAD(list);
struct ehca_cq *cq;
unsigned long flags_cct;
spin_lock_irqsave(&cct->task_lock, flags_cct);
spin_lock_irq(&cct->task_lock);
cct->cq_jobs = 0;
cct->active = 0;
list_splice_init(&cct->cq_list, &list);
spin_unlock_irq(&cct->task_lock);
while (!list_empty(&list)) {
cq = list_entry(cct->cq_list.next, struct ehca_cq, entry);
cpu = find_next_online_cpu(pool);
target = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
thread = *per_cpu_ptr(pool->cpu_comp_threads, cpu);
spin_lock_irq(&target->task_lock);
list_for_each_entry_safe(cq, tmp, &list, entry) {
list_del(&cq->entry);
__queue_comp_task(cq, this_cpu_ptr(pool->cpu_comp_tasks));
__queue_comp_task(cq, target, thread);
}
spin_unlock_irqrestore(&cct->task_lock, flags_cct);
spin_unlock_irq(&target->task_lock);
}
static int __cpuinit comp_pool_callback(struct notifier_block *nfb,
unsigned long action,
void *hcpu)
static void comp_task_stop(unsigned int cpu, bool online)
{
unsigned int cpu = (unsigned long)hcpu;
struct ehca_cpu_comp_task *cct;
struct ehca_cpu_comp_task *cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
switch (action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
ehca_gen_dbg("CPU: %x (CPU_PREPARE)", cpu);
if (!create_comp_task(pool, cpu)) {
ehca_gen_err("Can't create comp_task for cpu: %x", cpu);
return notifier_from_errno(-ENOMEM);
}
break;
case CPU_UP_CANCELED:
case CPU_UP_CANCELED_FROZEN:
ehca_gen_dbg("CPU: %x (CPU_CANCELED)", cpu);
cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
kthread_bind(cct->task, cpumask_any(cpu_online_mask));
destroy_comp_task(pool, cpu);
break;
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
ehca_gen_dbg("CPU: %x (CPU_ONLINE)", cpu);
cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
kthread_bind(cct->task, cpu);
wake_up_process(cct->task);
break;
case CPU_DOWN_PREPARE:
case CPU_DOWN_PREPARE_FROZEN:
ehca_gen_dbg("CPU: %x (CPU_DOWN_PREPARE)", cpu);
break;
case CPU_DOWN_FAILED:
case CPU_DOWN_FAILED_FROZEN:
ehca_gen_dbg("CPU: %x (CPU_DOWN_FAILED)", cpu);
break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
ehca_gen_dbg("CPU: %x (CPU_DEAD)", cpu);
destroy_comp_task(pool, cpu);
take_over_work(pool, cpu);
break;
}
return NOTIFY_OK;
spin_lock_irq(&cct->task_lock);
cct->cq_jobs = 0;
cct->active = 0;
WARN_ON(!list_empty(&cct->cq_list));
spin_unlock_irq(&cct->task_lock);
}
static struct notifier_block comp_pool_callback_nb __cpuinitdata = {
.notifier_call = comp_pool_callback,
.priority = 0,
static int comp_task_should_run(unsigned int cpu)
{
struct ehca_cpu_comp_task *cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
return cct->cq_jobs;
}
static void comp_task(unsigned int cpu)
{
struct ehca_cpu_comp_task *cct = this_cpu_ptr(pool->cpu_comp_tasks);
int cql_empty;
spin_lock_irq(&cct->task_lock);
cql_empty = list_empty(&cct->cq_list);
if (!cql_empty) {
__set_current_state(TASK_RUNNING);
run_comp_task(cct);
}
spin_unlock_irq(&cct->task_lock);
}
static struct smp_hotplug_thread comp_pool_threads = {
.thread_should_run = comp_task_should_run,
.thread_fn = comp_task,
.thread_comm = "ehca_comp/%u",
.cleanup = comp_task_stop,
.park = comp_task_park,
};
int ehca_create_comp_pool(void)
{
int cpu;
struct task_struct *task;
int cpu, ret = -ENOMEM;
if (!ehca_scaling_code)
return 0;
@ -905,38 +825,46 @@ int ehca_create_comp_pool(void)
pool->last_cpu = cpumask_any(cpu_online_mask);
pool->cpu_comp_tasks = alloc_percpu(struct ehca_cpu_comp_task);
if (pool->cpu_comp_tasks == NULL) {
kfree(pool);
return -EINVAL;
if (!pool->cpu_comp_tasks)
goto out_pool;
pool->cpu_comp_threads = alloc_percpu(struct task_struct *);
if (!pool->cpu_comp_threads)
goto out_tasks;
for_each_present_cpu(cpu) {
struct ehca_cpu_comp_task *cct;
cct = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
spin_lock_init(&cct->task_lock);
INIT_LIST_HEAD(&cct->cq_list);
}
for_each_online_cpu(cpu) {
task = create_comp_task(pool, cpu);
if (task) {
kthread_bind(task, cpu);
wake_up_process(task);
}
}
comp_pool_threads.store = pool->cpu_comp_threads;
ret = smpboot_register_percpu_thread(&comp_pool_threads);
if (ret)
goto out_threads;
register_hotcpu_notifier(&comp_pool_callback_nb);
pr_info("eHCA scaling code enabled\n");
return ret;
printk(KERN_INFO "eHCA scaling code enabled\n");
return 0;
out_threads:
free_percpu(pool->cpu_comp_threads);
out_tasks:
free_percpu(pool->cpu_comp_tasks);
out_pool:
kfree(pool);
return ret;
}
void ehca_destroy_comp_pool(void)
{
int i;
if (!ehca_scaling_code)
return;
unregister_hotcpu_notifier(&comp_pool_callback_nb);
for_each_online_cpu(i)
destroy_comp_task(pool, i);
smpboot_unregister_percpu_thread(&comp_pool_threads);
free_percpu(pool->cpu_comp_threads);
free_percpu(pool->cpu_comp_tasks);
kfree(pool);
}

6
drivers/infiniband/hw/ehca/ehca_irq.h
View File

@ -58,15 +58,15 @@ void ehca_tasklet_eq(unsigned long data);
void ehca_process_eq(struct ehca_shca *shca, int is_irq);
struct ehca_cpu_comp_task {
wait_queue_head_t wait_queue;
struct list_head cq_list;
struct task_struct *task;
spinlock_t task_lock;
int cq_jobs;
int active;
};
struct ehca_comp_pool {
struct ehca_cpu_comp_task *cpu_comp_tasks;
struct ehca_cpu_comp_task __percpu *cpu_comp_tasks;
struct task_struct * __percpu *cpu_comp_threads;
int last_cpu;
spinlock_t last_cpu_lock;
};

2
include/linux/interrupt.h
View File

@ -430,6 +430,8 @@ enum
NR_SOFTIRQS
};
#define SOFTIRQ_STOP_IDLE_MASK (~(1 << RCU_SOFTIRQ))
/* map softirq index to softirq name. update 'softirq_to_name' in
* kernel/softirq.c when adding a new softirq.
*/

11
include/linux/kthread.h
View File

@ -14,6 +14,11 @@ struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
kthread_create_on_node(threadfn, data, -1, namefmt, ##arg)
struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data),
void *data,
unsigned int cpu,
const char *namefmt);
/**
* kthread_run - create and wake a thread.
* @threadfn: the function to run until signal_pending(current).
@ -34,9 +39,13 @@ struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
void kthread_bind(struct task_struct *k, unsigned int cpu);
int kthread_stop(struct task_struct *k);
int kthread_should_stop(void);
bool kthread_should_stop(void);
bool kthread_should_park(void);
bool kthread_freezable_should_stop(bool *was_frozen);
void *kthread_data(struct task_struct *k);
int kthread_park(struct task_struct *k);
void kthread_unpark(struct task_struct *k);
void kthread_parkme(void);
int kthreadd(void *unused);
extern struct task_struct *kthreadd_task;

6
include/linux/rcupdate.h
View File

@ -210,14 +210,12 @@ extern void exit_rcu(void);
* to nest RCU_NONIDLE() wrappers, but the nesting level is currently
* quite limited. If deeper nesting is required, it will be necessary
* to adjust DYNTICK_TASK_NESTING_VALUE accordingly.
*
* This macro may be used from process-level code only.
*/
#define RCU_NONIDLE(a) \
do { \
rcu_idle_exit(); \
rcu_irq_enter(); \
do { a; } while (0); \
rcu_idle_enter(); \
rcu_irq_exit(); \
} while (0)
/*

43
include/linux/smpboot.h Normal file
View File

@ -0,0 +1,43 @@
#ifndef _LINUX_SMPBOOT_H
#define _LINUX_SMPBOOT_H
#include <linux/types.h>
struct task_struct;
/* Cookie handed to the thread_fn*/
struct smpboot_thread_data;
/**
* struct smp_hotplug_thread - CPU hotplug related thread descriptor
* @store: Pointer to per cpu storage for the task pointers
* @list: List head for core management
* @thread_should_run: Check whether the thread should run or not. Called with
* preemption disabled.
* @thread_fn: The associated thread function
* @setup: Optional setup function, called when the thread gets
* operational the first time
* @cleanup: Optional cleanup function, called when the thread
* should stop (module exit)
* @park: Optional park function, called when the thread is
* parked (cpu offline)
* @unpark: Optional unpark function, called when the thread is
* unparked (cpu online)
* @thread_comm: The base name of the thread
*/
struct smp_hotplug_thread {
struct task_struct __percpu **store;
struct list_head list;
int (*thread_should_run)(unsigned int cpu);
void (*thread_fn)(unsigned int cpu);
void (*setup)(unsigned int cpu);
void (*cleanup)(unsigned int cpu, bool online);
void (*park)(unsigned int cpu);
void (*unpark)(unsigned int cpu);
const char *thread_comm;
};
int smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread);
void smpboot_unregister_percpu_thread(struct smp_hotplug_thread *plug_thread);
int smpboot_thread_schedule(void);
#endif

3
kernel/Makefile
View File

@ -10,7 +10,7 @@ obj-y = fork.o exec_domain.o panic.o printk.o \
kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
hrtimer.o rwsem.o nsproxy.o srcu.o semaphore.o \
notifier.o ksysfs.o cred.o \
async.o range.o groups.o lglock.o
async.o range.o groups.o lglock.o smpboot.o
ifdef CONFIG_FUNCTION_TRACER
# Do not trace debug files and internal ftrace files
@ -46,7 +46,6 @@ obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o
obj-$(CONFIG_RT_MUTEX_TESTER) += rtmutex-tester.o
obj-$(CONFIG_GENERIC_ISA_DMA) += dma.o
obj-$(CONFIG_SMP) += smp.o
obj-$(CONFIG_SMP) += smpboot.o
ifneq ($(CONFIG_SMP),y)
obj-y += up.o
endif

10
kernel/cpu.c
View File

@ -280,12 +280,13 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
__func__, cpu);
goto out_release;
}
smpboot_park_threads(cpu);
err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
if (err) {
/* CPU didn't die: tell everyone. Can't complain. */
smpboot_unpark_threads(cpu);
cpu_notify_nofail(CPU_DOWN_FAILED | mod, hcpu);
goto out_release;
}
BUG_ON(cpu_online(cpu));
@ -354,6 +355,10 @@ static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
goto out;
}
ret = smpboot_create_threads(cpu);
if (ret)
goto out;
ret = __cpu_notify(CPU_UP_PREPARE | mod, hcpu, -1, &nr_calls);
if (ret) {
nr_calls--;
@ -368,6 +373,9 @@ static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
goto out_notify;
BUG_ON(!cpu_online(cpu));
/* Wake the per cpu threads */
smpboot_unpark_threads(cpu);
/* Now call notifier in preparation. */
cpu_notify(CPU_ONLINE | mod, hcpu);

185
kernel/kthread.c
View File

@ -37,11 +37,20 @@ struct kthread_create_info
};
struct kthread {
int should_stop;
unsigned long flags;
unsigned int cpu;
void *data;
struct completion parked;
struct completion exited;
};
enum KTHREAD_BITS {
KTHREAD_IS_PER_CPU = 0,
KTHREAD_SHOULD_STOP,
KTHREAD_SHOULD_PARK,
KTHREAD_IS_PARKED,
};
#define to_kthread(tsk) \
container_of((tsk)->vfork_done, struct kthread, exited)
@ -52,12 +61,28 @@ struct kthread {
* and this will return true. You should then return, and your return
* value will be passed through to kthread_stop().
*/
int kthread_should_stop(void)
bool kthread_should_stop(void)
{
return to_kthread(current)->should_stop;
return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags);
}
EXPORT_SYMBOL(kthread_should_stop);
/**
* kthread_should_park - should this kthread park now?
*
* When someone calls kthread_park() on your kthread, it will be woken
* and this will return true. You should then do the necessary
* cleanup and call kthread_parkme()
*
* Similar to kthread_should_stop(), but this keeps the thread alive
* and in a park position. kthread_unpark() "restarts" the thread and
* calls the thread function again.
*/
bool kthread_should_park(void)
{
return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(current)->flags);
}
/**
* kthread_freezable_should_stop - should this freezable kthread return now?
* @was_frozen: optional out parameter, indicates whether %current was frozen
@ -96,6 +121,24 @@ void *kthread_data(struct task_struct *task)
return to_kthread(task)->data;
}
static void __kthread_parkme(struct kthread *self)
{
__set_current_state(TASK_INTERRUPTIBLE);
while (test_bit(KTHREAD_SHOULD_PARK, &self->flags)) {
if (!test_and_set_bit(KTHREAD_IS_PARKED, &self->flags))
complete(&self->parked);
schedule();
__set_current_state(TASK_INTERRUPTIBLE);
}
clear_bit(KTHREAD_IS_PARKED, &self->flags);
__set_current_state(TASK_RUNNING);
}
void kthread_parkme(void)
{
__kthread_parkme(to_kthread(current));
}
static int kthread(void *_create)
{
/* Copy data: it's on kthread's stack */
@ -105,9 +148,10 @@ static int kthread(void *_create)
struct kthread self;
int ret;
self.should_stop = 0;
self.flags = 0;
self.data = data;
init_completion(&self.exited);
init_completion(&self.parked);
current->vfork_done = &self.exited;
/* OK, tell user we're spawned, wait for stop or wakeup */
@ -117,9 +161,11 @@ static int kthread(void *_create)
schedule();
ret = -EINTR;
if (!self.should_stop)
ret = threadfn(data);
if (!test_bit(KTHREAD_SHOULD_STOP, &self.flags)) {
__kthread_parkme(&self);
ret = threadfn(data);
}
/* we can't just return, we must preserve "self" on stack */
do_exit(ret);
}
@ -172,8 +218,7 @@ static void create_kthread(struct kthread_create_info *create)
* Returns a task_struct or ERR_PTR(-ENOMEM).
*/
struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
void *data,
int node,
void *data, int node,
const char namefmt[],
...)
{
@ -210,6 +255,13 @@ struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
}
EXPORT_SYMBOL(kthread_create_on_node);
static void __kthread_bind(struct task_struct *p, unsigned int cpu)
{
/* It's safe because the task is inactive. */
do_set_cpus_allowed(p, cpumask_of(cpu));
p->flags |= PF_THREAD_BOUND;
}
/**
* kthread_bind - bind a just-created kthread to a cpu.
* @p: thread created by kthread_create().
@ -226,13 +278,111 @@ void kthread_bind(struct task_struct *p, unsigned int cpu)
WARN_ON(1);
return;
}
/* It's safe because the task is inactive. */
do_set_cpus_allowed(p, cpumask_of(cpu));
p->flags |= PF_THREAD_BOUND;
__kthread_bind(p, cpu);
}
EXPORT_SYMBOL(kthread_bind);
/**
* kthread_create_on_cpu - Create a cpu bound kthread
* @threadfn: the function to run until signal_pending(current).
* @data: data ptr for @threadfn.
* @cpu: The cpu on which the thread should be bound,
* @namefmt: printf-style name for the thread. Format is restricted
* to "name.*%u". Code fills in cpu number.
*
* Description: This helper function creates and names a kernel thread
* The thread will be woken and put into park mode.
*/
struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data),
void *data, unsigned int cpu,
const char *namefmt)
{
struct task_struct *p;
p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt,
cpu);
if (IS_ERR(p))
return p;
set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags);
to_kthread(p)->cpu = cpu;
/* Park the thread to get it out of TASK_UNINTERRUPTIBLE state */
kthread_park(p);
return p;
}
static struct kthread *task_get_live_kthread(struct task_struct *k)
{
struct kthread *kthread;
get_task_struct(k);
kthread = to_kthread(k);
/* It might have exited */
barrier();
if (k->vfork_done != NULL)
return kthread;
return NULL;
}
/**
* kthread_unpark - unpark a thread created by kthread_create().
* @k: thread created by kthread_create().
*
* Sets kthread_should_park() for @k to return false, wakes it, and
* waits for it to return. If the thread is marked percpu then its
* bound to the cpu again.
*/
void kthread_unpark(struct task_struct *k)
{
struct kthread *kthread = task_get_live_kthread(k);
if (kthread) {
clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
/*
* We clear the IS_PARKED bit here as we don't wait
* until the task has left the park code. So if we'd
* park before that happens we'd see the IS_PARKED bit
* which might be about to be cleared.
*/
if (test_and_clear_bit(KTHREAD_IS_PARKED, &kthread->flags)) {
if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags))
__kthread_bind(k, kthread->cpu);
wake_up_process(k);
}
}
put_task_struct(k);
}
/**
* kthread_park - park a thread created by kthread_create().
* @k: thread created by kthread_create().
*
* Sets kthread_should_park() for @k to return true, wakes it, and
* waits for it to return. This can also be called after kthread_create()
* instead of calling wake_up_process(): the thread will park without
* calling threadfn().
*
* Returns 0 if the thread is parked, -ENOSYS if the thread exited.
* If called by the kthread itself just the park bit is set.
*/
int kthread_park(struct task_struct *k)
{
struct kthread *kthread = task_get_live_kthread(k);
int ret = -ENOSYS;
if (kthread) {
if (!test_bit(KTHREAD_IS_PARKED, &kthread->flags)) {
set_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
if (k != current) {
wake_up_process(k);
wait_for_completion(&kthread->parked);
}
}
ret = 0;
}
put_task_struct(k);
return ret;
}
/**
* kthread_stop - stop a thread created by kthread_create().
* @k: thread created by kthread_create().
@ -250,16 +400,13 @@ EXPORT_SYMBOL(kthread_bind);
*/
int kthread_stop(struct task_struct *k)
{
struct kthread *kthread;
struct kthread *kthread = task_get_live_kthread(k);
int ret;
trace_sched_kthread_stop(k);
get_task_struct(k);
kthread = to_kthread(k);
barrier(); /* it might have exited */
if (k->vfork_done != NULL) {
kthread->should_stop = 1;
if (kthread) {
set_bit(KTHREAD_SHOULD_STOP, &kthread->flags);
clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
wake_up_process(k);
wait_for_completion(&kthread->exited);
}

4
kernel/rcupdate.c
View File

@ -45,6 +45,7 @@
#include <linux/mutex.h>
#include <linux/export.h>
#include <linux/hardirq.h>
#include <linux/delay.h>
#define CREATE_TRACE_POINTS
#include <trace/events/rcu.h>
@ -81,6 +82,9 @@ void __rcu_read_unlock(void)
} else {
barrier(); /* critical section before exit code. */
t->rcu_read_lock_nesting = INT_MIN;
#ifdef CONFIG_PROVE_RCU_DELAY
udelay(10); /* Make preemption more probable. */
#endif /* #ifdef CONFIG_PROVE_RCU_DELAY */
barrier(); /* assign before ->rcu_read_unlock_special load */
if (unlikely(ACCESS_ONCE(t->rcu_read_unlock_special)))
rcu_read_unlock_special(t);

33
kernel/rcutiny.c
View File

@ -56,25 +56,28 @@ static void __call_rcu(struct rcu_head *head,
static long long rcu_dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
/* Common code for rcu_idle_enter() and rcu_irq_exit(), see kernel/rcutree.c. */
static void rcu_idle_enter_common(long long oldval)
static void rcu_idle_enter_common(long long newval)
{
if (rcu_dynticks_nesting) {
if (newval) {
RCU_TRACE(trace_rcu_dyntick("--=",
oldval, rcu_dynticks_nesting));
rcu_dynticks_nesting, newval));
rcu_dynticks_nesting = newval;
return;
}
RCU_TRACE(trace_rcu_dyntick("Start", oldval, rcu_dynticks_nesting));
RCU_TRACE(trace_rcu_dyntick("Start", rcu_dynticks_nesting, newval));
if (!is_idle_task(current)) {
struct task_struct *idle = idle_task(smp_processor_id());
RCU_TRACE(trace_rcu_dyntick("Error on entry: not idle task",
oldval, rcu_dynticks_nesting));
rcu_dynticks_nesting, newval));
ftrace_dump(DUMP_ALL);
WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
current->pid, current->comm,
idle->pid, idle->comm); /* must be idle task! */
}
rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */
barrier();
rcu_dynticks_nesting = newval;
}
/*
@ -84,17 +87,16 @@ static void rcu_idle_enter_common(long long oldval)
void rcu_idle_enter(void)
{
unsigned long flags;
long long oldval;
long long newval;
local_irq_save(flags);
oldval = rcu_dynticks_nesting;
WARN_ON_ONCE((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0);
if ((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) ==
DYNTICK_TASK_NEST_VALUE)
rcu_dynticks_nesting = 0;
newval = 0;
else
rcu_dynticks_nesting -= DYNTICK_TASK_NEST_VALUE;
rcu_idle_enter_common(oldval);
newval = rcu_dynticks_nesting - DYNTICK_TASK_NEST_VALUE;
rcu_idle_enter_common(newval);
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(rcu_idle_enter);
@ -105,15 +107,15 @@ EXPORT_SYMBOL_GPL(rcu_idle_enter);
void rcu_irq_exit(void)
{
unsigned long flags;
long long oldval;
long long newval;
local_irq_save(flags);
oldval = rcu_dynticks_nesting;
rcu_dynticks_nesting--;
WARN_ON_ONCE(rcu_dynticks_nesting < 0);
rcu_idle_enter_common(oldval);
newval = rcu_dynticks_nesting - 1;
WARN_ON_ONCE(newval < 0);
rcu_idle_enter_common(newval);
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(rcu_irq_exit);
/* Common code for rcu_idle_exit() and rcu_irq_enter(), see kernel/rcutree.c. */
static void rcu_idle_exit_common(long long oldval)
@ -171,6 +173,7 @@ void rcu_irq_enter(void)
rcu_idle_exit_common(oldval);
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(rcu_irq_enter);
#ifdef CONFIG_DEBUG_LOCK_ALLOC

10
kernel/rcutiny_plugin.h
View File

@ -278,7 +278,7 @@ static int rcu_boost(void)
rcu_preempt_ctrlblk.exp_tasks == NULL)
return 0; /* Nothing to boost. */
raw_local_irq_save(flags);
local_irq_save(flags);
/*
* Recheck with irqs disabled: all tasks in need of boosting
@ -287,7 +287,7 @@ static int rcu_boost(void)
*/
if (rcu_preempt_ctrlblk.boost_tasks == NULL &&
rcu_preempt_ctrlblk.exp_tasks == NULL) {
raw_local_irq_restore(flags);
local_irq_restore(flags);
return 0;
}
@ -317,7 +317,7 @@ static int rcu_boost(void)
t = container_of(tb, struct task_struct, rcu_node_entry);
rt_mutex_init_proxy_locked(&mtx, t);
t->rcu_boost_mutex = &mtx;
raw_local_irq_restore(flags);
local_irq_restore(flags);
rt_mutex_lock(&mtx);
rt_mutex_unlock(&mtx); /* Keep lockdep happy. */
@ -991,9 +991,9 @@ static void rcu_trace_sub_qlen(struct rcu_ctrlblk *rcp, int n)
{
unsigned long flags;
raw_local_irq_save(flags);
local_irq_save(flags);
rcp->qlen -= n;
raw_local_irq_restore(flags);
local_irq_restore(flags);
}
/*

159
kernel/rcutorture.c
View File

@ -53,10 +53,11 @@ MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@fre
static int nreaders = -1; /* # reader threads, defaults to 2*ncpus */
static int nfakewriters = 4; /* # fake writer threads */
static int stat_interval; /* Interval between stats, in seconds. */
/* Defaults to "only at end of test". */
static int stat_interval = 60; /* Interval between stats, in seconds. */
/* Zero means "only at end of test". */
static bool verbose; /* Print more debug info. */
static bool test_no_idle_hz; /* Test RCU's support for tickless idle CPUs. */
static bool test_no_idle_hz = true;
/* Test RCU support for tickless idle CPUs. */
static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
static int stutter = 5; /* Start/stop testing interval (in sec) */
static int irqreader = 1; /* RCU readers from irq (timers). */
@ -119,11 +120,11 @@ MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
#define TORTURE_FLAG "-torture:"
#define PRINTK_STRING(s) \
do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
do { pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
#define VERBOSE_PRINTK_STRING(s) \
do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
do { if (verbose) pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
#define VERBOSE_PRINTK_ERRSTRING(s) \
do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
do { if (verbose) pr_alert("%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
static char printk_buf[4096];
@ -176,8 +177,14 @@ static long n_rcu_torture_boosts;
static long n_rcu_torture_timers;
static long n_offline_attempts;
static long n_offline_successes;
static unsigned long sum_offline;
static int min_offline = -1;
static int max_offline;
static long n_online_attempts;
static long n_online_successes;
static unsigned long sum_online;
static int min_online = -1;
static int max_online;
static long n_barrier_attempts;
static long n_barrier_successes;
static struct list_head rcu_torture_removed;
@ -235,7 +242,7 @@ rcutorture_shutdown_notify(struct notifier_block *unused1,
if (fullstop == FULLSTOP_DONTSTOP)
fullstop = FULLSTOP_SHUTDOWN;
else
printk(KERN_WARNING /* but going down anyway, so... */
pr_warn(/* but going down anyway, so... */
"Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
mutex_unlock(&fullstop_mutex);
return NOTIFY_DONE;
@ -248,7 +255,7 @@ rcutorture_shutdown_notify(struct notifier_block *unused1,
static void rcutorture_shutdown_absorb(char *title)
{
if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
printk(KERN_NOTICE
pr_notice(
"rcutorture thread %s parking due to system shutdown\n",
title);
schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
@ -1214,11 +1221,13 @@ rcu_torture_printk(char *page)
n_rcu_torture_boost_failure,
n_rcu_torture_boosts,
n_rcu_torture_timers);
cnt += sprintf(&page[cnt], "onoff: %ld/%ld:%ld/%ld ",
n_online_successes,
n_online_attempts,
n_offline_successes,
n_offline_attempts);
cnt += sprintf(&page[cnt],
"onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
n_online_successes, n_online_attempts,
n_offline_successes, n_offline_attempts,
min_online, max_online,
min_offline, max_offline,
sum_online, sum_offline, HZ);
cnt += sprintf(&page[cnt], "barrier: %ld/%ld:%ld",
n_barrier_successes,
n_barrier_attempts,
@ -1267,7 +1276,7 @@ rcu_torture_stats_print(void)
int cnt;
cnt = rcu_torture_printk(printk_buf);
printk(KERN_ALERT "%s", printk_buf);
pr_alert("%s", printk_buf);
}
/*
@ -1380,20 +1389,20 @@ rcu_torture_stutter(void *arg)
static inline void
rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
{
printk(KERN_ALERT "%s" TORTURE_FLAG
"--- %s: nreaders=%d nfakewriters=%d "
"stat_interval=%d verbose=%d test_no_idle_hz=%d "
"shuffle_interval=%d stutter=%d irqreader=%d "
"fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
"test_boost=%d/%d test_boost_interval=%d "
"test_boost_duration=%d shutdown_secs=%d "
"onoff_interval=%d onoff_holdoff=%d\n",
torture_type, tag, nrealreaders, nfakewriters,
stat_interval, verbose, test_no_idle_hz, shuffle_interval,
stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
test_boost, cur_ops->can_boost,
test_boost_interval, test_boost_duration, shutdown_secs,
onoff_interval, onoff_holdoff);
pr_alert("%s" TORTURE_FLAG
"--- %s: nreaders=%d nfakewriters=%d "
"stat_interval=%d verbose=%d test_no_idle_hz=%d "
"shuffle_interval=%d stutter=%d irqreader=%d "
"fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
"test_boost=%d/%d test_boost_interval=%d "
"test_boost_duration=%d shutdown_secs=%d "
"onoff_interval=%d onoff_holdoff=%d\n",
torture_type, tag, nrealreaders, nfakewriters,
stat_interval, verbose, test_no_idle_hz, shuffle_interval,
stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
test_boost, cur_ops->can_boost,
test_boost_interval, test_boost_duration, shutdown_secs,
onoff_interval, onoff_holdoff);
}
static struct notifier_block rcutorture_shutdown_nb = {
@ -1460,9 +1469,9 @@ rcu_torture_shutdown(void *arg)
!kthread_should_stop()) {
delta = shutdown_time - jiffies_snap;
if (verbose)
printk(KERN_ALERT "%s" TORTURE_FLAG
"rcu_torture_shutdown task: %lu jiffies remaining\n",
torture_type, delta);
pr_alert("%s" TORTURE_FLAG
"rcu_torture_shutdown task: %lu jiffies remaining\n",
torture_type, delta);
schedule_timeout_interruptible(delta);
jiffies_snap = ACCESS_ONCE(jiffies);
}
@ -1490,8 +1499,10 @@ static int __cpuinit
rcu_torture_onoff(void *arg)
{
int cpu;
unsigned long delta;
int maxcpu = -1;
DEFINE_RCU_RANDOM(rand);
unsigned long starttime;
VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
for_each_online_cpu(cpu)
@ -1506,29 +1517,51 @@ rcu_torture_onoff(void *arg)
cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
if (verbose)
printk(KERN_ALERT "%s" TORTURE_FLAG
"rcu_torture_onoff task: offlining %d\n",
torture_type, cpu);
pr_alert("%s" TORTURE_FLAG
"rcu_torture_onoff task: offlining %d\n",
torture_type, cpu);
starttime = jiffies;
n_offline_attempts++;
if (cpu_down(cpu) == 0) {
if (verbose)
printk(KERN_ALERT "%s" TORTURE_FLAG
"rcu_torture_onoff task: offlined %d\n",
torture_type, cpu);
pr_alert("%s" TORTURE_FLAG
"rcu_torture_onoff task: offlined %d\n",
torture_type, cpu);
n_offline_successes++;
delta = jiffies - starttime;
sum_offline += delta;
if (min_offline < 0) {
min_offline = delta;
max_offline = delta;
}
if (min_offline > delta)
min_offline = delta;
if (max_offline < delta)
max_offline = delta;
}
} else if (cpu_is_hotpluggable(cpu)) {
if (verbose)
printk(KERN_ALERT "%s" TORTURE_FLAG
"rcu_torture_onoff task: onlining %d\n",
torture_type, cpu);
pr_alert("%s" TORTURE_FLAG
"rcu_torture_onoff task: onlining %d\n",
torture_type, cpu);
starttime = jiffies;
n_online_attempts++;
if (cpu_up(cpu) == 0) {
if (verbose)
printk(KERN_ALERT "%s" TORTURE_FLAG
"rcu_torture_onoff task: onlined %d\n",
torture_type, cpu);
pr_alert("%s" TORTURE_FLAG
"rcu_torture_onoff task: onlined %d\n",
torture_type, cpu);
n_online_successes++;
delta = jiffies - starttime;
sum_online += delta;
if (min_online < 0) {
min_online = delta;
max_online = delta;
}
if (min_online > delta)
min_online = delta;
if (max_online < delta)
max_online = delta;
}
}
schedule_timeout_interruptible(onoff_interval * HZ);
@ -1593,14 +1626,14 @@ static int __cpuinit rcu_torture_stall(void *args)
if (!kthread_should_stop()) {
stop_at = get_seconds() + stall_cpu;
/* RCU CPU stall is expected behavior in following code. */
printk(KERN_ALERT "rcu_torture_stall start.\n");
pr_alert("rcu_torture_stall start.\n");
rcu_read_lock();
preempt_disable();
while (ULONG_CMP_LT(get_seconds(), stop_at))
continue; /* Induce RCU CPU stall warning. */
preempt_enable();
rcu_read_unlock();
printk(KERN_ALERT "rcu_torture_stall end.\n");
pr_alert("rcu_torture_stall end.\n");
}
rcutorture_shutdown_absorb("rcu_torture_stall");
while (!kthread_should_stop())
@ -1716,12 +1749,12 @@ static int rcu_torture_barrier_init(void)
if (n_barrier_cbs == 0)
return 0;
if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
printk(KERN_ALERT "%s" TORTURE_FLAG
" Call or barrier ops missing for %s,\n",
torture_type, cur_ops->name);
printk(KERN_ALERT "%s" TORTURE_FLAG
" RCU barrier testing omitted from run.\n",
torture_type);
pr_alert("%s" TORTURE_FLAG
" Call or barrier ops missing for %s,\n",
torture_type, cur_ops->name);
pr_alert("%s" TORTURE_FLAG
" RCU barrier testing omitted from run.\n",
torture_type);
return 0;
}
atomic_set(&barrier_cbs_count, 0);
@ -1814,7 +1847,7 @@ rcu_torture_cleanup(void)
mutex_lock(&fullstop_mutex);
rcutorture_record_test_transition();
if (fullstop == FULLSTOP_SHUTDOWN) {
printk(KERN_WARNING /* but going down anyway, so... */
pr_warn(/* but going down anyway, so... */
"Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
mutex_unlock(&fullstop_mutex);
schedule_timeout_uninterruptible(10);
@ -1938,17 +1971,17 @@ rcu_torture_init(void)
break;
}
if (i == ARRAY_SIZE(torture_ops)) {
printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
torture_type);
printk(KERN_ALERT "rcu-torture types:");
pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
torture_type);
pr_alert("rcu-torture types:");
for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
printk(KERN_ALERT " %s", torture_ops[i]->name);
printk(KERN_ALERT "\n");
pr_alert(" %s", torture_ops[i]->name);
pr_alert("\n");
mutex_unlock(&fullstop_mutex);
return -EINVAL;
}
if (cur_ops->fqs == NULL && fqs_duration != 0) {
printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
fqs_duration = 0;
}
if (cur_ops->init)
@ -1996,14 +2029,15 @@ rcu_torture_init(void)
/* Start up the kthreads. */
VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
writer_task = kthread_run(rcu_torture_writer, NULL,
"rcu_torture_writer");
writer_task = kthread_create(rcu_torture_writer, NULL,
"rcu_torture_writer");
if (IS_ERR(writer_task)) {
firsterr = PTR_ERR(writer_task);
VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
writer_task = NULL;
goto unwind;
}
wake_up_process(writer_task);
fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
GFP_KERNEL);
if (fakewriter_tasks == NULL) {
@ -2118,14 +2152,15 @@ rcu_torture_init(void)
}
if (shutdown_secs > 0) {
shutdown_time = jiffies + shutdown_secs * HZ;
shutdown_task = kthread_run(rcu_torture_shutdown, NULL,
"rcu_torture_shutdown");
shutdown_task = kthread_create(rcu_torture_shutdown, NULL,
"rcu_torture_shutdown");
if (IS_ERR(shutdown_task)) {
firsterr = PTR_ERR(shutdown_task);
VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
shutdown_task = NULL;
goto unwind;
}
wake_up_process(shutdown_task);
}
i = rcu_torture_onoff_init();
if (i != 0) {

750
kernel/rcutree.c
View File

File diff suppressed because it is too large Load Diff

46
kernel/rcutree.h
View File

@ -196,12 +196,7 @@ struct rcu_node {
/* Refused to boost: not sure why, though. */
/* This can happen due to race conditions. */
#endif /* #ifdef CONFIG_RCU_BOOST */
struct task_struct *node_kthread_task;
/* kthread that takes care of this rcu_node */
/* structure, for example, awakening the */
/* per-CPU kthreads as needed. */
unsigned int node_kthread_status;
/* State of node_kthread_task for tracing. */
raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp;
} ____cacheline_internodealigned_in_smp;
/*
@ -245,8 +240,6 @@ struct rcu_data {
/* in order to detect GP end. */
unsigned long gpnum; /* Highest gp number that this CPU */
/* is aware of having started. */
unsigned long passed_quiesce_gpnum;
/* gpnum at time of quiescent state. */
bool passed_quiesce; /* User-mode/idle loop etc. */
bool qs_pending; /* Core waits for quiesc state. */
bool beenonline; /* CPU online at least once. */
@ -312,11 +305,13 @@ struct rcu_data {
unsigned long n_rp_cpu_needs_gp;
unsigned long n_rp_gp_completed;
unsigned long n_rp_gp_started;
unsigned long n_rp_need_fqs;
unsigned long n_rp_need_nothing;
/* 6) _rcu_barrier() callback. */
/* 6) _rcu_barrier() and OOM callbacks. */
struct rcu_head barrier_head;
#ifdef CONFIG_RCU_FAST_NO_HZ
struct rcu_head oom_head;
#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
int cpu;
struct rcu_state *rsp;
@ -375,20 +370,17 @@ struct rcu_state {
u8 fqs_state ____cacheline_internodealigned_in_smp;
/* Force QS state. */
u8 fqs_active; /* force_quiescent_state() */
/* is running. */
u8 fqs_need_gp; /* A CPU was prevented from */
/* starting a new grace */
/* period because */
/* force_quiescent_state() */
/* was running. */
u8 boost; /* Subject to priority boost. */
unsigned long gpnum; /* Current gp number. */
unsigned long completed; /* # of last completed gp. */
struct task_struct *gp_kthread; /* Task for grace periods. */
wait_queue_head_t gp_wq; /* Where GP task waits. */
int gp_flags; /* Commands for GP task. */
/* End of fields guarded by root rcu_node's lock. */
raw_spinlock_t onofflock; /* exclude on/offline and */
raw_spinlock_t onofflock ____cacheline_internodealigned_in_smp;
/* exclude on/offline and */
/* starting new GP. */
struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */
/* need a grace period. */
@ -398,16 +390,11 @@ struct rcu_state {
struct rcu_head **orphan_donetail; /* Tail of above. */
long qlen_lazy; /* Number of lazy callbacks. */
long qlen; /* Total number of callbacks. */
struct task_struct *rcu_barrier_in_progress;
/* Task doing rcu_barrier(), */
/* or NULL if no barrier. */
struct mutex barrier_mutex; /* Guards barrier fields. */
atomic_t barrier_cpu_count; /* # CPUs waiting on. */
struct completion barrier_completion; /* Wake at barrier end. */
unsigned long n_barrier_done; /* ++ at start and end of */
/* _rcu_barrier(). */
raw_spinlock_t fqslock; /* Only one task forcing */
/* quiescent states. */
unsigned long jiffies_force_qs; /* Time at which to invoke */
/* force_quiescent_state(). */
unsigned long n_force_qs; /* Number of calls to */
@ -426,6 +413,10 @@ struct rcu_state {
struct list_head flavors; /* List of RCU flavors. */
};
/* Values for rcu_state structure's gp_flags field. */
#define RCU_GP_FLAG_INIT 0x1 /* Need grace-period initialization. */
#define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */
extern struct list_head rcu_struct_flavors;
#define for_each_rcu_flavor(rsp) \
list_for_each_entry((rsp), &rcu_struct_flavors, flavors)
@ -468,7 +459,6 @@ static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
#ifdef CONFIG_HOTPLUG_CPU
static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp,
unsigned long flags);
static void rcu_stop_cpu_kthread(int cpu);
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
static void rcu_print_detail_task_stall(struct rcu_state *rsp);
static int rcu_print_task_stall(struct rcu_node *rnp);
@ -491,15 +481,9 @@ static void invoke_rcu_callbacks_kthread(void);
static bool rcu_is_callbacks_kthread(void);
#ifdef CONFIG_RCU_BOOST
static void rcu_preempt_do_callbacks(void);
static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp,
cpumask_var_t cm);
static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
struct rcu_node *rnp,
int rnp_index);
static void invoke_rcu_node_kthread(struct rcu_node *rnp);
static void rcu_yield(void (*f)(unsigned long), unsigned long arg);
struct rcu_node *rnp);
#endif /* #ifdef CONFIG_RCU_BOOST */
static void rcu_cpu_kthread_setrt(int cpu, int to_rt);
static void __cpuinit rcu_prepare_kthreads(int cpu);
static void rcu_prepare_for_idle_init(int cpu);
static void rcu_cleanup_after_idle(int cpu);

581
kernel/rcutree_plugin.h
View File

@ -25,6 +25,8 @@
*/
#include <linux/delay.h>
#include <linux/oom.h>
#include <linux/smpboot.h>
#define RCU_KTHREAD_PRIO 1
@ -118,7 +120,7 @@ EXPORT_SYMBOL_GPL(rcu_batches_completed);
*/
void rcu_force_quiescent_state(void)
{
force_quiescent_state(&rcu_preempt_state, 0);
force_quiescent_state(&rcu_preempt_state);
}
EXPORT_SYMBOL_GPL(rcu_force_quiescent_state);
@ -136,8 +138,6 @@ static void rcu_preempt_qs(int cpu)
{
struct rcu_data *rdp = &per_cpu(rcu_preempt_data, cpu);
rdp->passed_quiesce_gpnum = rdp->gpnum;
barrier();
if (rdp->passed_quiesce == 0)
trace_rcu_grace_period("rcu_preempt", rdp->gpnum, "cpuqs");
rdp->passed_quiesce = 1;
@ -422,9 +422,11 @@ static void rcu_print_detail_task_stall_rnp(struct rcu_node *rnp)
unsigned long flags;
struct task_struct *t;
if (!rcu_preempt_blocked_readers_cgp(rnp))
return;
raw_spin_lock_irqsave(&rnp->lock, flags);
if (!rcu_preempt_blocked_readers_cgp(rnp)) {
raw_spin_unlock_irqrestore(&rnp->lock, flags);
return;
}
t = list_entry(rnp->gp_tasks,
struct task_struct, rcu_node_entry);
list_for_each_entry_continue(t, &rnp->blkd_tasks, rcu_node_entry)
@ -584,17 +586,23 @@ static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
raw_spin_unlock(&rnp_root->lock); /* irqs still disabled */
}
rnp->gp_tasks = NULL;
rnp->exp_tasks = NULL;
#ifdef CONFIG_RCU_BOOST
/* In case root is being boosted and leaf is not. */
rnp->boost_tasks = NULL;
/*
* In case root is being boosted and leaf was not. Make sure
* that we boost the tasks blocking the current grace period
* in this case.
*/
raw_spin_lock(&rnp_root->lock); /* irqs already disabled */
if (rnp_root->boost_tasks != NULL &&
rnp_root->boost_tasks != rnp_root->gp_tasks)
rnp_root->boost_tasks != rnp_root->gp_tasks &&
rnp_root->boost_tasks != rnp_root->exp_tasks)
rnp_root->boost_tasks = rnp_root->gp_tasks;
raw_spin_unlock(&rnp_root->lock); /* irqs still disabled */
#endif /* #ifdef CONFIG_RCU_BOOST */
rnp->gp_tasks = NULL;
rnp->exp_tasks = NULL;
return retval;
}
@ -676,7 +684,7 @@ void synchronize_rcu(void)
EXPORT_SYMBOL_GPL(synchronize_rcu);
static DECLARE_WAIT_QUEUE_HEAD(sync_rcu_preempt_exp_wq);
static long sync_rcu_preempt_exp_count;
static unsigned long sync_rcu_preempt_exp_count;
static DEFINE_MUTEX(sync_rcu_preempt_exp_mutex);
/*
@ -791,41 +799,55 @@ void synchronize_rcu_expedited(void)
unsigned long flags;
struct rcu_node *rnp;
struct rcu_state *rsp = &rcu_preempt_state;
long snap;
unsigned long snap;
int trycount = 0;
smp_mb(); /* Caller's modifications seen first by other CPUs. */
snap = ACCESS_ONCE(sync_rcu_preempt_exp_count) + 1;
smp_mb(); /* Above access cannot bleed into critical section. */
/*
* Block CPU-hotplug operations. This means that any CPU-hotplug
* operation that finds an rcu_node structure with tasks in the
* process of being boosted will know that all tasks blocking
* this expedited grace period will already be in the process of
* being boosted. This simplifies the process of moving tasks
* from leaf to root rcu_node structures.
*/
get_online_cpus();
/*
* Acquire lock, falling back to synchronize_rcu() if too many
* lock-acquisition failures. Of course, if someone does the
* expedited grace period for us, just leave.
*/
while (!mutex_trylock(&sync_rcu_preempt_exp_mutex)) {
if (ULONG_CMP_LT(snap,
ACCESS_ONCE(sync_rcu_preempt_exp_count))) {
put_online_cpus();
goto mb_ret; /* Others did our work for us. */
}
if (trycount++ < 10) {
udelay(trycount * num_online_cpus());
} else {
put_online_cpus();
synchronize_rcu();
return;
}
if ((ACCESS_ONCE(sync_rcu_preempt_exp_count) - snap) > 0)
goto mb_ret; /* Others did our work for us. */
}
if ((ACCESS_ONCE(sync_rcu_preempt_exp_count) - snap) > 0)
if (ULONG_CMP_LT(snap, ACCESS_ONCE(sync_rcu_preempt_exp_count))) {
put_online_cpus();
goto unlock_mb_ret; /* Others did our work for us. */
}
/* force all RCU readers onto ->blkd_tasks lists. */
synchronize_sched_expedited();
raw_spin_lock_irqsave(&rsp->onofflock, flags);
/* Initialize ->expmask for all non-leaf rcu_node structures. */
rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) {
raw_spin_lock(&rnp->lock); /* irqs already disabled. */
raw_spin_lock_irqsave(&rnp->lock, flags);
rnp->expmask = rnp->qsmaskinit;
raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */
raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
/* Snapshot current state of ->blkd_tasks lists. */
@ -834,7 +856,7 @@ void synchronize_rcu_expedited(void)
if (NUM_RCU_NODES > 1)
sync_rcu_preempt_exp_init(rsp, rcu_get_root(rsp));
raw_spin_unlock_irqrestore(&rsp->onofflock, flags);
put_online_cpus();
/* Wait for snapshotted ->blkd_tasks lists to drain. */
rnp = rcu_get_root(rsp);
@ -1069,6 +1091,16 @@ static void rcu_initiate_boost_trace(struct rcu_node *rnp)
#endif /* #else #ifdef CONFIG_RCU_TRACE */
static void rcu_wake_cond(struct task_struct *t, int status)
{
/*
* If the thread is yielding, only wake it when this
* is invoked from idle
*/
if (status != RCU_KTHREAD_YIELDING || is_idle_task(current))
wake_up_process(t);
}
/*
* Carry out RCU priority boosting on the task indicated by ->exp_tasks
* or ->boost_tasks, advancing the pointer to the next task in the
@ -1140,17 +1172,6 @@ static int rcu_boost(struct rcu_node *rnp)
ACCESS_ONCE(rnp->boost_tasks) != NULL;
}
/*
* Timer handler to initiate waking up of boost kthreads that
* have yielded the CPU due to excessive numbers of tasks to
* boost. We wake up the per-rcu_node kthread, which in turn
* will wake up the booster kthread.
*/
static void rcu_boost_kthread_timer(unsigned long arg)
{
invoke_rcu_node_kthread((struct rcu_node *)arg);
}
/*
* Priority-boosting kthread. One per leaf rcu_node and one for the
* root rcu_node.
@ -1174,8 +1195,9 @@ static int rcu_boost_kthread(void *arg)
else
spincnt = 0;
if (spincnt > 10) {
rnp->boost_kthread_status = RCU_KTHREAD_YIELDING;
trace_rcu_utilization("End boost kthread@rcu_yield");
rcu_yield(rcu_boost_kthread_timer, (unsigned long)rnp);
schedule_timeout_interruptible(2);
trace_rcu_utilization("Start boost kthread@rcu_yield");
spincnt = 0;
}
@ -1191,9 +1213,9 @@ static int rcu_boost_kthread(void *arg)
* kthread to start boosting them. If there is an expedited grace
* period in progress, it is always time to boost.
*
* The caller must hold rnp->lock, which this function releases,
* but irqs remain disabled. The ->boost_kthread_task is immortal,
* so we don't need to worry about it going away.
* The caller must hold rnp->lock, which this function releases.
* The ->boost_kthread_task is immortal, so we don't need to worry
* about it going away.
*/
static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags)
{
@ -1213,8 +1235,8 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags)
rnp->boost_tasks = rnp->gp_tasks;
raw_spin_unlock_irqrestore(&rnp->lock, flags);
t = rnp->boost_kthread_task;
if (t != NULL)
wake_up_process(t);
if (t)
rcu_wake_cond(t, rnp->boost_kthread_status);
} else {
rcu_initiate_boost_trace(rnp);
raw_spin_unlock_irqrestore(&rnp->lock, flags);
@ -1231,8 +1253,10 @@ static void invoke_rcu_callbacks_kthread(void)
local_irq_save(flags);
__this_cpu_write(rcu_cpu_has_work, 1);
if (__this_cpu_read(rcu_cpu_kthread_task) != NULL &&
current != __this_cpu_read(rcu_cpu_kthread_task))
wake_up_process(__this_cpu_read(rcu_cpu_kthread_task));
current != __this_cpu_read(rcu_cpu_kthread_task)) {
rcu_wake_cond(__this_cpu_read(rcu_cpu_kthread_task),
__this_cpu_read(rcu_cpu_kthread_status));
}
local_irq_restore(flags);
}
@ -1245,21 +1269,6 @@ static bool rcu_is_callbacks_kthread(void)
return __get_cpu_var(rcu_cpu_kthread_task) == current;
}
/*
* Set the affinity of the boost kthread. The CPU-hotplug locks are
* held, so no one should be messing with the existence of the boost
* kthread.
*/
static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp,
cpumask_var_t cm)
{
struct task_struct *t;
t = rnp->boost_kthread_task;
if (t != NULL)
set_cpus_allowed_ptr(rnp->boost_kthread_task, cm);
}
#define RCU_BOOST_DELAY_JIFFIES DIV_ROUND_UP(CONFIG_RCU_BOOST_DELAY * HZ, 1000)
/*
@ -1276,15 +1285,19 @@ static void rcu_preempt_boost_start_gp(struct rcu_node *rnp)
* Returns zero if all is well, a negated errno otherwise.
*/
static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
struct rcu_node *rnp,
int rnp_index)
struct rcu_node *rnp)
{
int rnp_index = rnp - &rsp->node[0];
unsigned long flags;
struct sched_param sp;
struct task_struct *t;
if (&rcu_preempt_state != rsp)
return 0;
if (!rcu_scheduler_fully_active || rnp->qsmaskinit == 0)
return 0;
rsp->boost = 1;
if (rnp->boost_kthread_task != NULL)
return 0;
@ -1301,25 +1314,6 @@ static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
return 0;
}
#ifdef CONFIG_HOTPLUG_CPU
/*
* Stop the RCU's per-CPU kthread when its CPU goes offline,.
*/
static void rcu_stop_cpu_kthread(int cpu)
{
struct task_struct *t;
/* Stop the CPU's kthread. */
t = per_cpu(rcu_cpu_kthread_task, cpu);
if (t != NULL) {
per_cpu(rcu_cpu_kthread_task, cpu) = NULL;
kthread_stop(t);
}
}
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
static void rcu_kthread_do_work(void)
{
rcu_do_batch(&rcu_sched_state, &__get_cpu_var(rcu_sched_data));
@ -1327,112 +1321,22 @@ static void rcu_kthread_do_work(void)
rcu_preempt_do_callbacks();
}
/*
* Wake up the specified per-rcu_node-structure kthread.
* Because the per-rcu_node kthreads are immortal, we don't need
* to do anything to keep them alive.
*/
static void invoke_rcu_node_kthread(struct rcu_node *rnp)
{
struct task_struct *t;
t = rnp->node_kthread_task;
if (t != NULL)
wake_up_process(t);
}
/*
* Set the specified CPU's kthread to run RT or not, as specified by
* the to_rt argument. The CPU-hotplug locks are held, so the task
* is not going away.
*/
static void rcu_cpu_kthread_setrt(int cpu, int to_rt)
{
int policy;
struct sched_param sp;
struct task_struct *t;
t = per_cpu(rcu_cpu_kthread_task, cpu);
if (t == NULL)
return;
if (to_rt) {
policy = SCHED_FIFO;
sp.sched_priority = RCU_KTHREAD_PRIO;
} else {
policy = SCHED_NORMAL;
sp.sched_priority = 0;
}
sched_setscheduler_nocheck(t, policy, &sp);
}
/*
* Timer handler to initiate the waking up of per-CPU kthreads that
* have yielded the CPU due to excess numbers of RCU callbacks.
* We wake up the per-rcu_node kthread, which in turn will wake up
* the booster kthread.
*/
static void rcu_cpu_kthread_timer(unsigned long arg)
{
struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, arg);
struct rcu_node *rnp = rdp->mynode;
atomic_or(rdp->grpmask, &rnp->wakemask);
invoke_rcu_node_kthread(rnp);
}
/*
* Drop to non-real-time priority and yield, but only after posting a
* timer that will cause us to regain our real-time priority if we
* remain preempted. Either way, we restore our real-time priority
* before returning.
*/
static void rcu_yield(void (*f)(unsigned long), unsigned long arg)
static void rcu_cpu_kthread_setup(unsigned int cpu)
{
struct sched_param sp;
struct timer_list yield_timer;
int prio = current->rt_priority;
setup_timer_on_stack(&yield_timer, f, arg);
mod_timer(&yield_timer, jiffies + 2);
sp.sched_priority = 0;
sched_setscheduler_nocheck(current, SCHED_NORMAL, &sp);
set_user_nice(current, 19);
schedule();
set_user_nice(current, 0);
sp.sched_priority = prio;
sp.sched_priority = RCU_KTHREAD_PRIO;
sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
del_timer(&yield_timer);
}
/*
* Handle cases where the rcu_cpu_kthread() ends up on the wrong CPU.
* This can happen while the corresponding CPU is either coming online
* or going offline. We cannot wait until the CPU is fully online
* before starting the kthread, because the various notifier functions
* can wait for RCU grace periods. So we park rcu_cpu_kthread() until
* the corresponding CPU is online.
*
* Return 1 if the kthread needs to stop, 0 otherwise.
*
* Caller must disable bh. This function can momentarily enable it.
*/
static int rcu_cpu_kthread_should_stop(int cpu)
static void rcu_cpu_kthread_park(unsigned int cpu)
{
while (cpu_is_offline(cpu) ||
!cpumask_equal(&current->cpus_allowed, cpumask_of(cpu)) ||
smp_processor_id() != cpu) {
if (kthread_should_stop())
return 1;
per_cpu(rcu_cpu_kthread_status, cpu) = RCU_KTHREAD_OFFCPU;
per_cpu(rcu_cpu_kthread_cpu, cpu) = raw_smp_processor_id();
local_bh_enable();
schedule_timeout_uninterruptible(1);
if (!cpumask_equal(&current->cpus_allowed, cpumask_of(cpu)))
set_cpus_allowed_ptr(current, cpumask_of(cpu));
local_bh_disable();
}
per_cpu(rcu_cpu_kthread_cpu, cpu) = cpu;
return 0;
per_cpu(rcu_cpu_kthread_status, cpu) = RCU_KTHREAD_OFFCPU;
}
static int rcu_cpu_kthread_should_run(unsigned int cpu)
{
return __get_cpu_var(rcu_cpu_has_work);
}
/*
@ -1440,138 +1344,35 @@ static int rcu_cpu_kthread_should_stop(int cpu)
* RCU softirq used in flavors and configurations of RCU that do not
* support RCU priority boosting.
*/
static int rcu_cpu_kthread(void *arg)
static void rcu_cpu_kthread(unsigned int cpu)
{
int cpu = (int)(long)arg;
unsigned long flags;
int spincnt = 0;
unsigned int *statusp = &per_cpu(rcu_cpu_kthread_status, cpu);
char work;
char *workp = &per_cpu(rcu_cpu_has_work, cpu);
unsigned int *statusp = &__get_cpu_var(rcu_cpu_kthread_status);
char work, *workp = &__get_cpu_var(rcu_cpu_has_work);
int spincnt;
trace_rcu_utilization("Start CPU kthread@init");
for (;;) {
*statusp = RCU_KTHREAD_WAITING;
trace_rcu_utilization("End CPU kthread@rcu_wait");
rcu_wait(*workp != 0 || kthread_should_stop());
for (spincnt = 0; spincnt < 10; spincnt++) {
trace_rcu_utilization("Start CPU kthread@rcu_wait");
local_bh_disable();
if (rcu_cpu_kthread_should_stop(cpu)) {
local_bh_enable();
break;
}
*statusp = RCU_KTHREAD_RUNNING;
per_cpu(rcu_cpu_kthread_loops, cpu)++;
local_irq_save(flags);
this_cpu_inc(rcu_cpu_kthread_loops);
local_irq_disable();
work = *workp;
*workp = 0;
local_irq_restore(flags);
local_irq_enable();
if (work)
rcu_kthread_do_work();
local_bh_enable();
if (*workp != 0)
spincnt++;
else
spincnt = 0;
if (spincnt > 10) {
*statusp = RCU_KTHREAD_YIELDING;
trace_rcu_utilization("End CPU kthread@rcu_yield");
rcu_yield(rcu_cpu_kthread_timer, (unsigned long)cpu);
trace_rcu_utilization("Start CPU kthread@rcu_yield");
spincnt = 0;
if (*workp == 0) {
trace_rcu_utilization("End CPU kthread@rcu_wait");
*statusp = RCU_KTHREAD_WAITING;
return;
}
}
*statusp = RCU_KTHREAD_STOPPED;
trace_rcu_utilization("End CPU kthread@term");
return 0;
}
/*
* Spawn a per-CPU kthread, setting up affinity and priority.
* Because the CPU hotplug lock is held, no other CPU will be attempting
* to manipulate rcu_cpu_kthread_task. There might be another CPU
* attempting to access it during boot, but the locking in kthread_bind()
* will enforce sufficient ordering.
*
* Please note that we cannot simply refuse to wake up the per-CPU
* kthread because kthreads are created in TASK_UNINTERRUPTIBLE state,
* which can result in softlockup complaints if the task ends up being
* idle for more than a couple of minutes.
*
* However, please note also that we cannot bind the per-CPU kthread to its
* CPU until that CPU is fully online. We also cannot wait until the
* CPU is fully online before we create its per-CPU kthread, as this would
* deadlock the system when CPU notifiers tried waiting for grace
* periods. So we bind the per-CPU kthread to its CPU only if the CPU
* is online. If its CPU is not yet fully online, then the code in
* rcu_cpu_kthread() will wait until it is fully online, and then do
* the binding.
*/
static int __cpuinit rcu_spawn_one_cpu_kthread(int cpu)
{
struct sched_param sp;
struct task_struct *t;
if (!rcu_scheduler_fully_active ||
per_cpu(rcu_cpu_kthread_task, cpu) != NULL)
return 0;
t = kthread_create_on_node(rcu_cpu_kthread,
(void *)(long)cpu,
cpu_to_node(cpu),
"rcuc/%d", cpu);
if (IS_ERR(t))
return PTR_ERR(t);
if (cpu_online(cpu))
kthread_bind(t, cpu);
per_cpu(rcu_cpu_kthread_cpu, cpu) = cpu;
WARN_ON_ONCE(per_cpu(rcu_cpu_kthread_task, cpu) != NULL);
sp.sched_priority = RCU_KTHREAD_PRIO;
sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
per_cpu(rcu_cpu_kthread_task, cpu) = t;
wake_up_process(t); /* Get to TASK_INTERRUPTIBLE quickly. */
return 0;
}
/*
* Per-rcu_node kthread, which is in charge of waking up the per-CPU
* kthreads when needed. We ignore requests to wake up kthreads
* for offline CPUs, which is OK because force_quiescent_state()
* takes care of this case.
*/
static int rcu_node_kthread(void *arg)
{
int cpu;
unsigned long flags;
unsigned long mask;
struct rcu_node *rnp = (struct rcu_node *)arg;
struct sched_param sp;
struct task_struct *t;
for (;;) {
rnp->node_kthread_status = RCU_KTHREAD_WAITING;
rcu_wait(atomic_read(&rnp->wakemask) != 0);
rnp->node_kthread_status = RCU_KTHREAD_RUNNING;
raw_spin_lock_irqsave(&rnp->lock, flags);
mask = atomic_xchg(&rnp->wakemask, 0);
rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */
for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1) {
if ((mask & 0x1) == 0)
continue;
preempt_disable();
t = per_cpu(rcu_cpu_kthread_task, cpu);
if (!cpu_online(cpu) || t == NULL) {
preempt_enable();
continue;
}
per_cpu(rcu_cpu_has_work, cpu) = 1;
sp.sched_priority = RCU_KTHREAD_PRIO;
sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
preempt_enable();
}
}
/* NOTREACHED */
rnp->node_kthread_status = RCU_KTHREAD_STOPPED;
return 0;
*statusp = RCU_KTHREAD_YIELDING;
trace_rcu_utilization("Start CPU kthread@rcu_yield");
schedule_timeout_interruptible(2);
trace_rcu_utilization("End CPU kthread@rcu_yield");
*statusp = RCU_KTHREAD_WAITING;
}
/*
@ -1583,17 +1384,17 @@ static int rcu_node_kthread(void *arg)
* no outgoing CPU. If there are no CPUs left in the affinity set,
* this function allows the kthread to execute on any CPU.
*/
static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
{
struct task_struct *t = rnp->boost_kthread_task;
unsigned long mask = rnp->qsmaskinit;
cpumask_var_t cm;
int cpu;
unsigned long mask = rnp->qsmaskinit;
if (rnp->node_kthread_task == NULL)
if (!t)
return;
if (!alloc_cpumask_var(&cm, GFP_KERNEL))
if (!zalloc_cpumask_var(&cm, GFP_KERNEL))
return;
cpumask_clear(cm);
for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1)
if ((mask & 0x1) && cpu != outgoingcpu)
cpumask_set_cpu(cpu, cm);
@ -1603,62 +1404,36 @@ static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
cpumask_clear_cpu(cpu, cm);
WARN_ON_ONCE(cpumask_weight(cm) == 0);
}
set_cpus_allowed_ptr(rnp->node_kthread_task, cm);
rcu_boost_kthread_setaffinity(rnp, cm);
set_cpus_allowed_ptr(t, cm);
free_cpumask_var(cm);
}
/*
* Spawn a per-rcu_node kthread, setting priority and affinity.
* Called during boot before online/offline can happen, or, if
* during runtime, with the main CPU-hotplug locks held. So only
* one of these can be executing at a time.
*/
static int __cpuinit rcu_spawn_one_node_kthread(struct rcu_state *rsp,
struct rcu_node *rnp)
{
unsigned long flags;
int rnp_index = rnp - &rsp->node[0];
struct sched_param sp;
struct task_struct *t;
if (!rcu_scheduler_fully_active ||
rnp->qsmaskinit == 0)
return 0;
if (rnp->node_kthread_task == NULL) {
t = kthread_create(rcu_node_kthread, (void *)rnp,
"rcun/%d", rnp_index);
if (IS_ERR(t))
return PTR_ERR(t);
raw_spin_lock_irqsave(&rnp->lock, flags);
rnp->node_kthread_task = t;
raw_spin_unlock_irqrestore(&rnp->lock, flags);
sp.sched_priority = 99;
sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
wake_up_process(t); /* get to TASK_INTERRUPTIBLE quickly. */
}
return rcu_spawn_one_boost_kthread(rsp, rnp, rnp_index);
}
static struct smp_hotplug_thread rcu_cpu_thread_spec = {
.store = &rcu_cpu_kthread_task,
.thread_should_run = rcu_cpu_kthread_should_run,
.thread_fn = rcu_cpu_kthread,
.thread_comm = "rcuc/%u",
.setup = rcu_cpu_kthread_setup,
.park = rcu_cpu_kthread_park,
};
/*
* Spawn all kthreads -- called as soon as the scheduler is running.
*/
static int __init rcu_spawn_kthreads(void)
{
int cpu;
struct rcu_node *rnp;
int cpu;
rcu_scheduler_fully_active = 1;
for_each_possible_cpu(cpu) {
for_each_possible_cpu(cpu)
per_cpu(rcu_cpu_has_work, cpu) = 0;
if (cpu_online(cpu))
(void)rcu_spawn_one_cpu_kthread(cpu);
}
BUG_ON(smpboot_register_percpu_thread(&rcu_cpu_thread_spec));
rnp = rcu_get_root(rcu_state);
(void)rcu_spawn_one_node_kthread(rcu_state, rnp);
(void)rcu_spawn_one_boost_kthread(rcu_state, rnp);
if (NUM_RCU_NODES > 1) {
rcu_for_each_leaf_node(rcu_state, rnp)
(void)rcu_spawn_one_node_kthread(rcu_state, rnp);
(void)rcu_spawn_one_boost_kthread(rcu_state, rnp);
}
return 0;
}
@ -1670,11 +1445,8 @@ static void __cpuinit rcu_prepare_kthreads(int cpu)
struct rcu_node *rnp = rdp->mynode;
/* Fire up the incoming CPU's kthread and leaf rcu_node kthread. */
if (rcu_scheduler_fully_active) {
(void)rcu_spawn_one_cpu_kthread(cpu);
if (rnp->node_kthread_task == NULL)
(void)rcu_spawn_one_node_kthread(rcu_state, rnp);
}
if (rcu_scheduler_fully_active)
(void)rcu_spawn_one_boost_kthread(rcu_state, rnp);
}
#else /* #ifdef CONFIG_RCU_BOOST */
@ -1698,19 +1470,7 @@ static void rcu_preempt_boost_start_gp(struct rcu_node *rnp)
{
}
#ifdef CONFIG_HOTPLUG_CPU
static void rcu_stop_cpu_kthread(int cpu)
{
}
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
{
}
static void rcu_cpu_kthread_setrt(int cpu, int to_rt)
static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
{
}
@ -2075,16 +1835,16 @@ static void rcu_prepare_for_idle(int cpu)
#ifdef CONFIG_TREE_PREEMPT_RCU
if (per_cpu(rcu_preempt_data, cpu).nxtlist) {
rcu_preempt_qs(cpu);
force_quiescent_state(&rcu_preempt_state, 0);
force_quiescent_state(&rcu_preempt_state);
}
#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
if (per_cpu(rcu_sched_data, cpu).nxtlist) {
rcu_sched_qs(cpu);
force_quiescent_state(&rcu_sched_state, 0);
force_quiescent_state(&rcu_sched_state);
}
if (per_cpu(rcu_bh_data, cpu).nxtlist) {
rcu_bh_qs(cpu);
force_quiescent_state(&rcu_bh_state, 0);
force_quiescent_state(&rcu_bh_state);
}
/*
@ -2112,6 +1872,88 @@ static void rcu_idle_count_callbacks_posted(void)
__this_cpu_add(rcu_dynticks.nonlazy_posted, 1);
}
/*
* Data for flushing lazy RCU callbacks at OOM time.
*/
static atomic_t oom_callback_count;
static DECLARE_WAIT_QUEUE_HEAD(oom_callback_wq);
/*
* RCU OOM callback -- decrement the outstanding count and deliver the
* wake-up if we are the last one.
*/
static void rcu_oom_callback(struct rcu_head *rhp)
{
if (atomic_dec_and_test(&oom_callback_count))
wake_up(&oom_callback_wq);
}
/*
* Post an rcu_oom_notify callback on the current CPU if it has at
* least one lazy callback. This will unnecessarily post callbacks
* to CPUs that already have a non-lazy callback at the end of their
* callback list, but this is an infrequent operation, so accept some
* extra overhead to keep things simple.
*/
static void rcu_oom_notify_cpu(void *unused)
{
struct rcu_state *rsp;
struct rcu_data *rdp;
for_each_rcu_flavor(rsp) {
rdp = __this_cpu_ptr(rsp->rda);
if (rdp->qlen_lazy != 0) {
atomic_inc(&oom_callback_count);
rsp->call(&rdp->oom_head, rcu_oom_callback);
}
}
}
/*
* If low on memory, ensure that each CPU has a non-lazy callback.
* This will wake up CPUs that have only lazy callbacks, in turn
* ensuring that they free up the corresponding memory in a timely manner.
* Because an uncertain amount of memory will be freed in some uncertain
* timeframe, we do not claim to have freed anything.
*/
static int rcu_oom_notify(struct notifier_block *self,
unsigned long notused, void *nfreed)
{
int cpu;
/* Wait for callbacks from earlier instance to complete. */
wait_event(oom_callback_wq, atomic_read(&oom_callback_count) == 0);
/*
* Prevent premature wakeup: ensure that all increments happen
* before there is a chance of the counter reaching zero.
*/
atomic_set(&oom_callback_count, 1);
get_online_cpus();
for_each_online_cpu(cpu) {
smp_call_function_single(cpu, rcu_oom_notify_cpu, NULL, 1);
cond_resched();
}
put_online_cpus();
/* Unconditionally decrement: no need to wake ourselves up. */
atomic_dec(&oom_callback_count);
return NOTIFY_OK;
}
static struct notifier_block rcu_oom_nb = {
.notifier_call = rcu_oom_notify
};
static int __init rcu_register_oom_notifier(void)
{
register_oom_notifier(&rcu_oom_nb);
return 0;
}
early_initcall(rcu_register_oom_notifier);
#endif /* #else #if !defined(CONFIG_RCU_FAST_NO_HZ) */
#ifdef CONFIG_RCU_CPU_STALL_INFO
@ -2122,11 +1964,15 @@ static void print_cpu_stall_fast_no_hz(char *cp, int cpu)
{
struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
struct timer_list *tltp = &rdtp->idle_gp_timer;
char c;
sprintf(cp, "drain=%d %c timer=%lu",
rdtp->dyntick_drain,
rdtp->dyntick_holdoff == jiffies ? 'H' : '.',
timer_pending(tltp) ? tltp->expires - jiffies : -1);
c = rdtp->dyntick_holdoff == jiffies ? 'H' : '.';
if (timer_pending(tltp))
sprintf(cp, "drain=%d %c timer=%lu",
rdtp->dyntick_drain, c, tltp->expires - jiffies);
else
sprintf(cp, "drain=%d %c timer not pending",
rdtp->dyntick_drain, c);
}
#else /* #ifdef CONFIG_RCU_FAST_NO_HZ */
@ -2194,11 +2040,10 @@ static void zero_cpu_stall_ticks(struct rcu_data *rdp)
/* Increment ->ticks_this_gp for all flavors of RCU. */
static void increment_cpu_stall_ticks(void)
{
__get_cpu_var(rcu_sched_data).ticks_this_gp++;
__get_cpu_var(rcu_bh_data).ticks_this_gp++;
#ifdef CONFIG_TREE_PREEMPT_RCU
__get_cpu_var(rcu_preempt_data).ticks_this_gp++;
#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
struct rcu_state *rsp;
for_each_rcu_flavor(rsp)
__this_cpu_ptr(rsp->rda)->ticks_this_gp++;
}
#else /* #ifdef CONFIG_RCU_CPU_STALL_INFO */

22
kernel/rcutree_trace.c
View File

@ -51,8 +51,8 @@ static int show_rcubarrier(struct seq_file *m, void *unused)
struct rcu_state *rsp;
for_each_rcu_flavor(rsp)
seq_printf(m, "%s: %c bcc: %d nbd: %lu\n",
rsp->name, rsp->rcu_barrier_in_progress ? 'B' : '.',
seq_printf(m, "%s: bcc: %d nbd: %lu\n",
rsp->name,
atomic_read(&rsp->barrier_cpu_count),
rsp->n_barrier_done);
return 0;
@ -86,12 +86,11 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
{
if (!rdp->beenonline)
return;
seq_printf(m, "%3d%cc=%lu g=%lu pq=%d pgp=%lu qp=%d",
seq_printf(m, "%3d%cc=%lu g=%lu pq=%d qp=%d",
rdp->cpu,
cpu_is_offline(rdp->cpu) ? '!' : ' ',
rdp->completed, rdp->gpnum,
rdp->passed_quiesce, rdp->passed_quiesce_gpnum,
rdp->qs_pending);
rdp->passed_quiesce, rdp->qs_pending);
seq_printf(m, " dt=%d/%llx/%d df=%lu",
atomic_read(&rdp->dynticks->dynticks),
rdp->dynticks->dynticks_nesting,
@ -108,11 +107,10 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
rdp->nxttail[RCU_WAIT_TAIL]],
".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
#ifdef CONFIG_RCU_BOOST
seq_printf(m, " kt=%d/%c/%d ktl=%x",
seq_printf(m, " kt=%d/%c ktl=%x",
per_cpu(rcu_cpu_has_work, rdp->cpu),
convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
rdp->cpu)),
per_cpu(rcu_cpu_kthread_cpu, rdp->cpu),
per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff);
#endif /* #ifdef CONFIG_RCU_BOOST */
seq_printf(m, " b=%ld", rdp->blimit);
@ -150,12 +148,11 @@ static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp)
{
if (!rdp->beenonline)
return;
seq_printf(m, "%d,%s,%lu,%lu,%d,%lu,%d",
seq_printf(m, "%d,%s,%lu,%lu,%d,%d",
rdp->cpu,
cpu_is_offline(rdp->cpu) ? "\"N\"" : "\"Y\"",
rdp->completed, rdp->gpnum,
rdp->passed_quiesce, rdp->passed_quiesce_gpnum,
rdp->qs_pending);
rdp->passed_quiesce, rdp->qs_pending);
seq_printf(m, ",%d,%llx,%d,%lu",
atomic_read(&rdp->dynticks->dynticks),
rdp->dynticks->dynticks_nesting,
@ -186,7 +183,7 @@ static int show_rcudata_csv(struct seq_file *m, void *unused)
int cpu;
struct rcu_state *rsp;
seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pgp\",\"pq\",");
seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pq\",");
seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\",");
seq_puts(m, "\"of\",\"qll\",\"ql\",\"qs\"");
#ifdef CONFIG_RCU_BOOST
@ -386,10 +383,9 @@ static void print_one_rcu_pending(struct seq_file *m, struct rcu_data *rdp)
rdp->n_rp_report_qs,
rdp->n_rp_cb_ready,
rdp->n_rp_cpu_needs_gp);
seq_printf(m, "gpc=%ld gps=%ld nf=%ld nn=%ld\n",
seq_printf(m, "gpc=%ld gps=%ld nn=%ld\n",
rdp->n_rp_gp_completed,
rdp->n_rp_gp_started,
rdp->n_rp_need_fqs,
rdp->n_rp_need_nothing);
}

2
kernel/sched/core.c
View File

@ -5604,7 +5604,9 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
migrate_tasks(cpu);
BUG_ON(rq->nr_running != 1); /* the migration thread */
raw_spin_unlock_irqrestore(&rq->lock, flags);
break;
case CPU_DEAD:
calc_load_migrate(rq);
break;
#endif

233
kernel/smpboot.c
View File

@ -1,14 +1,22 @@
/*
* Common SMP CPU bringup/teardown functions
*/
#include <linux/cpu.h>
#include <linux/err.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/export.h>
#include <linux/percpu.h>
#include <linux/kthread.h>
#include <linux/smpboot.h>
#include "smpboot.h"
#ifdef CONFIG_SMP
#ifdef CONFIG_GENERIC_SMP_IDLE_THREAD
/*
* For the hotplug case we keep the task structs around and reuse
@ -65,3 +73,228 @@ void __init idle_threads_init(void)
}
}
#endif
#endif /* #ifdef CONFIG_SMP */
static LIST_HEAD(hotplug_threads);
static DEFINE_MUTEX(smpboot_threads_lock);
struct smpboot_thread_data {
unsigned int cpu;
unsigned int status;
struct smp_hotplug_thread *ht;
};
enum {
HP_THREAD_NONE = 0,
HP_THREAD_ACTIVE,
HP_THREAD_PARKED,
};
/**
* smpboot_thread_fn - percpu hotplug thread loop function
* @data: thread data pointer
*
* Checks for thread stop and park conditions. Calls the necessary
* setup, cleanup, park and unpark functions for the registered
* thread.
*
* Returns 1 when the thread should exit, 0 otherwise.
*/
static int smpboot_thread_fn(void *data)
{
struct smpboot_thread_data *td = data;
struct smp_hotplug_thread *ht = td->ht;
while (1) {
set_current_state(TASK_INTERRUPTIBLE);
preempt_disable();
if (kthread_should_stop()) {
set_current_state(TASK_RUNNING);
preempt_enable();
if (ht->cleanup)
ht->cleanup(td->cpu, cpu_online(td->cpu));
kfree(td);
return 0;
}
if (kthread_should_park()) {
__set_current_state(TASK_RUNNING);
preempt_enable();
if (ht->park && td->status == HP_THREAD_ACTIVE) {
BUG_ON(td->cpu != smp_processor_id());
ht->park(td->cpu);
td->status = HP_THREAD_PARKED;
}
kthread_parkme();
/* We might have been woken for stop */
continue;
}
BUG_ON(td->cpu != smp_processor_id());
/* Check for state change setup */
switch (td->status) {
case HP_THREAD_NONE:
preempt_enable();
if (ht->setup)
ht->setup(td->cpu);
td->status = HP_THREAD_ACTIVE;
preempt_disable();
break;
case HP_THREAD_PARKED:
preempt_enable();
if (ht->unpark)
ht->unpark(td->cpu);
td->status = HP_THREAD_ACTIVE;
preempt_disable();
break;
}
if (!ht->thread_should_run(td->cpu)) {
preempt_enable();
schedule();
} else {
set_current_state(TASK_RUNNING);
preempt_enable();
ht->thread_fn(td->cpu);
}
}
}
static int
__smpboot_create_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
{
struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
struct smpboot_thread_data *td;
if (tsk)
return 0;
td = kzalloc_node(sizeof(*td), GFP_KERNEL, cpu_to_node(cpu));
if (!td)
return -ENOMEM;
td->cpu = cpu;
td->ht = ht;
tsk = kthread_create_on_cpu(smpboot_thread_fn, td, cpu,
ht->thread_comm);
if (IS_ERR(tsk)) {
kfree(td);
return PTR_ERR(tsk);
}
get_task_struct(tsk);
*per_cpu_ptr(ht->store, cpu) = tsk;
return 0;
}
int smpboot_create_threads(unsigned int cpu)
{
struct smp_hotplug_thread *cur;
int ret = 0;
mutex_lock(&smpboot_threads_lock);
list_for_each_entry(cur, &hotplug_threads, list) {
ret = __smpboot_create_thread(cur, cpu);
if (ret)
break;
}
mutex_unlock(&smpboot_threads_lock);
return ret;
}
static void smpboot_unpark_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
{
struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
kthread_unpark(tsk);
}
void smpboot_unpark_threads(unsigned int cpu)
{
struct smp_hotplug_thread *cur;
mutex_lock(&smpboot_threads_lock);
list_for_each_entry(cur, &hotplug_threads, list)
smpboot_unpark_thread(cur, cpu);
mutex_unlock(&smpboot_threads_lock);
}
static void smpboot_park_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
{
struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
if (tsk)
kthread_park(tsk);
}
void smpboot_park_threads(unsigned int cpu)
{
struct smp_hotplug_thread *cur;
mutex_lock(&smpboot_threads_lock);
list_for_each_entry_reverse(cur, &hotplug_threads, list)
smpboot_park_thread(cur, cpu);
mutex_unlock(&smpboot_threads_lock);
}
static void smpboot_destroy_threads(struct smp_hotplug_thread *ht)
{
unsigned int cpu;
/* We need to destroy also the parked threads of offline cpus */
for_each_possible_cpu(cpu) {
struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
if (tsk) {
kthread_stop(tsk);
put_task_struct(tsk);
*per_cpu_ptr(ht->store, cpu) = NULL;
}
}
}
/**
* smpboot_register_percpu_thread - Register a per_cpu thread related to hotplug
* @plug_thread: Hotplug thread descriptor
*
* Creates and starts the threads on all online cpus.
*/
int smpboot_register_percpu_thread(struct smp_hotplug_thread *plug_thread)
{
unsigned int cpu;
int ret = 0;
mutex_lock(&smpboot_threads_lock);
for_each_online_cpu(cpu) {
ret = __smpboot_create_thread(plug_thread, cpu);
if (ret) {
smpboot_destroy_threads(plug_thread);
goto out;
}
smpboot_unpark_thread(plug_thread, cpu);
}
list_add(&plug_thread->list, &hotplug_threads);
out:
mutex_unlock(&smpboot_threads_lock);
return ret;
}
EXPORT_SYMBOL_GPL(smpboot_register_percpu_thread);
/**
* smpboot_unregister_percpu_thread - Unregister a per_cpu thread related to hotplug
* @plug_thread: Hotplug thread descriptor
*
* Stops all threads on all possible cpus.
*/
void smpboot_unregister_percpu_thread(struct smp_hotplug_thread *plug_thread)
{
get_online_cpus();
mutex_lock(&smpboot_threads_lock);
list_del(&plug_thread->list);
smpboot_destroy_threads(plug_thread);
mutex_unlock(&smpboot_threads_lock);
put_online_cpus();
}
EXPORT_SYMBOL_GPL(smpboot_unregister_percpu_thread);

4
kernel/smpboot.h
View File

@ -13,4 +13,8 @@ static inline void idle_thread_set_boot_cpu(void) { }
static inline void idle_threads_init(void) { }
#endif
int smpboot_create_threads(unsigned int cpu);
void smpboot_park_threads(unsigned int cpu);
void smpboot_unpark_threads(unsigned int cpu);
#endif

111
kernel/softirq.c
View File

@ -23,6 +23,7 @@
#include <linux/rcupdate.h>
#include <linux/ftrace.h>
#include <linux/smp.h>
#include <linux/smpboot.h>
#include <linux/tick.h>
#define CREATE_TRACE_POINTS
@ -742,49 +743,22 @@ void __init softirq_init(void)
open_softirq(HI_SOFTIRQ, tasklet_hi_action);
}
static int run_ksoftirqd(void * __bind_cpu)
static int ksoftirqd_should_run(unsigned int cpu)
{
set_current_state(TASK_INTERRUPTIBLE);
return local_softirq_pending();
}
while (!kthread_should_stop()) {
preempt_disable();
if (!local_softirq_pending()) {
schedule_preempt_disabled();
}
__set_current_state(TASK_RUNNING);
while (local_softirq_pending()) {
/* Preempt disable stops cpu going offline.
If already offline, we'll be on wrong CPU:
don't process */
if (cpu_is_offline((long)__bind_cpu))
goto wait_to_die;
local_irq_disable();
if (local_softirq_pending())
__do_softirq();
local_irq_enable();
sched_preempt_enable_no_resched();
cond_resched();
preempt_disable();
rcu_note_context_switch((long)__bind_cpu);
}
preempt_enable();
set_current_state(TASK_INTERRUPTIBLE);
static void run_ksoftirqd(unsigned int cpu)
{
local_irq_disable();
if (local_softirq_pending()) {
__do_softirq();
rcu_note_context_switch(cpu);
local_irq_enable();
cond_resched();
return;
}
__set_current_state(TASK_RUNNING);
return 0;
wait_to_die:
preempt_enable();
/* Wait for kthread_stop */
set_current_state(TASK_INTERRUPTIBLE);
while (!kthread_should_stop()) {
schedule();
set_current_state(TASK_INTERRUPTIBLE);
}
__set_current_state(TASK_RUNNING);
return 0;
local_irq_enable();
}
#ifdef CONFIG_HOTPLUG_CPU
@ -850,50 +824,14 @@ static int __cpuinit cpu_callback(struct notifier_block *nfb,
unsigned long action,
void *hcpu)
{
int hotcpu = (unsigned long)hcpu;
struct task_struct *p;
switch (action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
p = kthread_create_on_node(run_ksoftirqd,
hcpu,
cpu_to_node(hotcpu),
"ksoftirqd/%d", hotcpu);
if (IS_ERR(p)) {
printk("ksoftirqd for %i failed\n", hotcpu);
return notifier_from_errno(PTR_ERR(p));
}
kthread_bind(p, hotcpu);
per_cpu(ksoftirqd, hotcpu) = p;
break;
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
wake_up_process(per_cpu(ksoftirqd, hotcpu));
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
case CPU_UP_CANCELED_FROZEN:
if (!per_cpu(ksoftirqd, hotcpu))
break;
/* Unbind so it can run. Fall thru. */
kthread_bind(per_cpu(ksoftirqd, hotcpu),
cpumask_any(cpu_online_mask));
case CPU_DEAD:
case CPU_DEAD_FROZEN: {
static const struct sched_param param = {
.sched_priority = MAX_RT_PRIO-1
};
p = per_cpu(ksoftirqd, hotcpu);
per_cpu(ksoftirqd, hotcpu) = NULL;
sched_setscheduler_nocheck(p, SCHED_FIFO, &param);
kthread_stop(p);
takeover_tasklets(hotcpu);
case CPU_DEAD_FROZEN:
takeover_tasklets((unsigned long)hcpu);
break;
}
#endif /* CONFIG_HOTPLUG_CPU */
}
}
return NOTIFY_OK;
}
@ -901,14 +839,19 @@ static struct notifier_block __cpuinitdata cpu_nfb = {
.notifier_call = cpu_callback
};
static struct smp_hotplug_thread softirq_threads = {
.store = &ksoftirqd,
.thread_should_run = ksoftirqd_should_run,
.thread_fn = run_ksoftirqd,
.thread_comm = "ksoftirqd/%u",
};
static __init int spawn_ksoftirqd(void)
{
void *cpu = (void *)(long)smp_processor_id();
int err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
BUG_ON(err != NOTIFY_OK);
cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
register_cpu_notifier(&cpu_nfb);
BUG_ON(smpboot_register_percpu_thread(&softirq_threads));
return 0;
}
early_initcall(spawn_ksoftirqd);

3
kernel/time/tick-sched.c
View File

@ -436,7 +436,8 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
if (unlikely(local_softirq_pending() && cpu_online(cpu))) {
static int ratelimit;
if (ratelimit < 10) {
if (ratelimit < 10 &&
(local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) {
printk(KERN_ERR "NOHZ: local_softirq_pending %02x\n",
(unsigned int) local_softirq_pending());
ratelimit++;

269
kernel/watchdog.c
View File

@ -22,6 +22,7 @@
#include <linux/notifier.h>
#include <linux/module.h>
#include <linux/sysctl.h>
#include <linux/smpboot.h>
#include <asm/irq_regs.h>
#include <linux/kvm_para.h>
@ -29,16 +30,18 @@
int watchdog_enabled = 1;
int __read_mostly watchdog_thresh = 10;
static int __read_mostly watchdog_disabled;
static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer);
static DEFINE_PER_CPU(bool, softlockup_touch_sync);
static DEFINE_PER_CPU(bool, soft_watchdog_warn);
static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt);
#ifdef CONFIG_HARDLOCKUP_DETECTOR
static DEFINE_PER_CPU(bool, hard_watchdog_warn);
static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
#endif
@ -248,13 +251,15 @@ static void watchdog_overflow_callback(struct perf_event *event,
__this_cpu_write(hard_watchdog_warn, false);
return;
}
#endif /* CONFIG_HARDLOCKUP_DETECTOR */
static void watchdog_interrupt_count(void)
{
__this_cpu_inc(hrtimer_interrupts);
}
#else
static inline void watchdog_interrupt_count(void) { return; }
#endif /* CONFIG_HARDLOCKUP_DETECTOR */
static int watchdog_nmi_enable(unsigned int cpu);
static void watchdog_nmi_disable(unsigned int cpu);
/* watchdog kicker functions */
static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
@ -327,49 +332,68 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
return HRTIMER_RESTART;
}
/*
* The watchdog thread - touches the timestamp.
*/
static int watchdog(void *unused)
static void watchdog_set_prio(unsigned int policy, unsigned int prio)
{
struct sched_param param = { .sched_priority = prio };
sched_setscheduler(current, policy, &param);
}
static void watchdog_enable(unsigned int cpu)
{
struct sched_param param = { .sched_priority = 0 };
struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);
/* initialize timestamp */
__touch_watchdog();
if (!watchdog_enabled) {
kthread_park(current);
return;
}
/* Enable the perf event */
watchdog_nmi_enable(cpu);
/* kick off the timer for the hardlockup detector */
hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
hrtimer->function = watchdog_timer_fn;
/* done here because hrtimer_start can only pin to smp_processor_id() */
hrtimer_start(hrtimer, ns_to_ktime(get_sample_period()),
HRTIMER_MODE_REL_PINNED);
set_current_state(TASK_INTERRUPTIBLE);
/*
* Run briefly (kicked by the hrtimer callback function) once every
* get_sample_period() seconds (4 seconds by default) to reset the
* softlockup timestamp. If this gets delayed for more than
* 2*watchdog_thresh seconds then the debug-printout triggers in
* watchdog_timer_fn().
*/
while (!kthread_should_stop()) {
__touch_watchdog();
schedule();
if (kthread_should_stop())
break;
set_current_state(TASK_INTERRUPTIBLE);
}
/*
* Drop the policy/priority elevation during thread exit to avoid a
* scheduling latency spike.
*/
__set_current_state(TASK_RUNNING);
sched_setscheduler(current, SCHED_NORMAL, &param);
return 0;
/* initialize timestamp */
watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1);
__touch_watchdog();
}
static void watchdog_disable(unsigned int cpu)
{
struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);
watchdog_set_prio(SCHED_NORMAL, 0);
hrtimer_cancel(hrtimer);
/* disable the perf event */
watchdog_nmi_disable(cpu);
}
static int watchdog_should_run(unsigned int cpu)
{
return __this_cpu_read(hrtimer_interrupts) !=
__this_cpu_read(soft_lockup_hrtimer_cnt);
}
/*
* The watchdog thread function - touches the timestamp.
*
* It only runs once every get_sample_period() seconds (4 seconds by
* default) to reset the softlockup timestamp. If this gets delayed
* for more than 2*watchdog_thresh seconds then the debug-printout
* triggers in watchdog_timer_fn().
*/
static void watchdog(unsigned int cpu)
{
__this_cpu_write(soft_lockup_hrtimer_cnt,
__this_cpu_read(hrtimer_interrupts));
__touch_watchdog();
}
#ifdef CONFIG_HARDLOCKUP_DETECTOR
/*
@ -379,7 +403,7 @@ static int watchdog(void *unused)
*/
static unsigned long cpu0_err;
static int watchdog_nmi_enable(int cpu)
static int watchdog_nmi_enable(unsigned int cpu)
{
struct perf_event_attr *wd_attr;
struct perf_event *event = per_cpu(watchdog_ev, cpu);
@ -433,7 +457,7 @@ out:
return 0;
}
static void watchdog_nmi_disable(int cpu)
static void watchdog_nmi_disable(unsigned int cpu)
{
struct perf_event *event = per_cpu(watchdog_ev, cpu);
@ -447,107 +471,35 @@ static void watchdog_nmi_disable(int cpu)
return;
}
#else
static int watchdog_nmi_enable(int cpu) { return 0; }
static void watchdog_nmi_disable(int cpu) { return; }
static int watchdog_nmi_enable(unsigned int cpu) { return 0; }
static void watchdog_nmi_disable(unsigned int cpu) { return; }
#endif /* CONFIG_HARDLOCKUP_DETECTOR */
/* prepare/enable/disable routines */
static void watchdog_prepare_cpu(int cpu)
{
struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
WARN_ON(per_cpu(softlockup_watchdog, cpu));
hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
hrtimer->function = watchdog_timer_fn;
}
static int watchdog_enable(int cpu)
{
struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
int err = 0;
/* enable the perf event */
err = watchdog_nmi_enable(cpu);
/* Regardless of err above, fall through and start softlockup */
/* create the watchdog thread */
if (!p) {
struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
p = kthread_create_on_node(watchdog, NULL, cpu_to_node(cpu), "watchdog/%d", cpu);
if (IS_ERR(p)) {
pr_err("softlockup watchdog for %i failed\n", cpu);
if (!err) {
/* if hardlockup hasn't already set this */
err = PTR_ERR(p);
/* and disable the perf event */
watchdog_nmi_disable(cpu);
}
goto out;
}
sched_setscheduler(p, SCHED_FIFO, &param);
kthread_bind(p, cpu);
per_cpu(watchdog_touch_ts, cpu) = 0;
per_cpu(softlockup_watchdog, cpu) = p;
wake_up_process(p);
}
out:
return err;
}
static void watchdog_disable(int cpu)
{
struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
/*
* cancel the timer first to stop incrementing the stats
* and waking up the kthread
*/
hrtimer_cancel(hrtimer);
/* disable the perf event */
watchdog_nmi_disable(cpu);
/* stop the watchdog thread */
if (p) {
per_cpu(softlockup_watchdog, cpu) = NULL;
kthread_stop(p);
}
}
/* sysctl functions */
#ifdef CONFIG_SYSCTL
static void watchdog_enable_all_cpus(void)
{
int cpu;
watchdog_enabled = 0;
for_each_online_cpu(cpu)
if (!watchdog_enable(cpu))
/* if any cpu succeeds, watchdog is considered
enabled for the system */
watchdog_enabled = 1;
if (!watchdog_enabled)
pr_err("failed to be enabled on some cpus\n");
unsigned int cpu;
if (watchdog_disabled) {
watchdog_disabled = 0;
for_each_online_cpu(cpu)
kthread_unpark(per_cpu(softlockup_watchdog, cpu));
}
}
static void watchdog_disable_all_cpus(void)
{
int cpu;
unsigned int cpu;
for_each_online_cpu(cpu)
watchdog_disable(cpu);
/* if all watchdogs are disabled, then they are disabled for the system */
watchdog_enabled = 0;
if (!watchdog_disabled) {
watchdog_disabled = 1;
for_each_online_cpu(cpu)
kthread_park(per_cpu(softlockup_watchdog, cpu));
}
}
/*
* proc handler for /proc/sys/kernel/nmi_watchdog,watchdog_thresh
*/
@ -557,73 +509,36 @@ int proc_dowatchdog(struct ctl_table *table, int write,
{
int ret;
if (watchdog_disabled < 0)
return -ENODEV;
ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
if (ret || !write)
goto out;
return ret;
if (watchdog_enabled && watchdog_thresh)
watchdog_enable_all_cpus();
else
watchdog_disable_all_cpus();
out:
return ret;
}
#endif /* CONFIG_SYSCTL */
/*
* Create/destroy watchdog threads as CPUs come and go:
*/
static int __cpuinit
cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
{
int hotcpu = (unsigned long)hcpu;
switch (action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
watchdog_prepare_cpu(hotcpu);
break;
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
if (watchdog_enabled)
watchdog_enable(hotcpu);
break;
#ifdef CONFIG_HOTPLUG_CPU
case CPU_UP_CANCELED:
case CPU_UP_CANCELED_FROZEN:
watchdog_disable(hotcpu);
break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
watchdog_disable(hotcpu);
break;
#endif /* CONFIG_HOTPLUG_CPU */
}
/*
* hardlockup and softlockup are not important enough
* to block cpu bring up. Just always succeed and
* rely on printk output to flag problems.
*/
return NOTIFY_OK;
}
static struct notifier_block __cpuinitdata cpu_nfb = {
.notifier_call = cpu_callback
static struct smp_hotplug_thread watchdog_threads = {
.store = &softlockup_watchdog,
.thread_should_run = watchdog_should_run,
.thread_fn = watchdog,
.thread_comm = "watchdog/%u",
.setup = watchdog_enable,
.park = watchdog_disable,
.unpark = watchdog_enable,
};
void __init lockup_detector_init(void)
{
void *cpu = (void *)(long)smp_processor_id();
int err;
err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
WARN_ON(notifier_to_errno(err));
cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
register_cpu_notifier(&cpu_nfb);
return;
if (smpboot_register_percpu_thread(&watchdog_threads)) {
pr_err("Failed to create watchdog threads, disabled\n");
watchdog_disabled = -ENODEV;
}
}

14
lib/Kconfig.debug
View File

@ -629,6 +629,20 @@ config PROVE_RCU_REPEATEDLY
Say N if you are unsure.
config PROVE_RCU_DELAY
bool "RCU debugging: preemptible RCU race provocation"
depends on DEBUG_KERNEL && PREEMPT_RCU
default n
help
There is a class of races that involve an unlikely preemption
of __rcu_read_unlock() just after ->rcu_read_lock_nesting has
been set to INT_MIN. This feature inserts a delay at that
point to increase the probability of these races.
Say Y to increase probability of preemption of __rcu_read_unlock().
Say N if you are unsure.
config SPARSE_RCU_POINTER
bool "RCU debugging: sparse-based checks for pointer usage"
default n

6
mm/kmemleak.c
View File

@ -1483,13 +1483,11 @@ static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
struct kmemleak_object *prev_obj = v;
struct kmemleak_object *next_obj = NULL;
struct list_head *n = &prev_obj->object_list;
struct kmemleak_object *obj = prev_obj;
++(*pos);
list_for_each_continue_rcu(n, &object_list) {
struct kmemleak_object *obj =
list_entry(n, struct kmemleak_object, object_list);
list_for_each_entry_continue_rcu(obj, &object_list, object_list) {
if (get_object(obj)) {
next_obj = obj;
break;