add jiffies_delta_to_msecs() helper func to calculate the delta between
two times and eventually 0 if negative.
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Matteo Croce <mcroce@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Since the subsequent changes will need a TICK_USEC definition
analogous to TICK_NSEC, rename the existing TICK_USEC as
USER_TICK_USEC, update its users and redefine TICK_USEC
accordingly.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit 7c30f352c8 ("jiffies.h: declare jiffies and jiffies_64 with
____cacheline_aligned_in_smp") removed a section specification from the
jiffies declaration that caused conflicts on some platforms.
Unfortunately this change broke the build for frv:
kernel/built-in.o: In function `__do_softirq': (.text+0x6460): relocation truncated to fit: R_FRV_GPREL12 against symbol
`jiffies' defined in *ABS* section in .tmp_vmlinux1
kernel/built-in.o: In function `__do_softirq': (.text+0x6574): relocation truncated to fit: R_FRV_GPREL12 against symbol
`jiffies' defined in *ABS* section in .tmp_vmlinux1
kernel/built-in.o: In function `pwq_activate_delayed_work': workqueue.c:(.text+0x15b9c): relocation truncated to fit: R_FRV_GPREL12 against
symbol `jiffies' defined in *ABS* section in .tmp_vmlinux1
...
Add __jiffy_arch_data to the declaration of jiffies and use it on frv to
include the section specification. For all other platforms
__jiffy_arch_data (currently) has no effect.
Fixes: 7c30f352c8 ("jiffies.h: declare jiffies and jiffies_64 with ____cacheline_aligned_in_smp")
Link: http://lkml.kernel.org/r/20170516221333.177280-1-mka@chromium.org
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: David Howells <dhowells@redhat.com>
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
jiffies_64 is defined in kernel/time/timer.c with
____cacheline_aligned_in_smp, however this macro is not part of the
declaration of jiffies and jiffies_64 in jiffies.h.
As a result clang generates the following warning:
kernel/time/timer.c:57:26: error: section does not match previous declaration [-Werror,-Wsection]
__visible u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
^
include/linux/cache.h:39:36: note: expanded from macro '__cacheline_aligned_in_smp'
^
include/linux/cache.h:34:4: note: expanded from macro '__cacheline_aligned'
__section__(".data..cacheline_aligned")))
^
include/linux/jiffies.h:77:12: note: previous attribute is here
extern u64 __jiffy_data jiffies_64;
^
include/linux/jiffies.h:70:38: note: expanded from macro '__jiffy_data'
Link: http://lkml.kernel.org/r/20170403190200.70273-1-mka@chromium.org
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Cc: "Jason A . Donenfeld" <Jason@zx2c4.com>
Cc: Grant Grundler <grundler@chromium.org>
Cc: Michael Davidson <md@google.com>
Cc: Greg Hackmann <ghackmann@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This will be needed for the cputime_t to nsec conversion.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Though the time_before and time_after family of functions were nicely
extended to support jiffies64, so that the interface would be consistent,
it was forgotten to also extend the before/after jiffies functions to
support jiffies64. This commit brings the interface to parity between
jiffies and jiffies64, which is quite convenient.
Link: http://lkml.kernel.org/r/20160929033319.12188-1-Jason@zx2c4.com
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull timer updates from Thomas Gleixner:
"Rather large, but nothing exiting:
- new range check for settimeofday() to prevent that boot time
becomes negative.
- fix for file time rounding
- a few simplifications of the hrtimer code
- fix for the proc/timerlist code so the output of clock realtime
timers is accurate
- more y2038 work
- tree wide conversion of clockevent drivers to the new callbacks"
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (88 commits)
hrtimer: Handle failure of tick_init_highres() gracefully
hrtimer: Unconfuse switch_hrtimer_base() a bit
hrtimer: Simplify get_target_base() by returning current base
hrtimer: Drop return code of hrtimer_switch_to_hres()
time: Introduce timespec64_to_jiffies()/jiffies_to_timespec64()
time: Introduce current_kernel_time64()
time: Introduce struct itimerspec64
time: Add the common weak version of update_persistent_clock()
time: Always make sure wall_to_monotonic isn't positive
time: Fix nanosecond file time rounding in timespec_trunc()
timer_list: Add the base offset so remaining nsecs are accurate for non monotonic timers
cris/time: Migrate to new 'set-state' interface
kernel: broadcast-hrtimer: Migrate to new 'set-state' interface
xtensa/time: Migrate to new 'set-state' interface
unicore/time: Migrate to new 'set-state' interface
um/time: Migrate to new 'set-state' interface
sparc/time: Migrate to new 'set-state' interface
sh/localtimer: Migrate to new 'set-state' interface
score/time: Migrate to new 'set-state' interface
s390/time: Migrate to new 'set-state' interface
...
Pull NOHZ updates from Ingo Molnar:
"The main changes, mostly written by Frederic Weisbecker, include:
- Fix some jiffies based cputime assumptions. (No real harm because
the concerned code isn't used by full dynticks.)
- Simplify jiffies <-> usecs conversions. Remove dead code.
- Remove early hacks on nohz full code that avoided messing up idle
nohz internals. Now nohz integrates well full and idle and such
hack have become needless.
- Restart nohz full tick from irq exit. (A simplification and a
preparation for future optimization on scheduler kick to nohz
full)
- Code cleanups.
- Tile driver isolation enhancement on top of nohz. (Chris Metcalf)"
* 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
nohz: Remove useless argument on tick_nohz_task_switch()
nohz: Move tick_nohz_restart_sched_tick() above its users
nohz: Restart nohz full tick from irq exit
nohz: Remove idle task special case
nohz: Prevent tilegx network driver interrupts
alpha: Fix jiffies based cputime assumption
apm32: Fix cputime == jiffies assumption
jiffies: Remove HZ > USEC_PER_SEC special case
The conversion between struct timespec and jiffies is not year 2038
safe on 32bit systems. Introduce timespec64_to_jiffies() and
jiffies_to_timespec64() functions which use struct timespec64 to
make it ready for 2038 issue.
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
HZ never goes much further 1000 and a bit. And if we ever reach one tick
per microsecond, we might be having a problem.
Lets stop maintaining this special case, just leave a paranoid check.
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc; John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
To allow constant folding in usecs_to_jiffies() conditionally calls
the HZ dependent _usecs_to_jiffies() helpers or, when gcc can not
figure out constant folding, __usecs_to_jiffies, which is the renamed
original usecs_to_jiffies() function.
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Joe Perches <joe@perches.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Andrew Hunter <ahh@google.com>
Cc: Paul Turner <pjt@google.com>
Cc: Michal Marek <mmarek@suse.cz>
Link: http://lkml.kernel.org/r/1432832996-12129-2-git-send-email-hofrat@osadl.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Refactor the usecs_to_jiffies conditional code part in time.c and
jiffies.h putting it into conditional functions rather than #ifdefs
to improve readability. This is analogous to the msecs_to_jiffies()
cleanup in commit ca42aaf0c8 ("time: Refactor msecs_to_jiffies")
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Joe Perches <joe@perches.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Andrew Hunter <ahh@google.com>
Cc: Paul Turner <pjt@google.com>
Cc: Michal Marek <mmarek@suse.cz>
Link: http://lkml.kernel.org/r/1432832996-12129-1-git-send-email-hofrat@osadl.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Somehow I missed to clean that up when applying the patches. Fix it up
now.
Reported-by: Joe Perches <joe@perches.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
To allow constant folding in msecs_to_jiffies() conditionally calls
the HZ dependent _msecs_to_jiffies() helpers or, when gcc can not
figure out constant folding, __msecs_to_jiffies which is the renamed
original msecs_to_jiffies() function.
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Joe Perches <joe@perches.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Andrew Hunter <ahh@google.com>
Cc: Paul Turner <pjt@google.com>
Cc: Michal Marek <mmarek@suse.cz>
Link: http://lkml.kernel.org/r/1431951554-5563-3-git-send-email-hofrat@osadl.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Refactor the msecs_to_jiffies conditional code part in time.c and
jiffies.h putting it into conditional functions rather than #ifdefs
to improve readability.
[ tglx: Verified that there is no binary code change ]
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Joe Perches <joe@perches.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Andrew Hunter <ahh@google.com>
Cc: Paul Turner <pjt@google.com>
Cc: Michal Marek <mmarek@suse.cz>
Link: http://lkml.kernel.org/r/1431951554-5563-2-git-send-email-hofrat@osadl.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
timeval_to_jiffies tried to round a timeval up to an integral number
of jiffies, but the logic for doing so was incorrect: intervals
corresponding to exactly N jiffies would become N+1. This manifested
itself particularly repeatedly stopping/starting an itimer:
setitimer(ITIMER_PROF, &val, NULL);
setitimer(ITIMER_PROF, NULL, &val);
would add a full tick to val, _even if it was exactly representable in
terms of jiffies_ (say, the result of a previous rounding.) Doing
this repeatedly would cause unbounded growth in val. So fix the math.
Here's what was wrong with the conversion: we essentially computed
(eliding seconds)
jiffies = usec * (NSEC_PER_USEC/TICK_NSEC)
by using scaling arithmetic, which took the best approximation of
NSEC_PER_USEC/TICK_NSEC with denominator of 2^USEC_JIFFIE_SC =
x/(2^USEC_JIFFIE_SC), and computed:
jiffies = (usec * x) >> USEC_JIFFIE_SC
and rounded this calculation up in the intermediate form (since we
can't necessarily exactly represent TICK_NSEC in usec.) But the
scaling arithmetic is a (very slight) *over*approximation of the true
value; that is, instead of dividing by (1 usec/ 1 jiffie), we
effectively divided by (1 usec/1 jiffie)-epsilon (rounding
down). This would normally be fine, but we want to round timeouts up,
and we did so by adding 2^USEC_JIFFIE_SC - 1 before the shift; this
would be fine if our division was exact, but dividing this by the
slightly smaller factor was equivalent to adding just _over_ 1 to the
final result (instead of just _under_ 1, as desired.)
In particular, with HZ=1000, we consistently computed that 10000 usec
was 11 jiffies; the same was true for any exact multiple of
TICK_NSEC.
We could possibly still round in the intermediate form, adding
something less than 2^USEC_JIFFIE_SC - 1, but easier still is to
convert usec->nsec, round in nanoseconds, and then convert using
time*spec*_to_jiffies. This adds one constant multiplication, and is
not observably slower in microbenchmarks on recent x86 hardware.
Tested: the following program:
int main() {
struct itimerval zero = {{0, 0}, {0, 0}};
/* Initially set to 10 ms. */
struct itimerval initial = zero;
initial.it_interval.tv_usec = 10000;
setitimer(ITIMER_PROF, &initial, NULL);
/* Save and restore several times. */
for (size_t i = 0; i < 10; ++i) {
struct itimerval prev;
setitimer(ITIMER_PROF, &zero, &prev);
/* on old kernels, this goes up by TICK_USEC every iteration */
printf("previous value: %ld %ld %ld %ld\n",
prev.it_interval.tv_sec, prev.it_interval.tv_usec,
prev.it_value.tv_sec, prev.it_value.tv_usec);
setitimer(ITIMER_PROF, &prev, NULL);
}
return 0;
}
Cc: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul Turner <pjt@google.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Reviewed-by: Paul Turner <pjt@google.com>
Reported-by: Aaron Jacobs <jacobsa@google.com>
Signed-off-by: Andrew Hunter <ahh@google.com>
[jstultz: Tweaked to apply to 3.17-rc]
Signed-off-by: John Stultz <john.stultz@linaro.org>
While calculating the scheduler tick max deferment, the delta is
converted from microseconds to nanoseconds through a multiplication
against NSEC_PER_USEC.
But this microseconds operand is an unsigned int, thus the result may
likely overflow. The result is cast to u64 but only once the operation
is completed, which is too late to avoid overflown result.
This is currently not a problem because the scheduler tick max deferment
is 1 second. But this may become an issue as we plan to make this
value tunable.
So lets fix this by casting the usecs value to u64 before multiplying by
NSECS_PER_USEC.
Also to prevent from this kind of mistake to happen again, move this
ad-hoc jiffies -> nsecs conversion to a new helper.
Signed-off-by: Kevin Hilman <khilman@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alex Shi <alex.shi@linaro.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Kevin Hilman <khilman@linaro.org>
Link: http://lkml.kernel.org/r/1387315388-31676-2-git-send-email-khilman@linaro.org
[move ad-hoc conversion to jiffies_to_nsecs helper]
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
According to the C standard 3.4.3p3, overflow of a signed integer results
in undefined behavior. This commit therefore changes the definitions
of time_after(), time_after_eq(), time_after64(), and time_after_eq64()
to avoid this undefined behavior. The trick is that the subtraction
is done using unsigned arithmetic, which according to 6.2.5p9 cannot
overflow because it is defined as modulo arithmetic. This has the added
(though admittedly quite small) benefit of shortening four lines of code
by four characters each.
Note that the C standard considers the cast from unsigned to
signed to be implementation-defined, see 6.3.1.3p3. However, on a
two's-complement system, an implementation that defines anything other
than a reinterpretation of the bits is free to come to me, and I will be
happy to act as a witness for its being committed to an insane asylum.
(Although I have nothing against saturating arithmetic or signals in some
cases, these things really should not be the default when compiling an
operating-system kernel.)
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Kevin Easton <kevin@guarana.org>
[ paulmck: Included time_after64() and time_after_eq64(), as suggested
by Eric Dumazet, also fixed commit message.]
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Time in range will fail safely if we move to a different cpu with an
extremely large clock skew.
Add time_in_range64() and convert lls to use it.
changelog:
v2
- fixed double call to sched_clock in can_poll_ll
- fixed checkpatchisms
Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Nothing outside of the timekeeping core needs that lock.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Now that timekeeping is protected by its own locks, rename
the xtime_lock to jifffies_lock to better describe what it
protects.
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Pull timer core update from Thomas Gleixner:
- Bug fixes (one for a longstanding dead loop issue)
- Rework of time related vsyscalls
- Alarm timer updates
- Jiffies updates to remove compile time dependencies
* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
timekeeping: Cast raw_interval to u64 to avoid shift overflow
timers: Fix endless looping between cascade() and internal_add_timer()
time/jiffies: bring back unconditional LATCH definition
time: Convert x86_64 to using new update_vsyscall
time: Only do nanosecond rounding on GENERIC_TIME_VSYSCALL_OLD systems
time: Introduce new GENERIC_TIME_VSYSCALL
time: Convert CONFIG_GENERIC_TIME_VSYSCALL to CONFIG_GENERIC_TIME_VSYSCALL_OLD
time: Move update_vsyscall definitions to timekeeper_internal.h
time: Move timekeeper structure to timekeeper_internal.h for vsyscall changes
jiffies: Remove compile time assumptions about CLOCK_TICK_RATE
jiffies: Kill unused TICK_USEC_TO_NSEC
alarmtimer: Rename alarmtimer_remove to alarmtimer_dequeue
alarmtimer: Remove unused helpers & defines
alarmtimer: Use hrtimer per-alarm instead of per-base
alarmtimer: Implement minimum alarm interval for allowing suspend
Patch a7ea3bbf5d "time/jiffies: Allow CLOCK_TICK_RATE to be undefined"
breaks the compilation of targets that rely on the LATCH definition,
because of recursive header file inclusion not defining CLOCK_TICK_RATE
before it is checked here.
This fixes the problem by moving LATCH back to where it was, but it
seems that there are still cases where SHIFTED_HZ is defined incorrectly
because of the same problem. Need to investigate further.
Without this patch, building h7201_defconfig results in:
arch/arm/mach-h720x/common.c: In function 'h720x_gettimeoffset':
arch/arm/mach-h720x/common.c:50:73: error: 'LATCH' undeclared (first use in this function)
arch/arm/mach-h720x/common.c:50:73: note: each undeclared identifier is reported only once for each function it appears in
arch/arm/mach-h720x/common.c:51:1: warning: control reaches end of non-void function [-Wreturn-type]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
CLOCK_TICK_RATE is used to accurately caclulate exactly how
a tick will be at a given HZ.
This is useful, because while we'd expect NSEC_PER_SEC/HZ,
the underlying hardware will have some granularity limit,
so we won't be able to have exactly HZ ticks per second.
This slight error can cause timekeeping quality problems
when using the jiffies or other jiffies driven clocksources.
Thus we currently use compile time CLOCK_TICK_RATE value to
generate SHIFTED_HZ and NSEC_PER_JIFFIES, which we then use
to adjust the jiffies clocksource to correct this error.
Unfortunately though, since CLOCK_TICK_RATE is a compile
time value, and the jiffies clocksource is registered very
early during boot, there are a number of cases where there
are different possible hardware timers that have different
tick rates. This causes problems in cases like ARM where
there are numerous different types of hardware, each having
their own compile-time CLOCK_TICK_RATE, making it hard to
accurately support different hardware with a single kernel.
For the most part, this doesn't matter all that much, as not
too many systems actually utilize the jiffies or jiffies driven
clocksource. Usually there are other highres clocksources
who's granularity error is negligable.
Even so, we have some complicated calcualtions that we do
everywhere to handle these edge cases.
This patch removes the compile time SHIFTED_HZ value, and
introduces a register_refined_jiffies() function. This results
in the default jiffies clock as being assumed a perfect HZ
freq, and allows archtectures that care about jiffies accuracy
to call register_refined_jiffies() with the tick rate, specified
dynamically at boot.
This allows us, where necessary, to not have a compile time
CLOCK_TICK_RATE constant, simplifies the jiffies code, and
still provides a way to have an accurate jiffies clock.
NOTE: Since this patch does not add register_refinied_jiffies()
calls for every arch, it may cause time quality regressions
in some cases. Its likely these will not be noticable, but
if they are an issue, adding the following to the end of
setup_arch() should resolve the regression:
register_refinied_jiffies(CLOCK_TICK_RATE)
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
No one is using TICK_USEC_TO_NSEC, so kill it.
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Various /proc/net files sometimes report crazy timer values, expressed
in clock_t units.
This happens when an expired timer delta (expires - jiffies) is passed
to jiffies_to_clock_t().
This function has an overflow in :
return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
commit cbbc719fcc (time: Change jiffies_to_clock_t() argument type
to unsigned long) only got around the problem.
As we cant output negative values in /proc/net/tcp without breaking
various tools, I suggest adding a jiffies_delta_to_clock_t() wrapper
that caps the negative delta to a 0 value.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Maciej Żenczykowski <maze@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: hank <pyu@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Ingo noted that ACTHZ is a confusing name, and requested it
be renamed, so this patch renames ACTHZ to SHIFTED_HZ to
better describe it.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1343414893-45779-3-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
CLOCK_TICK_RATE is a legacy constant that defines the timer
device's granularity. On hardware with particularly coarse
granularity, this constant is used to reduce accumulated
time error when using jiffies as a clocksource, by calculating
the hardware's actual tick length rather then just assuming
it is 1sec/HZ.
However, for the most part this is unnecessary, as most modern
systems don't use jiffies for their clocksource, and their
tick device is sufficiently fine grained to avoid major error.
Thus, this patch allows an architecture to not define
CLOCK_TICK_RATE, in which case ACTHZ defaults to (HZ << 8).
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
[ Commit log & intention tweaks ]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1343414893-45779-2-git-send-email-john.stultz@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The parameter's origin type is long. On an i386 architecture, it can
easily be larger than 0x80000000, causing this function to convert it
to a sign-extended u64 type.
Change the type to unsigned long so we get the correct result.
Signed-off-by: hank <pyu@redhat.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: <stable@kernel.org>
[ build fix ]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add nsecs_to_cputime64 interface. This is used in following patches that
updates cpu irq stat based on ns granularity info in IRQ_TIME_ACCOUNTING.
Tested-by: Shaun Ruffell <sruffell@digium.com>
Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1292980144-28796-3-git-send-email-venki@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Use of msecs_to_jiffies() for nsecs_to_cputime() have some
problems:
- The type of msecs_to_jiffies()'s argument is unsigned int, so
it cannot convert msecs greater than UINT_MAX = about 49.7 days.
- msecs_to_jiffies() returns MAX_JIFFY_OFFSET if MSB of argument
is set, assuming that input was negative value. So it cannot
convert msecs greater than INT_MAX = about 24.8 days too.
This patch defines a new function nsecs_to_jiffies() that can
deal greater values, and that can deal all incoming values as
unsigned.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Spencer Candland <spencer@bluehost.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Amrico Wang <xiyou.wangcong@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <johnstul@linux.vnet.ibm.com>
LKML-Reference: <4B0E16E7.5070307@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Hi.
I've been looking at a bugzilla which describes a problem where
a customer was advised to use either the "noac" or "actimeo=0"
mount options to solve a consistency problem that they were
seeing in the file attributes. It turned out that this solution
did not work reliably for them because sometimes, the local
attribute cache was believed to be valid and not timed out.
(With an attribute cache timeout of 0, the cache should always
appear to be timed out.)
In looking at this situation, it appears to me that the problem
is that the attribute cache timeout code has an off-by-one
error in it. It is assuming that the cache is valid in the
region, [read_cache_jiffies, read_cache_jiffies + attrtimeo]. The
cache should be considered valid only in the region,
[read_cache_jiffies, read_cache_jiffies + attrtimeo). With this
change, the options, "noac" and "actimeo=0", work as originally
expected.
This problem was previously addressed by special casing the
attrtimeo == 0 case. However, since the problem is only an off-
by-one error, the cleaner solution is address the off-by-one
error and thus, not require the special case.
Thanx...
ps
Signed-off-by: Peter Staubach <staubach@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
x86 is the only arch right now, which provides an optimized for
div_long_long_rem and it has the downside that one has to be very careful that
the divide doesn't overflow.
The API is a little akward, as the arguments for the unsigned divide are
signed. The signed version also doesn't handle a negative divisor and
produces worse code on 64bit archs.
There is little incentive to keep this API alive, so this converts the few
users to the new API.
Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/juhl/trivial: (24 commits)
DOC: A couple corrections and clarifications in USB doc.
Generate a slightly more informative error msg for bad HZ
fix typo "is" -> "if" in Makefile
ext*: spelling fix prefered -> preferred
DOCUMENTATION: Use newer DEFINE_SPINLOCK macro in docs.
KEYS: Fix the comment to match the file name in rxrpc-type.h.
RAID: remove trailing space from printk line
DMA engine: typo fixes
Remove unused MAX_NODES_SHIFT
MAINTAINERS: Clarify access to OCFS2 development mailing list.
V4L: Storage class should be before const qualifier (sn9c102)
V4L: Storage class should be before const qualifier
sonypi: Storage class should be before const qualifier
intel_menlow: Storage class should be before const qualifier
DVB: Storage class should be before const qualifier
arm: Storage class should be before const qualifier
ALSA: Storage class should be before const qualifier
acpi: Storage class should be before const qualifier
firmware_sample_driver.c: fix coding style
MAINTAINERS: Add ati_remote2 driver
...
Fixed up trivial conflicts in firmware_sample_driver.c
Generate a slightly more informative error msg for bad HZ
in include/linux/jiffies.h
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Most of time_after like macros usages just compare jiffies and another number,
so here add some time_is_* macros for convenience.
Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Fix typo in comments.
BTW: I have to fix coding style in arch/ia64/kernel/time.c also, otherwise
checkpatch.pl will be complaining.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For some crazy reason (trying to work around hw problem in i810) I wanted
to use HZ around 4000.
Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Optionally add a boot delay after each kernel printk() call, crudely
measured in milliseconds, with a maximum delay of 10 seconds per printk.
Enable CONFIG_BOOT_PRINTK_DELAY=y and then add (e.g.):
"lpj=loops_per_jiffy boot_delay=100"
to the kernel command line.
It has been useful in cases like "during boot, my machine just reboots or the
screen goes black" by slowing down printk, (and adding initcall_debug), we can
usually see the last thing that happened before the lights went out which is
usually a valuable clue.
[akpm@linux-foundation.org: not all architectures implement CONFIG_HZ]
[akpm@linux-foundation.org: fix lots of stuff]
[bunk@stusta.de: kernel/printk.c: make 2 variables static]
[heiko.carstens@de.ibm.com: fix slow down printk on boot compile error]
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* git://git.linux-nfs.org/pub/linux/nfs-2.6: (131 commits)
NFSv4: Fix a typo in nfs_inode_reclaim_delegation
NFS: Add a boot parameter to disable 64 bit inode numbers
NFS: nfs_refresh_inode should clear cache_validity flags on success
NFS: Fix a connectathon regression in NFSv3 and NFSv4
NFS: Use nfs_refresh_inode() in ops that aren't expected to change the inode
SUNRPC: Don't call xprt_release in call refresh
SUNRPC: Don't call xprt_release() if call_allocate fails
SUNRPC: Fix buggy UDP transmission
[23/37] Clean up duplicate includes in
[2.6 patch] net/sunrpc/rpcb_clnt.c: make struct rpcb_program static
SUNRPC: Use correct type in buffer length calculations
SUNRPC: Fix default hostname created in rpc_create()
nfs: add server port to rpc_pipe info file
NFS: Get rid of some obsolete macros
NFS: Simplify filehandle revalidation
NFS: Ensure that nfs_link() returns a hashed dentry
NFS: Be strict about dentry revalidation when doing exclusive create
NFS: Don't zap the readdir caches upon error
NFS: Remove the redundant nfs_reval_fsid()
NFSv3: Always use directory post-op attributes in nfs3_proc_lookup
...
Fix up trivial conflict due to sock_owned_by_user() cleanup manually in
net/sunrpc/xprtsock.c
The x86 hpet cleanups allow removal of some unused macros.
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
I would like to discuss the idea that the current checks for attribute
timeout using time_after are inadequate for 32bit architectures, since
time_after works correctly only when the two timestamps being compared
are within 2^31 jiffies of each other. The signed overflow caused by
comparing values more than 2^31 jiffies apart will flip the result,
causing incorrect assumptions of validity.
2^31 jiffies is a fairly large period of time (~25 days) when compared
to the lifetime of most kernel data structures, but for long lived NFS
mounts that can sit idle for months (think that for some reason autofs
cannot be used), it is easy to compare inode attribute timestamps with
very disparate or even bogus values (as in when jiffies have wrapped
many times, where the comparison doesn't even make sense).
Currently the code tests for attribute timeout by simply adding the
desired amount of jiffies to the stored timestamp and comparing that
with the current timestamp of obtained attribute data with time_after.
This is incorrect, as it returns true for the desired timeout period
and another full 2^31 range of jiffies.
In testing with artificial jumps (several small jumps, not one big
crank) of the jiffies I was able to reproduce a problem found in a
server with very long lived NFS mounts, where attributes would not be
refreshed even after touching files and directories in the server:
Initial uptime:
03:42:01 up 6 min, 0 users, load average: 0.01, 0.12, 0.07
NFS volume is mounted and time is advanced:
03:38:09 up 25 days, 2 min, 0 users, load average: 1.22, 1.05, 1.08
# ls -l /local/A/foo/bar /nfs/A/foo/bar
-rw-r--r-- 1 root root 0 Dec 17 03:38 /local/A/foo/bar
-rw-r--r-- 1 root root 0 Nov 22 00:36 /nfs/A/foo/bar
# touch /local/A/foo/bar
# ls -l /local/A/foo/bar /nfs/A/foo/bar
-rw-r--r-- 1 root root 0 Dec 17 03:47 /local/A/foo/bar
-rw-r--r-- 1 root root 0 Nov 22 00:36 /nfs/A/foo/bar
We can see the local mtime is updated, but the NFS mount still shows
the old value. The patch below makes it work:
Initial setup...
07:11:02 up 25 days, 1 min, 0 users, load average: 0.15, 0.03, 0.04
# ls -l /local/A/foo/bar /nfs/A/foo/bar
-rw-r--r-- 1 root root 0 Jan 11 07:11 /local/A/foo/bar
-rw-r--r-- 1 root root 0 Jan 11 07:11 /nfs/A/foo/bar
# touch /local/A/foo/bar
# ls -l /local/A/foo/bar /nfs/A/foo/bar
-rw-r--r-- 1 root root 0 Jan 11 07:14 /local/A/foo/bar
-rw-r--r-- 1 root root 0 Jan 11 07:14 /nfs/A/foo/bar
Signed-off-by: Fabio Olive Leite <fleite@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Prevent timeout overflow if timer ticks are behind jiffies (due to high
softirq load or due to dyntick), by limiting the valid timeout range to
MAX_LONG/2.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are loads of fat functions hidden in jiffies.h. Uninline them. No code
changes.
[jeremy@goop.org: export fix]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
jiffies.h includes a comment informing that jiffies_64 must be read with the
assistance of the xtime_lock seqlock. The comment text, however, calls
jiffies_64 "not volatile", which should probably read "not atomic".
Signed-off-by: Chase Venters <chase.venters@clientec.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Matteo Croce