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| author | Steven Rostedt <rostedt@goodmis.org> | 2026-09-02 09:55:01 -0400 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2026-09-02 11:08:21 -0400 |
| commit | 4617721c502b2ddaa4e324e86da4997edf738fa5 (patch) | |
| tree | 350aa83b47da0b574a814795392b20b0bed83cbc /Documentation/tools/rtla/rtla-timerlat-hist.rst | |
| download | linux-stable-4617721c502b2ddaa4e324e86da4997edf738fa5.tar.gz linux-stable-4617721c502b2ddaa4e324e86da4997edf738fa5.zip | |
ftrace: Synchronize the initialization of ftrace_opsgrafted
There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.
Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'Documentation/tools/rtla/rtla-timerlat-hist.rst')
| -rw-r--r-- | Documentation/tools/rtla/rtla-timerlat-hist.rst | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/Documentation/tools/rtla/rtla-timerlat-hist.rst b/Documentation/tools/rtla/rtla-timerlat-hist.rst new file mode 100644 index 000000000..dab75677b --- /dev/null +++ b/Documentation/tools/rtla/rtla-timerlat-hist.rst @@ -0,0 +1,113 @@ +.. |tool| replace:: timerlat hist + +===================== +rtla-timerlat-hist +===================== +------------------------------------------------ +Histograms of the operating system timer latency +------------------------------------------------ + +:Manual section: 1 + +SYNOPSIS +======== +**rtla timerlat hist** [*OPTIONS*] ... + +DESCRIPTION +=========== + +.. include:: common_timerlat_description.txt + +The **rtla timerlat hist** displays a histogram of each tracer event +occurrence. This tool uses the periodic information, and the +**osnoise:** tracepoints are enabled when using the **-T** option. + +OPTIONS +======= + +.. include:: common_timerlat_options.txt + +.. include:: common_hist_options.txt + +.. include:: common_options.txt + +.. include:: common_timerlat_aa.txt + +EXAMPLE +======= +In the example below, **rtla timerlat hist** is set to run for *10* minutes, +in the cpus *0-4*, *skipping zero* only lines. Moreover, **rtla timerlat +hist** will change the priority of the *timerlat* threads to run under +*SCHED_DEADLINE* priority, with a *100us* runtime every *1ms* period. The +*1ms* period is also passed to the *timerlat* tracer. Auto-analysis is disabled +to reduce overhead :: + + [root@alien ~]# timerlat hist -d 10m -c 0-4 -P d:100us:1ms -p 1000 --no-aa + # RTLA timerlat histogram + # Time unit is microseconds (us) + # Duration: 0 00:10:00 + Index IRQ-000 Thr-000 IRQ-001 Thr-001 IRQ-002 Thr-002 IRQ-003 Thr-003 IRQ-004 Thr-004 + 0 276489 0 206089 0 466018 0 481102 0 205546 0 + 1 318327 35487 388149 30024 94531 48382 83082 71078 388026 55730 + 2 3282 122584 4019 126527 28231 109012 23311 89309 4568 98739 + 3 940 11815 837 9863 6209 16227 6895 17196 910 9780 + 4 444 17287 424 11574 2097 38443 2169 36736 462 13476 + 5 206 43291 255 25581 1223 101908 1304 101137 236 28913 + 6 132 101501 96 64584 635 213774 757 215471 99 73453 + 7 74 169347 65 124758 350 57466 441 53639 69 148573 + 8 53 85183 31 156751 229 9052 306 9026 39 139907 + 9 22 10387 12 42762 161 2554 225 2689 19 26192 + 10 13 1898 8 5770 114 1247 128 1405 13 3772 + 11 9 560 9 924 71 686 76 765 8 713 + 12 4 256 2 360 50 411 64 474 3 278 + 13 2 167 2 172 43 256 53 350 4 180 + 14 1 88 1 116 15 198 42 223 0 115 + 15 2 63 3 94 11 139 20 150 0 58 + 16 2 37 0 56 5 78 10 102 0 39 + 17 0 18 0 28 4 57 8 80 0 15 + 18 0 8 0 17 2 50 6 56 0 12 + 19 0 9 0 5 0 19 0 48 0 18 + 20 0 4 0 8 0 11 2 27 0 4 + 21 0 2 0 3 1 9 1 18 0 6 + 22 0 1 0 3 1 7 0 3 0 5 + 23 0 2 0 4 0 2 0 7 0 2 + 24 0 2 0 2 1 3 0 3 0 5 + 25 0 0 0 1 0 1 0 1 0 3 + 26 0 1 0 0 0 2 0 2 0 0 + 27 0 0 0 3 0 1 0 0 0 1 + 28 0 0 0 3 0 0 0 1 0 0 + 29 0 0 0 2 0 2 0 1 0 3 + 30 0 1 0 0 0 0 0 0 0 0 + 31 0 1 0 0 0 0 0 2 0 2 + 32 0 0 0 1 0 2 0 0 0 0 + 33 0 0 0 2 0 0 0 0 0 1 + 34 0 0 0 0 0 0 0 0 0 2 + 35 0 1 0 1 0 0 0 0 0 1 + 36 0 1 0 0 0 1 0 1 0 0 + 37 0 0 0 1 0 0 0 0 0 0 + 40 0 0 0 0 0 1 0 1 0 0 + 41 0 0 0 0 0 0 0 0 0 1 + 42 0 0 0 0 0 0 0 0 0 1 + 44 0 0 0 0 0 1 0 0 0 0 + 46 0 0 0 0 0 0 0 1 0 0 + 47 0 0 0 0 0 0 0 0 0 1 + 50 0 0 0 0 0 0 0 0 0 1 + 54 0 0 0 1 0 0 0 0 0 0 + 58 0 0 0 1 0 0 0 0 0 0 + over: 0 0 0 0 0 0 0 0 0 0 + count: 600002 600002 600002 600002 600002 600002 600002 600002 600002 600002 + min: 0 1 0 1 0 1 0 1 0 1 + avg: 0 5 0 5 0 4 0 4 0 5 + max: 16 36 15 58 24 44 21 46 13 50 + +SEE ALSO +======== +**rtla-timerlat**\(1), **rtla-timerlat-top**\(1) + +`Timerlat tracer <https://docs.kernel.org/trace/timerlat-tracer.html>`__ + +AUTHOR +====== +Written by Daniel Bristot de Oliveira <bristot@kernel.org> + +.. include:: common_appendix.txt |