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Date: Fri, 26 Aug 2022 09:42:40 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Darren Hart <dvhart@...radead.org>,
Davidlohr Bueso <dave@...olabs.net>,
"André Almeida" <andrealmeid@...lia.com>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Tom Rix <trix@...hat.com>, Weiguo Li <liwg06@...mail.com>,
Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
Thomas Richter <tmricht@...ux.ibm.com>,
Ravi Bangoria <ravi.bangoria@....com>,
Dario Petrillo <dario.pk1@...il.com>,
Hewenliang <hewenliang4@...wei.com>,
yaowenbin <yaowenbin1@...wei.com>,
Wenyu Liu <liuwenyu7@...wei.com>,
Song Liu <songliubraving@...com>,
Andrii Nakryiko <andrii@...nel.org>,
Dave Marchevsky <davemarchevsky@...com>,
Leo Yan <leo.yan@...aro.org>,
Kim Phillips <kim.phillips@....com>,
Pavithra Gurushankar <gpavithrasha@...il.com>,
Alexandre Truong <alexandre.truong@....com>,
Quentin Monnet <quentin@...valent.com>,
William Cohen <wcohen@...hat.com>,
Andres Freund <andres@...razel.de>,
Adrian Hunter <adrian.hunter@...el.com>,
"Martin Liška" <mliska@...e.cz>,
Colin Ian King <colin.king@...el.com>,
James Clark <james.clark@....com>,
Fangrui Song <maskray@...gle.com>,
Stephane Eranian <eranian@...gle.com>,
Kajol Jain <kjain@...ux.ibm.com>,
Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>,
Riccardo Mancini <rickyman7@...il.com>,
Andi Kleen <ak@...ux.intel.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
Zechuan Chen <chenzechuan1@...wei.com>,
Jason Wang <wangborong@...rlc.com>,
Christophe JAILLET <christophe.jaillet@...adoo.fr>,
Remi Bernon <rbernon@...eweavers.com>,
linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
bpf@...r.kernel.org, llvm@...ts.linux.dev
Cc: Ian Rogers <irogers@...gle.com>
Subject: [PATCH v4 16/18] perf sched: Fixes for thread safety analysis
Add annotations to describe lock behavior. Add unlocks so that mutexes
aren't conditionally held on exit from perf_sched__replay. Add an exit
variable so that thread_func can terminate, rather than leaving the
threads blocked on mutexes.
Signed-off-by: Ian Rogers <irogers@...gle.com>
---
tools/perf/builtin-sched.c | 46 ++++++++++++++++++++++++--------------
1 file changed, 29 insertions(+), 17 deletions(-)
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 7e4006d6b8bc..b483ff0d432e 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -246,6 +246,7 @@ struct perf_sched {
const char *time_str;
struct perf_time_interval ptime;
struct perf_time_interval hist_time;
+ volatile bool thread_funcs_exit;
};
/* per thread run time data */
@@ -633,31 +634,34 @@ static void *thread_func(void *ctx)
prctl(PR_SET_NAME, comm2);
if (fd < 0)
return NULL;
-again:
- ret = sem_post(&this_task->ready_for_work);
- BUG_ON(ret);
- mutex_lock(&sched->start_work_mutex);
- mutex_unlock(&sched->start_work_mutex);
- cpu_usage_0 = get_cpu_usage_nsec_self(fd);
+ while (!sched->thread_funcs_exit) {
+ ret = sem_post(&this_task->ready_for_work);
+ BUG_ON(ret);
+ mutex_lock(&sched->start_work_mutex);
+ mutex_unlock(&sched->start_work_mutex);
- for (i = 0; i < this_task->nr_events; i++) {
- this_task->curr_event = i;
- perf_sched__process_event(sched, this_task->atoms[i]);
- }
+ cpu_usage_0 = get_cpu_usage_nsec_self(fd);
- cpu_usage_1 = get_cpu_usage_nsec_self(fd);
- this_task->cpu_usage = cpu_usage_1 - cpu_usage_0;
- ret = sem_post(&this_task->work_done_sem);
- BUG_ON(ret);
+ for (i = 0; i < this_task->nr_events; i++) {
+ this_task->curr_event = i;
+ perf_sched__process_event(sched, this_task->atoms[i]);
+ }
- mutex_lock(&sched->work_done_wait_mutex);
- mutex_unlock(&sched->work_done_wait_mutex);
+ cpu_usage_1 = get_cpu_usage_nsec_self(fd);
+ this_task->cpu_usage = cpu_usage_1 - cpu_usage_0;
+ ret = sem_post(&this_task->work_done_sem);
+ BUG_ON(ret);
- goto again;
+ mutex_lock(&sched->work_done_wait_mutex);
+ mutex_unlock(&sched->work_done_wait_mutex);
+ }
+ return NULL;
}
static void create_tasks(struct perf_sched *sched)
+ EXCLUSIVE_LOCK_FUNCTION(sched->start_work_mutex)
+ EXCLUSIVE_LOCK_FUNCTION(sched->work_done_wait_mutex)
{
struct task_desc *task;
pthread_attr_t attr;
@@ -687,6 +691,8 @@ static void create_tasks(struct perf_sched *sched)
}
static void wait_for_tasks(struct perf_sched *sched)
+ EXCLUSIVE_LOCKS_REQUIRED(sched->work_done_wait_mutex)
+ EXCLUSIVE_LOCKS_REQUIRED(sched->start_work_mutex)
{
u64 cpu_usage_0, cpu_usage_1;
struct task_desc *task;
@@ -738,6 +744,8 @@ static void wait_for_tasks(struct perf_sched *sched)
}
static void run_one_test(struct perf_sched *sched)
+ EXCLUSIVE_LOCKS_REQUIRED(sched->work_done_wait_mutex)
+ EXCLUSIVE_LOCKS_REQUIRED(sched->start_work_mutex)
{
u64 T0, T1, delta, avg_delta, fluct;
@@ -3309,11 +3317,15 @@ static int perf_sched__replay(struct perf_sched *sched)
print_task_traces(sched);
add_cross_task_wakeups(sched);
+ sched->thread_funcs_exit = false;
create_tasks(sched);
printf("------------------------------------------------------------\n");
for (i = 0; i < sched->replay_repeat; i++)
run_one_test(sched);
+ sched->thread_funcs_exit = true;
+ mutex_unlock(&sched->start_work_mutex);
+ mutex_unlock(&sched->work_done_wait_mutex);
return 0;
}
--
2.37.2.672.g94769d06f0-goog
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