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Message-ID: <CAM9d7ciBh2DhH7wEVFfXucxtvaog_BBVkuYcNC4vX_XQDx-QCw@mail.gmail.com>
Date: Thu, 18 Aug 2022 09:41:44 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: 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>,
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>,
Athira Rajeev <atrajeev@...ux.vnet.ibm.com>,
Weiguo Li <liwg06@...mail.com>,
Pavithra Gurushankar <gpavithrasha@...il.com>,
Thomas Richter <tmricht@...ux.ibm.com>,
Ravi Bangoria <ravi.bangoria@....com>,
Dario Petrillo <dario.pk1@...il.com>,
Wenyu Liu <liuwenyu7@...wei.com>,
Hewenliang <hewenliang4@...wei.com>,
yaowenbin <yaowenbin1@...wei.com>,
Dave Marchevsky <davemarchevsky@...com>,
Andrii Nakryiko <andrii@...nel.org>,
Alexandre Truong <alexandre.truong@....com>,
Kim Phillips <kim.phillips@....com>,
Leo Yan <leo.yan@...aro.org>,
Quentin Monnet <quentin@...valent.com>,
William Cohen <wcohen@...hat.com>,
Andres Freund <andres@...razel.de>,
Song Liu <songliubraving@...com>,
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>,
Andi Kleen <ak@...ux.intel.com>,
Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>,
Riccardo Mancini <rickyman7@...il.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
Christophe JAILLET <christophe.jaillet@...adoo.fr>,
Zechuan Chen <chenzechuan1@...wei.com>,
Jason Wang <wangborong@...rlc.com>,
Lexi Shao <shaolexi@...wei.com>,
Remi Bernon <rbernon@...eweavers.com>,
linux-kernel <linux-kernel@...r.kernel.org>,
linux-perf-users <linux-perf-users@...r.kernel.org>,
llvm@...ts.linux.dev
Subject: Re: [PATCH v1 5/6] perf mutex: Fix thread safety analysis
On Tue, Aug 16, 2022 at 10:39 PM Ian Rogers <irogers@...gle.com> wrote:
>
> Add annotations to describe lock behavior. Add missing unlocks to
> perf_sched__replay. Alter hist_iter__top_callback as the thread-safety
> analysis cannot follow pointers through local variables.
>
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
> tools/perf/builtin-sched.c | 8 ++++++++
> tools/perf/builtin-top.c | 5 +++--
> 2 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
> index 0f52f73be896..a8a765ed28ce 100644
> --- a/tools/perf/builtin-sched.c
> +++ b/tools/perf/builtin-sched.c
> @@ -658,6 +658,8 @@ static void *thread_func(void *ctx)
> }
>
> 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 +689,8 @@ 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 +742,8 @@ 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;
>
> @@ -3314,6 +3320,8 @@ static int perf_sched__replay(struct perf_sched *sched)
> for (i = 0; i < sched->replay_repeat; i++)
> run_one_test(sched);
>
> + mutex_unlock(&sched->start_work_mutex);
> + mutex_unlock(&sched->work_done_wait_mutex);
But this would wake up the replay tasks and let them burn cpus unnecessarily.
Maybe we can make them exit at the moment.
> return 0;
> }
>
> diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
> index 3757292bfe86..e832f04e3076 100644
> --- a/tools/perf/builtin-top.c
> +++ b/tools/perf/builtin-top.c
> @@ -196,6 +196,7 @@ static void perf_top__record_precise_ip(struct perf_top *top,
> struct hist_entry *he,
> struct perf_sample *sample,
> struct evsel *evsel, u64 ip)
> + EXCLUSIVE_LOCKS_REQUIRED(he->hists->lock)
> {
> struct annotation *notes;
> struct symbol *sym = he->ms.sym;
> @@ -724,13 +725,13 @@ static void *display_thread(void *arg)
> static int hist_iter__top_callback(struct hist_entry_iter *iter,
> struct addr_location *al, bool single,
> void *arg)
> + EXCLUSIVE_LOCKS_REQUIRED(iter->he->hists->lock)
> {
> struct perf_top *top = arg;
> - struct hist_entry *he = iter->he;
> struct evsel *evsel = iter->evsel;
>
> if (perf_hpp_list.sym && single)
> - perf_top__record_precise_ip(top, he, iter->sample, evsel, al->addr);
> + perf_top__record_precise_ip(top, iter->he, iter->sample, evsel, al->addr);
>
> hist__account_cycles(iter->sample->branch_stack, al, iter->sample,
> !(top->record_opts.branch_stack & PERF_SAMPLE_BRANCH_ANY),
Looks like a separate change.
Thanks,
Namhyung
> --
> 2.37.1.595.g718a3a8f04-goog
>
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