From 59c266604922898ad8aa1ef881a60eb02fcb385f Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Fri, 26 Aug 2022 09:42:40 -0700 Subject: [PATCH] perf sched: Fixes for thread safety analysis MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Alexandre Truong Cc: Alexey Bayduraev Cc: Andi Kleen Cc: Andres Freund Cc: Andrii Nakryiko Cc: André Almeida Cc: Athira Jajeev Cc: Christophe JAILLET Cc: Colin Ian King Cc: Dario Petrillo Cc: Darren Hart Cc: Dave Marchevsky Cc: Davidlohr Bueso Cc: Fangrui Song Cc: Hewenliang Cc: Ingo Molnar Cc: James Clark Cc: Jason Wang Cc: Jiri Olsa Cc: Kajol Jain Cc: Kim Phillips Cc: Leo Yan Cc: Mark Rutland Cc: Martin Liška Cc: Masami Hiramatsu Cc: Nathan Chancellor Cc: Nick Desaulniers Cc: Pavithra Gurushankar Cc: Peter Zijlstra Cc: Quentin Monnet Cc: Ravi Bangoria Cc: Remi Bernon Cc: Riccardo Mancini Cc: Song Liu Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Thomas Richter Cc: Tom Rix Cc: Weiguo Li Cc: Wenyu Liu Cc: William Cohen Cc: Zechuan Chen Cc: bpf@vger.kernel.org Cc: llvm@lists.linux.dev Cc: yaowenbin Link: https://lore.kernel.org/r/20220826164242.43412-17-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo --- 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 46e3b96..a92610e 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; } -- 2.7.4