From cde8e88498c8de69271fcb6d4dd974979368fa67 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 13 Sep 2010 11:06:55 +0200 Subject: [PATCH] perf: Sanitize the RCU logic Simplify things and simply synchronize against two RCU variants for PMU unregister -- we don't care about performance, its module unload if anything. Reported-by: Frederic Weisbecker Signed-off-by: Peter Zijlstra Cc: Paul E. McKenney LKML-Reference: Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/kernel/perf_event.c b/kernel/perf_event.c index f29b52576ec1..bc46bff69620 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -3810,7 +3810,7 @@ static void perf_event_task_event(struct perf_task_event *task_event) struct pmu *pmu; int ctxn; - rcu_read_lock_sched(); + rcu_read_lock(); list_for_each_entry_rcu(pmu, &pmus, entry) { cpuctx = this_cpu_ptr(pmu->pmu_cpu_context); perf_event_task_ctx(&cpuctx->ctx, task_event); @@ -3825,7 +3825,7 @@ static void perf_event_task_event(struct perf_task_event *task_event) if (ctx) perf_event_task_ctx(ctx, task_event); } - rcu_read_unlock_sched(); + rcu_read_unlock(); } static void perf_event_task(struct task_struct *task, @@ -3943,7 +3943,7 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event) comm_event->event_id.header.size = sizeof(comm_event->event_id) + size; - rcu_read_lock_sched(); + rcu_read_lock(); list_for_each_entry_rcu(pmu, &pmus, entry) { cpuctx = this_cpu_ptr(pmu->pmu_cpu_context); perf_event_comm_ctx(&cpuctx->ctx, comm_event); @@ -3956,7 +3956,7 @@ static void perf_event_comm_event(struct perf_comm_event *comm_event) if (ctx) perf_event_comm_ctx(ctx, comm_event); } - rcu_read_unlock_sched(); + rcu_read_unlock(); } void perf_event_comm(struct task_struct *task) @@ -4126,7 +4126,7 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event) mmap_event->event_id.header.size = sizeof(mmap_event->event_id) + size; - rcu_read_lock_sched(); + rcu_read_lock(); list_for_each_entry_rcu(pmu, &pmus, entry) { cpuctx = this_cpu_ptr(pmu->pmu_cpu_context); perf_event_mmap_ctx(&cpuctx->ctx, mmap_event, @@ -4142,7 +4142,7 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event) vma->vm_flags & VM_EXEC); } } - rcu_read_unlock_sched(); + rcu_read_unlock(); kfree(buf); } @@ -5218,10 +5218,11 @@ void perf_pmu_unregister(struct pmu *pmu) mutex_unlock(&pmus_lock); /* - * We use the pmu list either under SRCU or preempt_disable, - * synchronize_srcu() implies synchronize_sched() so we're good. + * We dereference the pmu list under both SRCU and regular RCU, so + * synchronize against both of those. */ synchronize_srcu(&pmus_srcu); + synchronize_rcu(); free_percpu(pmu->pmu_disable_count); free_pmu_context(pmu->pmu_cpu_context); -- GitLab