Merge "perf: core: Avoid race condition when releasing perf-events" (c3ddbc3c) · Commits · e / devices / android_kernel_xiaomi_nabu

kernel/events/core.c

+17 −4

Original line number	Diff line number	Diff line
		@@ -4486,7 +4486,7 @@ static DEFINE_SPINLOCK(zombie_list_lock);
		* object, it will not preserve its functionality. Once the last 'user'
		* gives up the object, we'll destroy the thing.
		*/
		int perf_event_release_kernel(struct perf_event *event)
		static int __perf_event_release_kernel(struct perf_event *event)
		{
		struct perf_event_context *ctx = event->ctx;
		struct perf_event child, tmp;
		@@ -4500,8 +4500,7 @@ int perf_event_release_kernel(struct perf_event *event)
		if (event->state == PERF_EVENT_STATE_ZOMBIE)
		return 0;

		if (event->cpu != -1 && !cpu_online(event->cpu) &&
		event->state == PERF_EVENT_STATE_ACTIVE) {
		if (event->cpu != -1 && per_cpu(is_hotplugging, event->cpu)) {
		event->state = PERF_EVENT_STATE_ZOMBIE;

		spin_lock(&zombie_list_lock);
		@@ -4620,6 +4619,17 @@ int perf_event_release_kernel(struct perf_event *event)
		put_event(event); /* Must be the 'last' reference */
		return 0;
		}

		int perf_event_release_kernel(struct perf_event *event)
		{
		int ret;

		mutex_lock(&pmus_lock);
		ret = __perf_event_release_kernel(event);
		mutex_unlock(&pmus_lock);

		return ret;
		}
		EXPORT_SYMBOL_GPL(perf_event_release_kernel);

		/*
		@@ -11556,7 +11566,7 @@ static void perf_event_zombie_cleanup(unsigned int cpu)
		* PMU expects it to be in an active state
		*/
		event->state = PERF_EVENT_STATE_ACTIVE;
		perf_event_release_kernel(event);
		__perf_event_release_kernel(event);

		spin_lock(&zombie_list_lock);
		}
		@@ -11571,6 +11581,7 @@ int perf_event_start_swevents(unsigned int cpu)
		struct perf_event *event;
		int idx;

		mutex_lock(&pmus_lock);
		perf_event_zombie_cleanup(cpu);
		perf_deferred_install_in_context(cpu);

		@@ -11586,6 +11597,8 @@ int perf_event_start_swevents(unsigned int cpu)
		}
		srcu_read_unlock(&pmus_srcu, idx);
		per_cpu(is_hotplugging, cpu) = false;
		mutex_unlock(&pmus_lock);

		return 0;
		}