Merge "perf: Fix race in swevent hash" (c0f964b7) · Commits · e / devices / android_kernel_xiaomi_markw

kernel/events/core.c

+1 −19

Original line number	Diff line number	Diff line
		@@ -5731,9 +5731,6 @@ struct swevent_htable {

		/* Recursion avoidance in each contexts */
		int recursion[PERF_NR_CONTEXTS];

		/* Keeps track of cpu being initialized/exited */
		bool online;
		};

		static DEFINE_PER_CPU(struct swevent_htable, swevent_htable);
		@@ -5980,14 +5977,8 @@ static int perf_swevent_add(struct perf_event *event, int flags)
		hwc->state = !(flags & PERF_EF_START);

		head = find_swevent_head(swhash, event);
		if (!head) {
		/*
		* We can race with cpu hotplug code. Do not
		* WARN if the cpu just got unplugged.
		*/
		WARN_ON_ONCE(swhash->online);
		if (WARN_ON_ONCE(!head))
		return -EINVAL;
		}

		hlist_add_head_rcu(&event->hlist_entry, head);

		@@ -6054,7 +6045,6 @@ static int swevent_hlist_get_cpu(struct perf_event *event, int cpu)
		int err = 0;

		mutex_lock(&swhash->hlist_mutex);

		if (!swevent_hlist_deref(swhash) && cpu_online(cpu)) {
		struct swevent_hlist *hlist;

		@@ -8190,7 +8180,6 @@ static void perf_event_init_cpu(int cpu)
		struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);

		mutex_lock(&swhash->hlist_mutex);
		swhash->online = true;
		if (swhash->hlist_refcount > 0) {
		struct swevent_hlist *hlist;

		@@ -8290,14 +8279,7 @@ static void perf_event_start_swclock(int cpu)

		static void perf_event_exit_cpu(int cpu)
		{
		struct swevent_htable *swhash = &per_cpu(swevent_htable, cpu);

		perf_event_exit_cpu_context(cpu);

		mutex_lock(&swhash->hlist_mutex);
		swhash->online = false;
		swevent_hlist_release(swhash);
		mutex_unlock(&swhash->hlist_mutex);
		}
		#else
		static inline void perf_event_exit_cpu(int cpu) { }