1 files changed, 34 insertions, 17 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 6dd714955b04..f83a71a3e46d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -231,11 +231,29 @@ int perf_cpu_time_max_percent_handler(struct ctl_table *table, int write,
 #define NR_ACCUMULATED_SAMPLES 128
 static DEFINE_PER_CPU(u64, running_sample_length);
 
-void perf_sample_event_took(u64 sample_len_ns)
+static void perf_duration_warn(struct irq_work *w)
 {
+	u64 allowed_ns = ACCESS_ONCE(perf_sample_allowed_ns);
 	u64 avg_local_sample_len;
 	u64 local_samples_len;
+
+	local_samples_len = __get_cpu_var(running_sample_length);
+	avg_local_sample_len = local_samples_len/NR_ACCUMULATED_SAMPLES;
+
+	printk_ratelimited(KERN_WARNING
+			"perf interrupt took too long (%lld > %lld), lowering "
+			"kernel.perf_event_max_sample_rate to %d\n",
+			avg_local_sample_len, allowed_ns >> 1,
+			sysctl_perf_event_sample_rate);
+}
+
+static DEFINE_IRQ_WORK(perf_duration_work, perf_duration_warn);
+
+void perf_sample_event_took(u64 sample_len_ns)
+{
 	u64 allowed_ns = ACCESS_ONCE(perf_sample_allowed_ns);
+	u64 avg_local_sample_len;
+	u64 local_samples_len;
 
 	if (allowed_ns == 0)
 		return;
@@ -263,13 +281,14 @@ void perf_sample_event_took(u64 sample_len_ns)
 	sysctl_perf_event_sample_rate = max_samples_per_tick * HZ;
 	perf_sample_period_ns = NSEC_PER_SEC / sysctl_perf_event_sample_rate;
 
-	printk_ratelimited(KERN_WARNING
-			"perf samples too long (%lld > %lld), lowering "
-			"kernel.perf_event_max_sample_rate to %d\n",
-			avg_local_sample_len, allowed_ns,
-			sysctl_perf_event_sample_rate);
-
 	update_perf_cpu_limits();
+
+	if (!irq_work_queue(&perf_duration_work)) {
+		early_printk("perf interrupt took too long (%lld > %lld), lowering "
+			     "kernel.perf_event_max_sample_rate to %d\n",
+			     avg_local_sample_len, allowed_ns >> 1,
+			     sysctl_perf_event_sample_rate);
+	}
 }
 
 static atomic64_t perf_event_id;
@@ -1699,7 +1718,7 @@ group_sched_in(struct perf_event *group_event,
 	       struct perf_event_context *ctx)
 {
 	struct perf_event *event, *partial_group = NULL;
-	struct pmu *pmu = group_event->pmu;
+	struct pmu *pmu = ctx->pmu;
 	u64 now = ctx->time;
 	bool simulate = false;
 
@@ -2548,8 +2567,6 @@ static void perf_branch_stack_sched_in(struct task_struct *prev,
 		if (cpuctx->ctx.nr_branch_stack > 0
 		    && pmu->flush_branch_stack) {
 
-			pmu = cpuctx->ctx.pmu;
-
 			perf_ctx_lock(cpuctx, cpuctx->task_ctx);
 
 			perf_pmu_disable(pmu);
@@ -6279,7 +6296,7 @@ static int perf_event_idx_default(struct perf_event *event)
  * Ensures all contexts with the same task_ctx_nr have the same
  * pmu_cpu_context too.
  */
-static void *find_pmu_context(int ctxn)
+static struct perf_cpu_context __percpu *find_pmu_context(int ctxn)
 {
 	struct pmu *pmu;
 
@@ -7841,14 +7858,14 @@ static void perf_pmu_rotate_stop(struct pmu *pmu)
 static void __perf_event_exit_context(void *__info)
 {
 	struct perf_event_context *ctx = __info;
-	struct perf_event *event, *tmp;
+	struct perf_event *event;
 
 	perf_pmu_rotate_stop(ctx->pmu);
 
-	list_for_each_entry_safe(event, tmp, &ctx->pinned_groups, group_entry)
-		__perf_remove_from_context(event);
-	list_for_each_entry_safe(event, tmp, &ctx->flexible_groups, group_entry)
+	rcu_read_lock();
+	list_for_each_entry_rcu(event, &ctx->event_list, event_entry)
 		__perf_remove_from_context(event);
+	rcu_read_unlock();
 }
 
 static void perf_event_exit_cpu_context(int cpu)
@@ -7872,11 +7889,11 @@ 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);
 	swevent_hlist_release(swhash);
 	mutex_unlock(&swhash->hlist_mutex);
-
-	perf_event_exit_cpu_context(cpu);
 }
 #else
 static inline void perf_event_exit_cpu(int cpu) { }