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Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/core.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1d1ec6453a08..feb1329ca331 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5419,6 +5419,9 @@ 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);
@@ -5665,8 +5668,14 @@ static int perf_swevent_add(struct perf_event *event, int flags)
hwc->state = !(flags & PERF_EF_START);
head = find_swevent_head(swhash, event);
- if (WARN_ON_ONCE(!head))
+ if (!head) {
+ /*
+ * We can race with cpu hotplug code. Do not
+ * WARN if the cpu just got unplugged.
+ */
+ WARN_ON_ONCE(swhash->online);
return -EINVAL;
+ }
hlist_add_head_rcu(&event->hlist_entry, head);
@@ -7845,6 +7854,7 @@ 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;
@@ -7902,6 +7912,7 @@ static void perf_event_exit_cpu(int cpu)
perf_event_exit_cpu_context(cpu);
mutex_lock(&swhash->hlist_mutex);
+ swhash->online = false;
swevent_hlist_release(swhash);
mutex_unlock(&swhash->hlist_mutex);
}