diff options
| -rw-r--r-- | kernel/events/core.c | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c index a6c8e38a3..f02780529 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7029,7 +7029,6 @@ static void perf_mmap_close(struct vm_area_struct *vma) mapped_f unmapped = get_mapped(event, event_unmapped); struct perf_buffer *rb = ring_buffer_get(event); struct user_struct *mmap_user = rb->mmap_user; - bool detach_rest = false; /* FIXIES vs perf_pmu_unregister() */ if (unmapped) @@ -7060,17 +7059,18 @@ static void perf_mmap_close(struct vm_area_struct *vma) mutex_unlock(&rb->aux_mutex); } - if (refcount_dec_and_test(&rb->mmap_count)) - detach_rest = true; - - if (!refcount_dec_and_mutex_lock(&event->mmap_count, &event->mmap_mutex)) - goto out_put; - - ring_buffer_attach(event, NULL); - mutex_unlock(&event->mmap_mutex); + /* + * Drop references in reverse order of perf_mmap() to prevent + * rb revival after rb->mmap_count reaches zero. + */ + if (refcount_dec_and_mutex_lock(&event->mmap_count, + &event->mmap_mutex)) { + ring_buffer_attach(event, NULL); + mutex_unlock(&event->mmap_mutex); + } /* If there's still other mmap()s of this buffer, we're done. */ - if (!detach_rest) + if (!refcount_dec_and_test(&rb->mmap_count)) goto out_put; /* |