Merge drm/drm-fixes into drm-misc-fixes

Getting fixes and updates from v7.1-rc1.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

1 files changed, 10 insertions, 6 deletions

diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h
index ea9ca0e4172a..728fb5dee5ed 100644
--- a/include/linux/eventpoll.h
+++ b/include/linux/eventpoll.h
@@ -39,12 +39,16 @@ static inline void eventpoll_release(struct file *file)
 {
 
 	/*
-	 * Fast check to avoid the get/release of the semaphore. Since
-	 * we're doing this outside the semaphore lock, it might return
-	 * false negatives, but we don't care. It'll help in 99.99% of cases
-	 * to avoid the semaphore lock. False positives simply cannot happen
-	 * because the file in on the way to be removed and nobody ( but
-	 * eventpoll ) has still a reference to this file.
+	 * Fast check to skip the slow path in the common case where the
+	 * file was never attached to an epoll. Safe without file->f_lock
+	 * because every f_ep writer excludes a concurrent __fput() on
+	 * @file:
+	 *   - ep_insert() requires the file alive (refcount > 0);
+	 *   - ep_remove() holds @file pinned via epi_fget() across the
+	 *     write;
+	 *   - eventpoll_release_file() runs from __fput() itself.
+	 * We are in __fput() here, so none of those can race us: a NULL
+	 * observation truly means no epoll path has work left on @file.
 	 */
 	if (likely(!READ_ONCE(file->f_ep)))
 		return;