diff options
| author | David Sterba <dsterba@suse.com> | 2015-02-16 19:41:40 +0100 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2015-10-10 18:42:00 +0200 |
| commit | ee86395458072760d62e66aad10a5e9e8902b8cf (patch) | |
| tree | b3293bde46967a886b5d066028c5eceebd810dac /fs/btrfs/locking.c | |
| parent | 779adf0f647651f5a45eeee3442c881300ce989e (diff) | |
btrfs: comment the rest of implicit barriers before waitqueue_active
There are atomic operations that imply the barrier for waitqueue_active
mixed in an if-condition.
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/locking.c')
| -rw-r--r-- | fs/btrfs/locking.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index 03f8630dbaf2..8077461fc56a 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -79,6 +79,9 @@ void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw) write_lock(&eb->lock); WARN_ON(atomic_read(&eb->spinning_writers)); atomic_inc(&eb->spinning_writers); + /* + * atomic_dec_and_test implies a barrier for waitqueue_active + */ if (atomic_dec_and_test(&eb->blocking_writers) && waitqueue_active(&eb->write_lock_wq)) wake_up(&eb->write_lock_wq); @@ -86,6 +89,9 @@ void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw) BUG_ON(atomic_read(&eb->blocking_readers) == 0); read_lock(&eb->lock); atomic_inc(&eb->spinning_readers); + /* + * atomic_dec_and_test implies a barrier for waitqueue_active + */ if (atomic_dec_and_test(&eb->blocking_readers) && waitqueue_active(&eb->read_lock_wq)) wake_up(&eb->read_lock_wq); @@ -229,6 +235,9 @@ void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb) } btrfs_assert_tree_read_locked(eb); WARN_ON(atomic_read(&eb->blocking_readers) == 0); + /* + * atomic_dec_and_test implies a barrier for waitqueue_active + */ if (atomic_dec_and_test(&eb->blocking_readers) && waitqueue_active(&eb->read_lock_wq)) wake_up(&eb->read_lock_wq); |