By doing "make M=fs/ext4 C=2"
on commit ad6599ab3ac98a4474544086e048ce86ec15a4d1
sparse reports this warning:
CHECK fs/ext4/mballoc.c
fs/ext4/mballoc.c:5019:9: warning: context imbalance in
'ext4_trim_extent' - unexpected unlock
>From Documentation/sparse.txt:
Using sparse for lock checking
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The following macros are undefined for gcc and defined during a sparse
run to use the "context" tracking feature of sparse, applied to
locking. These annotations tell sparse when a lock is held, with
regard to the annotated function's entry and exit.
__must_hold - The specified lock is held on function entry and exit.
__acquires - The specified lock is held on function exit, but not entry.
__releases - The specified lock is held on function entry, but not exit.
If the function enters and exits without the lock held, acquiring and
releasing the lock inside the function in a balanced way, no
annotation is needed. The tree annotations above are for cases where
sparse would otherwise report a context imbalance.
Signed-off-by: "Jon Ernst" <jonernst07@xxxxxxxxx>
---
fs/ext4/mballoc.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 73ccbb3..c8238a2 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -5016,6 +5016,8 @@ error_return:
*/
static int ext4_trim_extent(struct super_block *sb, int start, int count,
ext4_group_t group, struct ext4_buddy *e4b)
+__releases(bitlock)
+__acquires(bitlock)
{
struct ext4_free_extent ex;
int ret = 0;
--
1.8.1.2
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