diff options
| author | Andreas Gruenbacher <agruenba@redhat.com> | 2018-03-29 09:07:46 +0200 |
|---|---|---|
| committer | Bob Peterson <rpeterso@redhat.com> | 2018-04-12 18:41:19 +0200 |
| commit | 450b1f6f56350c630e795f240dc5a77aa8aa2419 (patch) | |
| tree | d6809eb52cf4317836ddc5e51f582a72bb2a9c9a | |
| parent | Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost (diff) | |
| download | linux-450b1f6f56350c630e795f240dc5a77aa8aa2419.tar.xz linux-450b1f6f56350c630e795f240dc5a77aa8aa2419.zip | |
lockref: Add lockref_put_not_zero
Put a lockref unless the lockref is dead or its count would become zero.
This is the same as lockref_put_or_lock except that the lock is never
left held.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
| -rw-r--r-- | include/linux/lockref.h | 1 | ||||
| -rw-r--r-- | lib/lockref.c | 28 |
2 files changed, 29 insertions, 0 deletions
diff --git a/include/linux/lockref.h b/include/linux/lockref.h index 2eac32095113..99f17cc8e163 100644 --- a/include/linux/lockref.h +++ b/include/linux/lockref.h @@ -37,6 +37,7 @@ struct lockref { extern void lockref_get(struct lockref *); extern int lockref_put_return(struct lockref *); extern int lockref_get_not_zero(struct lockref *); +extern int lockref_put_not_zero(struct lockref *); extern int lockref_get_or_lock(struct lockref *); extern int lockref_put_or_lock(struct lockref *); diff --git a/lib/lockref.c b/lib/lockref.c index 47169ed7e964..3d468b53d4c9 100644 --- a/lib/lockref.c +++ b/lib/lockref.c @@ -81,6 +81,34 @@ int lockref_get_not_zero(struct lockref *lockref) EXPORT_SYMBOL(lockref_get_not_zero); /** + * lockref_put_not_zero - Decrements count unless count <= 1 before decrement + * @lockref: pointer to lockref structure + * Return: 1 if count updated successfully or 0 if count would become zero + */ +int lockref_put_not_zero(struct lockref *lockref) +{ + int retval; + + CMPXCHG_LOOP( + new.count--; + if (old.count <= 1) + return 0; + , + return 1; + ); + + spin_lock(&lockref->lock); + retval = 0; + if (lockref->count > 1) { + lockref->count--; + retval = 1; + } + spin_unlock(&lockref->lock); + return retval; +} +EXPORT_SYMBOL(lockref_put_not_zero); + +/** * lockref_get_or_lock - Increments count unless the count is 0 or dead * @lockref: pointer to lockref structure * Return: 1 if count updated successfully or 0 if count was zero |