diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2015-01-09 15:19:03 -0800 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2015-01-25 23:16:29 -0500 |
| commit | 360f54796ed65939093ae373b92ebd5ef3341776 (patch) | |
| tree | b89eeed53d0f4ff4ca9b753ca3f239e6fa0be005 /lib | |
| parent | 32426f6653cbfde1ca16aff27a530ee36332f796 (diff) | |
dcache: let the dentry count go down to zero without taking d_lock
We can be more aggressive about this, if we are clever and careful. This is subtle.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/lockref.c | 36 |
1 files changed, 28 insertions, 8 deletions
diff --git a/lib/lockref.c b/lib/lockref.c index d2233de9a86e..ecb9a665ec19 100644 --- a/lib/lockref.c +++ b/lib/lockref.c @@ -60,7 +60,7 @@ void lockref_get(struct lockref *lockref) EXPORT_SYMBOL(lockref_get); /** - * lockref_get_not_zero - Increments count unless the count is 0 + * lockref_get_not_zero - 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 */ @@ -70,7 +70,7 @@ int lockref_get_not_zero(struct lockref *lockref) CMPXCHG_LOOP( new.count++; - if (!old.count) + if (old.count <= 0) return 0; , return 1; @@ -78,7 +78,7 @@ int lockref_get_not_zero(struct lockref *lockref) spin_lock(&lockref->lock); retval = 0; - if (lockref->count) { + if (lockref->count > 0) { lockref->count++; retval = 1; } @@ -88,7 +88,7 @@ int lockref_get_not_zero(struct lockref *lockref) EXPORT_SYMBOL(lockref_get_not_zero); /** - * lockref_get_or_lock - Increments count unless the count is 0 + * 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 * and we got the lock instead. @@ -97,14 +97,14 @@ int lockref_get_or_lock(struct lockref *lockref) { CMPXCHG_LOOP( new.count++; - if (!old.count) + if (old.count <= 0) break; , return 1; ); spin_lock(&lockref->lock); - if (!lockref->count) + if (lockref->count <= 0) return 0; lockref->count++; spin_unlock(&lockref->lock); @@ -113,6 +113,26 @@ int lockref_get_or_lock(struct lockref *lockref) EXPORT_SYMBOL(lockref_get_or_lock); /** + * lockref_put_return - Decrement reference count if possible + * @lockref: pointer to lockref structure + * + * Decrement the reference count and return the new value. + * If the lockref was dead or locked, return an error. + */ +int lockref_put_return(struct lockref *lockref) +{ + CMPXCHG_LOOP( + new.count--; + if (old.count <= 0) + return -1; + , + return new.count; + ); + return -1; +} +EXPORT_SYMBOL(lockref_put_return); + +/** * lockref_put_or_lock - decrements count unless count <= 1 before decrement * @lockref: pointer to lockref structure * Return: 1 if count updated successfully or 0 if count <= 1 and lock taken @@ -158,7 +178,7 @@ int lockref_get_not_dead(struct lockref *lockref) CMPXCHG_LOOP( new.count++; - if ((int)old.count < 0) + if (old.count < 0) return 0; , return 1; @@ -166,7 +186,7 @@ int lockref_get_not_dead(struct lockref *lockref) spin_lock(&lockref->lock); retval = 0; - if ((int) lockref->count >= 0) { + if (lockref->count >= 0) { lockref->count++; retval = 1; } |