The new lockref_get_active ensures the count is nonzero and that the lockref is
not dead (i.e, count > 0). Simply comparing to zero was risky for the only
caller of this function (dget_parent), as it wasn't holding the lockref->lock.
Suggested-by: Linus Torvalds <torva...@linux-foundation.org>
Cc: NeilBrown <ne...@suse.de>
Cc: Al Viro <v...@zeniv.linux.org.uk>
Signed-off-by: Steven Noonan <ste...@uplinklabs.net>
---
fs/dcache.c | 2 +-
include/linux/lockref.h | 2 +-
lib/lockref.c | 13 +++++++------
3 files changed, 9 insertions(+), 8 deletions(-)
diff --git a/fs/dcache.c b/fs/dcache.c
index f7a592e..66ee98e 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -699,7 +699,7 @@ struct dentry *dget_parent(struct dentry *dentry)
*/
rcu_read_lock();
ret = ACCESS_ONCE(dentry->d_parent);
- gotref = lockref_get_not_zero(&ret->d_lockref);
+ gotref = lockref_get_active(&ret->d_lockref);
rcu_read_unlock();
if (likely(gotref)) {
if (likely(ret == ACCESS_ONCE(dentry->d_parent)))
diff --git a/include/linux/lockref.h b/include/linux/lockref.h
index 8558ff1..1a9827e 100644
--- a/include/linux/lockref.h
+++ b/include/linux/lockref.h
@@ -34,7 +34,7 @@ struct lockref {
};
extern void lockref_get(struct lockref *);
-extern int lockref_get_not_zero(struct lockref *);
+extern int lockref_get_active(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 e4c4255..318bef6 100644
--- a/lib/lockref.c
+++ b/lib/lockref.c
@@ -60,17 +60,18 @@ void lockref_get(struct lockref *lockref)
EXPORT_SYMBOL(lockref_get);
/**
- * lockref_get_not_zero - Increments count unless the count is 0
+ * lockref_get_active - Increments count unless the count is 0 or ref is dead
* @lockref: pointer to lockref structure
- * Return: 1 if count updated successfully or 0 if count was zero
+ * Return: 1 if count updated successfully or 0 if count was zero or lockref
+ * was dead
*/
-int lockref_get_not_zero(struct lockref *lockref)
+int lockref_get_active(struct lockref *lockref)
{
int retval;
CMPXCHG_LOOP(
new.count++;
- if (!old.count)
+ if (old.count < 1)
return 0;
,
return 1;
@@ -78,14 +79,14 @@ int lockref_get_not_zero(struct lockref *lockref)
spin_lock(&lockref->lock);
retval = 0;
- if (lockref->count) {
+ if (lockref->count >= 1) {
lockref->count++;
retval = 1;
}
spin_unlock(&lockref->lock);
return retval;
}
-EXPORT_SYMBOL(lockref_get_not_zero);
+EXPORT_SYMBOL(lockref_get_active);
/**
* lockref_get_or_lock - Increments count unless the count is 0
--
2.0.4
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
