sysfs: use atomic_inc_unless_negative in sysfs_get_active

It seems that sysfs has an interesting way of doing the same thing.
This removes the cpu_relax unfortunately, but if it's really needed,
it would be better to add this to include/linux/atomic.h to benefit
all atomic ops users.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 15 deletions

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 2fbdff6be25c..7f968ede20d6 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -165,21 +165,8 @@ struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd)
         if (unlikely(!sd))
                 return NULL;
 
-        while (1) {
-                int v, t;
-
-                v = atomic_read(&sd->s_active);
-                if (unlikely(v < 0))
-                        return NULL;
-
-                t = atomic_cmpxchg(&sd->s_active, v, v + 1);
-                if (likely(t == v))
-                        break;
-                if (t < 0)
-                        return NULL;
-
-                cpu_relax();
-        }
+        if (!atomic_inc_unless_negative(&sd->s_active))
+                return NULL;
 
         if (likely(!ignore_lockdep(sd)))
                 rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_);