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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>
This commit is contained in:
Maarten Lankhorst 2013-03-08 16:07:27 +01:00 committed by Greg Kroah-Hartman
parent 91721197de
commit 3db3c62584
1 changed files with 2 additions and 15 deletions
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17
fs/sysfs/dir.c
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@ -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_);