Commit 3db3c625 authored Mar 08, 2013 by Maarten Lankhorst Committed by Greg Kroah-Hartman Mar 25, 2013

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>

parent 91721197

fs/sysfs/dir.c

+2 −15

Original line number	Diff line number	Diff line
		@@ -165,22 +165,9 @@ 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)
		if (!atomic_inc_unless_negative(&sd->s_active))
		return NULL;

		cpu_relax();
		}

		if (likely(!ignore_lockdep(sd)))
		rwsem_acquire_read(&sd->dep_map, 0, 1, _RET_IP_);
		return sd;