On Mon, Mar 18, 2013 at 05:14:18PM -0700, Greg KH wrote:
> On Fri, Mar 08, 2013 at 04:07:27PM +0100, Maarten Lankhorst wrote:
> > 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.lankho...@canonical.com>
> > ---
>
> Tejun wrote this code originally, so I'll defer to him as to if the
> patch below is a valid cleanup or not.
Yeah, I think that code predates atomic_inc_unless_negative().
> > diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
> > index 2fbdff6..7f968ed 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;
Looks good to me.
Acked-by: Tejun Heo <t...@kernel.org>
Thanks.
--
tejun
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