On Wed, Feb 01, 2012 at 03:20:00PM +0800, Li Zefan wrote:
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
>
> >> diff --git a/net/core/sock.c b/net/core/sock.c
> >> index 213c856..c0bab23 100644
> >> --- a/net/core/sock.c
> >> +++ b/net/core/sock.c
> >> @@ -1160,9 +1160,7 @@ void sock_update_classid(struct sock *sk)
> >> {
> >> u32 classid;
> >>
> >> - rcu_read_lock(); /* doing current task, which cannot vanish. */
> >> classid = task_cls_classid(current);
> >> - rcu_read_unlock();
> >> if (classid && classid != sk->sk_classid)
> >> sk->sk_classid = classid;
> >
> > Yes, this seems fine.
> >
> > Then, I wonder why we do the "if (classid && classid != sk->sk_classid)"
> >
> > before the :
> >
> > sk->sk_classid = classid;
> >
> > This seems unnecessary checks.
> >
>
> I was wondering about this too. He who added this may provide us with an
> answer.
Well writing a cache-line unnecessarily is bad.
Cheers,
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
--
To unsubscribe from this list: send the line "unsubscribe cgroups" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
