Re: [PATCH 2.6.20-rc4 1/4] futex priority based wakeup

[Pierre Peiffer <pierre.peiffer@bull.net>]

Daniel Walker a écrit :
> On Tue, 2007-01-09 at 17:16 +0100, Pierre Peiffer wrote:
> > @@ -1358,7 +1366,7 @@ static int futex_unlock_pi(u32 __user *u
> >         struct futex_hash_bucket *hb;
> >         struct futex_q *this, *next;
> >         u32 uval;
> > -       struct list_head *head;
> > +       struct plist_head *head;
> >         union futex_key key;
> >         int ret, attempt = 0;
> >
> > @@ -1409,7 +1417,7 @@ retry_locked:
> >          */
> >         head = &hb->chain;
> >
> > -       list_for_each_entry_safe(this, next, head, list) {
> > +       plist_for_each_entry_safe(this, next, head, list) {
> >                 if (!match_futex (&this->key, &key))
> >                         continue;
> >                 ret = wake_futex_pi(uaddr, uval, this);
>
>
> Is this really necessary? The rtmutex will priority sort the waiters
> when you enable priority inheritance. Inside the wake_futex_pi() it
> actually just pulls the new owner off another plist inside the the
> rtmutex structure.

Yes. ... necessary for non-PI-futex (ie "normal" futex)...

As the hash_bucket_list is used and common for both futex and PI-futex, yes, in 
case of PI_futex, the task is queued two times in two plist.

--
Pierre
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