On 06/11, Paul E. McKenney wrote: > > On Wed, Jun 11, 2014 at 07:17:34PM +0200, Oleg Nesterov wrote: > > On 06/11, Oleg Nesterov wrote: > > > > > > On 06/11, Paul E. McKenney wrote: > > > > > > > raw_spin_unlock_irqrestore(&rnp->lock, flags); > > > > rt_mutex_lock(&mtx); /* Side effect: boosts task t's priority. > > > > */ > > > > rt_mutex_unlock(&mtx); /* Keep lockdep happy. */ > > > > > > > > + /* Wait until boostee is done accessing mtx before > > > > reinitializing. */ > > > > + wait_for_completion(&rnp->boost_completion); > > > > + > > > > > > I must have missed something, I dont understand why we need > > > ->boost_completion. > > > > > > What if you simply move that rt_mutex into rcu_node ? > > > > > > Or. Given that rcu_boost_kthread() never exits, it can declare this mutex > > > on stack and pass the pointer to rcu_boost() ? > > > > Ah, please ignore, I forgot about init_proxy_locked(). Although perhaps this > > can be solved easily. > > You beat me to it. ;-) > > I was thinking of ->boost_completion as the way to solve it easily, but > what did you have in mind?
I meant, rcu_boost() could probably just do "mtx->owner = t", we know that it was unlocked by us and nobody else can use it until we set t->rcu_boost_mutex. And if we move it into rcu_node, then we can probably kill ->rcu_boost_mutex, rcu_read_unlock_special() could check rnp->boost_mutex->owner == current. But you know, I also think that the dentist removed the rest of my brains along my tooth, so I am not sure if I actually have something in mind. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
