On Tue, 2015-04-28 at 10:50 -0700, Jason Low wrote:
> On Tue, 2015-04-28 at 19:17 +0200, Peter Zijlstra wrote:
>
> > To me it makes more sense to reverse these two branches (identical code
> > wise of course) and put the special case first.
> >
> > Alternatively we could also do something like the below, which to my
> > eyes looks a little better still, but I don't care too much.
> >
> > if (rwsem_has_spinner(sem)) {
> > /*
> > * comment ...
> > */
> > smp_rmb();
> > if (!raw_spin_trylock_irqsave(&sem->wait_lock, flags))
> > return sem;
> > goto locked;
> > }
> >
> > raw_spin_lock_irqsave(&sem->wait_lock, flags);
> > locked:
>
> How about putting this into its own function:
>
> static inline bool __rwsem_wake_acquire_wait_lock(sem)
> {
> /*
> *
> * Comments
> *
> */
> if (unlikely(rwsem_has_spinner(sem))) {
> /*
> * Comments
> */
> smp_rmb();
> if (!raw_spin_trylock_irqsave(&sem->wait_lock, flags))
> return false;
> }
>
> return true;
> }
That is, with the raw_spin_lock_irqsave() too :)
static inline bool __rwsem_wake_acquire_wait_lock(sem)
{
/*
*
* Comments
*
*/
if (unlikely(rwsem_has_spinner(sem))) {
/*
* Comments
*/
smp_rmb();
if (!raw_spin_trylock_irqsave(&sem->wait_lock, flags))
return false;
/* trylock successful */
return true;
}
raw_spin_lock_irqsave(&sem->wait_lock, flags);
return true;
}
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