lkml.org 
[lkml]   [2019]   [Apr]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v4 11/16] locking/rwsem: Enable readers spinning on writer
On Sat, Apr 13, 2019 at 01:22:54PM -0400, Waiman Long wrote:
> @@ -549,7 +582,7 @@ static noinline enum owner_state rwsem_spin_on_owner(struct rw_semaphore *sem)
> return !owner ? OWNER_NULL : OWNER_READER;
> }
>
> -static bool rwsem_optimistic_spin(struct rw_semaphore *sem)
> +static bool rwsem_optimistic_spin(struct rw_semaphore *sem, bool wlock)
> {
> bool taken = false;
> bool is_rt_task = rt_task(current);
> @@ -558,9 +591,6 @@ static bool rwsem_optimistic_spin(struct rw_semaphore *sem)
> preempt_disable();
>
> /* sem->wait_lock should not be held when doing optimistic spinning */
> - if (!rwsem_can_spin_on_owner(sem))
> - goto done;
> -
> if (!osq_lock(&sem->osq))
> goto done;
>
> @@ -580,10 +610,11 @@ static bool rwsem_optimistic_spin(struct rw_semaphore *sem)
> /*
> * Try to acquire the lock
> */
> - if (rwsem_try_write_lock_unqueued(sem)) {
> - taken = true;
> + taken = wlock ? rwsem_try_write_lock_unqueued(sem)
> + : rwsem_try_read_lock_unqueued(sem);
> +
> + if (taken)
> break;
> - }
>
> /*
> * An RT task cannot do optimistic spinning if it cannot

Alternatively you pass the trylock function as an argument:

static bool rwsem_optimistic_spin(struct rw_semaphore *sem,
bool (*trylock)(struct rw_semaphore *sem))
{
...
if (trylock(sem)) {
taken = true;
goto unlock;
}
...
}

\
 
 \ /
  Last update: 2019-04-17 15:57    [W:0.400 / U:4.100 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site