On Fri, 2013-03-15 at 03:54 -0700, Michel Lespinasse wrote: > This change reduces the size of the spinlocked and TASK_UNINTERRUPTIBLE > sections in rwsem_down_failed_common(): > > - We only need the sem->wait_lock to insert ourselves on the wait_list; > the waiter node can be prepared outside of the wait_lock. > > - The task state only needs to be set to TASK_UNINTERRUPTIBLE immediately > before checking if we actually need to sleep; it doesn't need to protect > the entire function. > > Signed-off-by: Michel Lespinasse <[email protected]> > > --- > lib/rwsem.c | 8 +++----- > 1 file changed, 3 insertions(+), 5 deletions(-) > > diff --git a/lib/rwsem.c b/lib/rwsem.c > index 672eb33218ac..40636454cf3c 100644 > --- a/lib/rwsem.c > +++ b/lib/rwsem.c > @@ -188,14 +188,12 @@ rwsem_down_failed_common(struct rw_semaphore *sem, > struct task_struct *tsk = current; > signed long count; > > - set_task_state(tsk, TASK_UNINTERRUPTIBLE); > - > /* set up my own style of waitqueue */ > - raw_spin_lock_irq(&sem->wait_lock); > waiter.task = tsk; > waiter.type = type; > get_task_struct(tsk); > > + raw_spin_lock_irq(&sem->wait_lock); > if (list_empty(&sem->wait_list)) > adjustment += RWSEM_WAITING_BIAS; > list_add_tail(&waiter.list, &sem->wait_list); > @@ -218,7 +216,8 @@ rwsem_down_failed_common(struct rw_semaphore *sem, > raw_spin_unlock_irq(&sem->wait_lock); > > /* wait to be given the lock */ > - for (;;) { > + while (true) {
I would drop this gratutious change. > + set_task_state(tsk, TASK_UNINTERRUPTIBLE); > if (!waiter.task) > break; > > @@ -231,7 +230,6 @@ rwsem_down_failed_common(struct rw_semaphore *sem, > } > raw_spin_unlock_irq(&sem->wait_lock); > schedule(); > - set_task_state(tsk, TASK_UNINTERRUPTIBLE); > } > > tsk->state = TASK_RUNNING; -- 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/
