From 933598be8552f313a22601ff32256b673d3f0642 Mon Sep 17 00:00:00 2001 From: Michel Lespinasse Date: Tue, 7 May 2013 06:45:55 -0700 Subject: [PATCH] --- yaml --- r: 373751 b: refs/heads/master c: 5ede972df1cd9294c82e9515949fd2103be81d7b h: refs/heads/master i: 373749: 0f7977fbb4a0fefeecaee94a9ad1d9a0f640d58e 373747: cba04135c05ef740116b1cb9c598281ea9d3c71c 373743: 297d6e05d83ab97376fcdecc5d2516dd29dcd4fd v: v3 --- [refs] | 2 +- trunk/lib/rwsem.c | 26 ++++++-------------------- 2 files changed, 7 insertions(+), 21 deletions(-) diff --git a/[refs] b/[refs] index d4384469b22d..7489b02c8515 100644 --- a/[refs] +++ b/[refs] @@ -1,2 +1,2 @@ --- -refs/heads/master: ed00f64346631dff035adfb9b0240daaa8b46c4e +refs/heads/master: 5ede972df1cd9294c82e9515949fd2103be81d7b diff --git a/trunk/lib/rwsem.c b/trunk/lib/rwsem.c index 2360bf204098..64c2dc007be2 100644 --- a/trunk/lib/rwsem.c +++ b/trunk/lib/rwsem.c @@ -142,25 +142,6 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wake_type) return sem; } -/* Try to get write sem, caller holds sem->wait_lock: */ -static int try_get_writer_sem(struct rw_semaphore *sem) -{ - long oldcount, adjustment; - - adjustment = RWSEM_ACTIVE_WRITE_BIAS; - if (list_is_singular(&sem->wait_list)) - adjustment -= RWSEM_WAITING_BIAS; - -try_again_write: - oldcount = rwsem_atomic_update(adjustment, sem) - adjustment; - if (!(oldcount & RWSEM_ACTIVE_MASK)) - return 1; - /* some one grabbed the sem already */ - if (rwsem_atomic_update(-adjustment, sem) & RWSEM_ACTIVE_MASK) - return 0; - goto try_again_write; -} - /* * wait for the read lock to be granted */ @@ -236,7 +217,12 @@ struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem) while (true) { set_task_state(tsk, TASK_UNINTERRUPTIBLE); - if (try_get_writer_sem(sem)) + /* Try acquiring the write lock. */ + count = RWSEM_ACTIVE_WRITE_BIAS; + if (!list_is_singular(&sem->wait_list)) + count += RWSEM_WAITING_BIAS; + if (cmpxchg(&sem->count, RWSEM_WAITING_BIAS, count) == + RWSEM_WAITING_BIAS) break; raw_spin_unlock_irq(&sem->wait_lock);