diff options
| -rw-r--r-- | lib/rwsem.c | 33 |
1 files changed, 9 insertions, 24 deletions
diff --git a/lib/rwsem.c b/lib/rwsem.c index 66f307e9076..c73bd96dc30 100644 --- a/lib/rwsem.c +++ b/lib/rwsem.c @@ -161,16 +161,8 @@ static int try_get_writer_sem(struct rw_semaphore *sem, try_again_write: oldcount = rwsem_atomic_update(adjustment, sem) - adjustment; - if (!(oldcount & RWSEM_ACTIVE_MASK)) { - /* No active lock: */ - struct task_struct *tsk = waiter->task; - - list_del(&waiter->list); - smp_mb(); - put_task_struct(tsk); - tsk->state = TASK_RUNNING; + if (!(oldcount & RWSEM_ACTIVE_MASK)) return 1; - } /* some one grabbed the sem already */ if (rwsem_atomic_update(-adjustment, sem) & RWSEM_ACTIVE_MASK) return 0; @@ -220,11 +212,10 @@ struct rw_semaphore __sched *rwsem_down_read_failed(struct rw_semaphore *sem) } /* - * wait for the write lock to be granted + * wait until we successfully acquire the write lock */ struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem) { - enum rwsem_waiter_type type = RWSEM_WAITING_FOR_WRITE; signed long adjustment = -RWSEM_ACTIVE_WRITE_BIAS; struct rwsem_waiter waiter; struct task_struct *tsk = current; @@ -232,8 +223,7 @@ struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem) /* set up my own style of waitqueue */ waiter.task = tsk; - waiter.type = type; - get_task_struct(tsk); + waiter.type = RWSEM_WAITING_FOR_WRITE; raw_spin_lock_irq(&sem->wait_lock); if (list_empty(&sem->wait_list)) @@ -255,25 +245,20 @@ struct rw_semaphore __sched *rwsem_down_write_failed(struct rw_semaphore *sem) adjustment == -RWSEM_ACTIVE_WRITE_BIAS) sem = __rwsem_do_wake(sem, RWSEM_WAKE_READ_OWNED); - raw_spin_unlock_irq(&sem->wait_lock); - - /* wait to be given the lock */ + /* wait until we successfully acquire the lock */ while (true) { set_task_state(tsk, TASK_UNINTERRUPTIBLE); - if (!waiter.task) + + if (try_get_writer_sem(sem, &waiter)) break; - raw_spin_lock_irq(&sem->wait_lock); - /* Try to get the writer sem, may steal from the head writer: */ - if (type == RWSEM_WAITING_FOR_WRITE) - if (try_get_writer_sem(sem, &waiter)) { - raw_spin_unlock_irq(&sem->wait_lock); - return sem; - } raw_spin_unlock_irq(&sem->wait_lock); schedule(); + raw_spin_lock_irq(&sem->wait_lock); } + list_del(&waiter.list); + raw_spin_unlock_irq(&sem->wait_lock); tsk->state = TASK_RUNNING; return sem; |