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Commit a8618a0e authored by Michel Lespinasse's avatar Michel Lespinasse Committed by Linus Torvalds
Browse files

rwsem: smaller wrappers around rwsem_down_failed_common 



More code can be pushed from rwsem_down_read_failed and
rwsem_down_write_failed into rwsem_down_failed_common.

Following change adding down_read_critical infrastructure support also
enjoys having flags available in a register rather than having to fish it
out in the struct rwsem_waiter...

Signed-off-by: default avatarMichel Lespinasse <walken@google.com>
Acked-by: default avatarDavid Howells <dhowells@redhat.com>
Cc: Mike Waychison <mikew@google.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Ying Han <yinghan@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 424acaae

lib/rwsem.c

+10 −15
Original line number Diff line number Diff line
@@ -171,8 +171,9 @@ __rwsem_do_wake(struct rw_semaphore *sem, int wake_type) 
 */

static struct rw_semaphore __sched *

rwsem_down_failed_common(struct rw_semaphore *sem,

			struct rwsem_waiter *waiter, signed long adjustment)

			 unsigned int flags, signed long adjustment)

{

	struct rwsem_waiter waiter;

	struct task_struct *tsk = current;

	signed long count;
@@ -180,12 +181,13 @@ rwsem_down_failed_common(struct rw_semaphore *sem, 


	/* set up my own style of waitqueue */

	spin_lock_irq(&sem->wait_lock);

	waiter->task = tsk;

	waiter.task = tsk;

	waiter.flags = flags;

	get_task_struct(tsk);



	if (list_empty(&sem->wait_list))

		adjustment += RWSEM_WAITING_BIAS;

	list_add_tail(&waiter->list, &sem->wait_list);

	list_add_tail(&waiter.list, &sem->wait_list);



	/* we're now waiting on the lock, but no longer actively locking */

	count = rwsem_atomic_update(adjustment, sem);
@@ -206,7 +208,7 @@ rwsem_down_failed_common(struct rw_semaphore *sem, 


	/* wait to be given the lock */

	for (;;) {

		if (!waiter->task)

		if (!waiter.task)

			break;

		schedule();

		set_task_state(tsk, TASK_UNINTERRUPTIBLE);
@@ -223,11 +225,8 @@ rwsem_down_failed_common(struct rw_semaphore *sem, 
asmregparm struct rw_semaphore __sched *

rwsem_down_read_failed(struct rw_semaphore *sem)

{

	struct rwsem_waiter waiter;



	waiter.flags = RWSEM_WAITING_FOR_READ;

	rwsem_down_failed_common(sem, &waiter, -RWSEM_ACTIVE_READ_BIAS);

	return sem;

	return rwsem_down_failed_common(sem, RWSEM_WAITING_FOR_READ,

					-RWSEM_ACTIVE_READ_BIAS);

}



/*
@@ -236,12 +235,8 @@ rwsem_down_read_failed(struct rw_semaphore *sem) 
asmregparm struct rw_semaphore __sched *

rwsem_down_write_failed(struct rw_semaphore *sem)

{

	struct rwsem_waiter waiter;



	waiter.flags = RWSEM_WAITING_FOR_WRITE;

	rwsem_down_failed_common(sem, &waiter, -RWSEM_ACTIVE_WRITE_BIAS);



	return sem;

	return rwsem_down_failed_common(sem, RWSEM_WAITING_FOR_WRITE,

					-RWSEM_ACTIVE_WRITE_BIAS);

}



/*