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Commit ab418d70 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

SUNRPC: Optimise rpciod_up() 



Instead of taking the mutex every time we just need to increment/decrement
rpciod_users, we can optmise by using atomic_inc_not_zero and
atomic_dec_and_test.

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent d431a555

net/sunrpc/sched.c

+21 −28
Original line number Diff line number Diff line
@@ -58,7 +58,7 @@ static DECLARE_WAIT_QUEUE_HEAD(client_kill_wait); 
 * rpciod-related stuff

 */

static DEFINE_MUTEX(rpciod_mutex);

static unsigned int		rpciod_users;

static atomic_t rpciod_users = ATOMIC_INIT(0);

struct workqueue_struct *rpciod_workqueue;



/*
@@ -1047,28 +1047,27 @@ rpciod_up(void) 
	struct workqueue_struct *wq;

	int error = 0;



	if (atomic_inc_not_zero(&rpciod_users))

		return 0;



	mutex_lock(&rpciod_mutex);

	dprintk("RPC:       rpciod_up: users %u\n", rpciod_users);

	rpciod_users++;

	if (rpciod_workqueue)

		goto out;

	/*

	 * If there's no pid, we should be the first user.

	 */

	if (rpciod_users > 1)

		printk(KERN_WARNING "rpciod_up: no workqueue, %u users??\n", rpciod_users);



	/* Guard against races with rpciod_down() */

	if (rpciod_workqueue != NULL)

		goto out_ok;

	/*

	 * Create the rpciod thread and wait for it to start.

	 */

	dprintk("RPC:       creating workqueue rpciod\n");

	error = -ENOMEM;

	wq = create_workqueue("rpciod");

	if (wq == NULL) {

		printk(KERN_WARNING "rpciod_up: create workqueue failed, error=%d\n", error);

		rpciod_users--;

	if (wq == NULL)

		goto out;

	}



	rpciod_workqueue = wq;

	error = 0;

out_ok:

	atomic_inc(&rpciod_users);

out:

	mutex_unlock(&rpciod_mutex);

	return error;
@@ -1077,23 +1076,17 @@ rpciod_up(void) 
void

rpciod_down(void)

{

	if (!atomic_dec_and_test(&rpciod_users))

		return;



	mutex_lock(&rpciod_mutex);

	dprintk("RPC:       rpciod_down sema %u\n", rpciod_users);

	if (rpciod_users) {

		if (--rpciod_users)

			goto out;

	} else

		printk(KERN_WARNING "rpciod_down: no users??\n");

	dprintk("RPC:       destroying workqueue rpciod\n");



	if (!rpciod_workqueue) {

		dprintk("RPC:       rpciod_down: Nothing to do!\n");

		goto out;

	}

	if (atomic_read(&rpciod_users) == 0 && rpciod_workqueue != NULL) {

		rpciod_killall();



		destroy_workqueue(rpciod_workqueue);

		rpciod_workqueue = NULL;

 out:

	}

	mutex_unlock(&rpciod_mutex);

}