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Commit 983c6844 authored by Trond Myklebust's avatar Trond Myklebust Committed by J. Bruce Fields
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SUNRPC: get rid of the request wait queue 



We're always _only_ waking up tasks from within the sp_threads list, so
we know that they are enqueued and alive. The rq_wait waitqueue is just
a distraction with extra atomic semantics.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 106f359c

include/linux/sunrpc/svc.h

+0 −1
Original line number Diff line number Diff line
@@ -280,7 +280,6 @@ struct svc_rqst { 
	bool			rq_splice_ok;   /* turned off in gss privacy

						 * to prevent encrypting page

						 * cache pages */

	wait_queue_head_t	rq_wait;	/* synchronization */

	struct task_struct	*rq_task;	/* service thread */

};

net/sunrpc/svc.c

+0 −2
Original line number Diff line number Diff line
@@ -612,8 +612,6 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node) 
	if (!rqstp)

		goto out_enomem;



	init_waitqueue_head(&rqstp->rq_wait);



	serv->sv_nrthreads++;

	spin_lock_bh(&pool->sp_lock);

	pool->sp_nrthreads++;

net/sunrpc/svc_xprt.c

+17 −15
Original line number Diff line number Diff line
@@ -348,8 +348,6 @@ static void svc_xprt_do_enqueue(struct svc_xprt *xprt) 


	cpu = get_cpu();

	pool = svc_pool_for_cpu(xprt->xpt_server, cpu);

	put_cpu();



	spin_lock_bh(&pool->sp_lock);



	if (!list_empty(&pool->sp_threads) &&
@@ -382,10 +380,15 @@ static void svc_xprt_do_enqueue(struct svc_xprt *xprt) 
			printk(KERN_ERR

				"svc_xprt_enqueue: server %p, rq_xprt=%p!\n",

				rqstp, rqstp->rq_xprt);

		rqstp->rq_xprt = xprt;

		/* Note the order of the following 3 lines:

		 * We want to assign xprt to rqstp->rq_xprt only _after_

		 * we've woken up the process, so that we don't race with

		 * the lockless check in svc_get_next_xprt().

		 */

		svc_xprt_get(xprt);

		wake_up_process(rqstp->rq_task);

		rqstp->rq_xprt = xprt;

		pool->sp_stats.threads_woken++;

		wake_up(&rqstp->rq_wait);

	} else {

		dprintk("svc: transport %p put into queue\n", xprt);

		list_add_tail(&xprt->xpt_ready, &pool->sp_sockets);
@@ -394,6 +397,7 @@ static void svc_xprt_do_enqueue(struct svc_xprt *xprt) 


out_unlock:

	spin_unlock_bh(&pool->sp_lock);

	put_cpu();

}



/*
@@ -509,7 +513,7 @@ void svc_wake_up(struct svc_serv *serv) 
			svc_thread_dequeue(pool, rqstp);

			rqstp->rq_xprt = NULL;

			 */

			wake_up(&rqstp->rq_wait);

			wake_up_process(rqstp->rq_task);

		} else

			pool->sp_task_pending = 1;

		spin_unlock_bh(&pool->sp_lock);
@@ -628,7 +632,6 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout) 
{

	struct svc_xprt *xprt;

	struct svc_pool		*pool = rqstp->rq_pool;

	DECLARE_WAITQUEUE(wait, current);

	long			time_left;



	/* Normally we will wait up to 5 seconds for any required
@@ -654,15 +657,15 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout) 
			xprt = ERR_PTR(-EAGAIN);

			goto out;

		}

		/* No data pending. Go to sleep */

		svc_thread_enqueue(pool, rqstp);



		/*

		 * We have to be able to interrupt this wait

		 * to bring down the daemons ...

		 */

		set_current_state(TASK_INTERRUPTIBLE);



		/* No data pending. Go to sleep */

		svc_thread_enqueue(pool, rqstp);



		/*

		 * checking kthread_should_stop() here allows us to avoid

		 * locking and signalling when stopping kthreads that call
@@ -676,14 +679,13 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout) 
			goto out;

		}



		add_wait_queue(&rqstp->rq_wait, &wait);

		spin_unlock_bh(&pool->sp_lock);



		time_left = schedule_timeout(timeout);

		__set_current_state(TASK_RUNNING);



		try_to_freeze();



		remove_wait_queue(&rqstp->rq_wait, &wait);

		xprt = rqstp->rq_xprt;

		if (xprt != NULL)

			return xprt;
@@ -786,10 +788,10 @@ int svc_recv(struct svc_rqst *rqstp, long timeout) 
		printk(KERN_ERR

			"svc_recv: service %p, transport not NULL!\n",

			 rqstp);

	if (waitqueue_active(&rqstp->rq_wait))

		printk(KERN_ERR

			"svc_recv: service %p, wait queue active!\n",

			 rqstp);



	/* Make sure the task pointer is set! */

	if (WARN_ON_ONCE(!rqstp->rq_task))

		rqstp->rq_task = current_task;



	err = svc_alloc_arg(rqstp);

	if (err)