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Commit 20a951af authored by Trond Myklebust's avatar Trond Myklebust Committed by Greg Kroah-Hartman
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SUNRPC: Partial revert of commit 6f9f17287e78 



commit ea7a1019d8baf8503ecd6e3ec8436dec283569e6 upstream.

The premise of commit 6f9f17287e78 ("SUNRPC: Mitigate cond_resched() in
xprt_transmit()") was that cond_resched() is expensive and unnecessary
when there has been just a single send.
The point of cond_resched() is to ensure that tasks that should pre-empt
this one get a chance to do so when it is safe to do so. The code prior
to commit 6f9f17287e78 failed to take into account that it was keeping a
rpc_task pinned for longer than it needed to, and so rather than doing a
full revert, let's just move the cond_resched.

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5b7a0a4f

net/sunrpc/xprt.c

+15 −13
Original line number Diff line number Diff line
@@ -1538,15 +1538,14 @@ xprt_transmit(struct rpc_task *task) 
{

	struct rpc_rqst *next, *req = task->tk_rqstp;

	struct rpc_xprt	*xprt = req->rq_xprt;

	int counter, status;

	int status;



	spin_lock(&xprt->queue_lock);

	counter = 0;

	while (!list_empty(&xprt->xmit_queue)) {

		if (++counter == 20)

			break;

		next = list_first_entry(&xprt->xmit_queue,

	for (;;) {

		next = list_first_entry_or_null(&xprt->xmit_queue,

						struct rpc_rqst, rq_xmit);

		if (!next)

			break;

		xprt_pin_rqst(next);

		spin_unlock(&xprt->queue_lock);

		status = xprt_request_transmit(next, task);
@@ -1554,14 +1553,17 @@ xprt_transmit(struct rpc_task *task) 
			status = 0;

		spin_lock(&xprt->queue_lock);

		xprt_unpin_rqst(next);

		if (status == 0) {

			if (!xprt_request_data_received(task) ||

			    test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))

				continue;

		} else if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))

		if (status < 0) {

			if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))

				task->tk_status = status;

			break;

		}

		/* Was @task transmitted, and has it received a reply? */

		if (xprt_request_data_received(task) &&

		    !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))

			break;

		cond_resched_lock(&xprt->queue_lock);

	}

	spin_unlock(&xprt->queue_lock);

}