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Commit af6b61d7 authored by Trond Myklebust's avatar Trond Myklebust
Browse files

Revert "SUNRPC: Micro-optimise when the task is known not to be sleeping" 



This reverts commit 009a82f6.

The ability to optimise here relies on compiler being able to optimise
away tail calls to avoid stack overflows. Unfortunately, we are seeing
reports of problems, so let's just revert.

Reported-by: default avatarDaniel Mack <daniel@zonque.org>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
parent 0769663b

include/linux/sunrpc/sched.h

+0 −8
Original line number Diff line number Diff line
@@ -304,12 +304,4 @@ rpc_clnt_swap_deactivate(struct rpc_clnt *clnt) 
}

#endif /* CONFIG_SUNRPC_SWAP */



static inline bool

rpc_task_need_resched(const struct rpc_task *task)

{

	if (RPC_IS_QUEUED(task) || task->tk_callback)

		return true;

	return false;

}



#endif /* _LINUX_SUNRPC_SCHED_H_ */

net/sunrpc/clnt.c

+8 −37
Original line number Diff line number Diff line
@@ -1540,7 +1540,6 @@ call_start(struct rpc_task *task) 
	clnt->cl_stats->rpccnt++;

	task->tk_action = call_reserve;

	rpc_task_set_transport(task, clnt);

	call_reserve(task);

}



/*
@@ -1554,9 +1553,6 @@ call_reserve(struct rpc_task *task) 
	task->tk_status  = 0;

	task->tk_action  = call_reserveresult;

	xprt_reserve(task);

	if (rpc_task_need_resched(task))

		return;

	 call_reserveresult(task);

}



static void call_retry_reserve(struct rpc_task *task);
@@ -1579,7 +1575,6 @@ call_reserveresult(struct rpc_task *task) 
	if (status >= 0) {

		if (task->tk_rqstp) {

			task->tk_action = call_refresh;

			call_refresh(task);

			return;

		}
@@ -1605,7 +1600,6 @@ call_reserveresult(struct rpc_task *task) 
		/* fall through */

	case -EAGAIN:	/* woken up; retry */

		task->tk_action = call_retry_reserve;

		call_retry_reserve(task);

		return;

	case -EIO:	/* probably a shutdown */

		break;
@@ -1628,9 +1622,6 @@ call_retry_reserve(struct rpc_task *task) 
	task->tk_status  = 0;

	task->tk_action  = call_reserveresult;

	xprt_retry_reserve(task);

	if (rpc_task_need_resched(task))

		return;

	call_reserveresult(task);

}



/*
@@ -1645,9 +1636,6 @@ call_refresh(struct rpc_task *task) 
	task->tk_status = 0;

	task->tk_client->cl_stats->rpcauthrefresh++;

	rpcauth_refreshcred(task);

	if (rpc_task_need_resched(task))

		return;

	call_refreshresult(task);

}



/*
@@ -1666,7 +1654,6 @@ call_refreshresult(struct rpc_task *task) 
	case 0:

		if (rpcauth_uptodatecred(task)) {

			task->tk_action = call_allocate;

			call_allocate(task);

			return;

		}

		/* Use rate-limiting and a max number of retries if refresh
@@ -1685,7 +1672,6 @@ call_refreshresult(struct rpc_task *task) 
		task->tk_cred_retry--;

		dprintk("RPC: %5u %s: retry refresh creds\n",

				task->tk_pid, __func__);

		call_refresh(task);

		return;

	}

	dprintk("RPC: %5u %s: refresh creds failed with error %d\n",
@@ -1711,10 +1697,8 @@ call_allocate(struct rpc_task *task) 
	task->tk_status = 0;

	task->tk_action = call_encode;



	if (req->rq_buffer) {

		call_encode(task);

	if (req->rq_buffer)

		return;

	}



	if (proc->p_proc != 0) {

		BUG_ON(proc->p_arglen == 0);
@@ -1740,12 +1724,8 @@ call_allocate(struct rpc_task *task) 


	status = xprt->ops->buf_alloc(task);

	xprt_inject_disconnect(xprt);

	if (status == 0) {

		if (rpc_task_need_resched(task))

			return;

		call_encode(task);

	if (status == 0)

		return;

	}

	if (status != -ENOMEM) {

		rpc_exit(task, status);

		return;
@@ -1828,8 +1808,12 @@ call_encode(struct rpc_task *task) 
		xprt_request_enqueue_receive(task);

	xprt_request_enqueue_transmit(task);

out:

	task->tk_action = call_transmit;

	/* Check that the connection is OK */

	if (!xprt_bound(task->tk_xprt))

		task->tk_action = call_bind;

	call_bind(task);

	else if (!xprt_connected(task->tk_xprt))

		task->tk_action = call_connect;

}



/*
@@ -1847,7 +1831,6 @@ rpc_task_handle_transmitted(struct rpc_task *task) 
{

	xprt_end_transmit(task);

	task->tk_action = call_transmit_status;

	call_transmit_status(task);

}



/*
@@ -1865,7 +1848,6 @@ call_bind(struct rpc_task *task) 


	if (xprt_bound(xprt)) {

		task->tk_action = call_connect;

		call_connect(task);

		return;

	}
@@ -1896,7 +1878,6 @@ call_bind_status(struct rpc_task *task) 
		dprint_status(task);

		task->tk_status = 0;

		task->tk_action = call_connect;

		call_connect(task);

		return;

	}
@@ -1981,7 +1962,6 @@ call_connect(struct rpc_task *task) 


	if (xprt_connected(xprt)) {

		task->tk_action = call_transmit;

		call_transmit(task);

		return;

	}
@@ -2051,7 +2031,6 @@ call_connect_status(struct rpc_task *task) 
	case 0:

		clnt->cl_stats->netreconn++;

		task->tk_action = call_transmit;

		call_transmit(task);

		return;

	}

	rpc_exit(task, status);
@@ -2087,9 +2066,6 @@ call_transmit(struct rpc_task *task) 
		xprt_transmit(task);

	}

	xprt_end_transmit(task);

	if (rpc_task_need_resched(task))

		return;

	call_transmit_status(task);

}



/*
@@ -2107,9 +2083,6 @@ call_transmit_status(struct rpc_task *task) 
	if (rpc_task_transmitted(task)) {

		if (task->tk_status == 0)

			xprt_request_wait_receive(task);

		if (rpc_task_need_resched(task))

			return;

		call_status(task);

		return;

	}
@@ -2170,7 +2143,6 @@ call_bc_encode(struct rpc_task *task) 
{

	xprt_request_enqueue_transmit(task);

	task->tk_action = call_bc_transmit;

	call_bc_transmit(task);

}



/*
@@ -2261,7 +2233,6 @@ call_status(struct rpc_task *task) 
	status = task->tk_status;

	if (status >= 0) {

		task->tk_action = call_decode;

		call_decode(task);

		return;

	}