SUNRPC: Fix races in xs_nospace() (06ea0bfe) · Commits · 戴 / test

When a send failure occurs due to the socket being out of buffer space, we call xs_nospace() in order to have the RPC task wait until the socket has drained enough to make it worth while trying again. The current patch fixes a race in which the socket is drained before we get round to setting up the machinery in xs_nospace(), and which is reported to cause hangs. Link: http://lkml.kernel.org/r/20140210170315.33dfc621@notabene.brown Fixes: (SUNRPC: Don't start the retransmission timer...) Reported-by:

Neil Brown <neilb@suse.com> Cc: stable@vger.kernel.org Signed-off-by:

Trond Myklebust <trond.myklebust@primarydata.com>

net/sunrpc/xprtsock.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -510,6 +510,7 @@ static int xs_nospace(struct rpc_task *task)
		struct rpc_rqst *req = task->tk_rqstp;
		struct rpc_xprt *xprt = req->rq_xprt;
		struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
		struct sock *sk = transport->inet;
		int ret = -EAGAIN;

		dprintk("RPC: %5u xmit incomplete (%u left of %u)\n",
		@@ -527,7 +528,7 @@ static int xs_nospace(struct rpc_task *task)
		* window size
		*/
		set_bit(SOCK_NOSPACE, &transport->sock->flags);
		transport->inet->sk_write_pending++;
		sk->sk_write_pending++;
		/* ...and wait for more buffer space */
		xprt_wait_for_buffer_space(task, xs_nospace_callback);
		}
		@@ -537,6 +538,9 @@ static int xs_nospace(struct rpc_task *task)
		}

		spin_unlock_bh(&xprt->transport_lock);

		/* Race breaker in case memory is freed before above code is called */
		sk->sk_write_space(sk);
		return ret;
		}

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