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SUNRPC: Fix races in xs_nospace()

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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: a9a6b52ee1 (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>
This commit is contained in:
Trond Myklebust 2014-02-11 09:15:54 -05:00
parent a699d65ec4
commit 06ea0bfe6e
1 changed files with 5 additions and 1 deletions
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6
net/sunrpc/xprtsock.c
View file

@ -510,6 +510,7 @@ static int xs_nospace(struct rpc_task *task)
struct rpc_rqst *req = task->tk_rqstp; struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt; struct rpc_xprt *xprt = req->rq_xprt;
struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt); struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt);
struct sock *sk = transport->inet;
int ret = -EAGAIN; int ret = -EAGAIN;
dprintk("RPC: %5u xmit incomplete (%u left of %u)\n", dprintk("RPC: %5u xmit incomplete (%u left of %u)\n",
@ -527,7 +528,7 @@ static int xs_nospace(struct rpc_task *task)
* window size * window size
*/ */
set_bit(SOCK_NOSPACE, &transport->sock->flags); set_bit(SOCK_NOSPACE, &transport->sock->flags);
transport->inet->sk_write_pending++; sk->sk_write_pending++;
/* ...and wait for more buffer space */ /* ...and wait for more buffer space */
xprt_wait_for_buffer_space(task, xs_nospace_callback); 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); 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; return ret;
} }