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SUNRPC: Fix a race in the receive code path 

commit 90d91b0cd3 upstream.

We must ensure that the call to rpc_sleep_on() in xprt_transmit() cannot
race with the call to xprt_complete_rqst().

Reported-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://bugzilla.linux-nfs.org/show_bug.cgi?id=317
Fixes: ce7c252a8c ("SUNRPC: Add a separate spinlock to protect..")
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
Trond Myklebust 2017-12-14 21:24:08 -05:00 committed by Greg Kroah-Hartman
parent fbce429b41
commit 7dd1362247
1 changed files with 23 additions and 13 deletions
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36
net/sunrpc/xprt.c
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@ -1001,6 +1001,7 @@ void xprt_transmit(struct rpc_task *task)
{
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = req->rq_xprt;
unsigned int connect_cookie;
int status, numreqs;
dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
@ -1024,6 +1025,7 @@ void xprt_transmit(struct rpc_task *task)
} else if (!req->rq_bytes_sent)
return;
connect_cookie = xprt->connect_cookie;
req->rq_xtime = ktime_get();
status = xprt->ops->send_request(task);
trace_xprt_transmit(xprt, req->rq_xid, status);
@ -1047,20 +1049,28 @@ void xprt_transmit(struct rpc_task *task)
xprt->stat.bklog_u += xprt->backlog.qlen;
xprt->stat.sending_u += xprt->sending.qlen;
xprt->stat.pending_u += xprt->pending.qlen;
/* Don't race with disconnect */
if (!xprt_connected(xprt))
task->tk_status = -ENOTCONN;
else {
/*
* Sleep on the pending queue since
* we're expecting a reply.
*/
if (!req->rq_reply_bytes_recvd && rpc_reply_expected(task))
rpc_sleep_on(&xprt->pending, task, xprt_timer);
req->rq_connect_cookie = xprt->connect_cookie;
}
spin_unlock_bh(&xprt->transport_lock);
req->rq_connect_cookie = connect_cookie;
if (rpc_reply_expected(task) && !READ_ONCE(req->rq_reply_bytes_recvd)) {
/*
* Sleep on the pending queue if we're expecting a reply.
* The spinlock ensures atomicity between the test of
* req->rq_reply_bytes_recvd, and the call to rpc_sleep_on().
*/
spin_lock(&xprt->recv_lock);
if (!req->rq_reply_bytes_recvd) {
rpc_sleep_on(&xprt->pending, task, xprt_timer);
/*
* Send an extra queue wakeup call if the
* connection was dropped in case the call to
* rpc_sleep_on() raced.
*/
if (!xprt_connected(xprt))
xprt_wake_pending_tasks(xprt, -ENOTCONN);
}
spin_unlock(&xprt->recv_lock);
}
}
static void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)