SUNRPC: Fix memory barriers for req->rq_received

We need to ensure that all writes to the XDR buffers are done before
req->rq_received is visible to other processors.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

net/sunrpc/clnt.c

@@ -1069,6 +1069,11 @@ call_decode(struct rpc_task *task)
 		return;
 	}
 
+	/*
+	 * Ensure that we see all writes made by xprt_complete_rqst()
+	 * before it changed req->rq_received.
+	 */
+	smp_rmb();
 	req->rq_rcv_buf.len = req->rq_private_buf.len;
 
 	/* Check that the softirq receive buffer is valid */