SUNRPC: Fix read ordering problems with req->rq_private_buf.len

We want to ensure that req->rq_private_buf.len is updated before
req->rq_received, so that call_decode() doesn't use an old value for
req->rq_rcv_buf.len.

In 'call_decode()' itself, instead of using task->tk_status (which is set
using req->rq_received) must use the actual value of
req->rq_private_buf.len when deciding whether or not the received RPC reply
is too short.

Finally ensure that we set req->rq_rcv_buf.len to zero when retrying a
request. A typo meant that we were resetting req->rq_private_buf.len in
call_decode(), and then clobbering that value with the old rq_rcv_buf.len
again in xprt_transmit().

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

1 files changed, 2 insertions, 1 deletions

diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 3ba64f9f84ba..5110a4ea7fdf 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -757,9 +757,10 @@ void xprt_complete_rqst(struct rpc_task *task, int copied)
         task->tk_rtt = (long)jiffies - req->rq_xtime;
 
         list_del_init(&req->rq_list);
+        req->rq_private_buf.len = copied;
         /* Ensure all writes are done before we update req->rq_received */
         smp_wmb();
-        req->rq_received = req->rq_private_buf.len = copied;
+        req->rq_received = copied;
         rpc_wake_up_queued_task(&xprt->pending, task);
 }
 EXPORT_SYMBOL_GPL(xprt_complete_rqst);