Author: Trond Myklebust 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 --- net/sunrpc/clnt.c | 5 +++++ net/sunrpc/xprt.c | 3 ++- 2 files changed, 7 insertions(+), 1 deletions(-) diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 9f77530..6e71d6a 100644 --- a/net/sunrpc/clnt.c +++ b/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 */ diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index 940dba9..4dd5b3c 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -651,6 +651,8 @@ void xprt_complete_rqst(struct rpc_task task->tk_rtt = (long)jiffies - req->rq_xtime; list_del_init(&req->rq_list); + /* Ensure all writes are done before we update req->rq_received */ + smp_wmb(); req->rq_received = req->rq_private_buf.len = copied; rpc_wake_up_task(task); } @@ -727,7 +729,6 @@ void xprt_transmit(struct rpc_task *task dprintk("RPC: %4d xprt_transmit(%u)\n", task->tk_pid, req->rq_slen); - smp_rmb(); if (!req->rq_received) { if (list_empty(&req->rq_list)) { spin_lock_bh(&xprt->transport_lock);