From 24b8b44780a2c53ecb738f4a1c08d114f5eda27c Mon Sep 17 00:00:00 2001 From: Tom Tucker Date: Wed, 13 Aug 2008 11:05:41 -0500 Subject: svcrdma: Fix race between svc_rdma_recvfrom thread and the dto_tasklet RDMA_READ completions are kept on a separate queue from the general I/O request queue. Since a separate lock is used to protect the RDMA_READ completion queue, a race exists between the dto_tasklet and the svc_rdma_recvfrom thread where the dto_tasklet sets the XPT_DATA bit and adds I/O to the read-completion queue. Concurrently, the recvfrom thread checks the generic queue, finds it empty and resets the XPT_DATA bit. A subsequent svc_xprt_enqueue will fail to enqueue the transport for I/O and cause the transport to "stall". The fix is to protect both lists with the same lock and set the XPT_DATA bit with this lock held. Signed-off-by: Tom Tucker Signed-off-by: J. Bruce Fields --- net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'net/sunrpc/xprtrdma/svc_rdma_recvfrom.c') diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c index b4b17f44cb2..74de31a0661 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c @@ -443,18 +443,18 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp) dprintk("svcrdma: rqstp=%p\n", rqstp); - spin_lock_bh(&rdma_xprt->sc_read_complete_lock); + spin_lock_bh(&rdma_xprt->sc_rq_dto_lock); if (!list_empty(&rdma_xprt->sc_read_complete_q)) { ctxt = list_entry(rdma_xprt->sc_read_complete_q.next, struct svc_rdma_op_ctxt, dto_q); list_del_init(&ctxt->dto_q); } - spin_unlock_bh(&rdma_xprt->sc_read_complete_lock); - if (ctxt) + if (ctxt) { + spin_unlock_bh(&rdma_xprt->sc_rq_dto_lock); return rdma_read_complete(rqstp, ctxt); + } - spin_lock_bh(&rdma_xprt->sc_rq_dto_lock); if (!list_empty(&rdma_xprt->sc_rq_dto_q)) { ctxt = list_entry(rdma_xprt->sc_rq_dto_q.next, struct svc_rdma_op_ctxt, -- cgit v1.2.3