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authorTom Tucker <tom@opengridcomputing.com>2008-08-13 12:05:41 -0400
committerJ. Bruce Fields <bfields@citi.umich.edu>2008-08-13 16:57:31 -0400
commit24b8b44780a2c53ecb738f4a1c08d114f5eda27c (patch)
treef772e59438783c6230158ea65bd5aeb3f84f4202 /net/sunrpc
parent30a2f3c60a84092c8084dfe788b710f8d0768cd4 (diff)
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 <tom@opengridcomputing.com> Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Diffstat (limited to 'net/sunrpc')
-rw-r--r--net/sunrpc/xprtrdma/svc_rdma_recvfrom.c8
-rw-r--r--net/sunrpc/xprtrdma/svc_rdma_transport.c5
2 files changed, 6 insertions, 7 deletions
diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
index b4b17f44cb29..74de31a06616 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)
443 443
444 dprintk("svcrdma: rqstp=%p\n", rqstp); 444 dprintk("svcrdma: rqstp=%p\n", rqstp);
445 445
446 spin_lock_bh(&rdma_xprt->sc_read_complete_lock); 446 spin_lock_bh(&rdma_xprt->sc_rq_dto_lock);
447 if (!list_empty(&rdma_xprt->sc_read_complete_q)) { 447 if (!list_empty(&rdma_xprt->sc_read_complete_q)) {
448 ctxt = list_entry(rdma_xprt->sc_read_complete_q.next, 448 ctxt = list_entry(rdma_xprt->sc_read_complete_q.next,
449 struct svc_rdma_op_ctxt, 449 struct svc_rdma_op_ctxt,
450 dto_q); 450 dto_q);
451 list_del_init(&ctxt->dto_q); 451 list_del_init(&ctxt->dto_q);
452 } 452 }
453 spin_unlock_bh(&rdma_xprt->sc_read_complete_lock); 453 if (ctxt) {
454 if (ctxt) 454 spin_unlock_bh(&rdma_xprt->sc_rq_dto_lock);
455 return rdma_read_complete(rqstp, ctxt); 455 return rdma_read_complete(rqstp, ctxt);
456 }
456 457
457 spin_lock_bh(&rdma_xprt->sc_rq_dto_lock);
458 if (!list_empty(&rdma_xprt->sc_rq_dto_q)) { 458 if (!list_empty(&rdma_xprt->sc_rq_dto_q)) {
459 ctxt = list_entry(rdma_xprt->sc_rq_dto_q.next, 459 ctxt = list_entry(rdma_xprt->sc_rq_dto_q.next,
460 struct svc_rdma_op_ctxt, 460 struct svc_rdma_op_ctxt,
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index 19ddc382b777..900cb69728c6 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -359,11 +359,11 @@ static void sq_cq_reap(struct svcxprt_rdma *xprt)
359 if (test_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags)) { 359 if (test_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags)) {
360 struct svc_rdma_op_ctxt *read_hdr = ctxt->read_hdr; 360 struct svc_rdma_op_ctxt *read_hdr = ctxt->read_hdr;
361 BUG_ON(!read_hdr); 361 BUG_ON(!read_hdr);
362 spin_lock_bh(&xprt->sc_rq_dto_lock);
362 set_bit(XPT_DATA, &xprt->sc_xprt.xpt_flags); 363 set_bit(XPT_DATA, &xprt->sc_xprt.xpt_flags);
363 spin_lock_bh(&xprt->sc_read_complete_lock);
364 list_add_tail(&read_hdr->dto_q, 364 list_add_tail(&read_hdr->dto_q,
365 &xprt->sc_read_complete_q); 365 &xprt->sc_read_complete_q);
366 spin_unlock_bh(&xprt->sc_read_complete_lock); 366 spin_unlock_bh(&xprt->sc_rq_dto_lock);
367 svc_xprt_enqueue(&xprt->sc_xprt); 367 svc_xprt_enqueue(&xprt->sc_xprt);
368 } 368 }
369 svc_rdma_put_context(ctxt, 0); 369 svc_rdma_put_context(ctxt, 0);
@@ -428,7 +428,6 @@ static struct svcxprt_rdma *rdma_create_xprt(struct svc_serv *serv,
428 init_waitqueue_head(&cma_xprt->sc_send_wait); 428 init_waitqueue_head(&cma_xprt->sc_send_wait);
429 429
430 spin_lock_init(&cma_xprt->sc_lock); 430 spin_lock_init(&cma_xprt->sc_lock);
431 spin_lock_init(&cma_xprt->sc_read_complete_lock);
432 spin_lock_init(&cma_xprt->sc_rq_dto_lock); 431 spin_lock_init(&cma_xprt->sc_rq_dto_lock);
433 432
434 cma_xprt->sc_ord = svcrdma_ord; 433 cma_xprt->sc_ord = svcrdma_ord;