RDMA/rxe: Fix a race condition in rxe_requester()
The rxe driver works as follows:
* The send queue, receive queue and completion queues are implemented as
circular buffers.
* ib_post_send() and ib_post_recv() calls are serialized through a spinlock.
* Removing elements from various queues happens from tasklet
context. Tasklets are guaranteed to run on at most one CPU. This serializes
access to these queues. See also rxe_completer(), rxe_requester() and
rxe_responder().
* rxe_completer() processes the skbs queued onto qp->resp_pkts.
* rxe_requester() handles the send queue (qp->sq.queue).
* rxe_responder() processes the skbs queued onto qp->req_pkts.
Since rxe_drain_req_pkts() processes qp->req_pkts, calling
rxe_drain_req_pkts() from rxe_requester() is racy. Hence this patch.
Reported-by: Moni Shoua <monis@mellanox.com>
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: stable@vger.kernel.org
Signed-off-by: Doug Ledford <dledford@redhat.com>
diff --git a/drivers/infiniband/sw/rxe/rxe_req.c b/drivers/infiniband/sw/rxe/rxe_req.c
index 26a7f92..7bdaf71 100644
--- a/drivers/infiniband/sw/rxe/rxe_req.c
+++ b/drivers/infiniband/sw/rxe/rxe_req.c
@@ -594,15 +594,8 @@ int rxe_requester(void *arg)
rxe_add_ref(qp);
next_wqe:
- if (unlikely(!qp->valid)) {
- rxe_drain_req_pkts(qp, true);
+ if (unlikely(!qp->valid || qp->req.state == QP_STATE_ERROR))
goto exit;
- }
-
- if (unlikely(qp->req.state == QP_STATE_ERROR)) {
- rxe_drain_req_pkts(qp, true);
- goto exit;
- }
if (unlikely(qp->req.state == QP_STATE_RESET)) {
qp->req.wqe_index = consumer_index(qp->sq.queue);