On 10/30/2014 3:50 PM, Bart Van Assche wrote:
At least LID reassignment can trigger a race condition in the SRP
initiator driver, namely the receive completion handler trying to
post a request on a QP during or after QP destruction and before
the CQ's have been destroyed. Avoid this race by modifying a QP
into the error state and by waiting until all receive completions
have been processed before destroying a QP.
Reported-by: Max Gurtuvoy <maxg@xxxxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
Reviewed-by: Sagi Grimberg <sagig@xxxxxxxxxxxx>
---
drivers/infiniband/ulp/srp/ib_srp.c | 59 +++++++++++++++++++++++++++++++------
drivers/infiniband/ulp/srp/ib_srp.h | 2 ++
2 files changed, 52 insertions(+), 9 deletions(-)
diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index c8b84a2..d3a5abe 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -453,6 +453,41 @@ static struct srp_fr_pool *srp_alloc_fr_pool(struct srp_target_port *target)
dev->max_pages_per_mr);
}
+/**
+ * srp_destroy_qp() - destroy an RDMA queue pair
+ * @ch: SRP RDMA channel.
+ *
+ * Change a queue pair into the error state and wait until all receive
+ * completions have been processed before destroying it. This avoids that
+ * the receive completion handler can access the queue pair while it is
+ * being destroyed.
+ */
+static void srp_destroy_qp(struct srp_rdma_ch *ch)
+{
+ struct srp_target_port *target = ch->target;
+ static struct ib_qp_attr attr = { .qp_state = IB_QPS_ERR };
+ static struct ib_recv_wr wr = { .wr_id = SRP_LAST_WR_ID };
+ struct ib_recv_wr *bad_wr;
+ int ret;
+
+ /* Destroying a QP and reusing ch->done is only safe if not connected */
+ WARN_ON_ONCE(target->connected);
I thought we agreed that cannot happen. I guess I don't mind keeping
it... BTW, were you able to reproduce this race as well?
Sagi.
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