From: Roi Dayan Date: Tue, 1 Apr 2014 13:28:38 +0000 (+0300) Subject: IB/iser: Drain the tx cq once before looping on the rx cq X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=1d6c2b736fd251c1f827704b1234d81b28c112d6;p=linux-beck.git IB/iser: Drain the tx cq once before looping on the rx cq The iser disconnection flow isn't done before all the inflight recv/send buffers posted to the QP are either flushed or normally completed to the CQ that serves this connection. The condition check is done in iser_handle_comp_error(). Currently, it's possible for the send buffer completion that makes the posted send buffers counter reach zero to be polled in the drain tx call, which is after the rx cq is fully drained. Since this completion might be not an error one (for example, it might be a completion of the logout request iSCSI PDU) we will skip iser_handle_comp_error(). So the connection will never terminate from the iscsi stack point of view, and we hang. To resolve this race, do the draining of the tx cq before the loop on the rx cq. Signed-off-by: Roi Dayan Signed-off-by: Or Gerlitz Signed-off-by: Roland Dreier --- diff --git a/drivers/infiniband/ulp/iser/iser_verbs.c b/drivers/infiniband/ulp/iser/iser_verbs.c index d2848e4e4274..89fadd85a776 100644 --- a/drivers/infiniband/ulp/iser/iser_verbs.c +++ b/drivers/infiniband/ulp/iser/iser_verbs.c @@ -1112,8 +1112,12 @@ static void iser_cq_tasklet_fn(unsigned long data) struct iser_rx_desc *desc; unsigned long xfer_len; struct iser_conn *ib_conn; - int completed_tx, completed_rx; - completed_tx = completed_rx = 0; + int completed_tx, completed_rx = 0; + + /* First do tx drain, so in a case where we have rx flushes and a successful + * tx completion we will still go through completion error handling. + */ + completed_tx = iser_drain_tx_cq(device, cq_index); while (ib_poll_cq(cq, 1, &wc) == 1) { desc = (struct iser_rx_desc *) (unsigned long) wc.wr_id; @@ -1141,7 +1145,6 @@ static void iser_cq_tasklet_fn(unsigned long data) * " would not cause interrupts to be missed" */ ib_req_notify_cq(cq, IB_CQ_NEXT_COMP); - completed_tx += iser_drain_tx_cq(device, cq_index); iser_dbg("got %d rx %d tx completions\n", completed_rx, completed_tx); }