From 093108cb3640844cfdabb0f506fa6b592b64272d Mon Sep 17 00:00:00 2001 From: Hariprasad S Date: Fri, 6 May 2016 22:18:09 +0530 Subject: [PATCH] RDMA/iw_cxgb4: Always wake up waiter in c4iw_peer_abort_intr() Currently c4iw_peer_abort_intr() does not wake up the waiter if the endpoint state indicates we're using MPAv2 and we're currently trying to connect. This was introduced with commit 7c0a33d61187a ("RDMA/cxgb4: Don't wakeup threads for MPAv2") However, this original fix is flawed because it introduces a race that can cause a deadlock of the iwarp stack. Here is the race: ->local side sets up an active offload connection. ->local side sends MPA_START request. ->peer sends MPA_START response. ->local side ingress cpl thread begins processing the MPA_START response, but before it changes the state from MPA_REQ_SENT to FPDU_MODE: ->peer sends a RST which results in a ABORT_REQ_RSS. This triggers peer_abort_intr() which sees the state in MPA_REQ_SENT and since mpa_rev is 2, it will avoid waking up the endpoint with -ECONNRESET, assuming the stack will re-attempt the connection using MPAv1. ->Meanwhile, the cpl thread moves the state to FPDU_MODE and calls c4iw_modify_rc_qp() which calls rdma_init() which sends a RI_WR/INIT WR to firmware. But since HW sent an abort, FW correctly drops the RI_WR/INIT WR. ->So the cpl thread is stuck waiting for a reply and cannot process the ABORT_REQ_RSS cpl sitting in its input queue. Thus everything comes to a halt because no more ingress cpls are processed by the stack... The correct fix for the issue is to always do the wake up in c4iw_abort_intr() but reinitialize the wait object in c4iw_reconnect(). Fixes: 7c0a33d61187a ("RDMA/cxgb4: Don't wakeup threads for MPAv2") Signed-off-by: Steve Wise Signed-off-by: Hariprasad Shenai Signed-off-by: Doug Ledford --- drivers/infiniband/hw/cxgb4/cm.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c index 0502fac4a214..4f8afa2b8e21 100644 --- a/drivers/infiniband/hw/cxgb4/cm.c +++ b/drivers/infiniband/hw/cxgb4/cm.c @@ -2136,6 +2136,7 @@ static int c4iw_reconnect(struct c4iw_ep *ep) PDBG("%s qp %p cm_id %p\n", __func__, ep->com.qp, ep->com.cm_id); init_timer(&ep->timer); + c4iw_init_wr_wait(&ep->com.wr_wait); /* * Allocate an active TID to initiate a TCP connection. @@ -4239,16 +4240,7 @@ static int peer_abort_intr(struct c4iw_dev *dev, struct sk_buff *skb) PDBG("%s ep %p tid %u state %u\n", __func__, ep, ep->hwtid, ep->com.state); - /* - * Wake up any threads in rdma_init() or rdma_fini(). - * However, if we are on MPAv2 and want to retry with MPAv1 - * then, don't wake up yet. - */ - if (mpa_rev == 2 && !ep->tried_with_mpa_v1) { - if (ep->com.state != MPA_REQ_SENT) - c4iw_wake_up(&ep->com.wr_wait, -ECONNRESET); - } else - c4iw_wake_up(&ep->com.wr_wait, -ECONNRESET); + c4iw_wake_up(&ep->com.wr_wait, -ECONNRESET); out: sched(dev, skb); return 0; -- 2.20.1