[ 73/98] IPoIB: Fix send lockup due to missed TX completion

Greg Kroah-Hartman
2013-03-26T23:33:21Z

From: Mike Marciniszyn <mike.marciniszyn@intel.com>

commit 1ee9e2aa7b31427303466776f455d43e5e3c9275 upstream.

Commit f0dc117abdfa ("IPoIB: Fix TX queue lockup with mixed UD/CM
traffic") attempts to solve an issue where unprocessed UD send
completions can deadlock the netdev.

The patch doesn't fully resolve the issue because if more than half
the tx_outstanding's were UD and all of the destinations are RC
reachable, arming the CQ doesn't solve the issue.

This patch uses the IB_CQ_REPORT_MISSED_EVENTS on the
ib_req_notify_cq(). If the rc is above 0, the UD send cq completion
callback is called directly to re-arm the send completion timer.

This issue is seen in very large parallel filesystem deployments
and the patch has been shown to correct the issue.

Reviewed-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/infiniband/ulp/ipoib/ipoib_cm.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/infiniband/ulp/ipoib/ipoib_cm.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
@@ -758,9 +758,13 @@ void ipoib_cm_send(struct net_device *de
if (++priv->tx_outstanding == ipoib_sendq_size) {
ipoib_dbg(priv, "TX ring 0x%x full, stopping kernel net queue\n",
tx->qp->qp_num);
- if (ib_req_notify_cq(priv->send_cq, IB_CQ_NEXT_COMP))
- ipoib_warn(priv, "request notify on send CQ failed\n");
netif_stop_queue(dev);
+ rc = ib_req_notify_cq(priv->send_cq,
+ IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS);
+ if (rc < 0)
+ ipoib_warn(priv, "request notify on send CQ failed\n");
+ else if (rc)
+ ipoib_send_comp_handler(priv->send_cq, dev);
}
}
}