[ofa-general] Re: [PATCH] ib/cm: fix stale connection detection

[Michael S. Tsirkin]

Thanks, Sean!
The patch looks OK to me.
I hope to be able to test it Sunday/Monday.

Quoting Sean Hefty <sean.hefty at intel.com>:
Subject: [PATCH] ib/cm: fix stale connection detection

The ib_cm can incorrectly detect a stale connection (a new connection
request for a QPN that is already connected) as a duplicate connection
request.  Separate the handling of potential duplicate REQs from stale
connections.

Signed-off-by: Sean Hefty <sean.hefty at intel.com>
---
Can you let me know if this fixes the issues for you?  I reworked the
code only to detect the stale connection properly.  More work is needed
to force the local QP into timewait if that is needed.  This would
likely require adding a new CM event to report that a stale connection
was detected on the QP.  Also, I left the duplicate request handling
as it was, since that should go in as a separate patch.


 drivers/infiniband/core/cm.c |   25 ++++++++++++++-----------
 1 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
index eff591d..c53d486 100644
--- a/drivers/infiniband/core/cm.c
+++ b/drivers/infiniband/core/cm.c
@@ -1295,26 +1295,29 @@ static struct cm_id_private * cm_match_req(struct cm_work *work,
 
 	req_msg = (struct cm_req_msg *)work->mad_recv_wc->recv_buf.mad;
 
-	/* Check for duplicate REQ and stale connections. */
+	/* Check for possible duplicate REQ. */
 	spin_lock_irqsave(&cm.lock, flags);
 	timewait_info = cm_insert_remote_id(cm_id_priv->timewait_info);
-	if (!timewait_info)
-		timewait_info = cm_insert_remote_qpn(cm_id_priv->timewait_info);
-
 	if (timewait_info) {
 		cur_cm_id_priv = cm_get_id(timewait_info->work.local_id,
 					   timewait_info->work.remote_id);
-		cm_cleanup_timewait(cm_id_priv->timewait_info);
 		spin_unlock_irqrestore(&cm.lock, flags);
 		if (cur_cm_id_priv) {
 			cm_dup_req_handler(work, cur_cm_id_priv);
 			cm_deref_id(cur_cm_id_priv);
-		} else
-			cm_issue_rej(work->port, work->mad_recv_wc,
-				     IB_CM_REJ_STALE_CONN, CM_MSG_RESPONSE_REQ,
-				     NULL, 0);
-		listen_cm_id_priv = NULL;
-		goto out;
+		}
+		return NULL;
+	}
+
+	/* Check for stale connections. */
+	timewait_info = cm_insert_remote_qpn(cm_id_priv->timewait_info);
+	if (timewait_info) {
+		cm_cleanup_timewait(cm_id_priv->timewait_info);
+		spin_unlock_irqrestore(&cm.lock, flags);
+		cm_issue_rej(work->port, work->mad_recv_wc,
+			     IB_CM_REJ_STALE_CONN, CM_MSG_RESPONSE_REQ,
+			     NULL, 0);
+		return NULL;
 	}
 
 	/* Find matching listen request. */

-- 
MST