Patch "IB/rxe: increment msn only when completing a request" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

IB/rxe: increment msn only when completing a request

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ib-rxe-increment-msn-only-when-completing-a-request.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: David Marchand <[email protected]>
Date: Fri, 24 Feb 2017 15:38:26 +0100
Subject: IB/rxe: increment msn only when completing a request

From: David Marchand <[email protected]>

[ Upstream commit 9fcd67d1772c43d2f23e8fca56acc7219e991676 ]

According to C9-147, MSN should only be incremented when the last packet of a multi packet request has been received.

"Logically, the requester associates a sequential Send Sequence Number (SSN) with each WQE posted to the send queue. The SSN bears a one- to-one relationship to the MSN returned by the responder in each re- sponse packet. Therefore, when the requester receives a response, it in- terprets the MSN as representing the SSN of the most recent request completed by the responder to determine which send WQE(s) can be completed."

---
 drivers/infiniband/sw/rxe/rxe_resp.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

@@ -799,18 +799,17 @@ static enum resp_states execute(struct r
 		/* Unreachable */
 		WARN_ON(1);
 
-	/* We successfully processed this new request. */
-	qp->resp.msn++;
-
 	/* next expected psn, read handles this separately */
 	qp->resp.psn = (pkt->psn + 1) & BTH_PSN_MASK;
 
 	qp->resp.opcode = pkt->opcode;
 	qp->resp.status = IB_WC_SUCCESS;
 
-	if (pkt->mask & RXE_COMP_MASK)
+	if (pkt->mask & RXE_COMP_MASK) {
+		/* We successfully processed this new request. */
+		qp->resp.msn++;
 		return RESPST_COMPLETE;
-	else if (qp_type(qp) == IB_QPT_RC)
+	} else if (qp_type(qp) == IB_QPT_RC)
 		return RESPST_ACKNOWLEDGE;
 	else
 		return RESPST_CLEANUP;

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/ib-rxe-increment-msn-only-when-completing-a-request.patch