Patch "ibmvscsis: Fix the incorrect req_lim_delta" 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

ibmvscsis: Fix the incorrect req_lim_delta

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:
ibmvscsis-fix-the-incorrect-req_lim_delta.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: "Bryant G. Ly" <[email protected]>
Date: Wed, 10 May 2017 14:35:47 -0500
Subject: ibmvscsis: Fix the incorrect req_lim_delta

From: Bryant G. Ly <[email protected]>

commit 75dbf2d36f6b122ad3c1070fe4bf95f71bbff321 upstream.

The current code is not correctly calculating the req_lim_delta.

We want to make sure vscsi->credit is always incremented when we do not send a response for the scsi op. Thus for the case where there is a successfully aborted task we need to make sure the vscsi->credit is incremented.

v2 - Moves the original location of the vscsi->credit increment to a better spot. Since if we increment credit, the next command we send back will have increased req_lim_delta. But we probably shouldn't be doing that until the aborted cmd is actually released. Otherwise the client will think that it can send a new command, and we could find ourselves short of command elements. Not likely, but could happen.

This patch depends on both:
commit 25e78531268e ("ibmvscsis: Do not send aborted task response") commit 98883f1b5415 ("ibmvscsis: Clear left-over abort_cmd pointers")

---
 drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c |   24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

@@ -1790,6 +1790,25 @@ static void ibmvscsis_send_messages(stru
 					list_del(&cmd->list);
 					ibmvscsis_free_cmd_resources(vscsi,
 								     cmd);
+					/*
+					 * With a successfully aborted op
+					 * through LIO we want to increment the
+					 * the vscsi credit so that when we dont
+					 * send a rsp to the original scsi abort
+					 * op (h_send_crq), but the tm rsp to
+					 * the abort is sent, the credit is
+					 * correctly sent with the abort tm rsp.
+					 * We would need 1 for the abort tm rsp
+					 * and 1 credit for the aborted scsi op.
+					 * Thus we need to increment here.
+					 * Also we want to increment the credit
+					 * here because we want to make sure
+					 * cmd is actually released first
+					 * otherwise the client will think it
+					 * it can send a new cmd, and we could
+					 * find ourselves short of cmd elements.
+					 */
+					vscsi->credit += 1;
 				} else {
 					iue = cmd->iue;
 

@@ -2964,10 +2983,7 @@ static long srp_build_response(struct sc
 
 	rsp->opcode = SRP_RSP;
 
-	if (vscsi->credit > 0 && vscsi->state == SRP_PROCESSING)
-		rsp->req_lim_delta = cpu_to_be32(vscsi->credit);
-	else
-		rsp->req_lim_delta = cpu_to_be32(1 + vscsi->credit);
+	rsp->req_lim_delta = cpu_to_be32(1 + vscsi->credit);
 	rsp->tag = cmd->rsp.tag;
 	rsp->flags = 0;
 

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

queue-4.9/ibmvscsis-fix-the-incorrect-req_lim_delta.patch queue-4.9/ibmvscsis-clear-left-over-abort_cmd-pointers.patch