From: AMEET M. PARANJAPE <aparanja@redhat.com>
Date: Fri, 26 Jun 2009 09:37:37 -0400
Subject: [scsi] ibmvfc: process async events before cmd responses
Message-id: 20090626133407.24116.53579.sendpatchset@squad5-lp1.lab.bos.redhat.com
O-Subject: [PATCH RHEL5.4 BZ508127 3/3] ibmvfc: Process async events before command responses
Bugzilla: 508127
RH-Acked-by: David Howells <dhowells@redhat.com>

RHBZ#:
======
https://bugzilla.redhat.com/show_bug.cgi?id=508127

Description:
===========
Since async events could indicate changes to link status, or events which could
affect decisions made during discovery, we should process async events prior to
command completion responses.

RHEL Version Found:
================
RHEL 5.4

kABI Status:
============
No symbols were harmed.

Brew:
=====
Built on all platforms.
http://brewweb.devel.redhat.com/brew/taskinfo?taskID=1862866

Upstream Status:
================
http://git.kernel.org/gitweb.cgi?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=f1d7fb7a8ab55357b6c7d44a53f644a043680ed1

Test Status:
============
Without this patch an environment setup of a Power 6 blade using QLogic FC
adapter with NPIV attached to a DS4800 will cause the blade to periodically
hang making the system unusable.

With the set of patches applied the system behaves normally.

===============================================================
Ameet Paranjape 978-392-3903 ext 23903
IBM on-site partner

Proposed Patch:
===============

diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
index c67c6f1..0f13ebe 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc.c
@@ -2821,27 +2821,27 @@ static void ibmvfc_tasklet(void *data)
 
 	spin_lock_irqsave(vhost->host->host_lock, flags);
 	while (!done) {
-		/* Pull all the valid messages off the CRQ */
-		while ((crq = ibmvfc_next_crq(vhost)) != NULL) {
-			ibmvfc_handle_crq(crq, vhost);
-			crq->valid = 0;
-		}
-
 		/* Pull all the valid messages off the async CRQ */
 		while ((async = ibmvfc_next_async_crq(vhost)) != NULL) {
 			ibmvfc_handle_async(async, vhost);
 			async->valid = 0;
 		}
 
-		vio_enable_interrupts(vdev);
-		if ((crq = ibmvfc_next_crq(vhost)) != NULL) {
-			vio_disable_interrupts(vdev);
+		/* Pull all the valid messages off the CRQ */
+		while ((crq = ibmvfc_next_crq(vhost)) != NULL) {
 			ibmvfc_handle_crq(crq, vhost);
 			crq->valid = 0;
-		} else if ((async = ibmvfc_next_async_crq(vhost)) != NULL) {
+		}
+
+		vio_enable_interrupts(vdev);
+		if ((async = ibmvfc_next_async_crq(vhost)) != NULL) {
 			vio_disable_interrupts(vdev);
 			ibmvfc_handle_async(async, vhost);
 			async->valid = 0;
+		} else if ((crq = ibmvfc_next_crq(vhost)) != NULL) {
+			vio_disable_interrupts(vdev);
+			ibmvfc_handle_crq(crq, vhost);
+			crq->valid = 0;
 		} else
 			done = 1;
 	}