From: Phillip Lougher <plougher@redhat.com>
Date: Wed, 04 May 2011 20:54:50 -0000
Subject: [block] cciss: fix lost command problem
Message-id: <20110504205450.9BCAB3FF90@plougher.csb>
Patchwork-id: 35808
O-Subject: [RHEL5.6.z PATCH] BZ#696503 cciss: fix lost command problem 
Bugzilla: 696503
RH-Acked-by: Tomas Henzl <thenzl@redhat.com>

BZ#696503

This is a trivial fix-up to allow it to be applied to 5.6.z.

Thanks

Phillip

>From e8c9bcabfe56f2ac3702e9b69f7549ae091f1d3a Mon Sep 17 00:00:00 2001
From: Tomas Henzl <thenzl@redhat.com>
Date: Wed, 13 Apr 2011 18:31:02 +0000
Subject: [PATCH] cciss: fix lost command problem

This is for bz#696153

Upstream - 1ddd5049545e0aa, https://patchwork.kernel.org/patch/656801/

"Under certain workloads a command may seem to get lost. IOW, the Smart Array
thinks all commands have been completed but we still have commands in our
completion queue. This may lead to system instability, filesystems going
read-only, or even panics depending on the affected filesystem. We add an
extra read to force the write to complete.

Testing shows this extra read avoids the problem."

TomasAcked-by: Jeff Moyer <jmoyer@redhat.com>
---
 drivers/block/cciss.h |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/block/cciss.h b/drivers/block/cciss.h
index 5558cce..ec3cda1 100644
--- a/drivers/block/cciss.h
+++ b/drivers/block/cciss.h
@@ -168,9 +168,10 @@ static void SA5_submit_command( ctlr_info_t *h, CommandList_struct *c)
 #ifdef CCISS_DEBUG
 	 printk("Sending %x - down to controller\n", c->busaddr );
 #endif /* CCISS_DEBUG */ 
-         writel(c->busaddr, h->vaddr + SA5_REQUEST_PORT_OFFSET);
-	 h->commands_outstanding++;
-	 if ( h->commands_outstanding > h->max_outstanding)
+	writel(c->busaddr, h->vaddr + SA5_REQUEST_PORT_OFFSET);
+	readl(h->vaddr + SA5_REQUEST_PORT_OFFSET);
+	h->commands_outstanding++;
+	if ( h->commands_outstanding > h->max_outstanding)
 		h->max_outstanding = h->commands_outstanding;
 }