[3.8.y.z extended stable] Patch "xen-blkfront: handle backend CLOSED without CLOSING" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    xen-blkfront: handle backend CLOSED without CLOSING

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.19.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From f923f004c2f7196e559a1bb9574eee499f078a23 Mon Sep 17 00:00:00 2001
From: David Vrabel <david.vrabel at citrix.com>
Date: Tue, 4 Feb 2014 18:53:56 +0000
Subject: xen-blkfront: handle backend CLOSED without CLOSING

commit 3661371701e714f0cea4120f6a365340858fb4e4 upstream.

Backend drivers shouldn't transistion to CLOSED unless the frontend is
CLOSED.  If a backend does transition to CLOSED too soon then the
frontend may not see the CLOSING state and will not properly shutdown.

So, treat an unexpected backend CLOSED state the same as CLOSING.

Signed-off-by: David Vrabel <david.vrabel at citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/block/xen-blkfront.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index de4a933..b6fb50c 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1485,13 +1485,16 @@ static void blkback_changed(struct xenbus_device *dev,
 	case XenbusStateReconfiguring:
 	case XenbusStateReconfigured:
 	case XenbusStateUnknown:
-	case XenbusStateClosed:
 		break;

 	case XenbusStateConnected:
 		blkfront_connect(info);
 		break;

+	case XenbusStateClosed:
+		if (dev->state == XenbusStateClosed)
+			break;
+		/* Missed the backend's Closing state -- fallthrough */
 	case XenbusStateClosing:
 		blkfront_closing(info);
 		break;
--
1.8.3.2