Patch "xenbus: don't bail early from xenbus_dev_request_and_reply()" has been added to the 4.6-stable tree

[<gregkh@linuxfoundation.org>]

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

    xenbus: don't bail early from xenbus_dev_request_and_reply()

to the 4.6-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:
     xenbus-don-t-bail-early-from-xenbus_dev_request_and_reply.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 7469be95a487319514adce2304ad2af3553d2fc9 Mon Sep 17 00:00:00 2001
From: Jan Beulich <JBeulich@suse.com>
Date: Thu, 7 Jul 2016 01:32:04 -0600
Subject: xenbus: don't bail early from xenbus_dev_request_and_reply()

From: Jan Beulich <JBeulich@suse.com>

commit 7469be95a487319514adce2304ad2af3553d2fc9 upstream.

xenbus_dev_request_and_reply() needs to track whether a transaction is
open.  For XS_TRANSACTION_START messages it calls transaction_start()
and for XS_TRANSACTION_END messages it calls transaction_end().

If sending an XS_TRANSACTION_START message fails or responds with an
an error, the transaction is not open and transaction_end() must be
called.

If sending an XS_TRANSACTION_END message fails, the transaction is
still open, but if an error response is returned the transaction is
closed.

Commit 027bd7e89906 ("xen/xenbus: Avoid synchronous wait on XenBus
stalling shutdown/restart") introduced a regression where failed
XS_TRANSACTION_START messages were leaving the transaction open.  This
can cause problems with suspend (and migration) as all transactions
must be closed before suspending.

It appears that the problematic change was added accidentally, so just
remove it.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/xen/xenbus/xenbus_xs.c |    3 ---
 1 file changed, 3 deletions(-)

--- a/drivers/xen/xenbus/xenbus_xs.c
+++ b/drivers/xen/xenbus/xenbus_xs.c
@@ -249,9 +249,6 @@ void *xenbus_dev_request_and_reply(struc
 
 	mutex_unlock(&xs_state.request_mutex);
 
-	if (IS_ERR(ret))
-		return ret;
-
 	if ((msg->type == XS_TRANSACTION_END) ||
 	    ((req_msg.type == XS_TRANSACTION_START) &&
 	     (msg->type == XS_ERROR)))


Patches currently in stable-queue which might be from JBeulich@suse.com are

queue-4.6/xen-pciback-fix-conf_space-read-write-overlap-check.patch
queue-4.6/xenbus-don-t-bail-early-from-xenbus_dev_request_and_reply.patch
queue-4.6/xenbus-don-t-bug-on-user-mode-induced-condition.patch