linux-kernel - [PATCH] xen: fix frontend driver disconnected from xenbus on removal

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Message-Id: <1517475439-10541-2-git-send-email-andr2000@gmail.com>
Date:   Thu,  1 Feb 2018 10:57:19 +0200
From:   Oleksandr Andrushchenko <andr2000@...il.com>
To:     xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Cc:     jgross@...e.com, david.vrabel@...rix.com,
        boris.ostrovsky@...cle.com, otubo@...hat.com,
        Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
Subject: [PATCH] xen: fix frontend driver disconnected from xenbus on removal

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>

Current xenbus frontend driver removal flow first disconnects
the driver from xenbus and then calls driver's remove callback.
This makes it impossible for the driver to listen to backend's
state changes and synchronize the removal procedure.

Fix this by removing other end XenBus watches after the
driver's remove callback is called.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
---
 drivers/xen/xenbus/xenbus_probe.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index 74888cacd0b0..9c63cd3f416b 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -258,11 +258,11 @@ int xenbus_dev_remove(struct device *_dev)
 
 	DPRINTK("%s", dev->nodename);
 
-	free_otherend_watch(dev);
-
 	if (drv->remove)
 		drv->remove(dev);
 
+	free_otherend_watch(dev);
+
 	free_otherend_details(dev);
 
 	xenbus_switch_state(dev, XenbusStateClosed);
-- 
2.7.4