From: Sebastian Ott <sebott@linux.vnet.ibm.com>
Date: Mon, 14 Jul 2008 07:59:20 +0000 (+0200)
Subject: [S390] cio: fix double unregistering of subchannels
X-Git-Tag: v2.6.27-rc1~1112^2~26
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ef60cd13ecee0ccf2439d63013cbfc798aea2bb9;p=profile%2Fivi%2Fkernel-x86-ivi.git

[S390] cio: fix double unregistering of subchannels

In some cases where the channel subsystem decides to drop a subchannel
device device_unregister may be called twice, which results in an oops.
The patch prevents this by only unregistering registered devices.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---

diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index 4e2f2bb..46c021d 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -164,7 +164,8 @@ static int css_sch_device_register(struct subchannel *sch)
 void css_sch_device_unregister(struct subchannel *sch)
 {
 	mutex_lock(&sch->reg_mutex);
-	device_unregister(&sch->dev);
+	if (device_is_registered(&sch->dev))
+		device_unregister(&sch->dev);
 	mutex_unlock(&sch->reg_mutex);
 }
 EXPORT_SYMBOL_GPL(css_sch_device_unregister);