[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 @@
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);