[PATCH 3.8 85/91] [SCSI] enclosure: fix WARN_ON in dual path device removing

From: Kamal Mostafa
Date: Thu Jan 02 2014 - 12:10:37 EST -stable review patch. If anyone has any objections, please let me know.


From: James Bottomley <JBottomley@xxxxxxxxxxxxx>

commit a1470c7bf3a4676e62e4c0fb204e339399eb5c59 upstream.

Bug report from: wenxiong@xxxxxxxxxxxxxxxxxx

The issue is happened in dual controller configuration. We got the
sysfs warnings when rmmod the ipr module.

enclosure_unregister() in drivers/msic/enclosure.c, call device_unregister()
for each componment deivce, device_unregister() ->device_del()->kobject_del()
->sysfs_remove_dir(). In sysfs_remove_dir(), set kobj->sd = NULL.

For each componment device,
in which checking kobj->sd again, it has been set as NULL when doing
device_unregister. So we saw all these sysfs WARNING.

Tested-by: wenxiong@xxxxxxxxxxxxxxxxxx
Signed-off-by: James Bottomley <JBottomley@xxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
drivers/misc/enclosure.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/misc/enclosure.c b/drivers/misc/enclosure.c
index 00e5fcac8..cbee842 100644
--- a/drivers/misc/enclosure.c
+++ b/drivers/misc/enclosure.c
@@ -198,6 +198,13 @@ static void enclosure_remove_links(struct enclosure_component *cdev)

+ /*
+ * In odd circumstances, like multipath devices, something else may
+ * already have removed the links, so check for this condition first.
+ */
+ if (!cdev->dev->kobj.sd)
+ return;
enclosure_link_name(cdev, name);
sysfs_remove_link(&cdev->dev->kobj, name);
sysfs_remove_link(&cdev->cdev.kobj, "device");

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