MD: Prevent sysfs operations on uninitialized kobjects
Device-mapper does not use sysfs; but when device-mapper is leveraging
MD's RAID personalities, MD sometimes attempts to update sysfs. This
patch adds checks for 'mddev-kobj.sd' in sysfs_[un]link_rdev to ensure
it is about to operate on something valid. This patch also checks for
'mddev->kobj.sd' before calling 'sysfs_notify' in 'remove_and_add_spares'.
Although 'sysfs_notify' already makes this check, doing so in
'remove_and_add_spares' prevents an additional mutex operation.
Signed-off-by: Jonathan Brassow <jbrassow@xxxxxxxxxx>
Index: linux-upstream/drivers/md/md.h
===================================================================
--- linux-upstream.orig/drivers/md/md.h
+++ linux-upstream/drivers/md/md.h
@@ -506,7 +506,7 @@ static inline char * mdname (struct mdde
static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
{
char nm[20];
- if (!test_bit(Replacement, &rdev->flags)) {
+ if (!test_bit(Replacement, &rdev->flags) && mddev->kobj.sd) {
sprintf(nm, "rd%d", rdev->raid_disk);
return sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
} else
@@ -516,7 +516,7 @@ static inline int sysfs_link_rdev(struct
static inline void sysfs_unlink_rdev(struct mddev *mddev, struct md_rdev *rdev)
{
char nm[20];
- if (!test_bit(Replacement, &rdev->flags)) {
+ if (!test_bit(Replacement, &rdev->flags) && mddev->kobj.sd) {
sprintf(nm, "rd%d", rdev->raid_disk);
sysfs_remove_link(&mddev->kobj, nm);
}
Index: linux-upstream/drivers/md/md.c
===================================================================
--- linux-upstream.orig/drivers/md/md.c
+++ linux-upstream/drivers/md/md.c
@@ -7646,10 +7646,8 @@ static int remove_and_add_spares(struct
removed++;
}
}
- if (removed)
- sysfs_notify(&mddev->kobj, NULL,
- "degraded");
-
+ if (removed && mddev->kobj.sd)
+ sysfs_notify(&mddev->kobj, NULL, "degraded");
rdev_for_each(rdev, mddev) {
if (rdev->raid_disk >= 0 &&
--
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