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Mikulas Patocka 4305714693 dm sysfs: fix a module unload race

commit 2995fa78e4 upstream.

This reverts commit be35f48610 ("dm: wait until embedded kobject is
released before destroying a device") and provides an improved fix.

The kobject release code that calls the completion must be placed in a
non-module file, otherwise there is a module unload race (if the process
calling dm_kobject_release is preempted and the DM module unloaded after
the completion is triggered, but before dm_kobject_release returns).

To fix this race, this patch moves the completion code to dm-builtin.c
which is always compiled directly into the kernel if BLK_DEV_DM is
selected.

The patch introduces a new dm_kobject_holder structure, its purpose is
to keep the completion and kobject in one place, so that it can be
accessed from non-module code without the need to export the layout of
struct mapped_device to that code.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
[bwh: Backported to 3.2:
 - Adjust context
 - Remove paranoid check of container_of() result in dm_get_from_kobject(),
   which would now be incorrect
 - Include <linux/export.h> in dm-builtin.c, included indirectly upstream]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

2014-04-02 00:58:43 +01:00

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Makefile for the kernel software RAID and LVM drivers.

dm-mod-y += dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o
dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o dm-multipath-y += dm-path-selector.o dm-mpath.o dm-snapshot-y += dm-snap.o dm-exception-store.o dm-snap-transient.o
dm-snap-persistent.o dm-mirror-y += dm-raid1.o dm-log-userspace-y
+= dm-log-userspace-base.o dm-log-userspace-transfer.o dm-thin-pool-y += dm-thin.o dm-thin-metadata.o md-mod-y += md.o bitmap.o raid456-y += raid5.o

Note: link order is important. All raid personalities

and must come before md.o, as they each initialise

themselves, and md.o may use the personalities when it

auto-initialised.

obj-$(CONFIG_MD_LINEAR) += linear.o obj-$(CONFIG_MD_RAID0) += raid0.o obj-$(CONFIG_MD_RAID1) += raid1.o obj-$(CONFIG_MD_RAID10) += raid10.o obj-$(CONFIG_MD_RAID456) += raid456.o obj-$(CONFIG_MD_MULTIPATH) += multipath.o obj-$(CONFIG_MD_FAULTY) += faulty.o obj-$(CONFIG_BLK_DEV_MD) += md-mod.o obj-$(CONFIG_BLK_DEV_DM) += dm-mod.o obj-$(CONFIG_BLK_DEV_DM_BUILTIN) += dm-builtin.o obj-$(CONFIG_DM_BUFIO) += dm-bufio.o obj-$(CONFIG_DM_CRYPT) += dm-crypt.o obj-$(CONFIG_DM_DELAY) += dm-delay.o obj-$(CONFIG_DM_FLAKEY) += dm-flakey.o obj-$(CONFIG_DM_MULTIPATH) += dm-multipath.o dm-round-robin.o obj-$(CONFIG_DM_MULTIPATH_QL) += dm-queue-length.o obj-$(CONFIG_DM_MULTIPATH_ST) += dm-service-time.o obj-$(CONFIG_DM_SNAPSHOT) += dm-snapshot.o obj-$(CONFIG_DM_PERSISTENT_DATA) += persistent-data/ obj-$(CONFIG_DM_MIRROR) += dm-mirror.o dm-log.o dm-region-hash.o obj-$(CONFIG_DM_LOG_USERSPACE) += dm-log-userspace.o obj-$(CONFIG_DM_ZERO) += dm-zero.o obj-$(CONFIG_DM_RAID) += dm-raid.o obj-$(CONFIG_DM_THIN_PROVISIONING) += dm-thin-pool.o

ifeq ($(CONFIG_DM_UEVENT),y) dm-mod-objs += dm-uevent.o endif

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