diff options
| author | Mikulas Patocka <mpatocka@redhat.com> | 2014-01-06 23:01:22 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-02-13 13:48:01 -0800 |
| commit | eef2b6df86323b5c9eaee154174afb1976741f38 (patch) | |
| tree | 65bd724a740d630ead573d12dbb49e93f8536b6b /drivers/md/dm.h | |
| parent | 025d61e0f163e55a7a7b08975640c5c75c2690b8 (diff) | |
dm: wait until embedded kobject is released before destroying a device
commit be35f486108227e10fe5d96fd42fb2b344c59983 upstream.
There may be other parts of the kernel holding a reference on the dm
kobject. We must wait until all references are dropped before
deallocating the mapped_device structure.
The dm_kobject_release method signals that all references are dropped
via completion. But dm_kobject_release doesn't free the kobject (which
is embedded in the mapped_device structure).
This is the sequence of operations:
* when destroying a DM device, call kobject_put from dm_sysfs_exit
* wait until all users stop using the kobject, when it happens the
release method is called
* the release method signals the completion and should return without
delay
* the dm device removal code that waits on the completion continues
* the dm device removal code drops the dm_mod reference the device had
* the dm device removal code frees the mapped_device structure that
contains the kobject
Using kobject this way should avoid the module unload race that was
mentioned at the beginning of this thread:
https://lkml.org/lkml/2014/1/4/83
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/md/dm.h')
| -rw-r--r-- | drivers/md/dm.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/md/dm.h b/drivers/md/dm.h index 45b97da1bd0..66cfb7d8d15 100644 --- a/drivers/md/dm.h +++ b/drivers/md/dm.h @@ -15,6 +15,7 @@ #include <linux/list.h> #include <linux/blkdev.h> #include <linux/hdreg.h> +#include <linux/completion.h> /* * Suspend feature flags @@ -129,6 +130,7 @@ int dm_sysfs_init(struct mapped_device *md); void dm_sysfs_exit(struct mapped_device *md); struct kobject *dm_kobject(struct mapped_device *md); struct mapped_device *dm_get_from_kobject(struct kobject *kobj); +struct completion *dm_get_completion_from_kobject(struct kobject *kobj); /* * Targets for linear and striped mappings |