diff options
| author | Mikulas Patocka <mpatocka@redhat.com> | 2014-01-13 19:37:54 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-02-13 13:48:02 -0800 |
| commit | 4f66403630544a1e5ad3b041fe0dba9db16ff6d9 (patch) | |
| tree | 8d04fbba988c181beb9241897161051118fb1456 /drivers/md/dm.h | |
| parent | b77d17778310cbe015bd1978a48b1e418b9370d1 (diff) | |
dm sysfs: fix a module unload race
commit 2995fa78e423d7193f3b57835f6c1c75006a0315 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>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/md/dm.h')
| -rw-r--r-- | drivers/md/dm.h | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/drivers/md/dm.h b/drivers/md/dm.h index 66cfb7d8d15..9b3222f4483 100644 --- a/drivers/md/dm.h +++ b/drivers/md/dm.h @@ -16,6 +16,7 @@ #include <linux/blkdev.h> #include <linux/hdreg.h> #include <linux/completion.h> +#include <linux/kobject.h> /* * Suspend feature flags @@ -126,11 +127,25 @@ void dm_interface_exit(void); /* * sysfs interface */ +struct dm_kobject_holder { + struct kobject kobj; + struct completion completion; +}; + +static inline struct completion *dm_get_completion_from_kobject(struct kobject *kobj) +{ + return &container_of(kobj, struct dm_kobject_holder, kobj)->completion; +} + 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); + +/* + * The kobject helper + */ +void dm_kobject_release(struct kobject *kobj); /* * Targets for linear and striped mappings |