[PATCH 4.9 65/86] ubi: Fix race condition between ubi volume creation and udev

Greg Kroah-Hartman
2018-03-16T15:23:28Z

From: Clay McClure <clay@daemons.net>

commit a51a0c8d213594bc094cb8e54aad0cb6d7f7b9a6 upstream.

Similar to commit 714fb87e8bc0 ("ubi: Fix race condition between ubi
device creation and udev"), we should make the volume active before
registering it.

Signed-off-by: Clay McClure <clay@daemons.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/mtd/ubi/vmt.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -265,6 +265,12 @@ int ubi_create_volume(struct ubi_device
vol->last_eb_bytes = vol->usable_leb_size;
}

+ /* Make volume "available" before it becomes accessible via sysfs */
+ spin_lock(&ubi->volumes_lock);
+ ubi->volumes[vol_id] = vol;
+ ubi->vol_count += 1;
+ spin_unlock(&ubi->volumes_lock);
+
/* Register character device for the volume */
cdev_init(&vol->cdev, &ubi_vol_cdev_operations);
vol->cdev.owner = THIS_MODULE;
@@ -304,11 +310,6 @@ int ubi_create_volume(struct ubi_device
if (err)
goto out_sysfs;

- spin_lock(&ubi->volumes_lock);
- ubi->volumes[vol_id] = vol;
- ubi->vol_count += 1;
- spin_unlock(&ubi->volumes_lock);
-
ubi_volume_notify(ubi, vol, UBI_VOLUME_ADDED);
self_check_volumes(ubi);
return err;
@@ -328,6 +329,10 @@ out_sysfs:
out_cdev:
cdev_del(&vol->cdev);
out_mapping:
+ spin_lock(&ubi->volumes_lock);
+ ubi->volumes[vol_id] = NULL;
+ ubi->vol_count -= 1;
+ spin_unlock(&ubi->volumes_lock);
if (do_free)
ubi_eba_destroy_table(eba_tbl);