ubi: Fix race condition between ubi volume creation and udev

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>
Signed-off-by: Richard Weinberger <richard@nod.at>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
index 863835f..83ac8b4 100644 (file)
--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -312,6 +312,12 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
                        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;
@@ -354,11 +360,6 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
        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);
        if (paranoid_check_volumes(ubi))
                dbg_err("check failed while creating volume %d", vol_id);
@@ -379,6 +380,10 @@ 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)
                kfree(vol->eba_tbl);
 out_acc: