md: tidy up error paths in md_alloc
As the recent bug in md_alloc showed, having a single exit path for
unlocking and putting is a good idea. So restructure md_alloc to have
a single mutex_unlock and mddev_put, and use gotos where necessary.
Found-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 58bee23..65fe35b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -3846,11 +3846,9 @@
flush_scheduled_work();
mutex_lock(&disks_mutex);
- if (mddev->gendisk) {
- mutex_unlock(&disks_mutex);
- mddev_put(mddev);
- return -EEXIST;
- }
+ error = -EEXIST;
+ if (mddev->gendisk)
+ goto abort;
if (name) {
/* Need to ensure that 'name' is not a duplicate.
@@ -3862,19 +3860,15 @@
if (mddev2->gendisk &&
strcmp(mddev2->gendisk->disk_name, name) == 0) {
spin_unlock(&all_mddevs_lock);
- mutex_unlock(&disks_mutex);
- mddev_put(mddev);
- return -EEXIST;
+ goto abort;
}
spin_unlock(&all_mddevs_lock);
}
+ error = -ENOMEM;
mddev->queue = blk_alloc_queue(GFP_KERNEL);
- if (!mddev->queue) {
- mutex_unlock(&disks_mutex);
- mddev_put(mddev);
- return -ENOMEM;
- }
+ if (!mddev->queue)
+ goto abort;
mddev->queue->queuedata = mddev;
/* Can be unlocked because the queue is new: no concurrency */
@@ -3884,11 +3878,9 @@
disk = alloc_disk(1 << shift);
if (!disk) {
- mutex_unlock(&disks_mutex);
blk_cleanup_queue(mddev->queue);
mddev->queue = NULL;
- mddev_put(mddev);
- return -ENOMEM;
+ goto abort;
}
disk->major = MAJOR(mddev->unit);
disk->first_minor = unit << shift;
@@ -3910,16 +3902,22 @@
mddev->gendisk = disk;
error = kobject_init_and_add(&mddev->kobj, &md_ktype,
&disk_to_dev(disk)->kobj, "%s", "md");
- mutex_unlock(&disks_mutex);
- if (error)
+ if (error) {
+ /* This isn't possible, but as kobject_init_and_add is marked
+ * __must_check, we must do something with the result
+ */
printk(KERN_WARNING "md: cannot register %s/md - name in use\n",
disk->disk_name);
- else {
+ error = 0;
+ }
+ abort:
+ mutex_unlock(&disks_mutex);
+ if (!error) {
kobject_uevent(&mddev->kobj, KOBJ_ADD);
mddev->sysfs_state = sysfs_get_dirent(mddev->kobj.sd, "array_state");
}
mddev_put(mddev);
- return 0;
+ return error;
}
static struct kobject *md_probe(dev_t dev, int *part, void *data)