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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>
This commit is contained in:
NeilBrown 2009-07-01 12:27:21 +10:00
parent 1ec22eb2b4
commit 0909dc448c
1 changed files with 18 additions and 20 deletions
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38
drivers/md/md.c
View File

@ -3846,11 +3846,9 @@ static int md_alloc(dev_t dev, char *name)
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 @@ static int md_alloc(dev_t dev, char *name)
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 @@ static int md_alloc(dev_t dev, char *name)
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 @@ static int md_alloc(dev_t dev, char *name)
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)