ACK: [Trusty][SRU] bcache: Fix a lockdep splat in an error path

[Brad Figg]

On Mon, Feb 29, 2016 at 10:30:00AM -0800, Kamal Mostafa wrote:
> From: Kent Overstreet <kmo at daterainc.com>
> 
> BugLink: http://bugs.launchpad.net/bugs/1551327
> 
> commit 4fa03402cda2fac1a54248c7578b939d95931dc0 upstream.
> 
> Signed-off-by: Kent Overstreet <kmo at daterainc.com>
> Signed-off-by: Kamal Mostafa <kamal at canonical.com>
> ---
>  drivers/md/bcache/super.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index c70521f..5136e11 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -1873,7 +1873,10 @@ static void register_cache(struct cache_sb *sb, struct page *sb_page,
>  	if (kobject_add(&ca->kobj, &part_to_dev(bdev->bd_part)->kobj, "bcache"))
>  		goto err;
>  
> +	mutex_lock(&bch_register_lock);
>  	err = register_cache_set(ca);
> +	mutex_unlock(&bch_register_lock);
> +
>  	if (err)
>  		goto err;
>  
> @@ -1935,8 +1938,6 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
>  	if (!try_module_get(THIS_MODULE))
>  		return -EBUSY;
>  
> -	mutex_lock(&bch_register_lock);
> -
>  	if (!(path = kstrndup(buffer, size, GFP_KERNEL)) ||
>  	    !(sb = kmalloc(sizeof(struct cache_sb), GFP_KERNEL)))
>  		goto err;
> @@ -1969,7 +1970,9 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
>  		if (!dc)
>  			goto err_close;
>  
> +		mutex_lock(&bch_register_lock);
>  		register_bdev(sb, sb_page, bdev, dc);
> +		mutex_unlock(&bch_register_lock);
>  	} else {
>  		struct cache *ca = kzalloc(sizeof(*ca), GFP_KERNEL);
>  		if (!ca)
> @@ -1982,7 +1985,6 @@ out:
>  		put_page(sb_page);
>  	kfree(sb);
>  	kfree(path);
> -	mutex_unlock(&bch_register_lock);
>  	module_put(THIS_MODULE);
>  	return ret;
>  
> -- 
> 2.7.0
> 
> 
> -- 
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> kernel-team at lists.ubuntu.com
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-- 
Brad Figg brad.figg at canonical.com http://www.canonical.com