Re: [PATCH 1/2] block: increase bio_slab_nr only for necessary case

[cgxu519 <cgxu519@gmx.com>]

On 3/8/19 6:15 PM, Chengguang Xu wrote:
> When fail to create new cache in bio_find_or_create_slab(),
> we should not increase bio_slab_nr because it will cause
> referring uninitilized data in subsequent search.
>
> Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
> ---
>   block/bio.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/block/bio.c b/block/bio.c
> index 4db1008309ed..8081906f5d01 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -109,7 +109,7 @@ static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size)
>   		bio_slabs = new_bio_slabs;
>   	}
>   	if (entry == -1)
> -		entry = bio_slab_nr++;
> +		entry = bio_slab_nr;
>
>   	bslab = &bio_slabs[entry];
>
> @@ -122,6 +122,10 @@ static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size)
>   	bslab->slab = slab;
>   	bslab->slab_ref = 1;
>   	bslab->slab_size = sz;
> +
> +	if (entry == bio_slab_nr)
> +		bio_slab_nr++;
> +
>   out_unlock:
>   	mutex_unlock(&bio_slab_lock);
>   	return slab;

Any suggestion?

Thanks.