Re: [PATCH] elevator: fix double release for elevator module

[Jens Axboe]

On 04/23/2015 08:59 AM, Jeff Moyer wrote:
> Chao Yu <chao2.yu@xxxxxxxxxxx> writes:
>
> > Our issue is descripted in below call path:
> > ->elevator_init
> >   ->elevator_init_fn
> >    ->{cfq,deadline,noop}_init_queue
> >     ->elevator_alloc
> >      ->kzalloc_node
> >     fail to call kzalloc_node and then put module in elevator_alloc;
> > fail to call elevator_init_fn and then put module again in elevator_init.
> >
> > Remove elevator_put invoking in error path of elevator_alloc to avoid
> > double release issue.
> >
> > Signed-off-by: Chao Yu <chao2.yu@xxxxxxxxxxx>
> > ---
> >   block/elevator.c | 5 +----
> >   1 file changed, 1 insertion(+), 4 deletions(-)
> >
> > diff --git a/block/elevator.c b/block/elevator.c
> > index d146a5e..8985038 100644
> > --- a/block/elevator.c
> > +++ b/block/elevator.c
> > @@ -157,7 +157,7 @@ struct elevator_queue *elevator_alloc(struct request_queue *q,
> >
> >   	eq = kzalloc_node(sizeof(*eq), GFP_KERNEL, q->node);
> >   	if (unlikely(!eq))
> > -		goto err;
> > +		return NULL;
> >
> >   	eq->type = e;
> >   	kobject_init(&eq->kobj, &elv_ktype);
> > @@ -165,9 +165,6 @@ struct elevator_queue *elevator_alloc(struct request_queue *q,
> >   	hash_init(eq->hash);
> >
> >   	return eq;
> > -err:
> > -	elevator_put(e);
> > -	return NULL;
> >   }
> >   EXPORT_SYMBOL(elevator_alloc);
>
> You could have posted the two patches together, as they are related.
> Anyway, looks good to me.
>
> Reviewed-by: Jeff Moyer <jmoyer@xxxxxxxxxx>

Agree, it should be one patch. I've combined them, and applied the fix 
for 4.1. Thanks.

--
Jens Axboe

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