Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1189963 > unrolled thread

Re: [PATCH 2/3] perpuc: check pcpu_first_chunk and pcpu_reserved_chunk to avoid handling them twice

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Re: [PATCH 2/3] perpuc: check pcpu_first_chunk and  pcpu_reserved_chunk to avoid handling them twice Tejun Heo <tj@kernel.org> - 2015-07-22 16:00 +0200
    Re: [PATCH 2/3] perpuc: check pcpu_first_chunk and  pcpu_reserved_chunk to avoid handling them twice Baoquan He <bhe@redhat.com> - 2015-07-22 16:30 +0200
      Re: [PATCH 2/3] perpuc: check pcpu_first_chunk and  pcpu_reserved_chunk to avoid handling them twice Tejun Heo <tj@kernel.org> - 2015-07-22 16:40 +0200

#1189963 — Re: [PATCH 2/3] perpuc: check pcpu_first_chunk and pcpu_reserved_chunk to avoid handling them twice

Hello,

On Wed, Jul 22, 2015 at 08:03:57AM +0800, Baoquan He wrote:
> Yes, dyn_size can't be zero. But in pcpu_setup_first_chunk(), the local
> variable dyn_size could be zero caused by below code:
> 
> if (ai->reserved_size) {
>                 schunk->free_size = ai->reserved_size;
>                 pcpu_reserved_chunk = schunk;
>                 pcpu_reserved_chunk_limit = ai->static_size +
> ai->reserved_size;
>         } else {
>                 schunk->free_size = dyn_size;
>                 dyn_size = 0;                   /* dynamic area covered
> */
>         }
> 
> So if no reserved_size dyn_size is assigned to zero, and is checked to
> see if dchunk need be created in below code:

Hmmm... but then pcpu_reserved_chunk is NULL so there still is no
duplicate on the list, no?

Thanks.

-- 
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[toc] | [next] | [standalone]

#1190005

On 07/22/15 at 09:52am, Tejun Heo wrote:
> Hello,
> 
> On Wed, Jul 22, 2015 at 08:03:57AM +0800, Baoquan He wrote:
> > Yes, dyn_size can't be zero. But in pcpu_setup_first_chunk(), the local
> > variable dyn_size could be zero caused by below code:
> > 
> > if (ai->reserved_size) {
> >                 schunk->free_size = ai->reserved_size;
> >                 pcpu_reserved_chunk = schunk;
> >                 pcpu_reserved_chunk_limit = ai->static_size +
> > ai->reserved_size;
> >         } else {
> >                 schunk->free_size = dyn_size;
> >                 dyn_size = 0;                   /* dynamic area covered
> > */
> >         }
> > 
> > So if no reserved_size dyn_size is assigned to zero, and is checked to
> > see if dchunk need be created in below code:
> 
> Hmmm... but then pcpu_reserved_chunk is NULL so there still is no
> duplicate on the list, no?

Yes, you are quite right. I was mistaken. So NACK this patch.

Thanks a lot.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[toc] | [prev] | [next] | [standalone]

#1190021

On Wed, Jul 22, 2015 at 10:29:00PM +0800, Baoquan He wrote:
> > > So if no reserved_size dyn_size is assigned to zero, and is checked to
> > > see if dchunk need be created in below code:
> > 
> > Hmmm... but then pcpu_reserved_chunk is NULL so there still is no
> > duplicate on the list, no?
> 
> Yes, you are quite right. I was mistaken. So NACK this patch.

But, yeah, it'd be great if we can add a WARN_ON() to ensure that this
really doesn't happen along with some comments.

Thanks!

-- 
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web