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SubjectRe: [PATCH 22/25] io-controller: Per io group bdi congestion interface
On Thu, Jul 16, 2009 at 08:16:10PM -0400, Munehiro Ikeda wrote:
> Hi,
>
> Vivek Goyal wrote, on 07/02/2009 04:01 PM:
> > diff --git a/block/blk-core.c b/block/blk-core.c
> > index 2035c20..79fe6a9 100644
> > --- a/block/blk-core.c
> > +++ b/block/blk-core.c
> > @@ -90,6 +90,27 @@ void blk_queue_congestion_threshold(struct request_queue *q)
> > q->nr_congestion_off = nr;
> > }
> >
> > +#ifdef CONFIG_GROUP_IOSCHED
> > +int blk_queue_io_group_congested(struct backing_dev_info *bdi, int bdi_bits,
> > + struct page *page)
> > +{
> > + int ret = 0;
> > + struct request_queue *q = bdi->unplug_io_data;
> > +
> > + if (!q&& !q->elevator)
> > + return bdi_congested(bdi, bdi_bits);
>
> It causes NULL pointer dereference for brd etc.
>
> Signed-off-by: Munehiro "Muuhh" Ikeda <m-ikeda@ds.jp.nec.com>
> ---
> block/blk-core.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 79fe6a9..39fab66 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -97,7 +97,7 @@ int blk_queue_io_group_congested(struct backing_dev_info *bdi, int bdi_bits,
> int ret = 0;
> struct request_queue *q = bdi->unplug_io_data;
>
> - if (!q && !q->elevator)
> + if (!q || !q->elevator)
> return bdi_congested(bdi, bdi_bits);
>

Hi,

Thanks for the patch. I also noticed this recently and fixed it for next
to be posted version.

Thanks
Vivek

> /* Do we need to hold queue lock? */
> --
> 1.6.2.5
>
>
> --
> IKEDA, Munehiro
> NEC Corporation of America
> m-ikeda@ds.jp.nec.com


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