[dm-devel] Re: [PATCH 22/25] io-controller: Per io group bdi congestion interface

[Munehiro Ikeda]

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 at 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);
 
 	/* Do we need to hold queue lock? */
-- 
1.6.2.5


-- 
IKEDA, Munehiro
  NEC Corporation of America
    m-ikeda at ds.jp.nec.com