Re: [PATCH RESEND] block: warn if tag is greater than real_max_depth.

From: Tao Ma
Date: Mon Oct 24 2011 - 11:03:32 EST


Hi Jens,
any option with this patch?

Thanks
Tao
On 09/14/2011 03:23 PM, Tao Ma wrote:
> From: Tao Ma <boyu.mt@xxxxxxxxxx>
>
> In case tag depth is reduced, it is max_depth not real_max_depth.
> So we should allow a request with tag >= max_depth, but for a
> tag >= real_max_depth, there really should be some problem.
>
> Cc: Jens Axboe <jaxboe@xxxxxxxxxxxx>
> Signed-off-by: Tao Ma <boyu.mt@xxxxxxxxxx>
> ---
> block/blk-tag.c | 6 ++++--
> 1 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/block/blk-tag.c b/block/blk-tag.c
> index ece65fc..e74d6d1 100644
> --- a/block/blk-tag.c
> +++ b/block/blk-tag.c
> @@ -286,12 +286,14 @@ void blk_queue_end_tag(struct request_queue *q, struct request *rq)
>
> BUG_ON(tag == -1);
>
> - if (unlikely(tag >= bqt->real_max_depth))
> + if (unlikely(tag >= bqt->max_depth)) {
> /*
> * This can happen after tag depth has been reduced.
> - * FIXME: how about a warning or info message here?
> + * But tag shouldn't be larger than real_max_depth.
> */
> + WARN_ON(tag >= bqt->real_max_depth);
> return;
> + }
>
> list_del_init(&rq->queuelist);
> rq->cmd_flags &= ~REQ_QUEUED;

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