Re: [PATCH v2 3/9] block: WARN if bdev inflight counter is negative

[John Garry <john.g.garry@oracle.com>]

On 27/04/2025 09:29, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@huawei.com>
> 
> Which means there is a BUG

nit: to me, BUG means symbol BUG(), and not a software bug (which I 
think that you mean)

> for related bio-based disk driver, or blk-mq
> for rq-based disk, it's better not to hide the BUG.

AFICS, this check was not present for mq, so is it really required now? 
I suppose that the code is simpler to always have the check. I find it 
an odd check to begin with...

> 
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> ---
>   block/genhd.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/block/genhd.c b/block/genhd.c
> index f671d9ee00c4..d158c25237b6 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -136,9 +136,9 @@ static void part_in_flight_rw(struct block_device *part,
>   		inflight[0] += part_stat_local_read_cpu(part, in_flight[0], cpu);
>   		inflight[1] += part_stat_local_read_cpu(part, in_flight[1], cpu);
>   	}
> -	if ((int)inflight[0] < 0)
> +	if (WARN_ON_ONCE((int)inflight[0] < 0))
>   		inflight[0] = 0;
> -	if ((int)inflight[1] < 0)
> +	if (WARN_ON_ONCE((int)inflight[1] < 0))
>   		inflight[1] = 0;
>   }
>