Re: [PATCH] md/raid5: Fix divide type in raid5_make_request()

[Song Liu]

On Thu, Jun 23, 2022 at 9:56 AM Logan Gunthorpe <logang@xxxxxxxxxxxx> wrote:
>
> 0day reports a build failure on the hexagon architecture:
>
>   ld.lld: error: undefined symbol: __hexagon_udivdi3
>      referenced by raid5.c
>         md/raid5.o:(raid5_make_request) in archive drivers/built-in.a
>      referenced by raid5.c
>         md/raid5.o:(raid5_make_request) in archive drivers/built-in.a
>      did you mean: __hexagon_udivsi3
>         defined in: arch/hexagon/built-in.a(lib/udivsi3.o)
>
> This is caused by using DIV_ROUND_UP on a sector_t type.
>
> The actual value is known to be less than 256 so a wide 64bit divide
> here is not desirable. Thus cast the argument to an int to ensure it
> uses a 32bit divide.

I force pushed an update that uses DIV_ROUND_UP_SECTOR_T instead.
I guess that should also work?

Thanks,
Song

>
> Fixes: 681fb14a7100 ("md/raid5: Pivot raid5_make_request()")
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
> ---
>  drivers/md/raid5.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index 5723a497108a..9d25696b793d 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -6091,7 +6091,7 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi)
>         bi->bi_next = NULL;
>
>         bitmap_set(ctx.sectors_to_do, 0,
> -                  DIV_ROUND_UP(ctx.last_sector - logical_sector,
> +                  DIV_ROUND_UP((int)(ctx.last_sector - logical_sector),
>                                 RAID5_STRIPE_SECTORS(conf)));
>
>         pr_debug("raid456: %s, logical %llu to %llu\n", __func__,
>
> base-commit: 57c19f921f8081c1a9444dc7f3f6b3ea43fe612e
> --
> 2.30.2
>