Re: [PATCH] mlxsw: spectrum_qdisc: Fix 64-bit division error in mlxsw_sp_qdisc_tbf_rate_kbps

Randy Dunlap
2020-01-31T01:44:01Z

On 1/30/20 3:26 PM, Nathan Chancellor wrote:
> When building arm32 allmodconfig:
>
> ERROR: "__aeabi_uldivmod"
> [drivers/net/ethernet/mellanox/mlxsw/mlxsw_spectrum.ko] undefined!
>
> rate_bytes_ps has type u64, we need to use a 64-bit division helper to
> avoid a build error.
>
> Fixes: a44f58c41bfb ("mlxsw: spectrum_qdisc: Support offloading of TBF Qdisc")
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
> drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
> index 79a2801d59f6..65e681ef01e8 100644
> --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
> +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
> @@ -614,7 +614,7 @@ mlxsw_sp_qdisc_tbf_rate_kbps(struct tc_tbf_qopt_offload_replace_params *p)
> /* TBF interface is in bytes/s, whereas Spectrum ASIC is configured in
> * Kbits/s.
> */
> - return p->rate.rate_bytes_ps / 1000 * 8;
> + return div_u64(p->rate.rate_bytes_ps, 1000 * 8);

not quite right AFAICT.

try either
return div_u64(p->rate.rate_bytes_ps * 8, 1000);
or
return div_u64(p->rate.rate_bytes_ps, 1000) * 8;

> }
>
> static int
>

--
~Randy