Re: [PATCH] net: openvswitch: use do_div() for 64-by-32 divisions:

[Eric Dumazet]

On 4/24/20 5:10 AM, Geert Uytterhoeven wrote:
> On 32-bit architectures (e.g. m68k):
> 
>     ERROR: modpost: "__udivdi3" [net/openvswitch/openvswitch.ko] undefined!
>     ERROR: modpost: "__divdi3" [net/openvswitch/openvswitch.ko] undefined!
> 
> Fixes: e57358873bb5d6ca ("net: openvswitch: use u64 for meter bucket")
> Reported-by: noreply@xxxxxxxxxxxxxx
> Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> ---
>  net/openvswitch/meter.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/openvswitch/meter.c b/net/openvswitch/meter.c
> index 915f31123f235c03..3498a5ab092ab2b8 100644
> --- a/net/openvswitch/meter.c
> +++ b/net/openvswitch/meter.c
> @@ -393,7 +393,7 @@ static struct dp_meter *dp_meter_create(struct nlattr **a)
>  		 * Start with a full bucket.
>  		 */
>  		band->bucket = (band->burst_size + band->rate) * 1000ULL;
> -		band_max_delta_t = band->bucket / band->rate;
> +		band_max_delta_t = do_div(band->bucket, band->rate);
>  		if (band_max_delta_t > meter->max_delta_t)
>  			meter->max_delta_t = band_max_delta_t;
>  		band++;
> 

This is fascinating... Have you tested this patch ?

Please double check what do_div() return value is supposed to be !

Thanks.