On Thu, 2017-10-12 at 17:40 -0700, Vinicius Costa Gomes wrote:
> This queueing discipline implements the shaper algorithm defined by
> the 802.1Q-2014 Section 8.6.8.2 and detailed in Annex L.
>
> It's primary usage is to apply some bandwidth reservation to user
> defined traffic classes, which are mapped to different queues via the
> mqprio qdisc.
>
> Only a simple software implementation is added for now.
>
> Signed-off-by: Vinicius Costa Gomes <vinicius.go...@intel.com>
> Signed-off-by: Jesus Sanchez-Palencia <jesus.sanchez-palen...@intel.com>
> ---
> +/* timediff is in ns, slope is in kbps */
> +static s64 timediff_to_credits(s64 timediff, s32 slope)
> +{
> + s64 credits = timediff * slope * BYTES_PER_KBIT;
> +
> + do_div(credits, NSEC_PER_SEC);
> +
> + return credits;
> +}
> +
> +static s64 delay_from_credits(s64 credits, s32 slope)
> +{
> + s64 rate = slope * BYTES_PER_KBIT;
> + s64 delay;
> +
> + if (unlikely(rate == 0))
> + return S64_MAX;
> +
> + delay = -credits * NSEC_PER_SEC;
> + do_div(delay, rate);
> +
> + return delay;
> +}
> +
> +static s64 credits_from_len(unsigned int len, s32 slope, s64 port_rate)
> +{
> + /* As do_div() only works on unsigned quantities, convert
> + * slope to a positive number here, and credits to a negative
> + * number before returning.
> + */
> + s64 rate = -slope * BYTES_PER_KBIT;
> + s64 credits;
> +
> + if (unlikely(port_rate == 0))
> + return S64_MAX;
> +
> + credits = len * rate;
> + do_div(credits, port_rate);
> +
> + return -credits;
> +}
> +
Your mixing of s64 and u64 is disturbing.
do_div() handles u64, not s64.
div64_s64() might be needed in place of do_div()
