linux-kernel - Re: [PATCH net-next 2/3] net: mscc: ocelot: Implement port policers via tc command

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Date:   Thu, 2 May 2019 14:32:45 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Joergen Andreasen <joergen.andreasen@...rochip.com>
Cc:     netdev@...r.kernel.org, Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Microchip Linux Driver Support <UNGLinuxDriver@...rochip.com>,
        "David S. Miller" <davem@...emloft.net>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Paul Burton <paul.burton@...s.com>,
        James Hogan <jhogan@...nel.org>, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 2/3] net: mscc: ocelot: Implement port policers
 via tc command

Hi Joergen

> +
> +#define MSCC_RC(expr)				\
> +	do {					\
> +		int __rc__ = (expr);		\
> +		if (__rc__ < 0)			\
> +			return __rc__;		\
> +	}					\
> +	while (0)

I'm sure checkpatch warned about this. A return inside a macros is a
bad idea. I inherited code doing this, and broke it when adding
locking, because it was not obvious there was a return.

> +
> +/* The following two functions do the same as in iproute2 */
> +#define TIME_UNITS_PER_SEC	1000000
> +static unsigned int tc_core_tick2time(unsigned int tick)
> +{
> +	return (tick * (u32)PSCHED_TICKS2NS(1)) / 1000;
> +}
> +
> +static unsigned int tc_calc_xmitsize(u64 rate, unsigned int ticks)
> +{
> +	return div_u64(rate * tc_core_tick2time(ticks), TIME_UNITS_PER_SEC);
> +}

Should these but put somewhere others can use them?

> +
> +enum mscc_qos_rate_mode {
> +	MSCC_QOS_RATE_MODE_DISABLED, /* Policer/shaper disabled */
> +	MSCC_QOS_RATE_MODE_LINE, /* Measure line rate in kbps incl. IPG */
> +	MSCC_QOS_RATE_MODE_DATA, /* Measures data rate in kbps excl. IPG */
> +	MSCC_QOS_RATE_MODE_FRAME, /* Measures frame rate in fps */
> +	__MSCC_QOS_RATE_MODE_END,
> +	NUM_MSCC_QOS_RATE_MODE = __MSCC_QOS_RATE_MODE_END,
> +	MSCC_QOS_RATE_MODE_MAX = __MSCC_QOS_RATE_MODE_END - 1,
> +};
> +
> +/* Round x divided by y to nearest integer. x and y are integers */
> +#define MSCC_ROUNDING_DIVISION(x, y) (((x) + ((y) / 2)) / (y))

linux/kernel.h defines DIV_ROUND_UP(). Maybe add DIV_ROUND_DOWN()?

> +
> +/* Round x divided by y to nearest higher integer. x and y are integers */
> +#define MSCC_DIV_ROUND_UP(x, y) (((x) + (y) - 1) / (y))

DIV_ROUND_UP() ?

> +	/* Limit to maximum values */
> +	pir = min_t(u32, GENMASK(15, 0), pir);
> +	cir = min_t(u32, GENMASK(15, 0), cir);
> +	pbs = min_t(u32, pbs_max, pbs);
> +	cbs = min_t(u32, cbs_max, cbs);

If it does need to limit, maybe return -EOPNOTSUPP?

> +int ocelot_port_policer_add(struct ocelot_port *port,
> +			    struct tcf_police *p)
> +{
> +	struct ocelot *ocelot = port->ocelot;
> +	struct qos_policer_conf pp;
> +
> +	if (!p)
> +		return -EINVAL;
> +
> +	netdev_dbg(port->dev,
> +		   "result %d ewma_rate %u burst %lld mtu %u mtu_pktoks %lld\n",
> +		   p->params->tcfp_result,
> +		   p->params->tcfp_ewma_rate,
> +		   p->params->tcfp_burst,
> +		   p->params->tcfp_mtu,
> +		   p->params->tcfp_mtu_ptoks);
> +
> +	if (p->params->rate_present)
> +		netdev_dbg(port->dev,
> +			   "rate: rate %llu mult %u over %u link %u shift %u\n",
> +			   p->params->rate.rate_bytes_ps,
> +			   p->params->rate.mult,
> +			   p->params->rate.overhead,
> +			   p->params->rate.linklayer,
> +			   p->params->rate.shift);
> +
> +	if (p->params->peak_present)
> +		netdev_dbg(port->dev,
> +			   "peak: rate %llu mult %u over %u link %u shift %u\n",
> +			   p->params->peak.rate_bytes_ps,
> +			   p->params->peak.mult,
> +			   p->params->peak.overhead,
> +			   p->params->peak.linklayer,
> +			   p->params->peak.shift);
> +
> +	memset(&pp, 0, sizeof(pp));

Rather than memset, you can do:

	struct qos_policer_conf pp = { 0 };

	Andrew