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710fb39689
This patch adds extack support for the cbs qdisc implementation by adding NL_SET_ERR_MSG in validation of user input. Also it serves to illustrate a use case of how the infrastructure ops api changes are to be used by individual qdiscs. Cc: David Ahern <dsahern@gmail.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: Alexander Aring <aring@mojatatu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
385 lines
9.4 KiB
C
385 lines
9.4 KiB
C
/*
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* net/sched/sch_cbs.c Credit Based Shaper
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Authors: Vinicius Costa Gomes <vinicius.gomes@intel.com>
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*
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*/
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/* Credit Based Shaper (CBS)
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* =========================
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*
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* This is a simple rate-limiting shaper aimed at TSN applications on
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* systems with known traffic workloads.
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*
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* Its algorithm is defined by the IEEE 802.1Q-2014 Specification,
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* Section 8.6.8.2, and explained in more detail in the Annex L of the
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* same specification.
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*
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* There are four tunables to be considered:
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*
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* 'idleslope': Idleslope is the rate of credits that is
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* accumulated (in kilobits per second) when there is at least
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* one packet waiting for transmission. Packets are transmitted
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* when the current value of credits is equal or greater than
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* zero. When there is no packet to be transmitted the amount of
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* credits is set to zero. This is the main tunable of the CBS
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* algorithm.
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*
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* 'sendslope':
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* Sendslope is the rate of credits that is depleted (it should be a
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* negative number of kilobits per second) when a transmission is
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* ocurring. It can be calculated as follows, (IEEE 802.1Q-2014 Section
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* 8.6.8.2 item g):
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*
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* sendslope = idleslope - port_transmit_rate
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*
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* 'hicredit': Hicredit defines the maximum amount of credits (in
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* bytes) that can be accumulated. Hicredit depends on the
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* characteristics of interfering traffic,
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* 'max_interference_size' is the maximum size of any burst of
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* traffic that can delay the transmission of a frame that is
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* available for transmission for this traffic class, (IEEE
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* 802.1Q-2014 Annex L, Equation L-3):
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*
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* hicredit = max_interference_size * (idleslope / port_transmit_rate)
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*
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* 'locredit': Locredit is the minimum amount of credits that can
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* be reached. It is a function of the traffic flowing through
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* this qdisc (IEEE 802.1Q-2014 Annex L, Equation L-2):
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*
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* locredit = max_frame_size * (sendslope / port_transmit_rate)
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/skbuff.h>
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#include <net/netlink.h>
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#include <net/sch_generic.h>
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#include <net/pkt_sched.h>
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#define BYTES_PER_KBIT (1000LL / 8)
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struct cbs_sched_data {
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bool offload;
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int queue;
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s64 port_rate; /* in bytes/s */
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s64 last; /* timestamp in ns */
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s64 credits; /* in bytes */
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s32 locredit; /* in bytes */
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s32 hicredit; /* in bytes */
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s64 sendslope; /* in bytes/s */
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s64 idleslope; /* in bytes/s */
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struct qdisc_watchdog watchdog;
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int (*enqueue)(struct sk_buff *skb, struct Qdisc *sch);
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struct sk_buff *(*dequeue)(struct Qdisc *sch);
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};
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static int cbs_enqueue_offload(struct sk_buff *skb, struct Qdisc *sch)
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{
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return qdisc_enqueue_tail(skb, sch);
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}
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static int cbs_enqueue_soft(struct sk_buff *skb, struct Qdisc *sch)
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{
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struct cbs_sched_data *q = qdisc_priv(sch);
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if (sch->q.qlen == 0 && q->credits > 0) {
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/* We need to stop accumulating credits when there's
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* no enqueued packets and q->credits is positive.
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*/
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q->credits = 0;
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q->last = ktime_get_ns();
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}
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return qdisc_enqueue_tail(skb, sch);
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}
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static int cbs_enqueue(struct sk_buff *skb, struct Qdisc *sch,
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struct sk_buff **to_free)
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{
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struct cbs_sched_data *q = qdisc_priv(sch);
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return q->enqueue(skb, sch);
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}
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/* timediff is in ns, slope is in bytes/s */
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static s64 timediff_to_credits(s64 timediff, s64 slope)
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{
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return div64_s64(timediff * slope, NSEC_PER_SEC);
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}
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static s64 delay_from_credits(s64 credits, s64 slope)
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{
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if (unlikely(slope == 0))
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return S64_MAX;
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return div64_s64(-credits * NSEC_PER_SEC, slope);
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}
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static s64 credits_from_len(unsigned int len, s64 slope, s64 port_rate)
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{
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if (unlikely(port_rate == 0))
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return S64_MAX;
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return div64_s64(len * slope, port_rate);
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}
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static struct sk_buff *cbs_dequeue_soft(struct Qdisc *sch)
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{
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struct cbs_sched_data *q = qdisc_priv(sch);
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s64 now = ktime_get_ns();
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struct sk_buff *skb;
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s64 credits;
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int len;
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if (q->credits < 0) {
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credits = timediff_to_credits(now - q->last, q->idleslope);
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credits = q->credits + credits;
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q->credits = min_t(s64, credits, q->hicredit);
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if (q->credits < 0) {
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s64 delay;
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delay = delay_from_credits(q->credits, q->idleslope);
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qdisc_watchdog_schedule_ns(&q->watchdog, now + delay);
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q->last = now;
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return NULL;
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}
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}
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skb = qdisc_dequeue_head(sch);
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if (!skb)
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return NULL;
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len = qdisc_pkt_len(skb);
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/* As sendslope is a negative number, this will decrease the
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* amount of q->credits.
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*/
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credits = credits_from_len(len, q->sendslope, q->port_rate);
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credits += q->credits;
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q->credits = max_t(s64, credits, q->locredit);
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q->last = now;
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return skb;
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}
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static struct sk_buff *cbs_dequeue_offload(struct Qdisc *sch)
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{
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return qdisc_dequeue_head(sch);
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}
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static struct sk_buff *cbs_dequeue(struct Qdisc *sch)
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{
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struct cbs_sched_data *q = qdisc_priv(sch);
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return q->dequeue(sch);
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}
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static const struct nla_policy cbs_policy[TCA_CBS_MAX + 1] = {
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[TCA_CBS_PARMS] = { .len = sizeof(struct tc_cbs_qopt) },
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};
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static void cbs_disable_offload(struct net_device *dev,
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struct cbs_sched_data *q)
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{
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struct tc_cbs_qopt_offload cbs = { };
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const struct net_device_ops *ops;
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int err;
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if (!q->offload)
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return;
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q->enqueue = cbs_enqueue_soft;
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q->dequeue = cbs_dequeue_soft;
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ops = dev->netdev_ops;
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if (!ops->ndo_setup_tc)
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return;
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cbs.queue = q->queue;
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cbs.enable = 0;
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err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_CBS, &cbs);
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if (err < 0)
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pr_warn("Couldn't disable CBS offload for queue %d\n",
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cbs.queue);
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}
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static int cbs_enable_offload(struct net_device *dev, struct cbs_sched_data *q,
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const struct tc_cbs_qopt *opt,
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struct netlink_ext_ack *extack)
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{
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const struct net_device_ops *ops = dev->netdev_ops;
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struct tc_cbs_qopt_offload cbs = { };
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int err;
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if (!ops->ndo_setup_tc) {
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NL_SET_ERR_MSG(extack, "Specified device does not support cbs offload");
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return -EOPNOTSUPP;
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}
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cbs.queue = q->queue;
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cbs.enable = 1;
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cbs.hicredit = opt->hicredit;
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cbs.locredit = opt->locredit;
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cbs.idleslope = opt->idleslope;
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cbs.sendslope = opt->sendslope;
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err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_CBS, &cbs);
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if (err < 0) {
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NL_SET_ERR_MSG(extack, "Specified device failed to setup cbs hardware offload");
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return err;
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}
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q->enqueue = cbs_enqueue_offload;
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q->dequeue = cbs_dequeue_offload;
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return 0;
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}
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static int cbs_change(struct Qdisc *sch, struct nlattr *opt,
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struct netlink_ext_ack *extack)
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{
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struct cbs_sched_data *q = qdisc_priv(sch);
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struct net_device *dev = qdisc_dev(sch);
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struct nlattr *tb[TCA_CBS_MAX + 1];
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struct tc_cbs_qopt *qopt;
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int err;
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err = nla_parse_nested(tb, TCA_CBS_MAX, opt, cbs_policy, extack);
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if (err < 0)
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return err;
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if (!tb[TCA_CBS_PARMS]) {
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NL_SET_ERR_MSG(extack, "Missing CBS parameter which are mandatory");
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return -EINVAL;
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}
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qopt = nla_data(tb[TCA_CBS_PARMS]);
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if (!qopt->offload) {
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struct ethtool_link_ksettings ecmd;
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s64 link_speed;
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if (!__ethtool_get_link_ksettings(dev, &ecmd))
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link_speed = ecmd.base.speed;
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else
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link_speed = SPEED_1000;
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q->port_rate = link_speed * 1000 * BYTES_PER_KBIT;
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cbs_disable_offload(dev, q);
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} else {
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err = cbs_enable_offload(dev, q, qopt, extack);
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if (err < 0)
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return err;
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}
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/* Everything went OK, save the parameters used. */
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q->hicredit = qopt->hicredit;
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q->locredit = qopt->locredit;
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q->idleslope = qopt->idleslope * BYTES_PER_KBIT;
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q->sendslope = qopt->sendslope * BYTES_PER_KBIT;
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q->offload = qopt->offload;
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return 0;
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}
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static int cbs_init(struct Qdisc *sch, struct nlattr *opt,
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struct netlink_ext_ack *extack)
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{
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struct cbs_sched_data *q = qdisc_priv(sch);
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struct net_device *dev = qdisc_dev(sch);
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if (!opt) {
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NL_SET_ERR_MSG(extack, "Missing CBS qdisc options which are mandatory");
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return -EINVAL;
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}
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q->queue = sch->dev_queue - netdev_get_tx_queue(dev, 0);
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q->enqueue = cbs_enqueue_soft;
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q->dequeue = cbs_dequeue_soft;
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qdisc_watchdog_init(&q->watchdog, sch);
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return cbs_change(sch, opt, extack);
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}
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static void cbs_destroy(struct Qdisc *sch)
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{
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struct cbs_sched_data *q = qdisc_priv(sch);
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struct net_device *dev = qdisc_dev(sch);
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qdisc_watchdog_cancel(&q->watchdog);
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cbs_disable_offload(dev, q);
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}
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static int cbs_dump(struct Qdisc *sch, struct sk_buff *skb)
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{
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struct cbs_sched_data *q = qdisc_priv(sch);
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struct tc_cbs_qopt opt = { };
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struct nlattr *nest;
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nest = nla_nest_start(skb, TCA_OPTIONS);
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if (!nest)
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goto nla_put_failure;
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opt.hicredit = q->hicredit;
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opt.locredit = q->locredit;
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opt.sendslope = div64_s64(q->sendslope, BYTES_PER_KBIT);
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opt.idleslope = div64_s64(q->idleslope, BYTES_PER_KBIT);
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opt.offload = q->offload;
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if (nla_put(skb, TCA_CBS_PARMS, sizeof(opt), &opt))
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goto nla_put_failure;
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return nla_nest_end(skb, nest);
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nla_put_failure:
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nla_nest_cancel(skb, nest);
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return -1;
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}
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static struct Qdisc_ops cbs_qdisc_ops __read_mostly = {
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.id = "cbs",
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.priv_size = sizeof(struct cbs_sched_data),
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.enqueue = cbs_enqueue,
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.dequeue = cbs_dequeue,
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.peek = qdisc_peek_dequeued,
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.init = cbs_init,
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.reset = qdisc_reset_queue,
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.destroy = cbs_destroy,
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.change = cbs_change,
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.dump = cbs_dump,
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.owner = THIS_MODULE,
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};
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static int __init cbs_module_init(void)
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{
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return register_qdisc(&cbs_qdisc_ops);
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}
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static void __exit cbs_module_exit(void)
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{
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unregister_qdisc(&cbs_qdisc_ops);
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}
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module_init(cbs_module_init)
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module_exit(cbs_module_exit)
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MODULE_LICENSE("GPL");
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