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![Jesus Sanchez-Palencia](/assets/img/avatar_default.png)
Currently on dequeue() ETF only drops the first expired packet, which causes a problem if the next packet is already expired. When this happens, the watchdog will be configured with a time in the past, fire straight way and the packet will finally be dropped once the dequeue() function of the qdisc is called again. We can save quite a few cycles and improve the overall behavior of the qdisc if we drop all expired packets if the next packet is expired. This should allow ETF to recover faster from bad situations. But packet drops are still a very serious warning that the requirements imposed on the system aren't reasonable. This was inspired by how the implementation of hrtimers use the rb_tree inside the kernel. Signed-off-by: Jesus Sanchez-Palencia <jesus.s.palencia@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
509 lines
11 KiB
C
509 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* net/sched/sch_etf.c Earliest TxTime First queueing discipline.
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*
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* Authors: Jesus Sanchez-Palencia <jesus.sanchez-palencia@intel.com>
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* Vinicius Costa Gomes <vinicius.gomes@intel.com>
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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/errqueue.h>
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#include <linux/rbtree.h>
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#include <linux/skbuff.h>
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#include <linux/posix-timers.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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#include <net/sock.h>
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#define DEADLINE_MODE_IS_ON(x) ((x)->flags & TC_ETF_DEADLINE_MODE_ON)
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#define OFFLOAD_IS_ON(x) ((x)->flags & TC_ETF_OFFLOAD_ON)
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struct etf_sched_data {
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bool offload;
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bool deadline_mode;
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int clockid;
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int queue;
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s32 delta; /* in ns */
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ktime_t last; /* The txtime of the last skb sent to the netdevice. */
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struct rb_root_cached head;
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struct qdisc_watchdog watchdog;
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ktime_t (*get_time)(void);
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};
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static const struct nla_policy etf_policy[TCA_ETF_MAX + 1] = {
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[TCA_ETF_PARMS] = { .len = sizeof(struct tc_etf_qopt) },
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};
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static inline int validate_input_params(struct tc_etf_qopt *qopt,
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struct netlink_ext_ack *extack)
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{
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/* Check if params comply to the following rules:
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* * Clockid and delta must be valid.
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*
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* * Dynamic clockids are not supported.
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*
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* * Delta must be a positive integer.
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*
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* Also note that for the HW offload case, we must
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* expect that system clocks have been synchronized to PHC.
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*/
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if (qopt->clockid < 0) {
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NL_SET_ERR_MSG(extack, "Dynamic clockids are not supported");
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return -ENOTSUPP;
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}
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if (qopt->clockid != CLOCK_TAI) {
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NL_SET_ERR_MSG(extack, "Invalid clockid. CLOCK_TAI must be used");
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return -EINVAL;
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}
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if (qopt->delta < 0) {
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NL_SET_ERR_MSG(extack, "Delta must be positive");
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return -EINVAL;
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}
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return 0;
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}
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static bool is_packet_valid(struct Qdisc *sch, struct sk_buff *nskb)
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{
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struct etf_sched_data *q = qdisc_priv(sch);
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ktime_t txtime = nskb->tstamp;
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struct sock *sk = nskb->sk;
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ktime_t now;
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if (!sk)
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return false;
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if (!sock_flag(sk, SOCK_TXTIME))
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return false;
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/* We don't perform crosstimestamping.
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* Drop if packet's clockid differs from qdisc's.
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*/
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if (sk->sk_clockid != q->clockid)
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return false;
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if (sk->sk_txtime_deadline_mode != q->deadline_mode)
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return false;
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now = q->get_time();
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if (ktime_before(txtime, now) || ktime_before(txtime, q->last))
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return false;
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return true;
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}
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static struct sk_buff *etf_peek_timesortedlist(struct Qdisc *sch)
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{
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struct etf_sched_data *q = qdisc_priv(sch);
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struct rb_node *p;
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p = rb_first_cached(&q->head);
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if (!p)
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return NULL;
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return rb_to_skb(p);
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}
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static void reset_watchdog(struct Qdisc *sch)
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{
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struct etf_sched_data *q = qdisc_priv(sch);
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struct sk_buff *skb = etf_peek_timesortedlist(sch);
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ktime_t next;
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if (!skb) {
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qdisc_watchdog_cancel(&q->watchdog);
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return;
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}
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next = ktime_sub_ns(skb->tstamp, q->delta);
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qdisc_watchdog_schedule_ns(&q->watchdog, ktime_to_ns(next));
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}
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static void report_sock_error(struct sk_buff *skb, u32 err, u8 code)
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{
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struct sock_exterr_skb *serr;
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struct sk_buff *clone;
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ktime_t txtime = skb->tstamp;
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if (!skb->sk || !(skb->sk->sk_txtime_report_errors))
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return;
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clone = skb_clone(skb, GFP_ATOMIC);
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if (!clone)
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return;
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serr = SKB_EXT_ERR(clone);
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serr->ee.ee_errno = err;
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serr->ee.ee_origin = SO_EE_ORIGIN_TXTIME;
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serr->ee.ee_type = 0;
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serr->ee.ee_code = code;
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serr->ee.ee_pad = 0;
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serr->ee.ee_data = (txtime >> 32); /* high part of tstamp */
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serr->ee.ee_info = txtime; /* low part of tstamp */
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if (sock_queue_err_skb(skb->sk, clone))
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kfree_skb(clone);
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}
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static int etf_enqueue_timesortedlist(struct sk_buff *nskb, struct Qdisc *sch,
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struct sk_buff **to_free)
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{
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struct etf_sched_data *q = qdisc_priv(sch);
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struct rb_node **p = &q->head.rb_root.rb_node, *parent = NULL;
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ktime_t txtime = nskb->tstamp;
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bool leftmost = true;
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if (!is_packet_valid(sch, nskb)) {
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report_sock_error(nskb, EINVAL,
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SO_EE_CODE_TXTIME_INVALID_PARAM);
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return qdisc_drop(nskb, sch, to_free);
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}
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while (*p) {
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struct sk_buff *skb;
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parent = *p;
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skb = rb_to_skb(parent);
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if (ktime_after(txtime, skb->tstamp)) {
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p = &parent->rb_right;
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leftmost = false;
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} else {
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p = &parent->rb_left;
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}
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}
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rb_link_node(&nskb->rbnode, parent, p);
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rb_insert_color_cached(&nskb->rbnode, &q->head, leftmost);
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qdisc_qstats_backlog_inc(sch, nskb);
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sch->q.qlen++;
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/* Now we may need to re-arm the qdisc watchdog for the next packet. */
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reset_watchdog(sch);
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return NET_XMIT_SUCCESS;
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}
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static void timesortedlist_drop(struct Qdisc *sch, struct sk_buff *skb,
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ktime_t now)
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{
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struct etf_sched_data *q = qdisc_priv(sch);
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struct sk_buff *to_free = NULL;
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struct sk_buff *tmp = NULL;
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skb_rbtree_walk_from_safe(skb, tmp) {
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if (ktime_after(skb->tstamp, now))
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break;
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rb_erase_cached(&skb->rbnode, &q->head);
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/* The rbnode field in the skb re-uses these fields, now that
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* we are done with the rbnode, reset them.
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*/
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skb->next = NULL;
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skb->prev = NULL;
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skb->dev = qdisc_dev(sch);
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report_sock_error(skb, ECANCELED, SO_EE_CODE_TXTIME_MISSED);
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qdisc_qstats_backlog_dec(sch, skb);
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qdisc_drop(skb, sch, &to_free);
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qdisc_qstats_overlimit(sch);
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sch->q.qlen--;
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}
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kfree_skb_list(to_free);
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}
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static void timesortedlist_remove(struct Qdisc *sch, struct sk_buff *skb)
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{
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struct etf_sched_data *q = qdisc_priv(sch);
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rb_erase_cached(&skb->rbnode, &q->head);
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/* The rbnode field in the skb re-uses these fields, now that
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* we are done with the rbnode, reset them.
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*/
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skb->next = NULL;
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skb->prev = NULL;
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skb->dev = qdisc_dev(sch);
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qdisc_qstats_backlog_dec(sch, skb);
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qdisc_bstats_update(sch, skb);
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q->last = skb->tstamp;
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sch->q.qlen--;
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}
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static struct sk_buff *etf_dequeue_timesortedlist(struct Qdisc *sch)
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{
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struct etf_sched_data *q = qdisc_priv(sch);
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struct sk_buff *skb;
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ktime_t now, next;
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skb = etf_peek_timesortedlist(sch);
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if (!skb)
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return NULL;
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now = q->get_time();
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/* Drop if packet has expired while in queue. */
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if (ktime_before(skb->tstamp, now)) {
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timesortedlist_drop(sch, skb, now);
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skb = NULL;
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goto out;
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}
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/* When in deadline mode, dequeue as soon as possible and change the
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* txtime from deadline to (now + delta).
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*/
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if (q->deadline_mode) {
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timesortedlist_remove(sch, skb);
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skb->tstamp = now;
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goto out;
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}
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next = ktime_sub_ns(skb->tstamp, q->delta);
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/* Dequeue only if now is within the [txtime - delta, txtime] range. */
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if (ktime_after(now, next))
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timesortedlist_remove(sch, skb);
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else
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skb = NULL;
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out:
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/* Now we may need to re-arm the qdisc watchdog for the next packet. */
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reset_watchdog(sch);
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return skb;
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}
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static void etf_disable_offload(struct net_device *dev,
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struct etf_sched_data *q)
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{
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struct tc_etf_qopt_offload etf = { };
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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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ops = dev->netdev_ops;
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if (!ops->ndo_setup_tc)
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return;
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etf.queue = q->queue;
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etf.enable = 0;
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err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_ETF, &etf);
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if (err < 0)
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pr_warn("Couldn't disable ETF offload for queue %d\n",
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etf.queue);
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}
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static int etf_enable_offload(struct net_device *dev, struct etf_sched_data *q,
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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_etf_qopt_offload etf = { };
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int err;
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if (q->offload)
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return 0;
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if (!ops->ndo_setup_tc) {
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NL_SET_ERR_MSG(extack, "Specified device does not support ETF offload");
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return -EOPNOTSUPP;
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}
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etf.queue = q->queue;
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etf.enable = 1;
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err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_ETF, &etf);
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if (err < 0) {
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NL_SET_ERR_MSG(extack, "Specified device failed to setup ETF hardware offload");
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return err;
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}
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return 0;
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}
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static int etf_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 etf_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_ETF_MAX + 1];
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struct tc_etf_qopt *qopt;
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int err;
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if (!opt) {
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NL_SET_ERR_MSG(extack,
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"Missing ETF qdisc options which are mandatory");
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return -EINVAL;
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}
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err = nla_parse_nested(tb, TCA_ETF_MAX, opt, etf_policy, extack);
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if (err < 0)
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return err;
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if (!tb[TCA_ETF_PARMS]) {
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NL_SET_ERR_MSG(extack, "Missing mandatory ETF parameters");
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return -EINVAL;
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}
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qopt = nla_data(tb[TCA_ETF_PARMS]);
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pr_debug("delta %d clockid %d offload %s deadline %s\n",
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qopt->delta, qopt->clockid,
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OFFLOAD_IS_ON(qopt) ? "on" : "off",
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DEADLINE_MODE_IS_ON(qopt) ? "on" : "off");
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err = validate_input_params(qopt, extack);
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if (err < 0)
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return err;
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q->queue = sch->dev_queue - netdev_get_tx_queue(dev, 0);
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if (OFFLOAD_IS_ON(qopt)) {
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err = etf_enable_offload(dev, q, 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->delta = qopt->delta;
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q->clockid = qopt->clockid;
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q->offload = OFFLOAD_IS_ON(qopt);
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q->deadline_mode = DEADLINE_MODE_IS_ON(qopt);
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switch (q->clockid) {
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case CLOCK_REALTIME:
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q->get_time = ktime_get_real;
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break;
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case CLOCK_MONOTONIC:
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q->get_time = ktime_get;
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break;
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case CLOCK_BOOTTIME:
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q->get_time = ktime_get_boottime;
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break;
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case CLOCK_TAI:
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q->get_time = ktime_get_clocktai;
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break;
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default:
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NL_SET_ERR_MSG(extack, "Clockid is not supported");
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return -ENOTSUPP;
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}
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qdisc_watchdog_init_clockid(&q->watchdog, sch, q->clockid);
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return 0;
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}
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static void timesortedlist_clear(struct Qdisc *sch)
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{
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struct etf_sched_data *q = qdisc_priv(sch);
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struct rb_node *p = rb_first_cached(&q->head);
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while (p) {
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struct sk_buff *skb = rb_to_skb(p);
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p = rb_next(p);
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rb_erase_cached(&skb->rbnode, &q->head);
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rtnl_kfree_skbs(skb, skb);
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sch->q.qlen--;
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}
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}
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static void etf_reset(struct Qdisc *sch)
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{
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struct etf_sched_data *q = qdisc_priv(sch);
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/* Only cancel watchdog if it's been initialized. */
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if (q->watchdog.qdisc == sch)
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qdisc_watchdog_cancel(&q->watchdog);
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/* No matter which mode we are on, it's safe to clear both lists. */
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timesortedlist_clear(sch);
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__qdisc_reset_queue(&sch->q);
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sch->qstats.backlog = 0;
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sch->q.qlen = 0;
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q->last = 0;
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}
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static void etf_destroy(struct Qdisc *sch)
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{
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struct etf_sched_data *q = qdisc_priv(sch);
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struct net_device *dev = qdisc_dev(sch);
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/* Only cancel watchdog if it's been initialized. */
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if (q->watchdog.qdisc == sch)
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qdisc_watchdog_cancel(&q->watchdog);
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etf_disable_offload(dev, q);
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}
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static int etf_dump(struct Qdisc *sch, struct sk_buff *skb)
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{
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struct etf_sched_data *q = qdisc_priv(sch);
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struct tc_etf_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.delta = q->delta;
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opt.clockid = q->clockid;
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if (q->offload)
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opt.flags |= TC_ETF_OFFLOAD_ON;
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if (q->deadline_mode)
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opt.flags |= TC_ETF_DEADLINE_MODE_ON;
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if (nla_put(skb, TCA_ETF_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 etf_qdisc_ops __read_mostly = {
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.id = "etf",
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.priv_size = sizeof(struct etf_sched_data),
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.enqueue = etf_enqueue_timesortedlist,
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.dequeue = etf_dequeue_timesortedlist,
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.peek = etf_peek_timesortedlist,
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.init = etf_init,
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.reset = etf_reset,
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.destroy = etf_destroy,
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.dump = etf_dump,
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.owner = THIS_MODULE,
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};
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static int __init etf_module_init(void)
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{
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return register_qdisc(&etf_qdisc_ops);
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}
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static void __exit etf_module_exit(void)
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{
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unregister_qdisc(&etf_qdisc_ops);
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}
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module_init(etf_module_init)
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module_exit(etf_module_exit)
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MODULE_LICENSE("GPL");
|