Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2574 insertions, 0 deletions

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
new file mode 100644
index 0000000000..1cb5e41c0e
--- /dev/null
+++ b/net/sched/sch_taprio.c
@@ -0,0 +1,2574 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* net/sched/sch_taprio.c	 Time Aware Priority Scheduler
+ *
+ * Authors:	Vinicius Costa Gomes <vinicius.gomes@intel.com>
+ *
+ */
+
+#include <linux/ethtool.h>
+#include <linux/ethtool_netlink.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/list.h>
+#include <linux/errno.h>
+#include <linux/skbuff.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/rcupdate.h>
+#include <linux/time.h>
+#include <net/gso.h>
+#include <net/netlink.h>
+#include <net/pkt_sched.h>
+#include <net/pkt_cls.h>
+#include <net/sch_generic.h>
+#include <net/sock.h>
+#include <net/tcp.h>
+
+#define TAPRIO_STAT_NOT_SET	(~0ULL)
+
+#include "sch_mqprio_lib.h"
+
+static LIST_HEAD(taprio_list);
+static struct static_key_false taprio_have_broken_mqprio;
+static struct static_key_false taprio_have_working_mqprio;
+
+#define TAPRIO_ALL_GATES_OPEN -1
+
+#define TXTIME_ASSIST_IS_ENABLED(flags) ((flags) & TCA_TAPRIO_ATTR_FLAG_TXTIME_ASSIST)
+#define FULL_OFFLOAD_IS_ENABLED(flags) ((flags) & TCA_TAPRIO_ATTR_FLAG_FULL_OFFLOAD)
+#define TAPRIO_FLAGS_INVALID U32_MAX
+
+struct sched_entry {
+	/* Durations between this GCL entry and the GCL entry where the
+	 * respective traffic class gate closes
+	 */
+	u64 gate_duration[TC_MAX_QUEUE];
+	atomic_t budget[TC_MAX_QUEUE];
+	/* The qdisc makes some effort so that no packet leaves
+	 * after this time
+	 */
+	ktime_t gate_close_time[TC_MAX_QUEUE];
+	struct list_head list;
+	/* Used to calculate when to advance the schedule */
+	ktime_t end_time;
+	ktime_t next_txtime;
+	int index;
+	u32 gate_mask;
+	u32 interval;
+	u8 command;
+};
+
+struct sched_gate_list {
+	/* Longest non-zero contiguous gate durations per traffic class,
+	 * or 0 if a traffic class gate never opens during the schedule.
+	 */
+	u64 max_open_gate_duration[TC_MAX_QUEUE];
+	u32 max_frm_len[TC_MAX_QUEUE]; /* for the fast path */
+	u32 max_sdu[TC_MAX_QUEUE]; /* for dump */
+	struct rcu_head rcu;
+	struct list_head entries;
+	size_t num_entries;
+	ktime_t cycle_end_time;
+	s64 cycle_time;
+	s64 cycle_time_extension;
+	s64 base_time;
+};
+
+struct taprio_sched {
+	struct Qdisc **qdiscs;
+	struct Qdisc *root;
+	u32 flags;
+	enum tk_offsets tk_offset;
+	int clockid;
+	bool offloaded;
+	bool detected_mqprio;
+	bool broken_mqprio;
+	atomic64_t picos_per_byte; /* Using picoseconds because for 10Gbps+
+				    * speeds it's sub-nanoseconds per byte
+				    */
+
+	/* Protects the update side of the RCU protected current_entry */
+	spinlock_t current_entry_lock;
+	struct sched_entry __rcu *current_entry;
+	struct sched_gate_list __rcu *oper_sched;
+	struct sched_gate_list __rcu *admin_sched;
+	struct hrtimer advance_timer;
+	struct list_head taprio_list;
+	int cur_txq[TC_MAX_QUEUE];
+	u32 max_sdu[TC_MAX_QUEUE]; /* save info from the user */
+	u32 fp[TC_QOPT_MAX_QUEUE]; /* only for dump and offloading */
+	u32 txtime_delay;
+};
+
+struct __tc_taprio_qopt_offload {
+	refcount_t users;
+	struct tc_taprio_qopt_offload offload;
+};
+
+static void taprio_calculate_gate_durations(struct taprio_sched *q,
+					    struct sched_gate_list *sched)
+{
+	struct net_device *dev = qdisc_dev(q->root);
+	int num_tc = netdev_get_num_tc(dev);
+	struct sched_entry *entry, *cur;
+	int tc;
+
+	list_for_each_entry(entry, &sched->entries, list) {
+		u32 gates_still_open = entry->gate_mask;
+
+		/* For each traffic class, calculate each open gate duration,
+		 * starting at this schedule entry and ending at the schedule
+		 * entry containing a gate close event for that TC.
+		 */
+		cur = entry;
+
+		do {
+			if (!gates_still_open)
+				break;
+
+			for (tc = 0; tc < num_tc; tc++) {
+				if (!(gates_still_open & BIT(tc)))
+					continue;
+
+				if (cur->gate_mask & BIT(tc))
+					entry->gate_duration[tc] += cur->interval;
+				else
+					gates_still_open &= ~BIT(tc);
+			}
+
+			cur = list_next_entry_circular(cur, &sched->entries, list);
+		} while (cur != entry);
+
+		/* Keep track of the maximum gate duration for each traffic
+		 * class, taking care to not confuse a traffic class which is
+		 * temporarily closed with one that is always closed.
+		 */
+		for (tc = 0; tc < num_tc; tc++)
+			if (entry->gate_duration[tc] &&
+			    sched->max_open_gate_duration[tc] < entry->gate_duration[tc])
+				sched->max_open_gate_duration[tc] = entry->gate_duration[tc];
+	}
+}
+
+static bool taprio_entry_allows_tx(ktime_t skb_end_time,
+				   struct sched_entry *entry, int tc)
+{
+	return ktime_before(skb_end_time, entry->gate_close_time[tc]);
+}
+
+static ktime_t sched_base_time(const struct sched_gate_list *sched)
+{
+	if (!sched)
+		return KTIME_MAX;
+
+	return ns_to_ktime(sched->base_time);
+}
+
+static ktime_t taprio_mono_to_any(const struct taprio_sched *q, ktime_t mono)
+{
+	/* This pairs with WRITE_ONCE() in taprio_parse_clockid() */
+	enum tk_offsets tk_offset = READ_ONCE(q->tk_offset);
+
+	switch (tk_offset) {
+	case TK_OFFS_MAX:
+		return mono;
+	default:
+		return ktime_mono_to_any(mono, tk_offset);
+	}
+}
+
+static ktime_t taprio_get_time(const struct taprio_sched *q)
+{
+	return taprio_mono_to_any(q, ktime_get());
+}
+
+static void taprio_free_sched_cb(struct rcu_head *head)
+{
+	struct sched_gate_list *sched = container_of(head, struct sched_gate_list, rcu);
+	struct sched_entry *entry, *n;
+
+	list_for_each_entry_safe(entry, n, &sched->entries, list) {
+		list_del(&entry->list);
+		kfree(entry);
+	}
+
+	kfree(sched);
+}
+
+static void switch_schedules(struct taprio_sched *q,
+			     struct sched_gate_list **admin,
+			     struct sched_gate_list **oper)
+{
+	rcu_assign_pointer(q->oper_sched, *admin);
+	rcu_assign_pointer(q->admin_sched, NULL);
+
+	if (*oper)
+		call_rcu(&(*oper)->rcu, taprio_free_sched_cb);
+
+	*oper = *admin;
+	*admin = NULL;
+}
+
+/* Get how much time has been already elapsed in the current cycle. */
+static s32 get_cycle_time_elapsed(struct sched_gate_list *sched, ktime_t time)
+{
+	ktime_t time_since_sched_start;
+	s32 time_elapsed;
+
+	time_since_sched_start = ktime_sub(time, sched->base_time);
+	div_s64_rem(time_since_sched_start, sched->cycle_time, &time_elapsed);
+
+	return time_elapsed;
+}
+
+static ktime_t get_interval_end_time(struct sched_gate_list *sched,
+				     struct sched_gate_list *admin,
+				     struct sched_entry *entry,
+				     ktime_t intv_start)
+{
+	s32 cycle_elapsed = get_cycle_time_elapsed(sched, intv_start);
+	ktime_t intv_end, cycle_ext_end, cycle_end;
+
+	cycle_end = ktime_add_ns(intv_start, sched->cycle_time - cycle_elapsed);
+	intv_end = ktime_add_ns(intv_start, entry->interval);
+	cycle_ext_end = ktime_add(cycle_end, sched->cycle_time_extension);
+
+	if (ktime_before(intv_end, cycle_end))
+		return intv_end;
+	else if (admin && admin != sched &&
+		 ktime_after(admin->base_time, cycle_end) &&
+		 ktime_before(admin->base_time, cycle_ext_end))
+		return admin->base_time;
+	else
+		return cycle_end;
+}
+
+static int length_to_duration(struct taprio_sched *q, int len)
+{
+	return div_u64(len * atomic64_read(&q->picos_per_byte), PSEC_PER_NSEC);
+}
+
+static int duration_to_length(struct taprio_sched *q, u64 duration)
+{
+	return div_u64(duration * PSEC_PER_NSEC, atomic64_read(&q->picos_per_byte));
+}
+
+/* Sets sched->max_sdu[] and sched->max_frm_len[] to the minimum between the
+ * q->max_sdu[] requested by the user and the max_sdu dynamically determined by
+ * the maximum open gate durations at the given link speed.
+ */
+static void taprio_update_queue_max_sdu(struct taprio_sched *q,
+					struct sched_gate_list *sched,
+					struct qdisc_size_table *stab)
+{
+	struct net_device *dev = qdisc_dev(q->root);
+	int num_tc = netdev_get_num_tc(dev);
+	u32 max_sdu_from_user;
+	u32 max_sdu_dynamic;
+	u32 max_sdu;
+	int tc;
+
+	for (tc = 0; tc < num_tc; tc++) {
+		max_sdu_from_user = q->max_sdu[tc] ?: U32_MAX;
+
+		/* TC gate never closes => keep the queueMaxSDU
+		 * selected by the user
+		 */
+		if (sched->max_open_gate_duration[tc] == sched->cycle_time) {
+			max_sdu_dynamic = U32_MAX;
+		} else {
+			u32 max_frm_len;
+
+			max_frm_len = duration_to_length(q, sched->max_open_gate_duration[tc]);
+			/* Compensate for L1 overhead from size table,
+			 * but don't let the frame size go negative
+			 */
+			if (stab) {
+				max_frm_len -= stab->szopts.overhead;
+				max_frm_len = max_t(int, max_frm_len,
+						    dev->hard_header_len + 1);
+			}
+			max_sdu_dynamic = max_frm_len - dev->hard_header_len;
+			if (max_sdu_dynamic > dev->max_mtu)
+				max_sdu_dynamic = U32_MAX;
+		}
+
+		max_sdu = min(max_sdu_dynamic, max_sdu_from_user);
+
+		if (max_sdu != U32_MAX) {
+			sched->max_frm_len[tc] = max_sdu + dev->hard_header_len;
+			sched->max_sdu[tc] = max_sdu;
+		} else {
+			sched->max_frm_len[tc] = U32_MAX; /* never oversized */
+			sched->max_sdu[tc] = 0;
+		}
+	}
+}
+
+/* Returns the entry corresponding to next available interval. If
+ * validate_interval is set, it only validates whether the timestamp occurs
+ * when the gate corresponding to the skb's traffic class is open.
+ */
+static struct sched_entry *find_entry_to_transmit(struct sk_buff *skb,
+						  struct Qdisc *sch,
+						  struct sched_gate_list *sched,
+						  struct sched_gate_list *admin,
+						  ktime_t time,
+						  ktime_t *interval_start,
+						  ktime_t *interval_end,
+						  bool validate_interval)
+{
+	ktime_t curr_intv_start, curr_intv_end, cycle_end, packet_transmit_time;
+	ktime_t earliest_txtime = KTIME_MAX, txtime, cycle, transmit_end_time;
+	struct sched_entry *entry = NULL, *entry_found = NULL;
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct net_device *dev = qdisc_dev(sch);
+	bool entry_available = false;
+	s32 cycle_elapsed;
+	int tc, n;
+
+	tc = netdev_get_prio_tc_map(dev, skb->priority);
+	packet_transmit_time = length_to_duration(q, qdisc_pkt_len(skb));
+
+	*interval_start = 0;
+	*interval_end = 0;
+
+	if (!sched)
+		return NULL;
+
+	cycle = sched->cycle_time;
+	cycle_elapsed = get_cycle_time_elapsed(sched, time);
+	curr_intv_end = ktime_sub_ns(time, cycle_elapsed);
+	cycle_end = ktime_add_ns(curr_intv_end, cycle);
+
+	list_for_each_entry(entry, &sched->entries, list) {
+		curr_intv_start = curr_intv_end;
+		curr_intv_end = get_interval_end_time(sched, admin, entry,
+						      curr_intv_start);
+
+		if (ktime_after(curr_intv_start, cycle_end))
+			break;
+
+		if (!(entry->gate_mask & BIT(tc)) ||
+		    packet_transmit_time > entry->interval)
+			continue;
+
+		txtime = entry->next_txtime;
+
+		if (ktime_before(txtime, time) || validate_interval) {
+			transmit_end_time = ktime_add_ns(time, packet_transmit_time);
+			if ((ktime_before(curr_intv_start, time) &&
+			     ktime_before(transmit_end_time, curr_intv_end)) ||
+			    (ktime_after(curr_intv_start, time) && !validate_interval)) {
+				entry_found = entry;
+				*interval_start = curr_intv_start;
+				*interval_end = curr_intv_end;
+				break;
+			} else if (!entry_available && !validate_interval) {
+				/* Here, we are just trying to find out the
+				 * first available interval in the next cycle.
+				 */
+				entry_available = true;
+				entry_found = entry;
+				*interval_start = ktime_add_ns(curr_intv_start, cycle);
+				*interval_end = ktime_add_ns(curr_intv_end, cycle);
+			}
+		} else if (ktime_before(txtime, earliest_txtime) &&
+			   !entry_available) {
+			earliest_txtime = txtime;
+			entry_found = entry;
+			n = div_s64(ktime_sub(txtime, curr_intv_start), cycle);
+			*interval_start = ktime_add(curr_intv_start, n * cycle);
+			*interval_end = ktime_add(curr_intv_end, n * cycle);
+		}
+	}
+
+	return entry_found;
+}
+
+static bool is_valid_interval(struct sk_buff *skb, struct Qdisc *sch)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct sched_gate_list *sched, *admin;
+	ktime_t interval_start, interval_end;
+	struct sched_entry *entry;
+
+	rcu_read_lock();
+	sched = rcu_dereference(q->oper_sched);
+	admin = rcu_dereference(q->admin_sched);
+
+	entry = find_entry_to_transmit(skb, sch, sched, admin, skb->tstamp,
+				       &interval_start, &interval_end, true);
+	rcu_read_unlock();
+
+	return entry;
+}
+
+static bool taprio_flags_valid(u32 flags)
+{
+	/* Make sure no other flag bits are set. */
+	if (flags & ~(TCA_TAPRIO_ATTR_FLAG_TXTIME_ASSIST |
+		      TCA_TAPRIO_ATTR_FLAG_FULL_OFFLOAD))
+		return false;
+	/* txtime-assist and full offload are mutually exclusive */
+	if ((flags & TCA_TAPRIO_ATTR_FLAG_TXTIME_ASSIST) &&
+	    (flags & TCA_TAPRIO_ATTR_FLAG_FULL_OFFLOAD))
+		return false;
+	return true;
+}
+
+/* This returns the tstamp value set by TCP in terms of the set clock. */
+static ktime_t get_tcp_tstamp(struct taprio_sched *q, struct sk_buff *skb)
+{
+	unsigned int offset = skb_network_offset(skb);
+	const struct ipv6hdr *ipv6h;
+	const struct iphdr *iph;
+	struct ipv6hdr _ipv6h;
+
+	ipv6h = skb_header_pointer(skb, offset, sizeof(_ipv6h), &_ipv6h);
+	if (!ipv6h)
+		return 0;
+
+	if (ipv6h->version == 4) {
+		iph = (struct iphdr *)ipv6h;
+		offset += iph->ihl * 4;
+
+		/* special-case 6in4 tunnelling, as that is a common way to get
+		 * v6 connectivity in the home
+		 */
+		if (iph->protocol == IPPROTO_IPV6) {
+			ipv6h = skb_header_pointer(skb, offset,
+						   sizeof(_ipv6h), &_ipv6h);
+
+			if (!ipv6h || ipv6h->nexthdr != IPPROTO_TCP)
+				return 0;
+		} else if (iph->protocol != IPPROTO_TCP) {
+			return 0;
+		}
+	} else if (ipv6h->version == 6 && ipv6h->nexthdr != IPPROTO_TCP) {
+		return 0;
+	}
+
+	return taprio_mono_to_any(q, skb->skb_mstamp_ns);
+}
+
+/* There are a few scenarios where we will have to modify the txtime from
+ * what is read from next_txtime in sched_entry. They are:
+ * 1. If txtime is in the past,
+ *    a. The gate for the traffic class is currently open and packet can be
+ *       transmitted before it closes, schedule the packet right away.
+ *    b. If the gate corresponding to the traffic class is going to open later
+ *       in the cycle, set the txtime of packet to the interval start.
+ * 2. If txtime is in the future, there are packets corresponding to the
+ *    current traffic class waiting to be transmitted. So, the following
+ *    possibilities exist:
+ *    a. We can transmit the packet before the window containing the txtime
+ *       closes.
+ *    b. The window might close before the transmission can be completed
+ *       successfully. So, schedule the packet in the next open window.
+ */
+static long get_packet_txtime(struct sk_buff *skb, struct Qdisc *sch)
+{
+	ktime_t transmit_end_time, interval_end, interval_start, tcp_tstamp;
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct sched_gate_list *sched, *admin;
+	ktime_t minimum_time, now, txtime;
+	int len, packet_transmit_time;
+	struct sched_entry *entry;
+	bool sched_changed;
+
+	now = taprio_get_time(q);
+	minimum_time = ktime_add_ns(now, q->txtime_delay);
+
+	tcp_tstamp = get_tcp_tstamp(q, skb);
+	minimum_time = max_t(ktime_t, minimum_time, tcp_tstamp);
+
+	rcu_read_lock();
+	admin = rcu_dereference(q->admin_sched);
+	sched = rcu_dereference(q->oper_sched);
+	if (admin && ktime_after(minimum_time, admin->base_time))
+		switch_schedules(q, &admin, &sched);
+
+	/* Until the schedule starts, all the queues are open */
+	if (!sched || ktime_before(minimum_time, sched->base_time)) {
+		txtime = minimum_time;
+		goto done;
+	}
+
+	len = qdisc_pkt_len(skb);
+	packet_transmit_time = length_to_duration(q, len);
+
+	do {
+		sched_changed = false;
+
+		entry = find_entry_to_transmit(skb, sch, sched, admin,
+					       minimum_time,
+					       &interval_start, &interval_end,
+					       false);
+		if (!entry) {
+			txtime = 0;
+			goto done;
+		}
+
+		txtime = entry->next_txtime;
+		txtime = max_t(ktime_t, txtime, minimum_time);
+		txtime = max_t(ktime_t, txtime, interval_start);
+
+		if (admin && admin != sched &&
+		    ktime_after(txtime, admin->base_time)) {
+			sched = admin;
+			sched_changed = true;
+			continue;
+		}
+
+		transmit_end_time = ktime_add(txtime, packet_transmit_time);
+		minimum_time = transmit_end_time;
+
+		/* Update the txtime of current entry to the next time it's
+		 * interval starts.
+		 */
+		if (ktime_after(transmit_end_time, interval_end))
+			entry->next_txtime = ktime_add(interval_start, sched->cycle_time);
+	} while (sched_changed || ktime_after(transmit_end_time, interval_end));
+
+	entry->next_txtime = transmit_end_time;
+
+done:
+	rcu_read_unlock();
+	return txtime;
+}
+
+/* Devices with full offload are expected to honor this in hardware */
+static bool taprio_skb_exceeds_queue_max_sdu(struct Qdisc *sch,
+					     struct sk_buff *skb)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct net_device *dev = qdisc_dev(sch);
+	struct sched_gate_list *sched;
+	int prio = skb->priority;
+	bool exceeds = false;
+	u8 tc;
+
+	tc = netdev_get_prio_tc_map(dev, prio);
+
+	rcu_read_lock();
+	sched = rcu_dereference(q->oper_sched);
+	if (sched && skb->len > sched->max_frm_len[tc])
+		exceeds = true;
+	rcu_read_unlock();
+
+	return exceeds;
+}
+
+static int taprio_enqueue_one(struct sk_buff *skb, struct Qdisc *sch,
+			      struct Qdisc *child, struct sk_buff **to_free)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+
+	/* sk_flags are only safe to use on full sockets. */
+	if (skb->sk && sk_fullsock(skb->sk) && sock_flag(skb->sk, SOCK_TXTIME)) {
+		if (!is_valid_interval(skb, sch))
+			return qdisc_drop(skb, sch, to_free);
+	} else if (TXTIME_ASSIST_IS_ENABLED(q->flags)) {
+		skb->tstamp = get_packet_txtime(skb, sch);
+		if (!skb->tstamp)
+			return qdisc_drop(skb, sch, to_free);
+	}
+
+	qdisc_qstats_backlog_inc(sch, skb);
+	sch->q.qlen++;
+
+	return qdisc_enqueue(skb, child, to_free);
+}
+
+static int taprio_enqueue_segmented(struct sk_buff *skb, struct Qdisc *sch,
+				    struct Qdisc *child,
+				    struct sk_buff **to_free)
+{
+	unsigned int slen = 0, numsegs = 0, len = qdisc_pkt_len(skb);
+	netdev_features_t features = netif_skb_features(skb);
+	struct sk_buff *segs, *nskb;
+	int ret;
+
+	segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
+	if (IS_ERR_OR_NULL(segs))
+		return qdisc_drop(skb, sch, to_free);
+
+	skb_list_walk_safe(segs, segs, nskb) {
+		skb_mark_not_on_list(segs);
+		qdisc_skb_cb(segs)->pkt_len = segs->len;
+		slen += segs->len;
+
+		/* FIXME: we should be segmenting to a smaller size
+		 * rather than dropping these
+		 */
+		if (taprio_skb_exceeds_queue_max_sdu(sch, segs))
+			ret = qdisc_drop(segs, sch, to_free);
+		else
+			ret = taprio_enqueue_one(segs, sch, child, to_free);
+
+		if (ret != NET_XMIT_SUCCESS) {
+			if (net_xmit_drop_count(ret))
+				qdisc_qstats_drop(sch);
+		} else {
+			numsegs++;
+		}
+	}
+
+	if (numsegs > 1)
+		qdisc_tree_reduce_backlog(sch, 1 - numsegs, len - slen);
+	consume_skb(skb);
+
+	return numsegs > 0 ? NET_XMIT_SUCCESS : NET_XMIT_DROP;
+}
+
+/* Will not be called in the full offload case, since the TX queues are
+ * attached to the Qdisc created using qdisc_create_dflt()
+ */
+static int taprio_enqueue(struct sk_buff *skb, struct Qdisc *sch,
+			  struct sk_buff **to_free)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct Qdisc *child;
+	int queue;
+
+	queue = skb_get_queue_mapping(skb);
+
+	child = q->qdiscs[queue];
+	if (unlikely(!child))
+		return qdisc_drop(skb, sch, to_free);
+
+	if (taprio_skb_exceeds_queue_max_sdu(sch, skb)) {
+		/* Large packets might not be transmitted when the transmission
+		 * duration exceeds any configured interval. Therefore, segment
+		 * the skb into smaller chunks. Drivers with full offload are
+		 * expected to handle this in hardware.
+		 */
+		if (skb_is_gso(skb))
+			return taprio_enqueue_segmented(skb, sch, child,
+							to_free);
+
+		return qdisc_drop(skb, sch, to_free);
+	}
+
+	return taprio_enqueue_one(skb, sch, child, to_free);
+}
+
+static struct sk_buff *taprio_peek(struct Qdisc *sch)
+{
+	WARN_ONCE(1, "taprio only supports operating as root qdisc, peek() not implemented");
+	return NULL;
+}
+
+static void taprio_set_budgets(struct taprio_sched *q,
+			       struct sched_gate_list *sched,
+			       struct sched_entry *entry)
+{
+	struct net_device *dev = qdisc_dev(q->root);
+	int num_tc = netdev_get_num_tc(dev);
+	int tc, budget;
+
+	for (tc = 0; tc < num_tc; tc++) {
+		/* Traffic classes which never close have infinite budget */
+		if (entry->gate_duration[tc] == sched->cycle_time)
+			budget = INT_MAX;
+		else
+			budget = div64_u64((u64)entry->gate_duration[tc] * PSEC_PER_NSEC,
+					   atomic64_read(&q->picos_per_byte));
+
+		atomic_set(&entry->budget[tc], budget);
+	}
+}
+
+/* When an skb is sent, it consumes from the budget of all traffic classes */
+static int taprio_update_budgets(struct sched_entry *entry, size_t len,
+				 int tc_consumed, int num_tc)
+{
+	int tc, budget, new_budget = 0;
+
+	for (tc = 0; tc < num_tc; tc++) {
+		budget = atomic_read(&entry->budget[tc]);
+		/* Don't consume from infinite budget */
+		if (budget == INT_MAX) {
+			if (tc == tc_consumed)
+				new_budget = budget;
+			continue;
+		}
+
+		if (tc == tc_consumed)
+			new_budget = atomic_sub_return(len, &entry->budget[tc]);
+		else
+			atomic_sub(len, &entry->budget[tc]);
+	}
+
+	return new_budget;
+}
+
+static struct sk_buff *taprio_dequeue_from_txq(struct Qdisc *sch, int txq,
+					       struct sched_entry *entry,
+					       u32 gate_mask)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct net_device *dev = qdisc_dev(sch);
+	struct Qdisc *child = q->qdiscs[txq];
+	int num_tc = netdev_get_num_tc(dev);
+	struct sk_buff *skb;
+	ktime_t guard;
+	int prio;
+	int len;
+	u8 tc;
+
+	if (unlikely(!child))
+		return NULL;
+
+	if (TXTIME_ASSIST_IS_ENABLED(q->flags))
+		goto skip_peek_checks;
+
+	skb = child->ops->peek(child);
+	if (!skb)
+		return NULL;
+
+	prio = skb->priority;
+	tc = netdev_get_prio_tc_map(dev, prio);
+
+	if (!(gate_mask & BIT(tc)))
+		return NULL;
+
+	len = qdisc_pkt_len(skb);
+	guard = ktime_add_ns(taprio_get_time(q), length_to_duration(q, len));
+
+	/* In the case that there's no gate entry, there's no
+	 * guard band ...
+	 */
+	if (gate_mask != TAPRIO_ALL_GATES_OPEN &&
+	    !taprio_entry_allows_tx(guard, entry, tc))
+		return NULL;
+
+	/* ... and no budget. */
+	if (gate_mask != TAPRIO_ALL_GATES_OPEN &&
+	    taprio_update_budgets(entry, len, tc, num_tc) < 0)
+		return NULL;
+
+skip_peek_checks:
+	skb = child->ops->dequeue(child);
+	if (unlikely(!skb))
+		return NULL;
+
+	qdisc_bstats_update(sch, skb);
+	qdisc_qstats_backlog_dec(sch, skb);
+	sch->q.qlen--;
+
+	return skb;
+}
+
+static void taprio_next_tc_txq(struct net_device *dev, int tc, int *txq)
+{
+	int offset = dev->tc_to_txq[tc].offset;
+	int count = dev->tc_to_txq[tc].count;
+
+	(*txq)++;
+	if (*txq == offset + count)
+		*txq = offset;
+}
+
+/* Prioritize higher traffic classes, and select among TXQs belonging to the
+ * same TC using round robin
+ */
+static struct sk_buff *taprio_dequeue_tc_priority(struct Qdisc *sch,
+						  struct sched_entry *entry,
+						  u32 gate_mask)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct net_device *dev = qdisc_dev(sch);
+	int num_tc = netdev_get_num_tc(dev);
+	struct sk_buff *skb;
+	int tc;
+
+	for (tc = num_tc - 1; tc >= 0; tc--) {
+		int first_txq = q->cur_txq[tc];
+
+		if (!(gate_mask & BIT(tc)))
+			continue;
+
+		do {
+			skb = taprio_dequeue_from_txq(sch, q->cur_txq[tc],
+						      entry, gate_mask);
+
+			taprio_next_tc_txq(dev, tc, &q->cur_txq[tc]);
+
+			if (q->cur_txq[tc] >= dev->num_tx_queues)
+				q->cur_txq[tc] = first_txq;
+
+			if (skb)
+				return skb;
+		} while (q->cur_txq[tc] != first_txq);
+	}
+
+	return NULL;
+}
+
+/* Broken way of prioritizing smaller TXQ indices and ignoring the traffic
+ * class other than to determine whether the gate is open or not
+ */
+static struct sk_buff *taprio_dequeue_txq_priority(struct Qdisc *sch,
+						   struct sched_entry *entry,
+						   u32 gate_mask)
+{
+	struct net_device *dev = qdisc_dev(sch);
+	struct sk_buff *skb;
+	int i;
+
+	for (i = 0; i < dev->num_tx_queues; i++) {
+		skb = taprio_dequeue_from_txq(sch, i, entry, gate_mask);
+		if (skb)
+			return skb;
+	}
+
+	return NULL;
+}
+
+/* Will not be called in the full offload case, since the TX queues are
+ * attached to the Qdisc created using qdisc_create_dflt()
+ */
+static struct sk_buff *taprio_dequeue(struct Qdisc *sch)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct sk_buff *skb = NULL;
+	struct sched_entry *entry;
+	u32 gate_mask;
+
+	rcu_read_lock();
+	entry = rcu_dereference(q->current_entry);
+	/* if there's no entry, it means that the schedule didn't
+	 * start yet, so force all gates to be open, this is in
+	 * accordance to IEEE 802.1Qbv-2015 Section 8.6.9.4.5
+	 * "AdminGateStates"
+	 */
+	gate_mask = entry ? entry->gate_mask : TAPRIO_ALL_GATES_OPEN;
+	if (!gate_mask)
+		goto done;
+
+	if (static_branch_unlikely(&taprio_have_broken_mqprio) &&
+	    !static_branch_likely(&taprio_have_working_mqprio)) {
+		/* Single NIC kind which is broken */
+		skb = taprio_dequeue_txq_priority(sch, entry, gate_mask);
+	} else if (static_branch_likely(&taprio_have_working_mqprio) &&
+		   !static_branch_unlikely(&taprio_have_broken_mqprio)) {
+		/* Single NIC kind which prioritizes properly */
+		skb = taprio_dequeue_tc_priority(sch, entry, gate_mask);
+	} else {
+		/* Mixed NIC kinds present in system, need dynamic testing */
+		if (q->broken_mqprio)
+			skb = taprio_dequeue_txq_priority(sch, entry, gate_mask);
+		else
+			skb = taprio_dequeue_tc_priority(sch, entry, gate_mask);
+	}
+
+done:
+	rcu_read_unlock();
+
+	return skb;
+}
+
+static bool should_restart_cycle(const struct sched_gate_list *oper,
+				 const struct sched_entry *entry)
+{
+	if (list_is_last(&entry->list, &oper->entries))
+		return true;
+
+	if (ktime_compare(entry->end_time, oper->cycle_end_time) == 0)
+		return true;
+
+	return false;
+}
+
+static bool should_change_schedules(const struct sched_gate_list *admin,
+				    const struct sched_gate_list *oper,
+				    ktime_t end_time)
+{
+	ktime_t next_base_time, extension_time;
+
+	if (!admin)
+		return false;
+
+	next_base_time = sched_base_time(admin);
+
+	/* This is the simple case, the end_time would fall after
+	 * the next schedule base_time.
+	 */
+	if (ktime_compare(next_base_time, end_time) <= 0)
+		return true;
+
+	/* This is the cycle_time_extension case, if the end_time
+	 * plus the amount that can be extended would fall after the
+	 * next schedule base_time, we can extend the current schedule
+	 * for that amount.
+	 */
+	extension_time = ktime_add_ns(end_time, oper->cycle_time_extension);
+
+	/* FIXME: the IEEE 802.1Q-2018 Specification isn't clear about
+	 * how precisely the extension should be made. So after
+	 * conformance testing, this logic may change.
+	 */
+	if (ktime_compare(next_base_time, extension_time) <= 0)
+		return true;
+
+	return false;
+}
+
+static enum hrtimer_restart advance_sched(struct hrtimer *timer)
+{
+	struct taprio_sched *q = container_of(timer, struct taprio_sched,
+					      advance_timer);
+	struct net_device *dev = qdisc_dev(q->root);
+	struct sched_gate_list *oper, *admin;
+	int num_tc = netdev_get_num_tc(dev);
+	struct sched_entry *entry, *next;
+	struct Qdisc *sch = q->root;
+	ktime_t end_time;
+	int tc;
+
+	spin_lock(&q->current_entry_lock);
+	entry = rcu_dereference_protected(q->current_entry,
+					  lockdep_is_held(&q->current_entry_lock));
+	oper = rcu_dereference_protected(q->oper_sched,
+					 lockdep_is_held(&q->current_entry_lock));
+	admin = rcu_dereference_protected(q->admin_sched,
+					  lockdep_is_held(&q->current_entry_lock));
+
+	if (!oper)
+		switch_schedules(q, &admin, &oper);
+
+	/* This can happen in two cases: 1. this is the very first run
+	 * of this function (i.e. we weren't running any schedule
+	 * previously); 2. The previous schedule just ended. The first
+	 * entry of all schedules are pre-calculated during the
+	 * schedule initialization.
+	 */
+	if (unlikely(!entry || entry->end_time == oper->base_time)) {
+		next = list_first_entry(&oper->entries, struct sched_entry,
+					list);
+		end_time = next->end_time;
+		goto first_run;
+	}
+
+	if (should_restart_cycle(oper, entry)) {
+		next = list_first_entry(&oper->entries, struct sched_entry,
+					list);
+		oper->cycle_end_time = ktime_add_ns(oper->cycle_end_time,
+						    oper->cycle_time);
+	} else {
+		next = list_next_entry(entry, list);
+	}
+
+	end_time = ktime_add_ns(entry->end_time, next->interval);
+	end_time = min_t(ktime_t, end_time, oper->cycle_end_time);
+
+	for (tc = 0; tc < num_tc; tc++) {
+		if (next->gate_duration[tc] == oper->cycle_time)
+			next->gate_close_time[tc] = KTIME_MAX;
+		else
+			next->gate_close_time[tc] = ktime_add_ns(entry->end_time,
+								 next->gate_duration[tc]);
+	}
+
+	if (should_change_schedules(admin, oper, end_time)) {
+		/* Set things so the next time this runs, the new
+		 * schedule runs.
+		 */
+		end_time = sched_base_time(admin);
+		switch_schedules(q, &admin, &oper);
+	}
+
+	next->end_time = end_time;
+	taprio_set_budgets(q, oper, next);
+
+first_run:
+	rcu_assign_pointer(q->current_entry, next);
+	spin_unlock(&q->current_entry_lock);
+
+	hrtimer_set_expires(&q->advance_timer, end_time);
+
+	rcu_read_lock();
+	__netif_schedule(sch);
+	rcu_read_unlock();
+
+	return HRTIMER_RESTART;
+}
+
+static const struct nla_policy entry_policy[TCA_TAPRIO_SCHED_ENTRY_MAX + 1] = {
+	[TCA_TAPRIO_SCHED_ENTRY_INDEX]	   = { .type = NLA_U32 },
+	[TCA_TAPRIO_SCHED_ENTRY_CMD]	   = { .type = NLA_U8 },
+	[TCA_TAPRIO_SCHED_ENTRY_GATE_MASK] = { .type = NLA_U32 },
+	[TCA_TAPRIO_SCHED_ENTRY_INTERVAL]  = { .type = NLA_U32 },
+};
+
+static const struct nla_policy taprio_tc_policy[TCA_TAPRIO_TC_ENTRY_MAX + 1] = {
+	[TCA_TAPRIO_TC_ENTRY_INDEX]	   = { .type = NLA_U32 },
+	[TCA_TAPRIO_TC_ENTRY_MAX_SDU]	   = { .type = NLA_U32 },
+	[TCA_TAPRIO_TC_ENTRY_FP]	   = NLA_POLICY_RANGE(NLA_U32,
+							      TC_FP_EXPRESS,
+							      TC_FP_PREEMPTIBLE),
+};
+
+static struct netlink_range_validation_signed taprio_cycle_time_range = {
+	.min = 0,
+	.max = INT_MAX,
+};
+
+static const struct nla_policy taprio_policy[TCA_TAPRIO_ATTR_MAX + 1] = {
+	[TCA_TAPRIO_ATTR_PRIOMAP]	       = {
+		.len = sizeof(struct tc_mqprio_qopt)
+	},
+	[TCA_TAPRIO_ATTR_SCHED_ENTRY_LIST]           = { .type = NLA_NESTED },
+	[TCA_TAPRIO_ATTR_SCHED_BASE_TIME]            = { .type = NLA_S64 },
+	[TCA_TAPRIO_ATTR_SCHED_SINGLE_ENTRY]         = { .type = NLA_NESTED },
+	[TCA_TAPRIO_ATTR_SCHED_CLOCKID]              = { .type = NLA_S32 },
+	[TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME]           =
+		NLA_POLICY_FULL_RANGE_SIGNED(NLA_S64, &taprio_cycle_time_range),
+	[TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME_EXTENSION] = { .type = NLA_S64 },
+	[TCA_TAPRIO_ATTR_FLAGS]                      = { .type = NLA_U32 },
+	[TCA_TAPRIO_ATTR_TXTIME_DELAY]		     = { .type = NLA_U32 },
+	[TCA_TAPRIO_ATTR_TC_ENTRY]		     = { .type = NLA_NESTED },
+};
+
+static int fill_sched_entry(struct taprio_sched *q, struct nlattr **tb,
+			    struct sched_entry *entry,
+			    struct netlink_ext_ack *extack)
+{
+	int min_duration = length_to_duration(q, ETH_ZLEN);
+	u32 interval = 0;
+
+	if (tb[TCA_TAPRIO_SCHED_ENTRY_CMD])
+		entry->command = nla_get_u8(
+			tb[TCA_TAPRIO_SCHED_ENTRY_CMD]);
+
+	if (tb[TCA_TAPRIO_SCHED_ENTRY_GATE_MASK])
+		entry->gate_mask = nla_get_u32(
+			tb[TCA_TAPRIO_SCHED_ENTRY_GATE_MASK]);
+
+	if (tb[TCA_TAPRIO_SCHED_ENTRY_INTERVAL])
+		interval = nla_get_u32(
+			tb[TCA_TAPRIO_SCHED_ENTRY_INTERVAL]);
+
+	/* The interval should allow at least the minimum ethernet
+	 * frame to go out.
+	 */
+	if (interval < min_duration) {
+		NL_SET_ERR_MSG(extack, "Invalid interval for schedule entry");
+		return -EINVAL;
+	}
+
+	entry->interval = interval;
+
+	return 0;
+}
+
+static int parse_sched_entry(struct taprio_sched *q, struct nlattr *n,
+			     struct sched_entry *entry, int index,
+			     struct netlink_ext_ack *extack)
+{
+	struct nlattr *tb[TCA_TAPRIO_SCHED_ENTRY_MAX + 1] = { };
+	int err;
+
+	err = nla_parse_nested_deprecated(tb, TCA_TAPRIO_SCHED_ENTRY_MAX, n,
+					  entry_policy, NULL);
+	if (err < 0) {
+		NL_SET_ERR_MSG(extack, "Could not parse nested entry");
+		return -EINVAL;
+	}
+
+	entry->index = index;
+
+	return fill_sched_entry(q, tb, entry, extack);
+}
+
+static int parse_sched_list(struct taprio_sched *q, struct nlattr *list,
+			    struct sched_gate_list *sched,
+			    struct netlink_ext_ack *extack)
+{
+	struct nlattr *n;
+	int err, rem;
+	int i = 0;
+
+	if (!list)
+		return -EINVAL;
+
+	nla_for_each_nested(n, list, rem) {
+		struct sched_entry *entry;
+
+		if (nla_type(n) != TCA_TAPRIO_SCHED_ENTRY) {
+			NL_SET_ERR_MSG(extack, "Attribute is not of type 'entry'");
+			continue;
+		}
+
+		entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+		if (!entry) {
+			NL_SET_ERR_MSG(extack, "Not enough memory for entry");
+			return -ENOMEM;
+		}
+
+		err = parse_sched_entry(q, n, entry, i, extack);
+		if (err < 0) {
+			kfree(entry);
+			return err;
+		}
+
+		list_add_tail(&entry->list, &sched->entries);
+		i++;
+	}
+
+	sched->num_entries = i;
+
+	return i;
+}
+
+static int parse_taprio_schedule(struct taprio_sched *q, struct nlattr **tb,
+				 struct sched_gate_list *new,
+				 struct netlink_ext_ack *extack)
+{
+	int err = 0;
+
+	if (tb[TCA_TAPRIO_ATTR_SCHED_SINGLE_ENTRY]) {
+		NL_SET_ERR_MSG(extack, "Adding a single entry is not supported");
+		return -ENOTSUPP;
+	}
+
+	if (tb[TCA_TAPRIO_ATTR_SCHED_BASE_TIME])
+		new->base_time = nla_get_s64(tb[TCA_TAPRIO_ATTR_SCHED_BASE_TIME]);
+
+	if (tb[TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME_EXTENSION])
+		new->cycle_time_extension = nla_get_s64(tb[TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME_EXTENSION]);
+
+	if (tb[TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME])
+		new->cycle_time = nla_get_s64(tb[TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME]);
+
+	if (tb[TCA_TAPRIO_ATTR_SCHED_ENTRY_LIST])
+		err = parse_sched_list(q, tb[TCA_TAPRIO_ATTR_SCHED_ENTRY_LIST],
+				       new, extack);
+	if (err < 0)
+		return err;
+
+	if (!new->cycle_time) {
+		struct sched_entry *entry;
+		ktime_t cycle = 0;
+
+		list_for_each_entry(entry, &new->entries, list)
+			cycle = ktime_add_ns(cycle, entry->interval);
+
+		if (!cycle) {
+			NL_SET_ERR_MSG(extack, "'cycle_time' can never be 0");
+			return -EINVAL;
+		}
+
+		if (cycle < 0 || cycle > INT_MAX) {
+			NL_SET_ERR_MSG(extack, "'cycle_time' is too big");
+			return -EINVAL;
+		}
+
+		new->cycle_time = cycle;
+	}
+
+	taprio_calculate_gate_durations(q, new);
+
+	return 0;
+}
+
+static int taprio_parse_mqprio_opt(struct net_device *dev,
+				   struct tc_mqprio_qopt *qopt,
+				   struct netlink_ext_ack *extack,
+				   u32 taprio_flags)
+{
+	bool allow_overlapping_txqs = TXTIME_ASSIST_IS_ENABLED(taprio_flags);
+
+	if (!qopt && !dev->num_tc) {
+		NL_SET_ERR_MSG(extack, "'mqprio' configuration is necessary");
+		return -EINVAL;
+	}
+
+	/* If num_tc is already set, it means that the user already
+	 * configured the mqprio part
+	 */
+	if (dev->num_tc)
+		return 0;
+
+	/* taprio imposes that traffic classes map 1:n to tx queues */
+	if (qopt->num_tc > dev->num_tx_queues) {
+		NL_SET_ERR_MSG(extack, "Number of traffic classes is greater than number of HW queues");
+		return -EINVAL;
+	}
+
+	/* For some reason, in txtime-assist mode, we allow TXQ ranges for
+	 * different TCs to overlap, and just validate the TXQ ranges.
+	 */
+	return mqprio_validate_qopt(dev, qopt, true, allow_overlapping_txqs,
+				    extack);
+}
+
+static int taprio_get_start_time(struct Qdisc *sch,
+				 struct sched_gate_list *sched,
+				 ktime_t *start)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	ktime_t now, base, cycle;
+	s64 n;
+
+	base = sched_base_time(sched);
+	now = taprio_get_time(q);
+
+	if (ktime_after(base, now)) {
+		*start = base;
+		return 0;
+	}
+
+	cycle = sched->cycle_time;
+
+	/* The qdisc is expected to have at least one sched_entry.  Moreover,
+	 * any entry must have 'interval' > 0. Thus if the cycle time is zero,
+	 * something went really wrong. In that case, we should warn about this
+	 * inconsistent state and return error.
+	 */
+	if (WARN_ON(!cycle))
+		return -EFAULT;
+
+	/* Schedule the start time for the beginning of the next
+	 * cycle.
+	 */
+	n = div64_s64(ktime_sub_ns(now, base), cycle);
+	*start = ktime_add_ns(base, (n + 1) * cycle);
+	return 0;
+}
+
+static void setup_first_end_time(struct taprio_sched *q,
+				 struct sched_gate_list *sched, ktime_t base)
+{
+	struct net_device *dev = qdisc_dev(q->root);
+	int num_tc = netdev_get_num_tc(dev);
+	struct sched_entry *first;
+	ktime_t cycle;
+	int tc;
+
+	first = list_first_entry(&sched->entries,
+				 struct sched_entry, list);
+
+	cycle = sched->cycle_time;
+
+	/* FIXME: find a better place to do this */
+	sched->cycle_end_time = ktime_add_ns(base, cycle);
+
+	first->end_time = ktime_add_ns(base, first->interval);
+	taprio_set_budgets(q, sched, first);
+
+	for (tc = 0; tc < num_tc; tc++) {
+		if (first->gate_duration[tc] == sched->cycle_time)
+			first->gate_close_time[tc] = KTIME_MAX;
+		else
+			first->gate_close_time[tc] = ktime_add_ns(base, first->gate_duration[tc]);
+	}
+
+	rcu_assign_pointer(q->current_entry, NULL);
+}
+
+static void taprio_start_sched(struct Qdisc *sch,
+			       ktime_t start, struct sched_gate_list *new)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	ktime_t expires;
+
+	if (FULL_OFFLOAD_IS_ENABLED(q->flags))
+		return;
+
+	expires = hrtimer_get_expires(&q->advance_timer);
+	if (expires == 0)
+		expires = KTIME_MAX;
+
+	/* If the new schedule starts before the next expiration, we
+	 * reprogram it to the earliest one, so we change the admin
+	 * schedule to the operational one at the right time.
+	 */
+	start = min_t(ktime_t, start, expires);
+
+	hrtimer_start(&q->advance_timer, start, HRTIMER_MODE_ABS);
+}
+
+static void taprio_set_picos_per_byte(struct net_device *dev,
+				      struct taprio_sched *q)
+{
+	struct ethtool_link_ksettings ecmd;
+	int speed = SPEED_10;
+	int picos_per_byte;
+	int err;
+
+	err = __ethtool_get_link_ksettings(dev, &ecmd);
+	if (err < 0)
+		goto skip;
+
+	if (ecmd.base.speed && ecmd.base.speed != SPEED_UNKNOWN)
+		speed = ecmd.base.speed;
+
+skip:
+	picos_per_byte = (USEC_PER_SEC * 8) / speed;
+
+	atomic64_set(&q->picos_per_byte, picos_per_byte);
+	netdev_dbg(dev, "taprio: set %s's picos_per_byte to: %lld, linkspeed: %d\n",
+		   dev->name, (long long)atomic64_read(&q->picos_per_byte),
+		   ecmd.base.speed);
+}
+
+static int taprio_dev_notifier(struct notifier_block *nb, unsigned long event,
+			       void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	struct sched_gate_list *oper, *admin;
+	struct qdisc_size_table *stab;
+	struct taprio_sched *q;
+
+	ASSERT_RTNL();
+
+	if (event != NETDEV_UP && event != NETDEV_CHANGE)
+		return NOTIFY_DONE;
+
+	list_for_each_entry(q, &taprio_list, taprio_list) {
+		if (dev != qdisc_dev(q->root))
+			continue;
+
+		taprio_set_picos_per_byte(dev, q);
+
+		stab = rtnl_dereference(q->root->stab);
+
+		oper = rtnl_dereference(q->oper_sched);
+		if (oper)
+			taprio_update_queue_max_sdu(q, oper, stab);
+
+		admin = rtnl_dereference(q->admin_sched);
+		if (admin)
+			taprio_update_queue_max_sdu(q, admin, stab);
+
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static void setup_txtime(struct taprio_sched *q,
+			 struct sched_gate_list *sched, ktime_t base)
+{
+	struct sched_entry *entry;
+	u64 interval = 0;
+
+	list_for_each_entry(entry, &sched->entries, list) {
+		entry->next_txtime = ktime_add_ns(base, interval);
+		interval += entry->interval;
+	}
+}
+
+static struct tc_taprio_qopt_offload *taprio_offload_alloc(int num_entries)
+{
+	struct __tc_taprio_qopt_offload *__offload;
+
+	__offload = kzalloc(struct_size(__offload, offload.entries, num_entries),
+			    GFP_KERNEL);
+	if (!__offload)
+		return NULL;
+
+	refcount_set(&__offload->users, 1);
+
+	return &__offload->offload;
+}
+
+struct tc_taprio_qopt_offload *taprio_offload_get(struct tc_taprio_qopt_offload
+						  *offload)
+{
+	struct __tc_taprio_qopt_offload *__offload;
+
+	__offload = container_of(offload, struct __tc_taprio_qopt_offload,
+				 offload);
+
+	refcount_inc(&__offload->users);
+
+	return offload;
+}
+EXPORT_SYMBOL_GPL(taprio_offload_get);
+
+void taprio_offload_free(struct tc_taprio_qopt_offload *offload)
+{
+	struct __tc_taprio_qopt_offload *__offload;
+
+	__offload = container_of(offload, struct __tc_taprio_qopt_offload,
+				 offload);
+
+	if (!refcount_dec_and_test(&__offload->users))
+		return;
+
+	kfree(__offload);
+}
+EXPORT_SYMBOL_GPL(taprio_offload_free);
+
+/* The function will only serve to keep the pointers to the "oper" and "admin"
+ * schedules valid in relation to their base times, so when calling dump() the
+ * users looks at the right schedules.
+ * When using full offload, the admin configuration is promoted to oper at the
+ * base_time in the PHC time domain.  But because the system time is not
+ * necessarily in sync with that, we can't just trigger a hrtimer to call
+ * switch_schedules at the right hardware time.
+ * At the moment we call this by hand right away from taprio, but in the future
+ * it will be useful to create a mechanism for drivers to notify taprio of the
+ * offload state (PENDING, ACTIVE, INACTIVE) so it can be visible in dump().
+ * This is left as TODO.
+ */
+static void taprio_offload_config_changed(struct taprio_sched *q)
+{
+	struct sched_gate_list *oper, *admin;
+
+	oper = rtnl_dereference(q->oper_sched);
+	admin = rtnl_dereference(q->admin_sched);
+
+	switch_schedules(q, &admin, &oper);
+}
+
+static u32 tc_map_to_queue_mask(struct net_device *dev, u32 tc_mask)
+{
+	u32 i, queue_mask = 0;
+
+	for (i = 0; i < dev->num_tc; i++) {
+		u32 offset, count;
+
+		if (!(tc_mask & BIT(i)))
+			continue;
+
+		offset = dev->tc_to_txq[i].offset;
+		count = dev->tc_to_txq[i].count;
+
+		queue_mask |= GENMASK(offset + count - 1, offset);
+	}
+
+	return queue_mask;
+}
+
+static void taprio_sched_to_offload(struct net_device *dev,
+				    struct sched_gate_list *sched,
+				    struct tc_taprio_qopt_offload *offload,
+				    const struct tc_taprio_caps *caps)
+{
+	struct sched_entry *entry;
+	int i = 0;
+
+	offload->base_time = sched->base_time;
+	offload->cycle_time = sched->cycle_time;
+	offload->cycle_time_extension = sched->cycle_time_extension;
+
+	list_for_each_entry(entry, &sched->entries, list) {
+		struct tc_taprio_sched_entry *e = &offload->entries[i];
+
+		e->command = entry->command;
+		e->interval = entry->interval;
+		if (caps->gate_mask_per_txq)
+			e->gate_mask = tc_map_to_queue_mask(dev,
+							    entry->gate_mask);
+		else
+			e->gate_mask = entry->gate_mask;
+
+		i++;
+	}
+
+	offload->num_entries = i;
+}
+
+static void taprio_detect_broken_mqprio(struct taprio_sched *q)
+{
+	struct net_device *dev = qdisc_dev(q->root);
+	struct tc_taprio_caps caps;
+
+	qdisc_offload_query_caps(dev, TC_SETUP_QDISC_TAPRIO,
+				 &caps, sizeof(caps));
+
+	q->broken_mqprio = caps.broken_mqprio;
+	if (q->broken_mqprio)
+		static_branch_inc(&taprio_have_broken_mqprio);
+	else
+		static_branch_inc(&taprio_have_working_mqprio);
+
+	q->detected_mqprio = true;
+}
+
+static void taprio_cleanup_broken_mqprio(struct taprio_sched *q)
+{
+	if (!q->detected_mqprio)
+		return;
+
+	if (q->broken_mqprio)
+		static_branch_dec(&taprio_have_broken_mqprio);
+	else
+		static_branch_dec(&taprio_have_working_mqprio);
+}
+
+static int taprio_enable_offload(struct net_device *dev,
+				 struct taprio_sched *q,
+				 struct sched_gate_list *sched,
+				 struct netlink_ext_ack *extack)
+{
+	const struct net_device_ops *ops = dev->netdev_ops;
+	struct tc_taprio_qopt_offload *offload;
+	struct tc_taprio_caps caps;
+	int tc, err = 0;
+
+	if (!ops->ndo_setup_tc) {
+		NL_SET_ERR_MSG(extack,
+			       "Device does not support taprio offload");
+		return -EOPNOTSUPP;
+	}
+
+	qdisc_offload_query_caps(dev, TC_SETUP_QDISC_TAPRIO,
+				 &caps, sizeof(caps));
+
+	if (!caps.supports_queue_max_sdu) {
+		for (tc = 0; tc < TC_MAX_QUEUE; tc++) {
+			if (q->max_sdu[tc]) {
+				NL_SET_ERR_MSG_MOD(extack,
+						   "Device does not handle queueMaxSDU");
+				return -EOPNOTSUPP;
+			}
+		}
+	}
+
+	offload = taprio_offload_alloc(sched->num_entries);
+	if (!offload) {
+		NL_SET_ERR_MSG(extack,
+			       "Not enough memory for enabling offload mode");
+		return -ENOMEM;
+	}
+	offload->cmd = TAPRIO_CMD_REPLACE;
+	offload->extack = extack;
+	mqprio_qopt_reconstruct(dev, &offload->mqprio.qopt);
+	offload->mqprio.extack = extack;
+	taprio_sched_to_offload(dev, sched, offload, &caps);
+	mqprio_fp_to_offload(q->fp, &offload->mqprio);
+
+	for (tc = 0; tc < TC_MAX_QUEUE; tc++)
+		offload->max_sdu[tc] = q->max_sdu[tc];
+
+	err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_TAPRIO, offload);
+	if (err < 0) {
+		NL_SET_ERR_MSG_WEAK(extack,
+				    "Device failed to setup taprio offload");
+		goto done;
+	}
+
+	q->offloaded = true;
+
+done:
+	/* The offload structure may linger around via a reference taken by the
+	 * device driver, so clear up the netlink extack pointer so that the
+	 * driver isn't tempted to dereference data which stopped being valid
+	 */
+	offload->extack = NULL;
+	offload->mqprio.extack = NULL;
+	taprio_offload_free(offload);
+
+	return err;
+}
+
+static int taprio_disable_offload(struct net_device *dev,
+				  struct taprio_sched *q,
+				  struct netlink_ext_ack *extack)
+{
+	const struct net_device_ops *ops = dev->netdev_ops;
+	struct tc_taprio_qopt_offload *offload;
+	int err;
+
+	if (!q->offloaded)
+		return 0;
+
+	offload = taprio_offload_alloc(0);
+	if (!offload) {
+		NL_SET_ERR_MSG(extack,
+			       "Not enough memory to disable offload mode");
+		return -ENOMEM;
+	}
+	offload->cmd = TAPRIO_CMD_DESTROY;
+
+	err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_TAPRIO, offload);
+	if (err < 0) {
+		NL_SET_ERR_MSG(extack,
+			       "Device failed to disable offload");
+		goto out;
+	}
+
+	q->offloaded = false;
+
+out:
+	taprio_offload_free(offload);
+
+	return err;
+}
+
+/* If full offload is enabled, the only possible clockid is the net device's
+ * PHC. For that reason, specifying a clockid through netlink is incorrect.
+ * For txtime-assist, it is implicitly assumed that the device's PHC is kept
+ * in sync with the specified clockid via a user space daemon such as phc2sys.
+ * For both software taprio and txtime-assist, the clockid is used for the
+ * hrtimer that advances the schedule and hence mandatory.
+ */
+static int taprio_parse_clockid(struct Qdisc *sch, struct nlattr **tb,
+				struct netlink_ext_ack *extack)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct net_device *dev = qdisc_dev(sch);
+	int err = -EINVAL;
+
+	if (FULL_OFFLOAD_IS_ENABLED(q->flags)) {
+		const struct ethtool_ops *ops = dev->ethtool_ops;
+		struct ethtool_ts_info info = {
+			.cmd = ETHTOOL_GET_TS_INFO,
+			.phc_index = -1,
+		};
+
+		if (tb[TCA_TAPRIO_ATTR_SCHED_CLOCKID]) {
+			NL_SET_ERR_MSG(extack,
+				       "The 'clockid' cannot be specified for full offload");
+			goto out;
+		}
+
+		if (ops && ops->get_ts_info)
+			err = ops->get_ts_info(dev, &info);
+
+		if (err || info.phc_index < 0) {
+			NL_SET_ERR_MSG(extack,
+				       "Device does not have a PTP clock");
+			err = -ENOTSUPP;
+			goto out;
+		}
+	} else if (tb[TCA_TAPRIO_ATTR_SCHED_CLOCKID]) {
+		int clockid = nla_get_s32(tb[TCA_TAPRIO_ATTR_SCHED_CLOCKID]);
+		enum tk_offsets tk_offset;
+
+		/* We only support static clockids and we don't allow
+		 * for it to be modified after the first init.
+		 */
+		if (clockid < 0 ||
+		    (q->clockid != -1 && q->clockid != clockid)) {
+			NL_SET_ERR_MSG(extack,
+				       "Changing the 'clockid' of a running schedule is not supported");
+			err = -ENOTSUPP;
+			goto out;
+		}
+
+		switch (clockid) {
+		case CLOCK_REALTIME:
+			tk_offset = TK_OFFS_REAL;
+			break;
+		case CLOCK_MONOTONIC:
+			tk_offset = TK_OFFS_MAX;
+			break;
+		case CLOCK_BOOTTIME:
+			tk_offset = TK_OFFS_BOOT;
+			break;
+		case CLOCK_TAI:
+			tk_offset = TK_OFFS_TAI;
+			break;
+		default:
+			NL_SET_ERR_MSG(extack, "Invalid 'clockid'");
+			err = -EINVAL;
+			goto out;
+		}
+		/* This pairs with READ_ONCE() in taprio_mono_to_any */
+		WRITE_ONCE(q->tk_offset, tk_offset);
+
+		q->clockid = clockid;
+	} else {
+		NL_SET_ERR_MSG(extack, "Specifying a 'clockid' is mandatory");
+		goto out;
+	}
+
+	/* Everything went ok, return success. */
+	err = 0;
+
+out:
+	return err;
+}
+
+static int taprio_parse_tc_entry(struct Qdisc *sch,
+				 struct nlattr *opt,
+				 u32 max_sdu[TC_QOPT_MAX_QUEUE],
+				 u32 fp[TC_QOPT_MAX_QUEUE],
+				 unsigned long *seen_tcs,
+				 struct netlink_ext_ack *extack)
+{
+	struct nlattr *tb[TCA_TAPRIO_TC_ENTRY_MAX + 1] = { };
+	struct net_device *dev = qdisc_dev(sch);
+	int err, tc;
+	u32 val;
+
+	err = nla_parse_nested(tb, TCA_TAPRIO_TC_ENTRY_MAX, opt,
+			       taprio_tc_policy, extack);
+	if (err < 0)
+		return err;
+
+	if (!tb[TCA_TAPRIO_TC_ENTRY_INDEX]) {
+		NL_SET_ERR_MSG_MOD(extack, "TC entry index missing");
+		return -EINVAL;
+	}
+
+	tc = nla_get_u32(tb[TCA_TAPRIO_TC_ENTRY_INDEX]);
+	if (tc >= TC_QOPT_MAX_QUEUE) {
+		NL_SET_ERR_MSG_MOD(extack, "TC entry index out of range");
+		return -ERANGE;
+	}
+
+	if (*seen_tcs & BIT(tc)) {
+		NL_SET_ERR_MSG_MOD(extack, "Duplicate TC entry");
+		return -EINVAL;
+	}
+
+	*seen_tcs |= BIT(tc);
+
+	if (tb[TCA_TAPRIO_TC_ENTRY_MAX_SDU]) {
+		val = nla_get_u32(tb[TCA_TAPRIO_TC_ENTRY_MAX_SDU]);
+		if (val > dev->max_mtu) {
+			NL_SET_ERR_MSG_MOD(extack, "TC max SDU exceeds device max MTU");
+			return -ERANGE;
+		}
+
+		max_sdu[tc] = val;
+	}
+
+	if (tb[TCA_TAPRIO_TC_ENTRY_FP])
+		fp[tc] = nla_get_u32(tb[TCA_TAPRIO_TC_ENTRY_FP]);
+
+	return 0;
+}
+
+static int taprio_parse_tc_entries(struct Qdisc *sch,
+				   struct nlattr *opt,
+				   struct netlink_ext_ack *extack)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct net_device *dev = qdisc_dev(sch);
+	u32 max_sdu[TC_QOPT_MAX_QUEUE];
+	bool have_preemption = false;
+	unsigned long seen_tcs = 0;
+	u32 fp[TC_QOPT_MAX_QUEUE];
+	struct nlattr *n;
+	int tc, rem;
+	int err = 0;
+
+	for (tc = 0; tc < TC_QOPT_MAX_QUEUE; tc++) {
+		max_sdu[tc] = q->max_sdu[tc];
+		fp[tc] = q->fp[tc];
+	}
+
+	nla_for_each_nested(n, opt, rem) {
+		if (nla_type(n) != TCA_TAPRIO_ATTR_TC_ENTRY)
+			continue;
+
+		err = taprio_parse_tc_entry(sch, n, max_sdu, fp, &seen_tcs,
+					    extack);
+		if (err)
+			return err;
+	}
+
+	for (tc = 0; tc < TC_QOPT_MAX_QUEUE; tc++) {
+		q->max_sdu[tc] = max_sdu[tc];
+		q->fp[tc] = fp[tc];
+		if (fp[tc] != TC_FP_EXPRESS)
+			have_preemption = true;
+	}
+
+	if (have_preemption) {
+		if (!FULL_OFFLOAD_IS_ENABLED(q->flags)) {
+			NL_SET_ERR_MSG(extack,
+				       "Preemption only supported with full offload");
+			return -EOPNOTSUPP;
+		}
+
+		if (!ethtool_dev_mm_supported(dev)) {
+			NL_SET_ERR_MSG(extack,
+				       "Device does not support preemption");
+			return -EOPNOTSUPP;
+		}
+	}
+
+	return err;
+}
+
+static int taprio_mqprio_cmp(const struct net_device *dev,
+			     const struct tc_mqprio_qopt *mqprio)
+{
+	int i;
+
+	if (!mqprio || mqprio->num_tc != dev->num_tc)
+		return -1;
+
+	for (i = 0; i < mqprio->num_tc; i++)
+		if (dev->tc_to_txq[i].count != mqprio->count[i] ||
+		    dev->tc_to_txq[i].offset != mqprio->offset[i])
+			return -1;
+
+	for (i = 0; i <= TC_BITMASK; i++)
+		if (dev->prio_tc_map[i] != mqprio->prio_tc_map[i])
+			return -1;
+
+	return 0;
+}
+
+/* The semantics of the 'flags' argument in relation to 'change()'
+ * requests, are interpreted following two rules (which are applied in
+ * this order): (1) an omitted 'flags' argument is interpreted as
+ * zero; (2) the 'flags' of a "running" taprio instance cannot be
+ * changed.
+ */
+static int taprio_new_flags(const struct nlattr *attr, u32 old,
+			    struct netlink_ext_ack *extack)
+{
+	u32 new = 0;
+
+	if (attr)
+		new = nla_get_u32(attr);
+
+	if (old != TAPRIO_FLAGS_INVALID && old != new) {
+		NL_SET_ERR_MSG_MOD(extack, "Changing 'flags' of a running schedule is not supported");
+		return -EOPNOTSUPP;
+	}
+
+	if (!taprio_flags_valid(new)) {
+		NL_SET_ERR_MSG_MOD(extack, "Specified 'flags' are not valid");
+		return -EINVAL;
+	}
+
+	return new;
+}
+
+static int taprio_change(struct Qdisc *sch, struct nlattr *opt,
+			 struct netlink_ext_ack *extack)
+{
+	struct qdisc_size_table *stab = rtnl_dereference(sch->stab);
+	struct nlattr *tb[TCA_TAPRIO_ATTR_MAX + 1] = { };
+	struct sched_gate_list *oper, *admin, *new_admin;
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct net_device *dev = qdisc_dev(sch);
+	struct tc_mqprio_qopt *mqprio = NULL;
+	unsigned long flags;
+	ktime_t start;
+	int i, err;
+
+	err = nla_parse_nested_deprecated(tb, TCA_TAPRIO_ATTR_MAX, opt,
+					  taprio_policy, extack);
+	if (err < 0)
+		return err;
+
+	if (tb[TCA_TAPRIO_ATTR_PRIOMAP])
+		mqprio = nla_data(tb[TCA_TAPRIO_ATTR_PRIOMAP]);
+
+	err = taprio_new_flags(tb[TCA_TAPRIO_ATTR_FLAGS],
+			       q->flags, extack);
+	if (err < 0)
+		return err;
+
+	q->flags = err;
+
+	err = taprio_parse_mqprio_opt(dev, mqprio, extack, q->flags);
+	if (err < 0)
+		return err;
+
+	err = taprio_parse_tc_entries(sch, opt, extack);
+	if (err)
+		return err;
+
+	new_admin = kzalloc(sizeof(*new_admin), GFP_KERNEL);
+	if (!new_admin) {
+		NL_SET_ERR_MSG(extack, "Not enough memory for a new schedule");
+		return -ENOMEM;
+	}
+	INIT_LIST_HEAD(&new_admin->entries);
+
+	oper = rtnl_dereference(q->oper_sched);
+	admin = rtnl_dereference(q->admin_sched);
+
+	/* no changes - no new mqprio settings */
+	if (!taprio_mqprio_cmp(dev, mqprio))
+		mqprio = NULL;
+
+	if (mqprio && (oper || admin)) {
+		NL_SET_ERR_MSG(extack, "Changing the traffic mapping of a running schedule is not supported");
+		err = -ENOTSUPP;
+		goto free_sched;
+	}
+
+	if (mqprio) {
+		err = netdev_set_num_tc(dev, mqprio->num_tc);
+		if (err)
+			goto free_sched;
+		for (i = 0; i < mqprio->num_tc; i++) {
+			netdev_set_tc_queue(dev, i,
+					    mqprio->count[i],
+					    mqprio->offset[i]);
+			q->cur_txq[i] = mqprio->offset[i];
+		}
+
+		/* Always use supplied priority mappings */
+		for (i = 0; i <= TC_BITMASK; i++)
+			netdev_set_prio_tc_map(dev, i,
+					       mqprio->prio_tc_map[i]);
+	}
+
+	err = parse_taprio_schedule(q, tb, new_admin, extack);
+	if (err < 0)
+		goto free_sched;
+
+	if (new_admin->num_entries == 0) {
+		NL_SET_ERR_MSG(extack, "There should be at least one entry in the schedule");
+		err = -EINVAL;
+		goto free_sched;
+	}
+
+	err = taprio_parse_clockid(sch, tb, extack);
+	if (err < 0)
+		goto free_sched;
+
+	taprio_set_picos_per_byte(dev, q);
+	taprio_update_queue_max_sdu(q, new_admin, stab);
+
+	if (FULL_OFFLOAD_IS_ENABLED(q->flags))
+		err = taprio_enable_offload(dev, q, new_admin, extack);
+	else
+		err = taprio_disable_offload(dev, q, extack);
+	if (err)
+		goto free_sched;
+
+	/* Protects against enqueue()/dequeue() */
+	spin_lock_bh(qdisc_lock(sch));
+
+	if (tb[TCA_TAPRIO_ATTR_TXTIME_DELAY]) {
+		if (!TXTIME_ASSIST_IS_ENABLED(q->flags)) {
+			NL_SET_ERR_MSG_MOD(extack, "txtime-delay can only be set when txtime-assist mode is enabled");
+			err = -EINVAL;
+			goto unlock;
+		}
+
+		q->txtime_delay = nla_get_u32(tb[TCA_TAPRIO_ATTR_TXTIME_DELAY]);
+	}
+
+	if (!TXTIME_ASSIST_IS_ENABLED(q->flags) &&
+	    !FULL_OFFLOAD_IS_ENABLED(q->flags) &&
+	    !hrtimer_active(&q->advance_timer)) {
+		hrtimer_init(&q->advance_timer, q->clockid, HRTIMER_MODE_ABS);
+		q->advance_timer.function = advance_sched;
+	}
+
+	err = taprio_get_start_time(sch, new_admin, &start);
+	if (err < 0) {
+		NL_SET_ERR_MSG(extack, "Internal error: failed get start time");
+		goto unlock;
+	}
+
+	setup_txtime(q, new_admin, start);
+
+	if (TXTIME_ASSIST_IS_ENABLED(q->flags)) {
+		if (!oper) {
+			rcu_assign_pointer(q->oper_sched, new_admin);
+			err = 0;
+			new_admin = NULL;
+			goto unlock;
+		}
+
+		rcu_assign_pointer(q->admin_sched, new_admin);
+		if (admin)
+			call_rcu(&admin->rcu, taprio_free_sched_cb);
+	} else {
+		setup_first_end_time(q, new_admin, start);
+
+		/* Protects against advance_sched() */
+		spin_lock_irqsave(&q->current_entry_lock, flags);
+
+		taprio_start_sched(sch, start, new_admin);
+
+		rcu_assign_pointer(q->admin_sched, new_admin);
+		if (admin)
+			call_rcu(&admin->rcu, taprio_free_sched_cb);
+
+		spin_unlock_irqrestore(&q->current_entry_lock, flags);
+
+		if (FULL_OFFLOAD_IS_ENABLED(q->flags))
+			taprio_offload_config_changed(q);
+	}
+
+	new_admin = NULL;
+	err = 0;
+
+	if (!stab)
+		NL_SET_ERR_MSG_MOD(extack,
+				   "Size table not specified, frame length estimations may be inaccurate");
+
+unlock:
+	spin_unlock_bh(qdisc_lock(sch));
+
+free_sched:
+	if (new_admin)
+		call_rcu(&new_admin->rcu, taprio_free_sched_cb);
+
+	return err;
+}
+
+static void taprio_reset(struct Qdisc *sch)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct net_device *dev = qdisc_dev(sch);
+	int i;
+
+	hrtimer_cancel(&q->advance_timer);
+
+	if (q->qdiscs) {
+		for (i = 0; i < dev->num_tx_queues; i++)
+			if (q->qdiscs[i])
+				qdisc_reset(q->qdiscs[i]);
+	}
+}
+
+static void taprio_destroy(struct Qdisc *sch)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct net_device *dev = qdisc_dev(sch);
+	struct sched_gate_list *oper, *admin;
+	unsigned int i;
+
+	list_del(&q->taprio_list);
+
+	/* Note that taprio_reset() might not be called if an error
+	 * happens in qdisc_create(), after taprio_init() has been called.
+	 */
+	hrtimer_cancel(&q->advance_timer);
+	qdisc_synchronize(sch);
+
+	taprio_disable_offload(dev, q, NULL);
+
+	if (q->qdiscs) {
+		for (i = 0; i < dev->num_tx_queues; i++)
+			qdisc_put(q->qdiscs[i]);
+
+		kfree(q->qdiscs);
+	}
+	q->qdiscs = NULL;
+
+	netdev_reset_tc(dev);
+
+	oper = rtnl_dereference(q->oper_sched);
+	admin = rtnl_dereference(q->admin_sched);
+
+	if (oper)
+		call_rcu(&oper->rcu, taprio_free_sched_cb);
+
+	if (admin)
+		call_rcu(&admin->rcu, taprio_free_sched_cb);
+
+	taprio_cleanup_broken_mqprio(q);
+}
+
+static int taprio_init(struct Qdisc *sch, struct nlattr *opt,
+		       struct netlink_ext_ack *extack)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct net_device *dev = qdisc_dev(sch);
+	int i, tc;
+
+	spin_lock_init(&q->current_entry_lock);
+
+	hrtimer_init(&q->advance_timer, CLOCK_TAI, HRTIMER_MODE_ABS);
+	q->advance_timer.function = advance_sched;
+
+	q->root = sch;
+
+	/* We only support static clockids. Use an invalid value as default
+	 * and get the valid one on taprio_change().
+	 */
+	q->clockid = -1;
+	q->flags = TAPRIO_FLAGS_INVALID;
+
+	list_add(&q->taprio_list, &taprio_list);
+
+	if (sch->parent != TC_H_ROOT) {
+		NL_SET_ERR_MSG_MOD(extack, "Can only be attached as root qdisc");
+		return -EOPNOTSUPP;
+	}
+
+	if (!netif_is_multiqueue(dev)) {
+		NL_SET_ERR_MSG_MOD(extack, "Multi-queue device is required");
+		return -EOPNOTSUPP;
+	}
+
+	q->qdiscs = kcalloc(dev->num_tx_queues, sizeof(q->qdiscs[0]),
+			    GFP_KERNEL);
+	if (!q->qdiscs)
+		return -ENOMEM;
+
+	if (!opt)
+		return -EINVAL;
+
+	for (i = 0; i < dev->num_tx_queues; i++) {
+		struct netdev_queue *dev_queue;
+		struct Qdisc *qdisc;
+
+		dev_queue = netdev_get_tx_queue(dev, i);
+		qdisc = qdisc_create_dflt(dev_queue,
+					  &pfifo_qdisc_ops,
+					  TC_H_MAKE(TC_H_MAJ(sch->handle),
+						    TC_H_MIN(i + 1)),
+					  extack);
+		if (!qdisc)
+			return -ENOMEM;
+
+		if (i < dev->real_num_tx_queues)
+			qdisc_hash_add(qdisc, false);
+
+		q->qdiscs[i] = qdisc;
+	}
+
+	for (tc = 0; tc < TC_QOPT_MAX_QUEUE; tc++)
+		q->fp[tc] = TC_FP_EXPRESS;
+
+	taprio_detect_broken_mqprio(q);
+
+	return taprio_change(sch, opt, extack);
+}
+
+static void taprio_attach(struct Qdisc *sch)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct net_device *dev = qdisc_dev(sch);
+	unsigned int ntx;
+
+	/* Attach underlying qdisc */
+	for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
+		struct netdev_queue *dev_queue = netdev_get_tx_queue(dev, ntx);
+		struct Qdisc *old, *dev_queue_qdisc;
+
+		if (FULL_OFFLOAD_IS_ENABLED(q->flags)) {
+			struct Qdisc *qdisc = q->qdiscs[ntx];
+
+			/* In offload mode, the root taprio qdisc is bypassed
+			 * and the netdev TX queues see the children directly
+			 */
+			qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
+			dev_queue_qdisc = qdisc;
+		} else {
+			/* In software mode, attach the root taprio qdisc
+			 * to all netdev TX queues, so that dev_qdisc_enqueue()
+			 * goes through taprio_enqueue().
+			 */
+			dev_queue_qdisc = sch;
+		}
+		old = dev_graft_qdisc(dev_queue, dev_queue_qdisc);
+		/* The qdisc's refcount requires to be elevated once
+		 * for each netdev TX queue it is grafted onto
+		 */
+		qdisc_refcount_inc(dev_queue_qdisc);
+		if (old)
+			qdisc_put(old);
+	}
+}
+
+static struct netdev_queue *taprio_queue_get(struct Qdisc *sch,
+					     unsigned long cl)
+{
+	struct net_device *dev = qdisc_dev(sch);
+	unsigned long ntx = cl - 1;
+
+	if (ntx >= dev->num_tx_queues)
+		return NULL;
+
+	return netdev_get_tx_queue(dev, ntx);
+}
+
+static int taprio_graft(struct Qdisc *sch, unsigned long cl,
+			struct Qdisc *new, struct Qdisc **old,
+			struct netlink_ext_ack *extack)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct net_device *dev = qdisc_dev(sch);
+	struct netdev_queue *dev_queue = taprio_queue_get(sch, cl);
+
+	if (!dev_queue)
+		return -EINVAL;
+
+	if (dev->flags & IFF_UP)
+		dev_deactivate(dev);
+
+	/* In offload mode, the child Qdisc is directly attached to the netdev
+	 * TX queue, and thus, we need to keep its refcount elevated in order
+	 * to counteract qdisc_graft()'s call to qdisc_put() once per TX queue.
+	 * However, save the reference to the new qdisc in the private array in
+	 * both software and offload cases, to have an up-to-date reference to
+	 * our children.
+	 */
+	*old = q->qdiscs[cl - 1];
+	if (FULL_OFFLOAD_IS_ENABLED(q->flags)) {
+		WARN_ON_ONCE(dev_graft_qdisc(dev_queue, new) != *old);
+		if (new)
+			qdisc_refcount_inc(new);
+		if (*old)
+			qdisc_put(*old);
+	}
+
+	q->qdiscs[cl - 1] = new;
+	if (new)
+		new->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
+
+	if (dev->flags & IFF_UP)
+		dev_activate(dev);
+
+	return 0;
+}
+
+static int dump_entry(struct sk_buff *msg,
+		      const struct sched_entry *entry)
+{
+	struct nlattr *item;
+
+	item = nla_nest_start_noflag(msg, TCA_TAPRIO_SCHED_ENTRY);
+	if (!item)
+		return -ENOSPC;
+
+	if (nla_put_u32(msg, TCA_TAPRIO_SCHED_ENTRY_INDEX, entry->index))
+		goto nla_put_failure;
+
+	if (nla_put_u8(msg, TCA_TAPRIO_SCHED_ENTRY_CMD, entry->command))
+		goto nla_put_failure;
+
+	if (nla_put_u32(msg, TCA_TAPRIO_SCHED_ENTRY_GATE_MASK,
+			entry->gate_mask))
+		goto nla_put_failure;
+
+	if (nla_put_u32(msg, TCA_TAPRIO_SCHED_ENTRY_INTERVAL,
+			entry->interval))
+		goto nla_put_failure;
+
+	return nla_nest_end(msg, item);
+
+nla_put_failure:
+	nla_nest_cancel(msg, item);
+	return -1;
+}
+
+static int dump_schedule(struct sk_buff *msg,
+			 const struct sched_gate_list *root)
+{
+	struct nlattr *entry_list;
+	struct sched_entry *entry;
+
+	if (nla_put_s64(msg, TCA_TAPRIO_ATTR_SCHED_BASE_TIME,
+			root->base_time, TCA_TAPRIO_PAD))
+		return -1;
+
+	if (nla_put_s64(msg, TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME,
+			root->cycle_time, TCA_TAPRIO_PAD))
+		return -1;
+
+	if (nla_put_s64(msg, TCA_TAPRIO_ATTR_SCHED_CYCLE_TIME_EXTENSION,
+			root->cycle_time_extension, TCA_TAPRIO_PAD))
+		return -1;
+
+	entry_list = nla_nest_start_noflag(msg,
+					   TCA_TAPRIO_ATTR_SCHED_ENTRY_LIST);
+	if (!entry_list)
+		goto error_nest;
+
+	list_for_each_entry(entry, &root->entries, list) {
+		if (dump_entry(msg, entry) < 0)
+			goto error_nest;
+	}
+
+	nla_nest_end(msg, entry_list);
+	return 0;
+
+error_nest:
+	nla_nest_cancel(msg, entry_list);
+	return -1;
+}
+
+static int taprio_dump_tc_entries(struct sk_buff *skb,
+				  struct taprio_sched *q,
+				  struct sched_gate_list *sched)
+{
+	struct nlattr *n;
+	int tc;
+
+	for (tc = 0; tc < TC_MAX_QUEUE; tc++) {
+		n = nla_nest_start(skb, TCA_TAPRIO_ATTR_TC_ENTRY);
+		if (!n)
+			return -EMSGSIZE;
+
+		if (nla_put_u32(skb, TCA_TAPRIO_TC_ENTRY_INDEX, tc))
+			goto nla_put_failure;
+
+		if (nla_put_u32(skb, TCA_TAPRIO_TC_ENTRY_MAX_SDU,
+				sched->max_sdu[tc]))
+			goto nla_put_failure;
+
+		if (nla_put_u32(skb, TCA_TAPRIO_TC_ENTRY_FP, q->fp[tc]))
+			goto nla_put_failure;
+
+		nla_nest_end(skb, n);
+	}
+
+	return 0;
+
+nla_put_failure:
+	nla_nest_cancel(skb, n);
+	return -EMSGSIZE;
+}
+
+static int taprio_put_stat(struct sk_buff *skb, u64 val, u16 attrtype)
+{
+	if (val == TAPRIO_STAT_NOT_SET)
+		return 0;
+	if (nla_put_u64_64bit(skb, attrtype, val, TCA_TAPRIO_OFFLOAD_STATS_PAD))
+		return -EMSGSIZE;
+	return 0;
+}
+
+static int taprio_dump_xstats(struct Qdisc *sch, struct gnet_dump *d,
+			      struct tc_taprio_qopt_offload *offload,
+			      struct tc_taprio_qopt_stats *stats)
+{
+	struct net_device *dev = qdisc_dev(sch);
+	const struct net_device_ops *ops;
+	struct sk_buff *skb = d->skb;
+	struct nlattr *xstats;
+	int err;
+
+	ops = qdisc_dev(sch)->netdev_ops;
+
+	/* FIXME I could use qdisc_offload_dump_helper(), but that messes
+	 * with sch->flags depending on whether the device reports taprio
+	 * stats, and I'm not sure whether that's a good idea, considering
+	 * that stats are optional to the offload itself
+	 */
+	if (!ops->ndo_setup_tc)
+		return 0;
+
+	memset(stats, 0xff, sizeof(*stats));
+
+	err = ops->ndo_setup_tc(dev, TC_SETUP_QDISC_TAPRIO, offload);
+	if (err == -EOPNOTSUPP)
+		return 0;
+	if (err)
+		return err;
+
+	xstats = nla_nest_start(skb, TCA_STATS_APP);
+	if (!xstats)
+		goto err;
+
+	if (taprio_put_stat(skb, stats->window_drops,
+			    TCA_TAPRIO_OFFLOAD_STATS_WINDOW_DROPS) ||
+	    taprio_put_stat(skb, stats->tx_overruns,
+			    TCA_TAPRIO_OFFLOAD_STATS_TX_OVERRUNS))
+		goto err_cancel;
+
+	nla_nest_end(skb, xstats);
+
+	return 0;
+
+err_cancel:
+	nla_nest_cancel(skb, xstats);
+err:
+	return -EMSGSIZE;
+}
+
+static int taprio_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
+{
+	struct tc_taprio_qopt_offload offload = {
+		.cmd = TAPRIO_CMD_STATS,
+	};
+
+	return taprio_dump_xstats(sch, d, &offload, &offload.stats);
+}
+
+static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct net_device *dev = qdisc_dev(sch);
+	struct sched_gate_list *oper, *admin;
+	struct tc_mqprio_qopt opt = { 0 };
+	struct nlattr *nest, *sched_nest;
+
+	oper = rtnl_dereference(q->oper_sched);
+	admin = rtnl_dereference(q->admin_sched);
+
+	mqprio_qopt_reconstruct(dev, &opt);
+
+	nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
+	if (!nest)
+		goto start_error;
+
+	if (nla_put(skb, TCA_TAPRIO_ATTR_PRIOMAP, sizeof(opt), &opt))
+		goto options_error;
+
+	if (!FULL_OFFLOAD_IS_ENABLED(q->flags) &&
+	    nla_put_s32(skb, TCA_TAPRIO_ATTR_SCHED_CLOCKID, q->clockid))
+		goto options_error;
+
+	if (q->flags && nla_put_u32(skb, TCA_TAPRIO_ATTR_FLAGS, q->flags))
+		goto options_error;
+
+	if (q->txtime_delay &&
+	    nla_put_u32(skb, TCA_TAPRIO_ATTR_TXTIME_DELAY, q->txtime_delay))
+		goto options_error;
+
+	if (oper && taprio_dump_tc_entries(skb, q, oper))
+		goto options_error;
+
+	if (oper && dump_schedule(skb, oper))
+		goto options_error;
+
+	if (!admin)
+		goto done;
+
+	sched_nest = nla_nest_start_noflag(skb, TCA_TAPRIO_ATTR_ADMIN_SCHED);
+	if (!sched_nest)
+		goto options_error;
+
+	if (dump_schedule(skb, admin))
+		goto admin_error;
+
+	nla_nest_end(skb, sched_nest);
+
+done:
+	return nla_nest_end(skb, nest);
+
+admin_error:
+	nla_nest_cancel(skb, sched_nest);
+
+options_error:
+	nla_nest_cancel(skb, nest);
+
+start_error:
+	return -ENOSPC;
+}
+
+static struct Qdisc *taprio_leaf(struct Qdisc *sch, unsigned long cl)
+{
+	struct taprio_sched *q = qdisc_priv(sch);
+	struct net_device *dev = qdisc_dev(sch);
+	unsigned int ntx = cl - 1;
+
+	if (ntx >= dev->num_tx_queues)
+		return NULL;
+
+	return q->qdiscs[ntx];
+}
+
+static unsigned long taprio_find(struct Qdisc *sch, u32 classid)
+{
+	unsigned int ntx = TC_H_MIN(classid);
+
+	if (!taprio_queue_get(sch, ntx))
+		return 0;
+	return ntx;
+}
+
+static int taprio_dump_class(struct Qdisc *sch, unsigned long cl,
+			     struct sk_buff *skb, struct tcmsg *tcm)
+{
+	struct Qdisc *child = taprio_leaf(sch, cl);
+
+	tcm->tcm_parent = TC_H_ROOT;
+	tcm->tcm_handle |= TC_H_MIN(cl);
+	tcm->tcm_info = child->handle;
+
+	return 0;
+}
+
+static int taprio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
+				   struct gnet_dump *d)
+	__releases(d->lock)
+	__acquires(d->lock)
+{
+	struct Qdisc *child = taprio_leaf(sch, cl);
+	struct tc_taprio_qopt_offload offload = {
+		.cmd = TAPRIO_CMD_QUEUE_STATS,
+		.queue_stats = {
+			.queue = cl - 1,
+		},
+	};
+
+	if (gnet_stats_copy_basic(d, NULL, &child->bstats, true) < 0 ||
+	    qdisc_qstats_copy(d, child) < 0)
+		return -1;
+
+	return taprio_dump_xstats(sch, d, &offload, &offload.queue_stats.stats);
+}
+
+static void taprio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
+{
+	struct net_device *dev = qdisc_dev(sch);
+	unsigned long ntx;
+
+	if (arg->stop)
+		return;
+
+	arg->count = arg->skip;
+	for (ntx = arg->skip; ntx < dev->num_tx_queues; ntx++) {
+		if (!tc_qdisc_stats_dump(sch, ntx + 1, arg))
+			break;
+	}
+}
+
+static struct netdev_queue *taprio_select_queue(struct Qdisc *sch,
+						struct tcmsg *tcm)
+{
+	return taprio_queue_get(sch, TC_H_MIN(tcm->tcm_parent));
+}
+
+static const struct Qdisc_class_ops taprio_class_ops = {
+	.graft		= taprio_graft,
+	.leaf		= taprio_leaf,
+	.find		= taprio_find,
+	.walk		= taprio_walk,
+	.dump		= taprio_dump_class,
+	.dump_stats	= taprio_dump_class_stats,
+	.select_queue	= taprio_select_queue,
+};
+
+static struct Qdisc_ops taprio_qdisc_ops __read_mostly = {
+	.cl_ops		= &taprio_class_ops,
+	.id		= "taprio",
+	.priv_size	= sizeof(struct taprio_sched),
+	.init		= taprio_init,
+	.change		= taprio_change,
+	.destroy	= taprio_destroy,
+	.reset		= taprio_reset,
+	.attach		= taprio_attach,
+	.peek		= taprio_peek,
+	.dequeue	= taprio_dequeue,
+	.enqueue	= taprio_enqueue,
+	.dump		= taprio_dump,
+	.dump_stats	= taprio_dump_stats,
+	.owner		= THIS_MODULE,
+};
+
+static struct notifier_block taprio_device_notifier = {
+	.notifier_call = taprio_dev_notifier,
+};
+
+static int __init taprio_module_init(void)
+{
+	int err = register_netdevice_notifier(&taprio_device_notifier);
+
+	if (err)
+		return err;
+
+	return register_qdisc(&taprio_qdisc_ops);
+}
+
+static void __exit taprio_module_exit(void)
+{
+	unregister_qdisc(&taprio_qdisc_ops);
+	unregister_netdevice_notifier(&taprio_device_notifier);
+}
+
+module_init(taprio_module_init);
+module_exit(taprio_module_exit);
+MODULE_LICENSE("GPL");