Commit c3194a67 authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

Merge branch 'small-tc-taprio-improvements' 

Vladimir Oltean says:

====================
Small tc-taprio improvements

This series contains:
- the proper protected variant of rcu_dereference() of admin and oper
  schedules for accesses from the slow path
- a removal of an extra function pointer indirection for
  qdisc->dequeue() and qdisc->peek()
- a removal of WARN_ON_ONCE() checks that can never trigger
- the addition of netlink extack messages to some qdisc->init() failures

These were split from an earlier patch set, hence the v2.
====================

Link: https://lore.kernel.org/r/20220915105046.2404072-1-vladimir.oltean@nxp.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parents 4d3c8848 2c08a4f8

net/sched/sch_taprio.c

+34 −78
Original line number Diff line number Diff line
@@ -78,8 +78,6 @@ struct taprio_sched { 
	struct sched_gate_list __rcu *admin_sched;

	struct hrtimer advance_timer;

	struct list_head taprio_list;

	struct sk_buff *(*dequeue)(struct Qdisc *sch);

	struct sk_buff *(*peek)(struct Qdisc *sch);

	u32 txtime_delay;

};
@@ -434,6 +432,9 @@ static int taprio_enqueue_one(struct sk_buff *skb, struct Qdisc *sch, 
	return qdisc_enqueue(skb, child, to_free);

}



/* 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)

{
@@ -441,11 +442,6 @@ static int taprio_enqueue(struct sk_buff *skb, struct Qdisc *sch, 
	struct Qdisc *child;

	int queue;



	if (unlikely(FULL_OFFLOAD_IS_ENABLED(q->flags))) {

		WARN_ONCE(1, "Trying to enqueue skb into the root of a taprio qdisc configured with full offload\n");

		return qdisc_drop(skb, sch, to_free);

	}



	queue = skb_get_queue_mapping(skb);



	child = q->qdiscs[queue];
@@ -454,10 +450,10 @@ static int taprio_enqueue(struct sk_buff *skb, struct Qdisc *sch, 


	/* Large packets might not be transmitted when the transmission duration

	 * exceeds any configured interval. Therefore, segment the skb into

	 * smaller chunks. Skip it for the full offload case, as the driver

	 * and/or the hardware is expected to handle this.

	 * smaller chunks. Drivers with full offload are expected to handle

	 * this in hardware.

	 */

	if (skb_is_gso(skb) && !FULL_OFFLOAD_IS_ENABLED(q->flags)) {

	if (skb_is_gso(skb)) {

		unsigned int slen = 0, numsegs = 0, len = qdisc_pkt_len(skb);

		netdev_features_t features = netif_skb_features(skb);

		struct sk_buff *segs, *nskb;
@@ -491,7 +487,10 @@ static int taprio_enqueue(struct sk_buff *skb, struct Qdisc *sch, 
	return taprio_enqueue_one(skb, sch, child, to_free);

}



static struct sk_buff *taprio_peek_soft(struct Qdisc *sch)

/* 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_peek(struct Qdisc *sch)

{

	struct taprio_sched *q = qdisc_priv(sch);

	struct net_device *dev = qdisc_dev(sch);
@@ -535,20 +534,6 @@ static struct sk_buff *taprio_peek_soft(struct Qdisc *sch) 
	return NULL;

}



static struct sk_buff *taprio_peek_offload(struct Qdisc *sch)

{

	WARN_ONCE(1, "Trying to peek into the root of a taprio qdisc configured with full offload\n");



	return NULL;

}



static struct sk_buff *taprio_peek(struct Qdisc *sch)

{

	struct taprio_sched *q = qdisc_priv(sch);



	return q->peek(sch);

}



static void taprio_set_budget(struct taprio_sched *q, struct sched_entry *entry)

{

	atomic_set(&entry->budget,
@@ -556,7 +541,10 @@ static void taprio_set_budget(struct taprio_sched *q, struct sched_entry *entry) 
			     atomic64_read(&q->picos_per_byte)));

}



static struct sk_buff *taprio_dequeue_soft(struct Qdisc *sch)

/* 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 net_device *dev = qdisc_dev(sch);
@@ -644,20 +632,6 @@ static struct sk_buff *taprio_dequeue_soft(struct Qdisc *sch) 
	return skb;

}



static struct sk_buff *taprio_dequeue_offload(struct Qdisc *sch)

{

	WARN_ONCE(1, "Trying to dequeue from the root of a taprio qdisc configured with full offload\n");



	return NULL;

}



static struct sk_buff *taprio_dequeue(struct Qdisc *sch)

{

	struct taprio_sched *q = qdisc_priv(sch);



	return q->dequeue(sch);

}



static bool should_restart_cycle(const struct sched_gate_list *oper,

				 const struct sched_entry *entry)

{
@@ -1193,16 +1167,10 @@ static void taprio_offload_config_changed(struct taprio_sched *q) 
{

	struct sched_gate_list *oper, *admin;



	spin_lock(&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));

	oper = rtnl_dereference(q->oper_sched);

	admin = rtnl_dereference(q->admin_sched);



	switch_schedules(q, &admin, &oper);



	spin_unlock(&q->current_entry_lock);

}



static u32 tc_map_to_queue_mask(struct net_device *dev, u32 tc_mask)
@@ -1490,10 +1458,8 @@ static int taprio_change(struct Qdisc *sch, struct nlattr *opt, 
	}

	INIT_LIST_HEAD(&new_admin->entries);



	rcu_read_lock();

	oper = rcu_dereference(q->oper_sched);

	admin = rcu_dereference(q->admin_sched);

	rcu_read_unlock();

	oper = rtnl_dereference(q->oper_sched);

	admin = rtnl_dereference(q->admin_sched);



	/* no changes - no new mqprio settings */

	if (!taprio_mqprio_cmp(dev, mqprio))
@@ -1563,17 +1529,6 @@ static int taprio_change(struct Qdisc *sch, struct nlattr *opt, 
		q->advance_timer.function = advance_sched;

	}



	if (FULL_OFFLOAD_IS_ENABLED(q->flags)) {

		q->dequeue = taprio_dequeue_offload;

		q->peek = taprio_peek_offload;

	} else {

		/* Be sure to always keep the function pointers

		 * in a consistent state.

		 */

		q->dequeue = taprio_dequeue_soft;

		q->peek = taprio_peek_soft;

	}



	err = taprio_get_start_time(sch, new_admin, &start);

	if (err < 0) {

		NL_SET_ERR_MSG(extack, "Internal error: failed get start time");
@@ -1642,6 +1597,7 @@ 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;



	spin_lock(&taprio_list_lock);
@@ -1665,11 +1621,14 @@ static void taprio_destroy(struct Qdisc *sch) 


	netdev_reset_tc(dev);



	if (q->oper_sched)

		call_rcu(&q->oper_sched->rcu, taprio_free_sched_cb);

	oper = rtnl_dereference(q->oper_sched);

	admin = rtnl_dereference(q->admin_sched);



	if (oper)

		call_rcu(&oper->rcu, taprio_free_sched_cb);



	if (q->admin_sched)

		call_rcu(&q->admin_sched->rcu, taprio_free_sched_cb);

	if (admin)

		call_rcu(&admin->rcu, taprio_free_sched_cb);

}



static int taprio_init(struct Qdisc *sch, struct nlattr *opt,
@@ -1684,9 +1643,6 @@ static int taprio_init(struct Qdisc *sch, struct nlattr *opt, 
	hrtimer_init(&q->advance_timer, CLOCK_TAI, HRTIMER_MODE_ABS);

	q->advance_timer.function = advance_sched;



	q->dequeue = taprio_dequeue_soft;

	q->peek = taprio_peek_soft;



	q->root = sch;



	/* We only support static clockids. Use an invalid value as default
@@ -1699,11 +1655,15 @@ static int taprio_init(struct Qdisc *sch, struct nlattr *opt, 
	list_add(&q->taprio_list, &taprio_list);

	spin_unlock(&taprio_list_lock);



	if (sch->parent != TC_H_ROOT)

	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))

	if (!netif_is_multiqueue(dev)) {

		NL_SET_ERR_MSG_MOD(extack, "Multi-queue device is required");

		return -EOPNOTSUPP;

	}



	/* pre-allocate qdisc, attachment can't fail */

	q->qdiscs = kcalloc(dev->num_tx_queues,
@@ -1884,9 +1844,8 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb) 
	struct nlattr *nest, *sched_nest;

	unsigned int i;



	rcu_read_lock();

	oper = rcu_dereference(q->oper_sched);

	admin = rcu_dereference(q->admin_sched);

	oper = rtnl_dereference(q->oper_sched);

	admin = rtnl_dereference(q->admin_sched);



	opt.num_tc = netdev_get_num_tc(dev);

	memcpy(opt.prio_tc_map, dev->prio_tc_map, sizeof(opt.prio_tc_map));
@@ -1930,8 +1889,6 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb) 
	nla_nest_end(skb, sched_nest);



done:

	rcu_read_unlock();



	return nla_nest_end(skb, nest);



admin_error:
@@ -1941,7 +1898,6 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb) 
	nla_nest_cancel(skb, nest);



start_error:

	rcu_read_unlock();

	return -ENOSPC;

}