--- /dev/null
+From: Felix Fietkau <nbd@nbd.name>
+Date: Sat, 28 May 2022 16:51:51 +0200
+Subject: [PATCH] mac80211: rework the airtime fairness implementation
+
+The current ATF implementation has a number of issues which have shown up
+during testing. Since it does not take into account the AQL budget of
+pending packets, the implementation might queue up large amounts of packets
+for a single txq until airtime gets reported after tx completion.
+The same then happens to the next txq afterwards. While the end result could
+still be considered fair, the bursty behavior introduces a large amount of
+latency.
+The current code also tries to avoid frequent re-sorting of txq entries in
+order to avoid having to re-balance the rbtree often.
+
+In order to fix these issues, introduce skip lists as a data structure, which
+offer similar lookup/insert/delete times as rbtree, but avoids the need for
+rebalacing by being probabilistic.
+Use this to keep tx entries sorted by virtual time + pending AQL budget and
+re-sort after each ieee80211_return_txq call.
+
+Since multiple txqs share a single air_time struct with a virtual time value,
+switch the active_txqs list to queue up air_time structs instead of queues.
+This helps avoid imbalance between shared txqs by servicing them round robin.
+
+ieee80211_next_txq now only dequeues the first element of active_txqs. To
+make that work for non-AQL or non-ATF drivers as well, add estimated tx
+airtime directly to air_info virtual time if either AQL or ATF is not
+supported.
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+ create mode 100644 include/linux/skiplist.h
+
+--- /dev/null
++++ b/include/linux/skiplist.h
+@@ -0,0 +1,250 @@
++/* SPDX-License-Identifier: GPL-2.0-or-later */
++/*
++ * A skip list is a probabilistic alternative to balanced trees. Unlike the
++ * red-black tree, it does not require rebalancing.
++ *
++ * This implementation uses only unidirectional next pointers and is optimized
++ * for use in a priority queue where elements are mostly deleted from the front
++ * of the queue.
++ *
++ * When storing up to 2^n elements in a n-level skiplist. lookup and deletion
++ * for the first element happens in O(1) time, other than that, insertion and
++ * deletion takes O(log n) time, assuming that the number of elements for an
++ * n-level list does not exceed 2^n.
++ *
++ * Usage:
++ * DECLARE_SKIPLIST_TYPE(foo, 5) will define the data types for a 5-level list:
++ * struct foo_list: the list data type
++ * struct foo_node: the node data for an element in the list
++ *
++ * DECLARE_SKIPLIST_IMPL(foo, foo_cmp_fn)
++ *
++ * Adds the skip list implementation. It depends on a provided function:
++ * int foo_cmp_fn(struct foo_list *list, struct foo_node *n1, struct foo_node *n2)
++ * This compares two elements given by their node pointers, returning values <0
++ * if n1 is less than n2, =0 and >0 for equal or bigger than respectively.
++ *
++ * This macro implements the following functions:
++ *
++ * void foo_list_init(struct foo_list *list)
++ * initializes the skip list
++ *
++ * void foo_node_init(struct foo_node *node)
++ * initializes a node. must be called before adding the node to the list
++ *
++ * struct foo_node *foo_node_next(struct foo_node *node)
++ * gets the node directly after the provided node, or NULL if it was the last
++ * element in the list.
++ *
++ * bool foo_is_queued(struct foo_node *node)
++ * returns true if the node is on a list
++ *
++ * struct foo_node *foo_dequeue(struct foo_list *list)
++ * deletes and returns the first element of the list (or returns NULL if empty)
++ *
++ * struct foo_node *foo_peek(struct foo_list *list)
++ * returns the first element of the list
++ *
++ * void foo_insert(struct foo_list *list, struct foo_node *node)
++ * inserts the node into the list. the node must be initialized and not on a
++ * list already.
++ *
++ * void foo_delete(struct foo_list *list, struct foo_node *node)
++ * deletes the node from the list, or does nothing if it's not on the list
++ */
++#ifndef __SKIPLIST_H
++#define __SKIPLIST_H
++
++#include <linux/bits.h>
++#include <linux/minmax.h>
++#include <linux/bug.h>
++#include <linux/prandom.h>
++
++#define SKIPLIST_POISON ((void *)1)
++
++#define DECLARE_SKIPLIST_TYPE(name, levels) \
++struct name##_node { \
++ struct name##_node *next[levels]; \
++}; \
++struct name##_list { \
++ struct name##_node head; \
++ unsigned int max_level; \
++ unsigned int count; \
++};
++
++#define DECLARE_SKIPLIST_IMPL(name, cmp_fn) \
++static inline void \
++name##_list_init(struct name##_list *list) \
++{ \
++ memset(list, 0, sizeof(*list)); \
++} \
++static inline void \
++name##_node_init(struct name##_node *node) \
++{ \
++ node->next[0] = SKIPLIST_POISON; \
++} \
++static inline struct name##_node * \
++name##_node_next(struct name##_node *node) \
++{ \
++ return node->next[0]; \
++} \
++static inline bool \
++name##_is_queued(struct name##_node *node) \
++{ \
++ return node->next[0] != SKIPLIST_POISON; \
++} \
++static inline int \
++__skiplist_##name##_cmp_impl(void *head, void *n1, void *n2) \
++{ \
++ return cmp_fn(head, n1, n2); \
++} \
++static inline void \
++__##name##_delete(struct name##_list *list) \
++{ \
++ list->count--; \
++ while (list->max_level && \
++ !list->head.next[list->max_level]) \
++ list->max_level--; \
++} \
++static inline struct name##_node * \
++name##_dequeue(struct name##_list *list) \
++{ \
++ struct name##_node *ret; \
++ unsigned int max_level = ARRAY_SIZE(list->head.next) - 1; \
++ ret = (void *)__skiplist_dequeue((void **)&list->head, \
++ max_level); \
++ if (!ret) \
++ return NULL; \
++ __##name##_delete(list); \
++ return ret; \
++} \
++static inline struct name##_node * \
++name##_peek(struct name##_list *list) \
++{ \
++ return list->head.next[0]; \
++} \
++static inline void \
++name##_insert(struct name##_list *list, struct name##_node *node) \
++{ \
++ int level = __skiplist_level(ARRAY_SIZE(list->head.next) - 1, \
++ list->count, prandom_u32()); \
++ level = min_t(int, level, list->max_level + 1); \
++ __skiplist_insert((void *)&list->head, (void *)node, level, \
++ __skiplist_##name##_cmp_impl); \
++ if (level > list->max_level) \
++ list->max_level = level; \
++ list->count++; \
++} \
++static inline void \
++name##_delete(struct name##_list *list, struct name##_node *node) \
++{ \
++ if (node->next[0] == SKIPLIST_POISON) \
++ return; \
++ __skiplist_delete((void *)&list->head, (void *)node, \
++ ARRAY_SIZE(list->head.next) - 1, \
++ __skiplist_##name##_cmp_impl); \
++ __##name##_delete(list); \
++}
++
++
++typedef int (*__skiplist_cmp_t)(void *head, void *n1, void *n2);
++
++#define __skiplist_cmp(cmp, head, cur, node) \
++ ({ \
++ int cmp_val = cmp(head, cur, node); \
++ if (!cmp_val) \
++ cmp_val = (unsigned long)(cur) - \
++ (unsigned long)(node); \
++ cmp_val; \
++ })
++
++static inline void *
++__skiplist_dequeue(void **list, int max_level)
++{
++ void **node = list[0];
++ unsigned int i;
++
++ if (!node)
++ return NULL;
++
++ list[0] = node[0];
++ for (i = 1; i <= max_level; i++) {
++ if (list[i] != node)
++ break;
++
++ list[i] = node[i];
++ }
++ node[0] = SKIPLIST_POISON;
++
++ return node;
++}
++
++static inline void
++__skiplist_insert(void **list, void **node, int level, __skiplist_cmp_t cmp)
++{
++ void **head = list;
++
++ if (WARN(node[0] != SKIPLIST_POISON, "Insert on already inserted or uninitialized node"))
++ return;
++ for (; level >= 0; level--) {
++ while (list[level] &&
++ __skiplist_cmp(cmp, head, list[level], node) < 0)
++ list = list[level];
++
++ node[level] = list[level];
++ list[level] = node;
++ }
++}
++
++
++static inline void
++__skiplist_delete(void **list, void **node, int max_level, __skiplist_cmp_t cmp)
++{
++ void *head = list;
++ int i;
++
++ for (i = max_level; i >= 0; i--) {
++ while (list[i] && list[i] != node &&
++ __skiplist_cmp(cmp, head, list[i], node) <= 0)
++ list = list[i];
++
++ if (list[i] != node)
++ continue;
++
++ list[i] = node[i];
++ }
++ node[0] = SKIPLIST_POISON;
++}
++
++static inline unsigned int
++__skiplist_level(unsigned int max_level, unsigned int count, unsigned int seed)
++{
++ unsigned int level = 0;
++
++ if (max_level >= 16 && !(seed & GENMASK(15, 0))) {
++ level += 16;
++ seed >>= 16;
++ }
++
++ if (max_level >= 8 && !(seed & GENMASK(7, 0))) {
++ level += 8;
++ seed >>= 8;
++ }
++
++ if (max_level >= 4 && !(seed & GENMASK(3, 0))) {
++ level += 4;
++ seed >>= 4;
++ }
++
++ if (!(seed & GENMASK(1, 0))) {
++ level += 2;
++ seed >>= 2;
++ }
++
++ if (!(seed & BIT(0)))
++ level++;
++
++ return min(level, max_level);
++}
++
++#endif
+--- a/net/mac80211/cfg.c
++++ b/net/mac80211/cfg.c
+@@ -1563,7 +1563,6 @@ static void sta_apply_airtime_params(str
+ for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
+ struct airtime_sched_info *air_sched = &local->airtime[ac];
+ struct airtime_info *air_info = &sta->airtime[ac];
+- struct txq_info *txqi;
+ u8 tid;
+
+ spin_lock_bh(&air_sched->lock);
+@@ -1575,10 +1574,6 @@ static void sta_apply_airtime_params(str
+
+ airtime_weight_set(air_info, params->airtime_weight);
+
+- txqi = to_txq_info(sta->sta.txq[tid]);
+- if (RB_EMPTY_NODE(&txqi->schedule_order))
+- continue;
+-
+ ieee80211_update_airtime_weight(local, air_sched,
+ 0, true);
+ }
+--- a/net/mac80211/ieee80211_i.h
++++ b/net/mac80211/ieee80211_i.h
+@@ -25,7 +25,8 @@
+ #include <linux/leds.h>
+ #include <linux/idr.h>
+ #include <linux/rhashtable.h>
+-#include <linux/rbtree.h>
++#include <linux/prandom.h>
++#include <linux/skiplist.h>
+ #include <net/ieee80211_radiotap.h>
+ #include <net/cfg80211.h>
+ #include <net/mac80211.h>
+@@ -854,6 +855,7 @@ enum txq_info_flags {
+ IEEE80211_TXQ_AMPDU,
+ IEEE80211_TXQ_NO_AMSDU,
+ IEEE80211_TXQ_STOP_NETIF_TX,
++ IEEE80211_TXQ_FORCE_ACTIVE,
+ };
+
+ /**
+@@ -870,7 +872,6 @@ struct txq_info {
+ struct fq_tin tin;
+ struct codel_vars def_cvars;
+ struct codel_stats cstats;
+- struct rb_node schedule_order;
+
+ struct sk_buff_head frags;
+ unsigned long flags;
+@@ -1185,8 +1186,7 @@ enum mac80211_scan_state {
+ *
+ * @lock: spinlock that protects all the fields in this struct
+ * @active_txqs: rbtree of currently backlogged queues, sorted by virtual time
+- * @schedule_pos: the current position maintained while a driver walks the tree
+- * with ieee80211_next_txq()
++ * @schedule_pos: last used airtime_info node while a driver walks the tree
+ * @active_list: list of struct airtime_info structs that were active within
+ * the last AIRTIME_ACTIVE_DURATION (100 ms), used to compute
+ * weight_sum
+@@ -1207,8 +1207,8 @@ enum mac80211_scan_state {
+ */
+ struct airtime_sched_info {
+ spinlock_t lock;
+- struct rb_root_cached active_txqs;
+- struct rb_node *schedule_pos;
++ struct airtime_sched_list active_txqs;
++ struct airtime_sched_node *schedule_pos;
+ struct list_head active_list;
+ u64 last_weight_update;
+ u64 last_schedule_activity;
+@@ -1663,6 +1663,20 @@ static inline struct airtime_info *to_ai
+ return &sdata->airtime[txq->ac];
+ }
+
++static inline int
++airtime_sched_cmp(struct airtime_sched_list *list,
++ struct airtime_sched_node *n1, struct airtime_sched_node *n2)
++{
++ struct airtime_info *a1, *a2;
++
++ a1 = container_of(n1, struct airtime_info, schedule_order);
++ a2 = container_of(n2, struct airtime_info, schedule_order);
++
++ return a1->v_t_cur - a2->v_t_cur;
++}
++
++DECLARE_SKIPLIST_IMPL(airtime_sched, airtime_sched_cmp);
++
+ /* To avoid divisions in the fast path, we keep pre-computed reciprocals for
+ * airtime weight calculations. There are two different weights to keep track
+ * of: The per-station weight and the sum of weights per phy.
+@@ -1750,6 +1764,7 @@ static inline void init_airtime_info(str
+ air_info->aql_limit_high = air_sched->aql_txq_limit_high;
+ airtime_weight_set(air_info, IEEE80211_DEFAULT_AIRTIME_WEIGHT);
+ INIT_LIST_HEAD(&air_info->list);
++ airtime_sched_node_init(&air_info->schedule_order);
+ }
+
+ static inline int ieee80211_bssid_match(const u8 *raddr, const u8 *addr)
+--- a/net/mac80211/main.c
++++ b/net/mac80211/main.c
+@@ -709,7 +709,7 @@ struct ieee80211_hw *ieee80211_alloc_hw_
+ for (i = 0; i < IEEE80211_NUM_ACS; i++) {
+ struct airtime_sched_info *air_sched = &local->airtime[i];
+
+- air_sched->active_txqs = RB_ROOT_CACHED;
++ airtime_sched_list_init(&air_sched->active_txqs);
+ INIT_LIST_HEAD(&air_sched->active_list);
+ spin_lock_init(&air_sched->lock);
+ air_sched->aql_txq_limit_low = IEEE80211_DEFAULT_AQL_TXQ_LIMIT_L;
+--- a/net/mac80211/sta_info.c
++++ b/net/mac80211/sta_info.c
+@@ -1902,8 +1902,7 @@ void ieee80211_register_airtime(struct i
+ air_sched = &local->airtime[txq->ac];
+ air_info = to_airtime_info(txq);
+
+- if (local->airtime_flags & AIRTIME_USE_TX)
+- airtime += tx_airtime;
++ airtime += tx_airtime;
+ if (local->airtime_flags & AIRTIME_USE_RX)
+ airtime += rx_airtime;
+
+--- a/net/mac80211/sta_info.h
++++ b/net/mac80211/sta_info.h
+@@ -135,11 +135,14 @@ enum ieee80211_agg_stop_reason {
+ #define AIRTIME_USE_TX BIT(0)
+ #define AIRTIME_USE_RX BIT(1)
+
++DECLARE_SKIPLIST_TYPE(airtime_sched, 5);
+
+ struct airtime_info {
++ struct airtime_sched_node schedule_order;
++ struct ieee80211_txq *txq[3];
+ u64 rx_airtime;
+ u64 tx_airtime;
+- u64 v_t;
++ u64 v_t, v_t_cur;
+ u64 last_scheduled;
+ struct list_head list;
+ atomic_t aql_tx_pending; /* Estimated airtime for frames pending */
+@@ -147,6 +150,7 @@ struct airtime_info {
+ u32 aql_limit_high;
+ u32 weight_reciprocal;
+ u16 weight;
++ u8 txq_idx;
+ };
+
+ void ieee80211_sta_update_pending_airtime(struct ieee80211_local *local,
+--- a/net/mac80211/tx.c
++++ b/net/mac80211/tx.c
+@@ -19,6 +19,7 @@
+ #include <linux/rcupdate.h>
+ #include <linux/export.h>
+ #include <linux/timekeeping.h>
++#include <linux/prandom.h>
+ #include <net/net_namespace.h>
+ #include <net/ieee80211_radiotap.h>
+ #include <net/cfg80211.h>
+@@ -1476,11 +1477,12 @@ void ieee80211_txq_init(struct ieee80211
+ struct sta_info *sta,
+ struct txq_info *txqi, int tid)
+ {
++ struct airtime_info *air_info;
++
+ fq_tin_init(&txqi->tin);
+ codel_vars_init(&txqi->def_cvars);
+ codel_stats_init(&txqi->cstats);
+ __skb_queue_head_init(&txqi->frags);
+- RB_CLEAR_NODE(&txqi->schedule_order);
+
+ txqi->txq.vif = &sdata->vif;
+
+@@ -1489,7 +1491,7 @@ void ieee80211_txq_init(struct ieee80211
+ txqi->txq.tid = 0;
+ txqi->txq.ac = IEEE80211_AC_BE;
+
+- return;
++ goto out;
+ }
+
+ if (tid == IEEE80211_NUM_TIDS) {
+@@ -1511,6 +1513,12 @@ void ieee80211_txq_init(struct ieee80211
+ txqi->txq.sta = &sta->sta;
+ txqi->txq.tid = tid;
+ sta->sta.txq[tid] = &txqi->txq;
++
++out:
++ air_info = to_airtime_info(&txqi->txq);
++ air_info->txq[air_info->txq_idx++] = &txqi->txq;
++ if (air_info->txq_idx == ARRAY_SIZE(air_info->txq))
++ air_info->txq_idx--;
+ }
+
+ void ieee80211_txq_purge(struct ieee80211_local *local,
+@@ -3633,6 +3641,8 @@ struct sk_buff *ieee80211_tx_dequeue(str
+ struct ieee80211_tx_data tx;
+ ieee80211_tx_result r;
+ struct ieee80211_vif *vif = txq->vif;
++ u32 airtime;
++ bool ampdu;
+
+ WARN_ON_ONCE(softirq_count() == 0);
+
+@@ -3791,21 +3801,26 @@ begin:
+ encap_out:
+ IEEE80211_SKB_CB(skb)->control.vif = vif;
+
+- if (vif &&
+- wiphy_ext_feature_isset(local->hw.wiphy, NL80211_EXT_FEATURE_AQL)) {
+- bool ampdu = txq->ac != IEEE80211_AC_VO;
+- u32 airtime;
+-
+- airtime = ieee80211_calc_expected_tx_airtime(hw, vif, txq->sta,
+- skb->len, ampdu);
+- if (airtime) {
+- airtime = ieee80211_info_set_tx_time_est(info, airtime);
+- ieee80211_sta_update_pending_airtime(local, tx.sta,
+- txq->ac,
+- airtime,
+- false);
+- }
+- }
++ if (!vif)
++ return skb;
++
++ ampdu = txq->ac != IEEE80211_AC_VO;
++ airtime = ieee80211_calc_expected_tx_airtime(hw, vif, txq->sta,
++ skb->len, ampdu);
++ if (!airtime)
++ return skb;
++
++ if (!wiphy_ext_feature_isset(local->hw.wiphy, NL80211_EXT_FEATURE_AQL) ||
++ !wiphy_ext_feature_isset(local->hw.wiphy,
++ NL80211_EXT_FEATURE_AIRTIME_FAIRNESS))
++ ieee80211_register_airtime(txq, airtime, 0);
++
++ if (!wiphy_ext_feature_isset(local->hw.wiphy, NL80211_EXT_FEATURE_AQL))
++ return skb;
++
++ airtime = ieee80211_info_set_tx_time_est(info, airtime);
++ ieee80211_sta_update_pending_airtime(local, tx.sta, txq->ac,
++ airtime, false);
+
+ return skb;
+
+@@ -3816,85 +3831,95 @@ out:
+ }
+ EXPORT_SYMBOL(ieee80211_tx_dequeue);
+
++static void
++airtime_info_next_txq_idx(struct airtime_info *air_info)
++{
++ air_info->txq_idx++;
++ if (air_info->txq_idx >= ARRAY_SIZE(air_info->txq) ||
++ !air_info->txq[air_info->txq_idx])
++ air_info->txq_idx = 0;
++}
++
+ struct ieee80211_txq *ieee80211_next_txq(struct ieee80211_hw *hw, u8 ac)
+ {
+ struct ieee80211_local *local = hw_to_local(hw);
+ struct airtime_sched_info *air_sched;
+ u64 now = ktime_get_coarse_boottime_ns();
+- struct ieee80211_txq *ret = NULL;
++ struct airtime_sched_node *node = NULL;
++ struct ieee80211_txq *txq;
+ struct airtime_info *air_info;
+ struct txq_info *txqi = NULL;
+- struct rb_node *node;
+- bool first = false;
++ u8 txq_idx;
+
+ air_sched = &local->airtime[ac];
+ spin_lock_bh(&air_sched->lock);
+
+- node = air_sched->schedule_pos;
+-
+ begin:
+- if (!node) {
+- node = rb_first_cached(&air_sched->active_txqs);
+- first = true;
+- } else {
+- node = rb_next(node);
+- }
++ txq = NULL;
++ if (airtime_sched_peek(&air_sched->active_txqs) ==
++ air_sched->schedule_pos)
++ goto out;
+
++ node = airtime_sched_dequeue(&air_sched->active_txqs);
+ if (!node)
+ goto out;
+
+- txqi = container_of(node, struct txq_info, schedule_order);
+- air_info = to_airtime_info(&txqi->txq);
++ air_info = container_of(node, struct airtime_info, schedule_order);
+
+- if (air_info->v_t > air_sched->v_t &&
+- (!first || !airtime_catchup_v_t(air_sched, air_info->v_t, now)))
+- goto out;
+-
+- if (!ieee80211_txq_airtime_check(hw, &txqi->txq)) {
+- first = false;
++ airtime_info_next_txq_idx(air_info);
++ txq_idx = air_info->txq_idx;
++ txq = air_info->txq[txq_idx];
++ if (!txq || !ieee80211_txq_airtime_check(hw, txq))
+ goto begin;
++
++ while (1) {
++ txqi = to_txq_info(txq);
++ if (test_and_clear_bit(IEEE80211_TXQ_FORCE_ACTIVE, &txqi->flags))
++ break;
++
++ if (txq_has_queue(txq))
++ break;
++
++ airtime_info_next_txq_idx(air_info);
++ txq = air_info->txq[air_info->txq_idx];
++ if (txq_idx == air_info->txq_idx)
++ goto begin;
++ }
++
++ if (air_info->v_t_cur > air_sched->v_t) {
++ if (node == airtime_sched_peek(&air_sched->active_txqs))
++ airtime_catchup_v_t(air_sched, air_info->v_t_cur, now);
+ }
+
+ air_sched->schedule_pos = node;
+ air_sched->last_schedule_activity = now;
+- ret = &txqi->txq;
+ out:
+ spin_unlock_bh(&air_sched->lock);
+- return ret;
++ return txq;
+ }
+ EXPORT_SYMBOL(ieee80211_next_txq);
+
+-static void __ieee80211_insert_txq(struct rb_root_cached *root,
++static void __ieee80211_insert_txq(struct ieee80211_local *local,
++ struct airtime_sched_info *air_sched,
+ struct txq_info *txqi)
+ {
+- struct rb_node **new = &root->rb_root.rb_node;
+- struct airtime_info *old_air, *new_air;
+- struct rb_node *parent = NULL;
+- struct txq_info *__txqi;
+- bool leftmost = true;
+-
+- while (*new) {
+- parent = *new;
+- __txqi = rb_entry(parent, struct txq_info, schedule_order);
+- old_air = to_airtime_info(&__txqi->txq);
+- new_air = to_airtime_info(&txqi->txq);
++ struct airtime_info *air_info = to_airtime_info(&txqi->txq);
++ u32 aql_time = 0;
+
+- if (new_air->v_t <= old_air->v_t) {
+- new = &parent->rb_left;
+- } else {
+- new = &parent->rb_right;
+- leftmost = false;
+- }
++ if (wiphy_ext_feature_isset(local->hw.wiphy, NL80211_EXT_FEATURE_AQL)) {
++ aql_time = atomic_read(&air_info->aql_tx_pending);
++ aql_time *= air_info->weight_reciprocal;
++ aql_time >>= IEEE80211_RECIPROCAL_SHIFT_STA - IEEE80211_WEIGHT_SHIFT;
+ }
+
+- rb_link_node(&txqi->schedule_order, parent, new);
+- rb_insert_color_cached(&txqi->schedule_order, root, leftmost);
++ airtime_sched_delete(&air_sched->active_txqs, &air_info->schedule_order);
++ air_info->v_t_cur = air_info->v_t + aql_time;
++ airtime_sched_insert(&air_sched->active_txqs, &air_info->schedule_order);
+ }
+
+ void ieee80211_resort_txq(struct ieee80211_hw *hw,
+ struct ieee80211_txq *txq)
+ {
+- struct airtime_info *air_info = to_airtime_info(txq);
+ struct ieee80211_local *local = hw_to_local(hw);
+ struct txq_info *txqi = to_txq_info(txq);
+ struct airtime_sched_info *air_sched;
+@@ -3902,41 +3927,7 @@ void ieee80211_resort_txq(struct ieee802
+ air_sched = &local->airtime[txq->ac];
+
+ lockdep_assert_held(&air_sched->lock);
+-
+- if (!RB_EMPTY_NODE(&txqi->schedule_order)) {
+- struct airtime_info *a_prev = NULL, *a_next = NULL;
+- struct txq_info *t_prev, *t_next;
+- struct rb_node *n_prev, *n_next;
+-
+- /* Erasing a node can cause an expensive rebalancing operation,
+- * so we check the previous and next nodes first and only remove
+- * and re-insert if the current node is not already in the
+- * correct position.
+- */
+- if ((n_prev = rb_prev(&txqi->schedule_order)) != NULL) {
+- t_prev = container_of(n_prev, struct txq_info,
+- schedule_order);
+- a_prev = to_airtime_info(&t_prev->txq);
+- }
+-
+- if ((n_next = rb_next(&txqi->schedule_order)) != NULL) {
+- t_next = container_of(n_next, struct txq_info,
+- schedule_order);
+- a_next = to_airtime_info(&t_next->txq);
+- }
+-
+- if ((!a_prev || a_prev->v_t <= air_info->v_t) &&
+- (!a_next || a_next->v_t > air_info->v_t))
+- return;
+-
+- if (air_sched->schedule_pos == &txqi->schedule_order)
+- air_sched->schedule_pos = n_prev;
+-
+- rb_erase_cached(&txqi->schedule_order,
+- &air_sched->active_txqs);
+- RB_CLEAR_NODE(&txqi->schedule_order);
+- __ieee80211_insert_txq(&air_sched->active_txqs, txqi);
+- }
++ __ieee80211_insert_txq(local, air_sched, txqi);
+ }
+
+ void ieee80211_update_airtime_weight(struct ieee80211_local *local,
+@@ -3985,7 +3976,7 @@ void ieee80211_schedule_txq(struct ieee8
+ was_active = airtime_is_active(air_info, now);
+ airtime_set_active(air_sched, air_info, now);
+
+- if (!RB_EMPTY_NODE(&txqi->schedule_order))
++ if (airtime_sched_is_queued(&air_info->schedule_order))
+ goto out;
+
+ /* If the station has been inactive for a while, catch up its v_t so it
+@@ -3997,7 +3988,7 @@ void ieee80211_schedule_txq(struct ieee8
+ air_info->v_t = air_sched->v_t;
+
+ ieee80211_update_airtime_weight(local, air_sched, now, !was_active);
+- __ieee80211_insert_txq(&air_sched->active_txqs, txqi);
++ __ieee80211_insert_txq(local, air_sched, txqi);
+
+ out:
+ spin_unlock_bh(&air_sched->lock);
+@@ -4023,19 +4014,10 @@ static void __ieee80211_unschedule_txq(s
+ ieee80211_update_airtime_weight(local, air_sched, 0, true);
+ }
+
+- if (RB_EMPTY_NODE(&txqi->schedule_order))
+- return;
+-
+- if (air_sched->schedule_pos == &txqi->schedule_order)
+- air_sched->schedule_pos = rb_prev(&txqi->schedule_order);
+-
++ airtime_sched_delete(&air_sched->active_txqs, &air_info->schedule_order);
+ if (!purge)
+ airtime_set_active(air_sched, air_info,
+ ktime_get_coarse_boottime_ns());
+-
+- rb_erase_cached(&txqi->schedule_order,
+- &air_sched->active_txqs);
+- RB_CLEAR_NODE(&txqi->schedule_order);
+ }
+
+ void ieee80211_unschedule_txq(struct ieee80211_hw *hw,
+@@ -4055,14 +4037,24 @@ void ieee80211_return_txq(struct ieee802
+ {
+ struct ieee80211_local *local = hw_to_local(hw);
+ struct txq_info *txqi = to_txq_info(txq);
++ struct airtime_sched_info *air_sched;
++ struct airtime_info *air_info;
+
+- spin_lock_bh(&local->airtime[txq->ac].lock);
++ air_sched = &local->airtime[txq->ac];
++ air_info = to_airtime_info(&txqi->txq);
+
+- if (!RB_EMPTY_NODE(&txqi->schedule_order) && !force &&
+- !txq_has_queue(txq))
+- __ieee80211_unschedule_txq(hw, txq, false);
++ if (force)
++ set_bit(IEEE80211_TXQ_FORCE_ACTIVE, &txqi->flags);
+
+- spin_unlock_bh(&local->airtime[txq->ac].lock);
++ spin_lock_bh(&air_sched->lock);
++ if (!ieee80211_txq_airtime_check(hw, &txqi->txq))
++ airtime_sched_delete(&air_sched->active_txqs,
++ &air_info->schedule_order);
++ else if (txq_has_queue(txq) || force)
++ __ieee80211_insert_txq(local, air_sched, txqi);
++ else
++ __ieee80211_unschedule_txq(hw, txq, false);
++ spin_unlock_bh(&air_sched->lock);
+ }
+ EXPORT_SYMBOL(ieee80211_return_txq);
+
+@@ -4101,46 +4093,48 @@ EXPORT_SYMBOL(ieee80211_txq_airtime_chec
+ bool ieee80211_txq_may_transmit(struct ieee80211_hw *hw,
+ struct ieee80211_txq *txq)
+ {
+- struct txq_info *first_txqi = NULL, *txqi = to_txq_info(txq);
++ struct txq_info *txqi = to_txq_info(txq);
+ struct ieee80211_local *local = hw_to_local(hw);
+ struct airtime_sched_info *air_sched;
++ struct airtime_sched_node *node = NULL;
+ struct airtime_info *air_info;
+- struct rb_node *node = NULL;
+ bool ret = false;
++ u32 aql_slack;
+ u64 now;
+
+-
+ if (!ieee80211_txq_airtime_check(hw, txq))
+ return false;
+
+ air_sched = &local->airtime[txq->ac];
+ spin_lock_bh(&air_sched->lock);
+
+- if (RB_EMPTY_NODE(&txqi->schedule_order))
+- goto out;
+-
+ now = ktime_get_coarse_boottime_ns();
+
+ /* Like in ieee80211_next_txq(), make sure the first station in the
+ * scheduling order is eligible for transmission to avoid starvation.
+ */
+- node = rb_first_cached(&air_sched->active_txqs);
++ node = airtime_sched_peek(&air_sched->active_txqs);
+ if (node) {
+- first_txqi = container_of(node, struct txq_info,
+- schedule_order);
+- air_info = to_airtime_info(&first_txqi->txq);
++ air_info = container_of(node, struct airtime_info,
++ schedule_order);
+
+ if (air_sched->v_t < air_info->v_t)
+ airtime_catchup_v_t(air_sched, air_info->v_t, now);
+ }
+
+ air_info = to_airtime_info(&txqi->txq);
+- if (air_info->v_t <= air_sched->v_t) {
++ aql_slack = air_info->aql_limit_low;
++ aql_slack *= air_info->weight_reciprocal;
++ aql_slack >>= IEEE80211_RECIPROCAL_SHIFT_STA - IEEE80211_WEIGHT_SHIFT;
++ /*
++ * add extra slack of aql_limit_low in order to avoid queue
++ * starvation when bypassing normal scheduling order
++ */
++ if (air_info->v_t <= air_sched->v_t + aql_slack) {
+ air_sched->last_schedule_activity = now;
+ ret = true;
+ }
+
+-out:
+ spin_unlock_bh(&air_sched->lock);
+ return ret;
+ }
+@@ -4151,9 +4145,7 @@ void ieee80211_txq_schedule_start(struct
+ struct ieee80211_local *local = hw_to_local(hw);
+ struct airtime_sched_info *air_sched = &local->airtime[ac];
+
+- spin_lock_bh(&air_sched->lock);
+ air_sched->schedule_pos = NULL;
+- spin_unlock_bh(&air_sched->lock);
+ }
+ EXPORT_SYMBOL(ieee80211_txq_schedule_start);
+
projects / openwrt / staging / lynxis.git / commitdiff