diff options
Diffstat (limited to 'package/kernel/mac80211/patches/subsys/330-mac80211-fix-overflow-issues-in-airtime-fairness-cod.patch')
| -rw-r--r-- | package/kernel/mac80211/patches/subsys/330-mac80211-fix-overflow-issues-in-airtime-fairness-cod.patch | 132 |
1 files changed, 0 insertions, 132 deletions
diff --git a/package/kernel/mac80211/patches/subsys/330-mac80211-fix-overflow-issues-in-airtime-fairness-cod.patch b/package/kernel/mac80211/patches/subsys/330-mac80211-fix-overflow-issues-in-airtime-fairness-cod.patch deleted file mode 100644 index 037ab8e180..0000000000 --- a/package/kernel/mac80211/patches/subsys/330-mac80211-fix-overflow-issues-in-airtime-fairness-cod.patch +++ /dev/null @@ -1,132 +0,0 @@ -From: Felix Fietkau <nbd@nbd.name> -Date: Sat, 28 May 2022 16:44:53 +0200 -Subject: [PATCH] mac80211: fix overflow issues in airtime fairness code - -The airtime weight calculation overflows with a default weight value of 256 -whenever more than 8ms worth of airtime is reported. -Bigger weight values impose even smaller limits on maximum airtime values. -This can mess up airtime based calculations for drivers that don't report -per-PPDU airtime values, but batch up values instead. - -Fix this by reordering multiplications/shifts and by reducing unnecessary -intermediate precision (which was lost in a later stage anyway). - -The new shift value limits the maximum weight to 4096, which should be more -than enough. Any values bigger than that will be clamped to the upper limit. - -Signed-off-by: Felix Fietkau <nbd@nbd.name> ---- - ---- a/net/mac80211/ieee80211_i.h -+++ b/net/mac80211/ieee80211_i.h -@@ -1666,50 +1666,34 @@ static inline struct airtime_info *to_ai - /* 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. -- * -- * For the per-station weights (kept in airtime_info below), we use 32-bit -- * reciprocals with a devisor of 2^19. This lets us keep the multiplications and -- * divisions for the station weights as 32-bit operations at the cost of a bit -- * of rounding error for high weights; but the choice of divisor keeps rounding -- * errors <10% for weights <2^15, assuming no more than 8ms of airtime is -- * reported at a time. -- * -- * For the per-phy sum of weights the values can get higher, so we use 64-bit -- * operations for those with a 32-bit divisor, which should avoid any -- * significant rounding errors. -+ * The per-sta shift value supports weight values of 1-4096 - */ --#define IEEE80211_RECIPROCAL_DIVISOR_64 0x100000000ULL --#define IEEE80211_RECIPROCAL_SHIFT_64 32 --#define IEEE80211_RECIPROCAL_DIVISOR_32 0x80000U --#define IEEE80211_RECIPROCAL_SHIFT_32 19 -+#define IEEE80211_RECIPROCAL_SHIFT_SUM 24 -+#define IEEE80211_RECIPROCAL_SHIFT_STA 12 -+#define IEEE80211_WEIGHT_SHIFT 8 - --static inline void airtime_weight_set(struct airtime_info *air_info, u16 weight) -+static inline void airtime_weight_set(struct airtime_info *air_info, u32 weight) - { -+ weight = min_t(u32, weight, BIT(IEEE80211_RECIPROCAL_SHIFT_STA)); - if (air_info->weight == weight) - return; - - air_info->weight = weight; -- if (weight) { -- air_info->weight_reciprocal = -- IEEE80211_RECIPROCAL_DIVISOR_32 / weight; -- } else { -- air_info->weight_reciprocal = 0; -- } -+ if (weight) -+ weight = BIT(IEEE80211_RECIPROCAL_SHIFT_STA) / weight; -+ air_info->weight_reciprocal = weight; - } - - static inline void airtime_weight_sum_set(struct airtime_sched_info *air_sched, -- int weight_sum) -+ u32 weight_sum) - { - if (air_sched->weight_sum == weight_sum) - return; - - air_sched->weight_sum = weight_sum; -- if (air_sched->weight_sum) { -- air_sched->weight_sum_reciprocal = IEEE80211_RECIPROCAL_DIVISOR_64; -- do_div(air_sched->weight_sum_reciprocal, air_sched->weight_sum); -- } else { -- air_sched->weight_sum_reciprocal = 0; -- } -+ if (weight_sum) -+ weight_sum = BIT(IEEE80211_RECIPROCAL_SHIFT_SUM) / weight_sum; -+ air_sched->weight_sum_reciprocal = weight_sum; - } - - /* A problem when trying to enforce airtime fairness is that we want to divide ---- a/net/mac80211/sta_info.c -+++ b/net/mac80211/sta_info.c -@@ -1894,9 +1894,9 @@ void ieee80211_register_airtime(struct i - { - struct ieee80211_sub_if_data *sdata = vif_to_sdata(txq->vif); - struct ieee80211_local *local = sdata->local; -- u64 weight_sum, weight_sum_reciprocal; - struct airtime_sched_info *air_sched; - struct airtime_info *air_info; -+ u64 weight_sum_reciprocal; - u32 airtime = 0; - - air_sched = &local->airtime[txq->ac]; -@@ -1907,27 +1907,21 @@ void ieee80211_register_airtime(struct i - if (local->airtime_flags & AIRTIME_USE_RX) - airtime += rx_airtime; - -- /* Weights scale so the unit weight is 256 */ -- airtime <<= 8; -- - spin_lock_bh(&air_sched->lock); - - air_info->tx_airtime += tx_airtime; - air_info->rx_airtime += rx_airtime; - -- if (air_sched->weight_sum) { -- weight_sum = air_sched->weight_sum; -+ if (air_sched->weight_sum) - weight_sum_reciprocal = air_sched->weight_sum_reciprocal; -- } else { -- weight_sum = air_info->weight; -+ else - weight_sum_reciprocal = air_info->weight_reciprocal; -- } - - /* Round the calculation of global vt */ -- air_sched->v_t += (u64)((airtime + (weight_sum >> 1)) * -- weight_sum_reciprocal) >> IEEE80211_RECIPROCAL_SHIFT_64; -- air_info->v_t += (u32)((airtime + (air_info->weight >> 1)) * -- air_info->weight_reciprocal) >> IEEE80211_RECIPROCAL_SHIFT_32; -+ air_sched->v_t += ((u64)airtime * weight_sum_reciprocal) >> -+ (IEEE80211_RECIPROCAL_SHIFT_SUM - IEEE80211_WEIGHT_SHIFT); -+ air_info->v_t += (airtime * air_info->weight_reciprocal) >> -+ (IEEE80211_RECIPROCAL_SHIFT_STA - IEEE80211_WEIGHT_SHIFT); - ieee80211_resort_txq(&local->hw, txq); - - spin_unlock_bh(&air_sched->lock); |