[Make-wifi-fast] [PATCH v6] mac80211: Move reorder-sensitive TX handlers to after TXQ dequeue.
Toke Høiland-Jørgensen
toke at toke.dk
Fri Sep 2 09:41:04 EDT 2016
The TXQ intermediate queues can cause packet reordering when more than
one flow is active to a single station. Since some of the wifi-specific
packet handling (notably sequence number and encryption handling) is
sensitive to re-ordering, things break if they are applied before the
TXQ.
This splits up the TX handlers and fast_xmit logic into two parts: An
early part and a late part. The former is applied before TXQ enqueue,
and the latter after dequeue. The non-TXQ path just applies both parts
at once.
Because fragments shouldn't be split up or reordered, the fragmentation
handler is run after dequeue. Any fragments are then kept in the TXQ and
on subsequent dequeues they take precedence over dequeueing from the FQ
structure.
This approach avoids having to scatter special cases for when TXQ is
enabled, at the cost of making the fast_xmit and TX handler code
slightly more complex.
Signed-off-by: Toke Høiland-Jørgensen <toke at toke.dk>
---
Changes since v5:
- Move the fragmentation handler to *after* TXQ dequeue. Fragments are
kept in the TXQ for subsequent dequeues. This change also means that
the changes to make some of the handlers fragmentation aware are no
longer necessary.
- One of the TX stats updates in the fast path was done before the
enqueue step; move that to xmit_fast_finish().
- Move the rate selection handler to after dequeue, so it's run closer
to the time where the packet is actually transmitted.
include/net/mac80211.h | 2 +
net/mac80211/ieee80211_i.h | 2 +
net/mac80211/tx.c | 207 +++++++++++++++++++++++++++++++++++----------
3 files changed, 168 insertions(+), 43 deletions(-)
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index cca510a..9a6a3e9 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -715,6 +715,7 @@ enum mac80211_tx_info_flags {
* frame (PS-Poll or uAPSD).
* @IEEE80211_TX_CTRL_RATE_INJECT: This frame is injected with rate information
* @IEEE80211_TX_CTRL_AMSDU: This frame is an A-MSDU frame
+ * @IEEE80211_TX_CTRL_FAST_XMIT: This frame is going through the fast_xmit path
*
* These flags are used in tx_info->control.flags.
*/
@@ -723,6 +724,7 @@ enum mac80211_tx_control_flags {
IEEE80211_TX_CTRL_PS_RESPONSE = BIT(1),
IEEE80211_TX_CTRL_RATE_INJECT = BIT(2),
IEEE80211_TX_CTRL_AMSDU = BIT(3),
+ IEEE80211_TX_CTRL_FAST_XMIT = BIT(4),
};
/*
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index f56d342..de9991d 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -813,11 +813,13 @@ enum txq_info_flags {
* @def_flow: used as a fallback flow when a packet destined to @tin hashes to
* a fq_flow which is already owned by a different tin
* @def_cvars: codel vars for @def_flow
+ * @frags: used to keep fragments created after dequeue
*/
struct txq_info {
struct fq_tin tin;
struct fq_flow def_flow;
struct codel_vars def_cvars;
+ struct sk_buff_head frags;
unsigned long flags;
/* keep last! */
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 1d0746d..a3a4593 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -38,6 +38,12 @@
#include "wme.h"
#include "rate.h"
+static int invoke_tx_handlers_late(struct ieee80211_tx_data *tx);
+static bool ieee80211_xmit_fast_finish(struct ieee80211_sub_if_data *sdata,
+ struct sta_info *sta,
+ struct ieee80211_fast_tx *fast_tx,
+ struct sk_buff *skb, bool xmit);
+
/* misc utils */
static inline void ieee80211_tx_stats(struct net_device *dev, u32 len)
@@ -1403,6 +1409,7 @@ void ieee80211_txq_init(struct ieee80211_sub_if_data *sdata,
fq_tin_init(&txqi->tin);
fq_flow_init(&txqi->def_flow);
codel_vars_init(&txqi->def_cvars);
+ __skb_queue_head_init(&txqi->frags);
txqi->txq.vif = &sdata->vif;
@@ -1425,6 +1432,7 @@ void ieee80211_txq_purge(struct ieee80211_local *local,
struct fq_tin *tin = &txqi->tin;
fq_tin_reset(fq, tin, fq_skb_free_func);
+ ieee80211_purge_tx_queue(&local->hw, &txqi->frags);
}
int ieee80211_txq_setup_flows(struct ieee80211_local *local)
@@ -1481,33 +1489,62 @@ struct sk_buff *ieee80211_tx_dequeue(struct ieee80211_hw *hw,
{
struct ieee80211_local *local = hw_to_local(hw);
struct txq_info *txqi = container_of(txq, struct txq_info, txq);
- struct ieee80211_hdr *hdr;
struct sk_buff *skb = NULL;
struct fq *fq = &local->fq;
struct fq_tin *tin = &txqi->tin;
+ struct ieee80211_tx_info *info;
spin_lock_bh(&fq->lock);
if (test_bit(IEEE80211_TXQ_STOP, &txqi->flags))
goto out;
+ /* Make sure fragments stay together. */
+ skb = __skb_dequeue(&txqi->frags);
+ if (skb)
+ goto out;
+
+begin:
skb = fq_tin_dequeue(fq, tin, fq_tin_dequeue_func);
if (!skb)
goto out;
ieee80211_set_skb_vif(skb, txqi);
- hdr = (struct ieee80211_hdr *)skb->data;
- if (txq->sta && ieee80211_is_data_qos(hdr->frame_control)) {
+ info = IEEE80211_SKB_CB(skb);
+ if (txq->sta && info->control.flags & IEEE80211_TX_CTRL_FAST_XMIT) {
struct sta_info *sta = container_of(txq->sta, struct sta_info,
sta);
- struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+ struct ieee80211_fast_tx *fast_tx;
- hdr->seq_ctrl = ieee80211_tx_next_seq(sta, txq->tid);
- if (test_bit(IEEE80211_TXQ_AMPDU, &txqi->flags))
- info->flags |= IEEE80211_TX_CTL_AMPDU;
- else
- info->flags &= ~IEEE80211_TX_CTL_AMPDU;
+ fast_tx = rcu_dereference(sta->fast_tx);
+ if (WARN_ON(!fast_tx)) {
+ /* lost the fast_tx pointer while the packet was queued */
+ ieee80211_free_txskb(hw, skb);
+ goto begin;
+ }
+ ieee80211_xmit_fast_finish(sta->sdata, sta, fast_tx, skb, false);
+ } else {
+ struct ieee80211_tx_data tx = { };
+
+ __skb_queue_head_init(&tx.skbs);
+ tx.local = local;
+ tx.skb = skb;
+ if (txq->sta) {
+ tx.sta = container_of(txq->sta, struct sta_info, sta);
+ tx.sdata = tx.sta->sdata;
+ } else {
+ tx.sdata = vif_to_sdata(info->control.vif);
+ }
+
+
+ if (invoke_tx_handlers_late(&tx))
+ goto begin;
+
+ skb = __skb_dequeue(&tx.skbs);
+
+ if (!skb_queue_empty(&tx.skbs))
+ skb_queue_splice_tail(&tx.skbs, &txqi->frags);
}
out:
@@ -1521,6 +1558,47 @@ out:
}
EXPORT_SYMBOL(ieee80211_tx_dequeue);
+static bool ieee80211_queue_skb(struct ieee80211_local *local,
+ struct ieee80211_sub_if_data *sdata,
+ struct sta_info *sta,
+ struct sk_buff *skb)
+{
+ struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+ struct fq *fq = &local->fq;
+ struct ieee80211_vif *vif;
+ struct txq_info *txqi;
+ struct ieee80211_sta *pubsta;
+
+ if (!local->ops->wake_tx_queue ||
+ sdata->vif.type == NL80211_IFTYPE_MONITOR)
+ return false;
+
+ if (sta && sta->uploaded)
+ pubsta = &sta->sta;
+ else
+ pubsta = NULL;
+
+ if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
+ sdata = container_of(sdata->bss,
+ struct ieee80211_sub_if_data, u.ap);
+
+ vif = &sdata->vif;
+ txqi = ieee80211_get_txq(local, vif, pubsta, skb);
+
+ if (!txqi)
+ return false;
+
+ info->control.vif = vif;
+
+ spin_lock_bh(&fq->lock);
+ ieee80211_txq_enqueue(local, txqi, skb);
+ spin_unlock_bh(&fq->lock);
+
+ drv_wake_tx_queue(local, txqi);
+
+ return true;
+}
+
static bool ieee80211_tx_frags(struct ieee80211_local *local,
struct ieee80211_vif *vif,
struct ieee80211_sta *sta,
@@ -1528,9 +1606,7 @@ static bool ieee80211_tx_frags(struct ieee80211_local *local,
bool txpending)
{
struct ieee80211_tx_control control = {};
- struct fq *fq = &local->fq;
struct sk_buff *skb, *tmp;
- struct txq_info *txqi;
unsigned long flags;
skb_queue_walk_safe(skbs, skb, tmp) {
@@ -1545,21 +1621,6 @@ static bool ieee80211_tx_frags(struct ieee80211_local *local,
}
#endif
- txqi = ieee80211_get_txq(local, vif, sta, skb);
- if (txqi) {
- info->control.vif = vif;
-
- __skb_unlink(skb, skbs);
-
- spin_lock_bh(&fq->lock);
- ieee80211_txq_enqueue(local, txqi, skb);
- spin_unlock_bh(&fq->lock);
-
- drv_wake_tx_queue(local, txqi);
-
- continue;
- }
-
spin_lock_irqsave(&local->queue_stop_reason_lock, flags);
if (local->queue_stop_reasons[q] ||
(!txpending && !skb_queue_empty(&local->pending[q]))) {
@@ -1680,10 +1741,13 @@ static bool __ieee80211_tx(struct ieee80211_local *local,
/*
* Invoke TX handlers, return 0 on success and non-zero if the
* frame was dropped or queued.
+ *
+ * The handlers are split into an early and late part. The latter is everything
+ * that can be sensitive to reordering, and will be deferred to after packets
+ * are dequeued from the intermediate queues (when they are enabled).
*/
-static int invoke_tx_handlers(struct ieee80211_tx_data *tx)
+static int invoke_tx_handlers_early(struct ieee80211_tx_data *tx)
{
- struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
ieee80211_tx_result res = TX_DROP;
#define CALL_TXH(txh) \
@@ -1697,7 +1761,28 @@ static int invoke_tx_handlers(struct ieee80211_tx_data *tx)
CALL_TXH(ieee80211_tx_h_check_assoc);
CALL_TXH(ieee80211_tx_h_ps_buf);
CALL_TXH(ieee80211_tx_h_check_control_port_protocol);
- CALL_TXH(ieee80211_tx_h_select_key);
+
+ txh_done:
+ if (unlikely(res == TX_DROP)) {
+ I802_DEBUG_INC(tx->local->tx_handlers_drop);
+ if (tx->skb)
+ ieee80211_free_txskb(&tx->local->hw, tx->skb);
+ else
+ ieee80211_purge_tx_queue(&tx->local->hw, &tx->skbs);
+ return -1;
+ } else if (unlikely(res == TX_QUEUED)) {
+ I802_DEBUG_INC(tx->local->tx_handlers_queued);
+ return -1;
+ }
+
+ return 0;
+}
+
+static int invoke_tx_handlers_late(struct ieee80211_tx_data *tx)
+{
+ struct ieee80211_tx_info *info = IEEE80211_SKB_CB(tx->skb);
+ ieee80211_tx_result res = TX_DROP;
+
if (!ieee80211_hw_check(&tx->local->hw, HAS_RATE_CONTROL))
CALL_TXH(ieee80211_tx_h_rate_ctrl);
@@ -1707,6 +1792,7 @@ static int invoke_tx_handlers(struct ieee80211_tx_data *tx)
goto txh_done;
}
+ CALL_TXH(ieee80211_tx_h_select_key);
CALL_TXH(ieee80211_tx_h_michael_mic_add);
CALL_TXH(ieee80211_tx_h_sequence);
CALL_TXH(ieee80211_tx_h_fragment);
@@ -1733,6 +1819,15 @@ static int invoke_tx_handlers(struct ieee80211_tx_data *tx)
return 0;
}
+static int invoke_tx_handlers(struct ieee80211_tx_data *tx)
+{
+ int r = invoke_tx_handlers_early(tx);
+ if (r)
+ return r;
+
+ return invoke_tx_handlers_late(tx);
+}
+
bool ieee80211_tx_prepare_skb(struct ieee80211_hw *hw,
struct ieee80211_vif *vif, struct sk_buff *skb,
int band, struct ieee80211_sta **sta)
@@ -1807,7 +1902,13 @@ static bool ieee80211_tx(struct ieee80211_sub_if_data *sdata,
info->hw_queue =
sdata->vif.hw_queue[skb_get_queue_mapping(skb)];
- if (!invoke_tx_handlers(&tx))
+ if (invoke_tx_handlers_early(&tx))
+ return false;
+
+ if (ieee80211_queue_skb(local, sdata, tx.sta, tx.skb))
+ return true;
+
+ if (!invoke_tx_handlers_late(&tx))
result = __ieee80211_tx(local, &tx.skbs, led_len,
tx.sta, txpending);
@@ -3159,7 +3260,7 @@ out:
}
static bool ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
- struct net_device *dev, struct sta_info *sta,
+ struct sta_info *sta,
struct ieee80211_fast_tx *fast_tx,
struct sk_buff *skb)
{
@@ -3170,8 +3271,6 @@ static bool ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
struct ethhdr eth;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
struct ieee80211_hdr *hdr = (void *)fast_tx->hdr;
- struct ieee80211_tx_data tx;
- ieee80211_tx_result r;
struct tid_ampdu_tx *tid_tx = NULL;
u8 tid = IEEE80211_NUM_TIDS;
@@ -3210,8 +3309,6 @@ static bool ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
return true;
}
- ieee80211_tx_stats(dev, skb->len + extra_head);
-
if ((hdr->frame_control & cpu_to_le16(IEEE80211_STYPE_QOS_DATA)) &&
ieee80211_amsdu_aggregate(sdata, sta, fast_tx, skb))
return true;
@@ -3240,11 +3337,32 @@ static bool ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
info->flags = IEEE80211_TX_CTL_FIRST_FRAGMENT |
IEEE80211_TX_CTL_DONTFRAG |
(tid_tx ? IEEE80211_TX_CTL_AMPDU : 0);
+ info->control.flags = IEEE80211_TX_CTRL_FAST_XMIT;
+
+ if (ieee80211_queue_skb(local, sdata, sta, skb))
+ return true;
+
+ return ieee80211_xmit_fast_finish(sdata, sta, fast_tx, skb, true);
+}
+
+static bool ieee80211_xmit_fast_finish(struct ieee80211_sub_if_data *sdata,
+ struct sta_info *sta,
+ struct ieee80211_fast_tx *fast_tx,
+ struct sk_buff *skb, bool xmit)
+{
+ struct ieee80211_local *local = sdata->local;
+ struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+ struct ieee80211_hdr *hdr = (void *)skb->data;
+ struct ieee80211_tx_data tx;
+ ieee80211_tx_result r;
+ u8 tid = IEEE80211_NUM_TIDS;
+
+ ieee80211_tx_stats(skb->dev, skb->len);
if (hdr->frame_control & cpu_to_le16(IEEE80211_STYPE_QOS_DATA)) {
+ tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;
*ieee80211_get_qos_ctl(hdr) = tid;
- if (!sta->sta.txq[0])
- hdr->seq_ctrl = ieee80211_tx_next_seq(sta, tid);
+ hdr->seq_ctrl = ieee80211_tx_next_seq(sta, tid);
} else {
info->flags |= IEEE80211_TX_CTL_ASSIGN_SEQ;
hdr->seq_ctrl = cpu_to_le16(sdata->sequence_number);
@@ -3309,12 +3427,15 @@ static bool ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
}
}
- if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
- sdata = container_of(sdata->bss,
- struct ieee80211_sub_if_data, u.ap);
+ if (xmit) {
+ if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
+ sdata = container_of(sdata->bss,
+ struct ieee80211_sub_if_data, u.ap);
+
+ __skb_queue_tail(&tx.skbs, skb);
+ ieee80211_tx_frags(local, &sdata->vif, &sta->sta, &tx.skbs, false);
+ }
- __skb_queue_tail(&tx.skbs, skb);
- ieee80211_tx_frags(local, &sdata->vif, &sta->sta, &tx.skbs, false);
return true;
}
@@ -3342,7 +3463,7 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
fast_tx = rcu_dereference(sta->fast_tx);
if (fast_tx &&
- ieee80211_xmit_fast(sdata, dev, sta, fast_tx, skb))
+ ieee80211_xmit_fast(sdata, sta, fast_tx, skb))
goto out;
}
--
2.9.3
More information about the Make-wifi-fast
mailing list