wifi: mac80211: mesh fast xmit support

Previously, fast xmit only worked on interface types where initially a
sta lookup is performed, and a cached header can be attached to the sta,
requiring only some fields to be updated at runtime.

This technique is not directly applicable for a mesh device type due
to the dynamic nature of the topology and protocol. There are more
addresses that need to be filled, and there is an extra header with a
dynamic length based on the addressing mode.

Change the code to cache entries contain a copy of the mesh subframe header +
bridge tunnel header, as well as an embedded struct ieee80211_fast_tx, which
contains the information for building the 802.11 header.

Add a mesh specific early fast xmit call, which looks up a cached entry and
adds only the mesh subframe header, before passing it over to the generic
fast xmit code.

To ensure the changes in network are reflected in these cached headers,
flush affected cached entries on path changes, as well as other conditions
that currently trigger a fast xmit check in other modes (key changes etc.)

This code is loosely based on a previous implementation by:
Sriram R <quic_srirrama@quicinc.com>

Cc: Sriram R <quic_srirrama@quicinc.com>
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20230314095956.62085-4-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 32 insertions, 15 deletions

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 628d60f3db2a..ad6193693363 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -3019,6 +3019,9 @@ void ieee80211_check_fast_xmit(struct sta_info *sta)
 	if (!ieee80211_hw_check(&local->hw, SUPPORT_FAST_XMIT))
 		return;
 
+	if (ieee80211_vif_is_mesh(&sdata->vif))
+		mesh_fast_tx_flush_sta(sdata, sta);
+
 	/* Locking here protects both the pointer itself, and against concurrent
 	 * invocations winning data access races to, e.g., the key pointer that
 	 * is used.
@@ -3371,7 +3374,8 @@ static bool ieee80211_amsdu_prepare_head(struct ieee80211_sub_if_data *sdata,
 static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata,
 				      struct sta_info *sta,
 				      struct ieee80211_fast_tx *fast_tx,
-				      struct sk_buff *skb)
+				      struct sk_buff *skb,
+				      const u8 *da, const u8 *sa)
 {
 	struct ieee80211_local *local = sdata->local;
 	struct fq *fq = &local->fq;
@@ -3400,6 +3404,9 @@ static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata,
 	if (sdata->vif.offload_flags & IEEE80211_OFFLOAD_ENCAP_ENABLED)
 		return false;
 
+	if (ieee80211_vif_is_mesh(&sdata->vif))
+		return false;
+
 	if (skb_is_gso(skb))
 		return false;
 
@@ -3484,7 +3491,8 @@ static bool ieee80211_amsdu_aggregate(struct ieee80211_sub_if_data *sdata,
 
 	ret = true;
 	data = skb_push(skb, ETH_ALEN + 2);
-	memmove(data, data + ETH_ALEN + 2, 2 * ETH_ALEN);
+	ether_addr_copy(data, da);
+	ether_addr_copy(data + ETH_ALEN, sa);
 
 	data += 2 * ETH_ALEN;
 	len = cpu_to_be16(subframe_len);
@@ -3632,10 +3640,11 @@ free:
 	return NULL;
 }
 
-static void __ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
-				  struct sta_info *sta,
-				  struct ieee80211_fast_tx *fast_tx,
-				  struct sk_buff *skb, u8 tid, bool ampdu)
+void __ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
+			   struct sta_info *sta,
+			   struct ieee80211_fast_tx *fast_tx,
+			   struct sk_buff *skb, bool ampdu,
+			   const u8 *da, const u8 *sa)
 {
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_hdr *hdr = (void *)fast_tx->hdr;
@@ -3644,14 +3653,13 @@ static void __ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
 	ieee80211_tx_result r;
 	int hw_headroom = sdata->local->hw.extra_tx_headroom;
 	int extra_head = fast_tx->hdr_len - (ETH_HLEN - 2);
-	struct ethhdr eth;
 
 	skb = skb_share_check(skb, GFP_ATOMIC);
 	if (unlikely(!skb))
 		return;
 
 	if ((hdr->frame_control & cpu_to_le16(IEEE80211_STYPE_QOS_DATA)) &&
-	    ieee80211_amsdu_aggregate(sdata, sta, fast_tx, skb))
+	    ieee80211_amsdu_aggregate(sdata, sta, fast_tx, skb, da, sa))
 		return;
 
 	/* will not be crypto-handled beyond what we do here, so use false
@@ -3664,11 +3672,10 @@ static void __ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
 					  ENCRYPT_NO)))
 		goto free;
 
-	memcpy(&eth, skb->data, ETH_HLEN - 2);
 	hdr = skb_push(skb, extra_head);
 	memcpy(skb->data, fast_tx->hdr, fast_tx->hdr_len);
-	memcpy(skb->data + fast_tx->da_offs, eth.h_dest, ETH_ALEN);
-	memcpy(skb->data + fast_tx->sa_offs, eth.h_source, ETH_ALEN);
+	memcpy(skb->data + fast_tx->da_offs, da, ETH_ALEN);
+	memcpy(skb->data + fast_tx->sa_offs, sa, ETH_ALEN);
 
 	info = IEEE80211_SKB_CB(skb);
 	memset(info, 0, sizeof(*info));
@@ -3686,7 +3693,8 @@ static void __ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
 #endif
 
 	if (hdr->frame_control & cpu_to_le16(IEEE80211_STYPE_QOS_DATA)) {
-		tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;
+		u8 tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;
+
 		*ieee80211_get_qos_ctl(hdr) = tid;
 	}
 
@@ -3729,6 +3737,7 @@ static bool ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
 	struct ieee80211_hdr *hdr = (void *)fast_tx->hdr;
 	struct tid_ampdu_tx *tid_tx = NULL;
 	struct sk_buff *next;
+	struct ethhdr eth;
 	u8 tid = IEEE80211_NUM_TIDS;
 
 	/* control port protocol needs a lot of special handling */
@@ -3754,6 +3763,8 @@ static bool ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
 		}
 	}
 
+	memcpy(&eth, skb->data, ETH_HLEN - 2);
+
 	/* after this point (skb is modified) we cannot return false */
 	skb = ieee80211_tx_skb_fixup(skb, ieee80211_sdata_netdev_features(sdata));
 	if (!skb)
@@ -3761,7 +3772,8 @@ static bool ieee80211_xmit_fast(struct ieee80211_sub_if_data *sdata,
 
 	skb_list_walk_safe(skb, skb, next) {
 		skb_mark_not_on_list(skb);
-		__ieee80211_xmit_fast(sdata, sta, fast_tx, skb, tid, tid_tx);
+		__ieee80211_xmit_fast(sdata, sta, fast_tx, skb, tid_tx,
+				      eth.h_dest, eth.h_source);
 	}
 
 	return true;
@@ -4245,8 +4257,15 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
 		return;
 	}
 
+	sk_pacing_shift_update(skb->sk, sdata->local->hw.tx_sk_pacing_shift);
+
 	rcu_read_lock();
 
+	if (ieee80211_vif_is_mesh(&sdata->vif) &&
+	    ieee80211_hw_check(&local->hw, SUPPORT_FAST_XMIT) &&
+	    ieee80211_mesh_xmit_fast(sdata, skb, ctrl_flags))
+		goto out;
+
 	if (ieee80211_lookup_ra_sta(sdata, skb, &sta))
 		goto out_free;
 
@@ -4256,8 +4275,6 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
 	skb_set_queue_mapping(skb, ieee80211_select_queue(sdata, sta, skb));
 	ieee80211_aggr_check(sdata, sta, skb);
 
-	sk_pacing_shift_update(skb->sk, sdata->local->hw.tx_sk_pacing_shift);
-
 	if (sta) {
 		struct ieee80211_fast_tx *fast_tx;