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, 92 insertions, 0 deletions

diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
index 0608ed415831..6b94cf2a4046 100644
--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -10,6 +10,7 @@
 #include <asm/unaligned.h>
 #include "ieee80211_i.h"
 #include "mesh.h"
+#include "wme.h"
 #include "driver-ops.h"
 
 static int mesh_allocated;
@@ -698,6 +699,95 @@ ieee80211_mesh_update_bss_params(struct ieee80211_sub_if_data *sdata,
 			__le32_to_cpu(he_oper->he_oper_params);
 }
 
+bool ieee80211_mesh_xmit_fast(struct ieee80211_sub_if_data *sdata,
+			      struct sk_buff *skb, u32 ctrl_flags)
+{
+	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+	struct ieee80211_mesh_fast_tx *entry;
+	struct ieee80211s_hdr *meshhdr;
+	u8 sa[ETH_ALEN] __aligned(2);
+	struct tid_ampdu_tx *tid_tx;
+	struct sta_info *sta;
+	bool copy_sa = false;
+	u16 ethertype;
+	u8 tid;
+
+	if (ctrl_flags & IEEE80211_TX_CTRL_SKIP_MPATH_LOOKUP)
+		return false;
+
+	if (ifmsh->mshcfg.dot11MeshNolearn)
+		return false;
+
+	/* Add support for these cases later */
+	if (ifmsh->ps_peers_light_sleep || ifmsh->ps_peers_deep_sleep)
+		return false;
+
+	if (is_multicast_ether_addr(skb->data))
+		return false;
+
+	ethertype = (skb->data[12] << 8) | skb->data[13];
+	if (ethertype < ETH_P_802_3_MIN)
+		return false;
+
+	if (skb->sk && skb_shinfo(skb)->tx_flags & SKBTX_WIFI_STATUS)
+		return false;
+
+	if (skb->ip_summed == CHECKSUM_PARTIAL) {
+		skb_set_transport_header(skb, skb_checksum_start_offset(skb));
+		if (skb_checksum_help(skb))
+			return false;
+	}
+
+	entry = mesh_fast_tx_get(sdata, skb->data);
+	if (!entry)
+		return false;
+
+	if (skb_headroom(skb) < entry->hdrlen + entry->fast_tx.hdr_len)
+		return false;
+
+	sta = rcu_dereference(entry->mpath->next_hop);
+	if (!sta)
+		return false;
+
+	tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;
+	tid_tx = rcu_dereference(sta->ampdu_mlme.tid_tx[tid]);
+	if (tid_tx) {
+		if (!test_bit(HT_AGG_STATE_OPERATIONAL, &tid_tx->state))
+			return false;
+		if (tid_tx->timeout)
+			tid_tx->last_tx = jiffies;
+	}
+
+	skb = skb_share_check(skb, GFP_ATOMIC);
+	if (!skb)
+		return true;
+
+	skb_set_queue_mapping(skb, ieee80211_select_queue(sdata, sta, skb));
+
+	meshhdr = (struct ieee80211s_hdr *)entry->hdr;
+	if ((meshhdr->flags & MESH_FLAGS_AE) == MESH_FLAGS_AE_A5_A6) {
+		/* preserve SA from eth header for 6-addr frames */
+		ether_addr_copy(sa, skb->data + ETH_ALEN);
+		copy_sa = true;
+	}
+
+	memcpy(skb_push(skb, entry->hdrlen - 2 * ETH_ALEN), entry->hdr,
+	       entry->hdrlen);
+
+	meshhdr = (struct ieee80211s_hdr *)skb->data;
+	put_unaligned_le32(atomic_inc_return(&sdata->u.mesh.mesh_seqnum),
+			   &meshhdr->seqnum);
+	meshhdr->ttl = sdata->u.mesh.mshcfg.dot11MeshTTL;
+	if (copy_sa)
+	    ether_addr_copy(meshhdr->eaddr2, sa);
+
+	skb_push(skb, 2 * ETH_ALEN);
+	__ieee80211_xmit_fast(sdata, sta, &entry->fast_tx, skb, tid_tx,
+			      entry->mpath->dst, sdata->vif.addr);
+
+	return true;
+}
+
 /**
  * ieee80211_fill_mesh_addresses - fill addresses of a locally originated mesh frame
  * @hdr:	802.11 frame header
@@ -780,6 +870,8 @@ static void ieee80211_mesh_housekeeping(struct ieee80211_sub_if_data *sdata)
 	changed = mesh_accept_plinks_update(sdata);
 	ieee80211_mbss_info_change_notify(sdata, changed);
 
+	mesh_fast_tx_gc(sdata);
+
 	mod_timer(&ifmsh->housekeeping_timer,
 		  round_jiffies(jiffies +
 				IEEE80211_MESH_HOUSEKEEPING_INTERVAL));