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, 28 insertions, 9 deletions

diff --git a/net/mac80211/mesh_hwmp.c b/net/mac80211/mesh_hwmp.c
index 9b1ce7c3925a..5217e1d97dd6 100644
--- a/net/mac80211/mesh_hwmp.c
+++ b/net/mac80211/mesh_hwmp.c
@@ -394,6 +394,7 @@ static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
 	u32 orig_sn, orig_metric;
 	unsigned long orig_lifetime, exp_time;
 	u32 last_hop_metric, new_metric;
+	bool flush_mpath = false;
 	bool process = true;
 	u8 hopcount;
 
@@ -491,8 +492,10 @@ static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
 		}
 
 		if (fresh_info) {
-			if (rcu_access_pointer(mpath->next_hop) != sta)
+			if (rcu_access_pointer(mpath->next_hop) != sta) {
 				mpath->path_change_count++;
+				flush_mpath = true;
+			}
 			mesh_path_assign_nexthop(mpath, sta);
 			mpath->flags |= MESH_PATH_SN_VALID;
 			mpath->metric = new_metric;
@@ -502,6 +505,8 @@ static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
 			mpath->hop_count = hopcount;
 			mesh_path_activate(mpath);
 			spin_unlock_bh(&mpath->state_lock);
+			if (flush_mpath)
+				mesh_fast_tx_flush_mpath(mpath);
 			ewma_mesh_fail_avg_init(&sta->mesh->fail_avg);
 			/* init it at a low value - 0 start is tricky */
 			ewma_mesh_fail_avg_add(&sta->mesh->fail_avg, 1);
@@ -539,8 +544,10 @@ static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
 		}
 
 		if (fresh_info) {
-			if (rcu_access_pointer(mpath->next_hop) != sta)
+			if (rcu_access_pointer(mpath->next_hop) != sta) {
 				mpath->path_change_count++;
+				flush_mpath = true;
+			}
 			mesh_path_assign_nexthop(mpath, sta);
 			mpath->metric = last_hop_metric;
 			mpath->exp_time = time_after(mpath->exp_time, exp_time)
@@ -548,6 +555,8 @@ static u32 hwmp_route_info_get(struct ieee80211_sub_if_data *sdata,
 			mpath->hop_count = 1;
 			mesh_path_activate(mpath);
 			spin_unlock_bh(&mpath->state_lock);
+			if (flush_mpath)
+				mesh_fast_tx_flush_mpath(mpath);
 			ewma_mesh_fail_avg_init(&sta->mesh->fail_avg);
 			/* init it at a low value - 0 start is tricky */
 			ewma_mesh_fail_avg_add(&sta->mesh->fail_avg, 1);
@@ -1215,6 +1224,20 @@ static int mesh_nexthop_lookup_nolearn(struct ieee80211_sub_if_data *sdata,
 	return 0;
 }
 
+void mesh_path_refresh(struct ieee80211_sub_if_data *sdata,
+		       struct mesh_path *mpath, const u8 *addr)
+{
+	if (mpath->flags & (MESH_PATH_REQ_QUEUED | MESH_PATH_FIXED |
+			    MESH_PATH_RESOLVING))
+		return;
+
+	if (time_after(jiffies,
+		       mpath->exp_time -
+		       msecs_to_jiffies(sdata->u.mesh.mshcfg.path_refresh_time)) &&
+	    (!addr || ether_addr_equal(sdata->vif.addr, addr)))
+		mesh_queue_preq(mpath, PREQ_Q_F_START | PREQ_Q_F_REFRESH);
+}
+
 /**
  * mesh_nexthop_lookup - put the appropriate next hop on a mesh frame. Calling
  * this function is considered "using" the associated mpath, so preempt a path
@@ -1242,19 +1265,15 @@ int mesh_nexthop_lookup(struct ieee80211_sub_if_data *sdata,
 	if (!mpath || !(mpath->flags & MESH_PATH_ACTIVE))
 		return -ENOENT;
 
-	if (time_after(jiffies,
-		       mpath->exp_time -
-		       msecs_to_jiffies(sdata->u.mesh.mshcfg.path_refresh_time)) &&
-	    ether_addr_equal(sdata->vif.addr, hdr->addr4) &&
-	    !(mpath->flags & MESH_PATH_RESOLVING) &&
-	    !(mpath->flags & MESH_PATH_FIXED))
-		mesh_queue_preq(mpath, PREQ_Q_F_START | PREQ_Q_F_REFRESH);
+	mesh_path_refresh(sdata, mpath, hdr->addr4);
 
 	next_hop = rcu_dereference(mpath->next_hop);
 	if (next_hop) {
 		memcpy(hdr->addr1, next_hop->sta.addr, ETH_ALEN);
 		memcpy(hdr->addr2, sdata->vif.addr, ETH_ALEN);
 		ieee80211_mps_set_frame_flags(sdata, next_hop, hdr);
+		if (ieee80211_hw_check(&sdata->local->hw, SUPPORT_FAST_XMIT))
+			mesh_fast_tx_cache(sdata, skb, mpath);
 		return 0;
 	}