mac80211: cache mesh beacon

Previously, the entire mesh beacon would be generated each
time the beacon timer fired. Instead generate a beacon
head and tail (so the TIM can easily be inserted when mesh
power save is on) when starting a mesh or the MBSS
parameters change.

Also add a mutex for protecting beacon updates and
preventing leaks.

Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

6 files changed, 171 insertions, 65 deletions

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index c3869ba42343..0800fb331ce5 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1800,11 +1800,10 @@ static int ieee80211_update_mesh_config(struct wiphy *wiphy,
                 conf->power_mode = nconf->power_mode;
                 ieee80211_mps_local_status_update(sdata);
         }
-        if (_chg_mesh_attr(NL80211_MESHCONF_AWAKE_WINDOW, mask)) {
+        if (_chg_mesh_attr(NL80211_MESHCONF_AWAKE_WINDOW, mask))
                 conf->dot11MeshAwakeWindowDuration =
                         nconf->dot11MeshAwakeWindowDuration;
-                ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON);
-        }
+        ieee80211_mbss_info_change_notify(sdata, BSS_CHANGED_BEACON);
         return 0;
 }
 
@@ -1830,9 +1829,7 @@ static int ieee80211_join_mesh(struct wiphy *wiphy, struct net_device *dev,
         if (err)
                 return err;
 
-        ieee80211_start_mesh(sdata);
-
-        return 0;
+        return ieee80211_start_mesh(sdata);
 }
 
 static int ieee80211_leave_mesh(struct wiphy *wiphy, struct net_device *dev)
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index d702f7dc321b..388580a1bada 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -580,6 +580,9 @@ struct ieee80211_if_mesh {
         u32 mesh_seqnum;
         bool accepting_plinks;
         int num_gates;
+        struct beacon_data __rcu *beacon;
+        /* just protects beacon updates for now */
+        struct mutex mtx;
         const u8 *ie;
         u8 ie_len;
         enum {
diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
index 0adec3d539d3..6ff8ee9d9ff5 100644
--- a/net/mac80211/mesh.c
+++ b/net/mac80211/mesh.c
@@ -171,7 +171,7 @@ void mesh_sta_cleanup(struct sta_info *sta)
         }
 
         if (changed)
-                ieee80211_bss_info_change_notify(sdata, changed);
+                ieee80211_mbss_info_change_notify(sdata, changed);
 }
 
 int mesh_rmc_init(struct ieee80211_sub_if_data *sdata)
@@ -593,7 +593,7 @@ static void ieee80211_mesh_housekeeping(struct ieee80211_sub_if_data *sdata,
         mesh_path_expire(sdata);
 
         changed = mesh_accept_plinks_update(sdata);
-        ieee80211_bss_info_change_notify(sdata, changed);
+        ieee80211_mbss_info_change_notify(sdata, changed);
 
         mod_timer(&ifmsh->housekeeping_timer,
                   round_jiffies(jiffies + IEEE80211_MESH_HOUSEKEEPING_INTERVAL));
@@ -644,7 +644,140 @@ void ieee80211_mesh_restart(struct ieee80211_sub_if_data *sdata)
 }
 #endif
 
-void ieee80211_start_mesh(struct ieee80211_sub_if_data *sdata)
+static int
+ieee80211_mesh_build_beacon(struct ieee80211_if_mesh *ifmsh)
+{
+        struct beacon_data *bcn;
+        int head_len, tail_len;
+        struct sk_buff *skb;
+        struct ieee80211_mgmt *mgmt;
+        struct ieee80211_chanctx_conf *chanctx_conf;
+        enum ieee80211_band band;
+        u8 *pos;
+        struct ieee80211_sub_if_data *sdata;
+        int hdr_len = offsetof(struct ieee80211_mgmt, u.beacon) +
+                      sizeof(mgmt->u.beacon);
+
+        sdata = container_of(ifmsh, struct ieee80211_sub_if_data, u.mesh);
+        rcu_read_lock();
+        chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
+        band = chanctx_conf->def.chan->band;
+        rcu_read_unlock();
+
+        head_len = hdr_len +
+                   2 + /* NULL SSID */
+                   2 + 8 + /* supported rates */
+                   2 + 3; /* DS params */
+        tail_len = 2 + (IEEE80211_MAX_SUPP_RATES - 8) +
+                   2 + sizeof(struct ieee80211_ht_cap) +
+                   2 + sizeof(struct ieee80211_ht_operation) +
+                   2 + ifmsh->mesh_id_len +
+                   2 + sizeof(struct ieee80211_meshconf_ie) +
+                   2 + sizeof(__le16) + /* awake window */
+                   ifmsh->ie_len;
+
+        bcn = kzalloc(sizeof(*bcn) + head_len + tail_len, GFP_KERNEL);
+        /* need an skb for IE builders to operate on */
+        skb = dev_alloc_skb(max(head_len, tail_len));
+
+        if (!bcn || !skb)
+                goto out_free;
+
+        /*
+         * pointers go into the block we allocated,
+         * memory is | beacon_data | head | tail |
+         */
+        bcn->head = ((u8 *) bcn) + sizeof(*bcn);
+
+        /* fill in the head */
+        mgmt = (struct ieee80211_mgmt *) skb_put(skb, hdr_len);
+        memset(mgmt, 0, hdr_len);
+        mgmt->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
+                                          IEEE80211_STYPE_BEACON);
+        eth_broadcast_addr(mgmt->da);
+        memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
+        memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
+        ieee80211_mps_set_frame_flags(sdata, NULL, (void *) mgmt);
+        mgmt->u.beacon.beacon_int =
+                cpu_to_le16(sdata->vif.bss_conf.beacon_int);
+        mgmt->u.beacon.capab_info |= cpu_to_le16(
+                sdata->u.mesh.security ? WLAN_CAPABILITY_PRIVACY : 0);
+
+        pos = skb_put(skb, 2);
+        *pos++ = WLAN_EID_SSID;
+        *pos++ = 0x0;
+
+        if (ieee80211_add_srates_ie(sdata, skb, true, band) ||
+            mesh_add_ds_params_ie(skb, sdata))
+                goto out_free;
+
+        bcn->head_len = skb->len;
+        memcpy(bcn->head, skb->data, bcn->head_len);
+
+        /* now the tail */
+        skb_trim(skb, 0);
+        bcn->tail = bcn->head + bcn->head_len;
+
+        if (ieee80211_add_ext_srates_ie(sdata, skb, true, band) ||
+            mesh_add_rsn_ie(skb, sdata) ||
+            mesh_add_ht_cap_ie(skb, sdata) ||
+            mesh_add_ht_oper_ie(skb, sdata) ||
+            mesh_add_meshid_ie(skb, sdata) ||
+            mesh_add_meshconf_ie(skb, sdata) ||
+            mesh_add_awake_window_ie(skb, sdata) ||
+            mesh_add_vendor_ies(skb, sdata))
+                goto out_free;
+
+        bcn->tail_len = skb->len;
+        memcpy(bcn->tail, skb->data, bcn->tail_len);
+
+        dev_kfree_skb(skb);
+        rcu_assign_pointer(ifmsh->beacon, bcn);
+        return 0;
+out_free:
+        kfree(bcn);
+        dev_kfree_skb(skb);
+        return -ENOMEM;
+}
+
+static int
+ieee80211_mesh_rebuild_beacon(struct ieee80211_if_mesh *ifmsh)
+{
+        struct ieee80211_sub_if_data *sdata;
+        struct beacon_data *old_bcn;
+        int ret;
+        sdata = container_of(ifmsh, struct ieee80211_sub_if_data, u.mesh);
+
+        mutex_lock(&ifmsh->mtx);
+
+        old_bcn = rcu_dereference_protected(ifmsh->beacon,
+                                            lockdep_is_held(&ifmsh->mtx));
+        ret = ieee80211_mesh_build_beacon(ifmsh);
+        if (ret)
+                /* just reuse old beacon */
+                goto out;
+
+        if (old_bcn)
+                kfree_rcu(old_bcn, rcu_head);
+out:
+        mutex_unlock(&ifmsh->mtx);
+        return ret;
+}
+
+void ieee80211_mbss_info_change_notify(struct ieee80211_sub_if_data *sdata,
+                                       u32 changed)
+{
+        if (sdata->vif.bss_conf.enable_beacon &&
+            (changed & (BSS_CHANGED_BEACON |
+                        BSS_CHANGED_HT |
+                        BSS_CHANGED_BASIC_RATES |
+                        BSS_CHANGED_BEACON_INT)))
+                if (ieee80211_mesh_rebuild_beacon(&sdata->u.mesh))
+                        return;
+        ieee80211_bss_info_change_notify(sdata, changed);
+}
+
+int ieee80211_start_mesh(struct ieee80211_sub_if_data *sdata)
 {
         struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
         struct ieee80211_local *local = sdata->local;
@@ -677,15 +810,22 @@ void ieee80211_start_mesh(struct ieee80211_sub_if_data *sdata)
 
         changed |= ieee80211_mps_local_status_update(sdata);
 
+        if (ieee80211_mesh_build_beacon(ifmsh)) {
+                ieee80211_stop_mesh(sdata);
+                return -ENOMEM;
+        }
+
         ieee80211_bss_info_change_notify(sdata, changed);
 
         netif_carrier_on(sdata->dev);
+        return 0;
 }
 
 void ieee80211_stop_mesh(struct ieee80211_sub_if_data *sdata)
 {
         struct ieee80211_local *local = sdata->local;
         struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+        struct beacon_data *bcn;
 
         netif_carrier_off(sdata->dev);
 
@@ -694,6 +834,12 @@ void ieee80211_stop_mesh(struct ieee80211_sub_if_data *sdata)
         sdata->vif.bss_conf.enable_beacon = false;
         clear_bit(SDATA_STATE_OFFCHANNEL_BEACON_STOPPED, &sdata->state);
         ieee80211_bss_info_change_notify(sdata, BSS_CHANGED_BEACON_ENABLED);
+        mutex_lock(&ifmsh->mtx);
+        bcn = rcu_dereference_protected(ifmsh->beacon,
+                                        lockdep_is_held(&ifmsh->mtx));
+        rcu_assign_pointer(ifmsh->beacon, NULL);
+        kfree_rcu(bcn, rcu_head);
+        mutex_unlock(&ifmsh->mtx);
 
         /* flush STAs and mpaths on this iface */
         sta_info_flush(sdata);
@@ -883,6 +1029,8 @@ void ieee80211_mesh_init_sdata(struct ieee80211_sub_if_data *sdata)
         skb_queue_head_init(&ifmsh->ps.bc_buf);
         spin_lock_init(&ifmsh->mesh_preq_queue_lock);
         spin_lock_init(&ifmsh->sync_offset_lock);
+        RCU_INIT_POINTER(ifmsh->beacon, NULL);
+        mutex_init(&ifmsh->mtx);
 
         sdata->vif.bss_conf.bssid = zero_addr;
 }
diff --git a/net/mac80211/mesh.h b/net/mac80211/mesh.h
index a1bad310f2e9..1a1da877b1d2 100644
--- a/net/mac80211/mesh.h
+++ b/net/mac80211/mesh.h
@@ -239,10 +239,13 @@ void ieee80211s_update_metric(struct ieee80211_local *local,
                 struct sta_info *sta, struct sk_buff *skb);
 void ieee80211s_stop(void);
 void ieee80211_mesh_init_sdata(struct ieee80211_sub_if_data *sdata);
-void ieee80211_start_mesh(struct ieee80211_sub_if_data *sdata);
+int ieee80211_start_mesh(struct ieee80211_sub_if_data *sdata);
 void ieee80211_stop_mesh(struct ieee80211_sub_if_data *sdata);
 void ieee80211_mesh_root_setup(struct ieee80211_if_mesh *ifmsh);
 const struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method);
+/* wrapper for ieee80211_bss_info_change_notify() */
+void ieee80211_mbss_info_change_notify(struct ieee80211_sub_if_data *sdata,
+                                       u32 changed);
 
 /* mesh power save */
 u32 ieee80211_mps_local_status_update(struct ieee80211_sub_if_data *sdata);
diff --git a/net/mac80211/mesh_plink.c b/net/mac80211/mesh_plink.c
index 7765139b24aa..f7526e509aa8 100644
--- a/net/mac80211/mesh_plink.c
+++ b/net/mac80211/mesh_plink.c
@@ -508,7 +508,7 @@ void mesh_neighbour_update(struct ieee80211_sub_if_data *sdata,
         ieee80211_mps_frame_release(sta, elems);
 out:
         rcu_read_unlock();
-        ieee80211_bss_info_change_notify(sdata, changed);
+        ieee80211_mbss_info_change_notify(sdata, changed);
 }
 
 static void mesh_plink_timer(unsigned long data)
@@ -1090,5 +1090,5 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata, struct ieee80211_m
         rcu_read_unlock();
 
         if (changed)
-                ieee80211_bss_info_change_notify(sdata, changed);
+                ieee80211_mbss_info_change_notify(sdata, changed);
 }
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 7d8c629f1e6a..fe644f91ae05 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -2444,71 +2444,26 @@ struct sk_buff *ieee80211_beacon_get_tim(struct ieee80211_hw *hw,
                 hdr->frame_control = cpu_to_le16(IEEE80211_FTYPE_MGMT |
                                                  IEEE80211_STYPE_BEACON);
         } else if (ieee80211_vif_is_mesh(&sdata->vif)) {
-                struct ieee80211_mgmt *mgmt;
                 struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
-                u8 *pos;
-                int hdr_len = offsetof(struct ieee80211_mgmt, u.beacon) +
-                              sizeof(mgmt->u.beacon);
+                struct beacon_data *bcn = rcu_dereference(ifmsh->beacon);
 
-#ifdef CONFIG_MAC80211_MESH
-                if (!sdata->u.mesh.mesh_id_len)
+                if (!bcn)
                         goto out;
-#endif
 
                 if (ifmsh->sync_ops)
                         ifmsh->sync_ops->adjust_tbtt(
                                                 sdata);
 
                 skb = dev_alloc_skb(local->tx_headroom +
-                                    hdr_len +
-                                    2 + /* NULL SSID */
-                                    2 + 8 + /* supported rates */
-                                    2 + 3 + /* DS params */
+                                    bcn->head_len +
                                     256 + /* TIM IE */
-                                    2 + (IEEE80211_MAX_SUPP_RATES - 8) +
-                                    2 + sizeof(struct ieee80211_ht_cap) +
-                                    2 + sizeof(struct ieee80211_ht_operation) +
-                                    2 + sdata->u.mesh.mesh_id_len +
-                                    2 + sizeof(struct ieee80211_meshconf_ie) +
-                                    sdata->u.mesh.ie_len +
-                                    2 + sizeof(__le16)); /* awake window */
+                                    bcn->tail_len);
                 if (!skb)
                         goto out;
-
-                skb_reserve(skb, local->hw.extra_tx_headroom);
-                mgmt = (struct ieee80211_mgmt *) skb_put(skb, hdr_len);
-                memset(mgmt, 0, hdr_len);
-                mgmt->frame_control =
-                    cpu_to_le16(IEEE80211_FTYPE_MGMT | IEEE80211_STYPE_BEACON);
-                eth_broadcast_addr(mgmt->da);
-                memcpy(mgmt->sa, sdata->vif.addr, ETH_ALEN);
-                memcpy(mgmt->bssid, sdata->vif.addr, ETH_ALEN);
-                ieee80211_mps_set_frame_flags(sdata, NULL, (void *) mgmt);
-                mgmt->u.beacon.beacon_int =
-                        cpu_to_le16(sdata->vif.bss_conf.beacon_int);
-                mgmt->u.beacon.capab_info |= cpu_to_le16(
-                        sdata->u.mesh.security ? WLAN_CAPABILITY_PRIVACY : 0);
-
-                pos = skb_put(skb, 2);
-                *pos++ = WLAN_EID_SSID;
-                *pos++ = 0x0;
-
-                band = chanctx_conf->def.chan->band;
-
-                if (ieee80211_add_srates_ie(sdata, skb, true, band) ||
-                    mesh_add_ds_params_ie(skb, sdata) ||
-                    ieee80211_beacon_add_tim(sdata, &ifmsh->ps, skb) ||
-                    ieee80211_add_ext_srates_ie(sdata, skb, true, band) ||
-                    mesh_add_rsn_ie(skb, sdata) ||
-                    mesh_add_ht_cap_ie(skb, sdata) ||
-                    mesh_add_ht_oper_ie(skb, sdata) ||
-                    mesh_add_meshid_ie(skb, sdata) ||
-                    mesh_add_meshconf_ie(skb, sdata) ||
-                    mesh_add_awake_window_ie(skb, sdata) ||
-                    mesh_add_vendor_ies(skb, sdata)) {
-                        pr_err("o11s: couldn't add ies!\n");
-                        goto out;
-                }
+                skb_reserve(skb, local->tx_headroom);
+                memcpy(skb_put(skb, bcn->head_len), bcn->head, bcn->head_len);
+                ieee80211_beacon_add_tim(sdata, &ifmsh->ps, skb);
+                memcpy(skb_put(skb, bcn->tail_len), bcn->tail, bcn->tail_len);
         } else {
                 WARN_ON(1);
                 goto out;