mac80211: factor out 802.11 header building code
authorJohannes Berg <johannes.berg@intel.com>
Sun, 9 Nov 2014 16:50:10 +0000 (18:50 +0200)
committerJohannes Berg <johannes.berg@intel.com>
Wed, 19 Nov 2014 17:44:38 +0000 (18:44 +0100)
Factor out the 802.11 header building code from the xmit function
to be able to use it separately in a later commit.

While at it, fix up some documentation.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
net/mac80211/tx.c

index c4a5494..55d69fd 100644 (file)
@@ -1784,24 +1784,26 @@ static void ieee80211_tx_latency_start_msrmnt(struct ieee80211_local *local,
 }
 
 /**
- * __ieee80211_subif_start_xmit - netif start_xmit function for Ethernet-type
- * subinterfaces (wlan#, WDS, and VLAN interfaces)
- * @skb: packet to be sent
- * @dev: incoming interface
+ * ieee80211_build_hdr - build 802.11 header in the given frame
+ * @sdata: virtual interface to build the header for
+ * @skb: the skb to build the header in
  * @info_flags: skb flags to set
  *
- * On failure skb will be freed.
+ * This function takes the skb with 802.3 header and reformats the header to
+ * the appropriate IEEE 802.11 header based on which interface the packet is
+ * being transmitted on.
+ *
+ * Note that this function also takes care of the TX status request and
+ * potential unsharing of the SKB - this needs to be interleaved with the
+ * header building.
+ *
+ * The function requires the read-side RCU lock held
  *
- * This function takes in an Ethernet header and encapsulates it with suitable
- * IEEE 802.11 header based on which interface the packet is coming in. The
- * encapsulated packet will then be passed to master interface, wlan#.11, for
- * transmission (through low-level driver).
+ * Returns: the (possibly reallocated) skb or an ERR_PTR() code
  */
-void __ieee80211_subif_start_xmit(struct sk_buff *skb,
-                                 struct net_device *dev,
-                                 u32 info_flags)
+static struct sk_buff *ieee80211_build_hdr(struct ieee80211_sub_if_data *sdata,
+                                          struct sk_buff *skb, u32 info_flags)
 {
-       struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
        struct ieee80211_local *local = sdata->local;
        struct ieee80211_tx_info *info;
        int head_need;
@@ -1821,20 +1823,13 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
        struct ieee80211_chanctx_conf *chanctx_conf;
        struct ieee80211_sub_if_data *ap_sdata;
        enum ieee80211_band band;
-
-       if (unlikely(skb->len < ETH_HLEN))
-               goto fail;
+       int ret;
 
        /* convert Ethernet header to proper 802.11 header (based on
         * operation mode) */
        ethertype = (skb->data[12] << 8) | skb->data[13];
        fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA);
 
-       rcu_read_lock();
-
-       /* Measure frame arrival for Tx latency statistics calculation */
-       ieee80211_tx_latency_start_msrmnt(local, skb);
-
        switch (sdata->vif.type) {
        case NL80211_IFTYPE_AP_VLAN:
                sta = rcu_dereference(sdata->u.vlan.sta);
@@ -1852,8 +1847,10 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
                ap_sdata = container_of(sdata->bss, struct ieee80211_sub_if_data,
                                        u.ap);
                chanctx_conf = rcu_dereference(ap_sdata->vif.chanctx_conf);
-               if (!chanctx_conf)
-                       goto fail_rcu;
+               if (!chanctx_conf) {
+                       ret = -ENOTCONN;
+                       goto free;
+               }
                band = chanctx_conf->def.chan->band;
                if (sta)
                        break;
@@ -1861,8 +1858,10 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
        case NL80211_IFTYPE_AP:
                if (sdata->vif.type == NL80211_IFTYPE_AP)
                        chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
-               if (!chanctx_conf)
-                       goto fail_rcu;
+               if (!chanctx_conf) {
+                       ret = -ENOTCONN;
+                       goto free;
+               }
                fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS);
                /* DA BSSID SA */
                memcpy(hdr.addr1, skb->data, ETH_ALEN);
@@ -1949,8 +1948,10 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
 
                }
                chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
-               if (!chanctx_conf)
-                       goto fail_rcu;
+               if (!chanctx_conf) {
+                       ret = -ENOTCONN;
+                       goto free;
+               }
                band = chanctx_conf->def.chan->band;
                break;
 #endif
@@ -1980,8 +1981,10 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
                 * of a link teardown after a TDLS sta is removed due to being
                 * unreachable.
                 */
-               if (tdls_peer && !tdls_auth && !tdls_setup_frame)
-                       goto fail_rcu;
+               if (tdls_peer && !tdls_auth && !tdls_setup_frame) {
+                       ret = -EINVAL;
+                       goto free;
+               }
 
                /* send direct packets to authorized TDLS peers */
                if (tdls_peer && tdls_auth) {
@@ -2009,8 +2012,10 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
                        hdrlen = 24;
                }
                chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
-               if (!chanctx_conf)
-                       goto fail_rcu;
+               if (!chanctx_conf) {
+                       ret = -ENOTCONN;
+                       goto free;
+               }
                band = chanctx_conf->def.chan->band;
                break;
        case NL80211_IFTYPE_OCB:
@@ -2020,8 +2025,10 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
                eth_broadcast_addr(hdr.addr3);
                hdrlen = 24;
                chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
-               if (!chanctx_conf)
-                       goto fail_rcu;
+               if (!chanctx_conf) {
+                       ret = -ENOTCONN;
+                       goto free;
+               }
                band = chanctx_conf->def.chan->band;
                break;
        case NL80211_IFTYPE_ADHOC:
@@ -2031,12 +2038,15 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
                memcpy(hdr.addr3, sdata->u.ibss.bssid, ETH_ALEN);
                hdrlen = 24;
                chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
-               if (!chanctx_conf)
-                       goto fail_rcu;
+               if (!chanctx_conf) {
+                       ret = -ENOTCONN;
+                       goto free;
+               }
                band = chanctx_conf->def.chan->band;
                break;
        default:
-               goto fail_rcu;
+               ret = -EINVAL;
+               goto free;
        }
 
        /*
@@ -2074,12 +2084,13 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
                      !ether_addr_equal(sdata->vif.addr, skb->data + ETH_ALEN)))) {
 #ifdef CONFIG_MAC80211_VERBOSE_DEBUG
                net_info_ratelimited("%s: dropped frame to %pM (unauthorized port)\n",
-                                   dev->name, hdr.addr1);
+                                   sdata->name, hdr.addr1);
 #endif
 
                I802_DEBUG_INC(local->tx_handlers_drop_unauth_port);
 
-               goto fail_rcu;
+               ret = -EPERM;
+               goto free;
        }
 
        if (unlikely(!multicast && skb->sk &&
@@ -2116,8 +2127,10 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
                skb = skb_clone(skb, GFP_ATOMIC);
                kfree_skb(tmp_skb);
 
-               if (!skb)
-                       goto fail_rcu;
+               if (!skb) {
+                       ret = -ENOMEM;
+                       goto free;
+               }
        }
 
        hdr.frame_control = fc;
@@ -2166,7 +2179,7 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
                if (ieee80211_skb_resize(sdata, skb, head_need, true)) {
                        ieee80211_free_txskb(&local->hw, skb);
                        skb = NULL;
-                       goto fail_rcu;
+                       return ERR_PTR(-ENOMEM);
                }
        }
 
@@ -2200,9 +2213,6 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
        nh_pos += hdrlen;
        h_pos += hdrlen;
 
-       dev->stats.tx_packets++;
-       dev->stats.tx_bytes += skb->len;
-
        /* Update skb pointers to various headers since this modified frame
         * is going to go through Linux networking code that may potentially
         * need things like pointer to IP header. */
@@ -2213,23 +2223,53 @@ void __ieee80211_subif_start_xmit(struct sk_buff *skb,
        info = IEEE80211_SKB_CB(skb);
        memset(info, 0, sizeof(*info));
 
-       dev->trans_start = jiffies;
-
        info->flags = info_flags;
        info->ack_frame_id = info_id;
        info->band = band;
 
-       ieee80211_xmit(sdata, skb);
-       rcu_read_unlock();
+       return skb;
+ free:
+       kfree_skb(skb);
+       return ERR_PTR(ret);
+}
+
+void __ieee80211_subif_start_xmit(struct sk_buff *skb,
+                                 struct net_device *dev,
+                                 u32 info_flags)
+{
+       struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
+       struct ieee80211_local *local = sdata->local;
+
+       if (unlikely(skb->len < ETH_HLEN)) {
+               kfree_skb(skb);
+               return;
+       }
+
+       rcu_read_lock();
+
+       /* Measure frame arrival for Tx latency statistics calculation */
+       ieee80211_tx_latency_start_msrmnt(local, skb);
+
+       skb = ieee80211_build_hdr(sdata, skb, info_flags);
+       if (IS_ERR(skb))
+               goto out;
 
-       return;
+       dev->stats.tx_packets++;
+       dev->stats.tx_bytes += skb->len;
+       dev->trans_start = jiffies;
 
- fail_rcu:
+       ieee80211_xmit(sdata, skb);
+ out:
        rcu_read_unlock();
- fail:
-       dev_kfree_skb(skb);
 }
 
+/**
+ * ieee80211_subif_start_xmit - netif start_xmit function for 802.3 vifs
+ * @skb: packet to be sent
+ * @dev: incoming interface
+ *
+ * On failure skb will be freed.
+ */
 netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
                                       struct net_device *dev)
 {