mac80211: refactor ieee80211_set_qos_hdr

Return early if not a QoS Data frame.
Give proper documentation.

Signed-off-by: Marco Porsch <marco.porsch@etit.tu-chemnitz.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 23 insertions, 17 deletions

diff --git a/net/mac80211/wme.c b/net/mac80211/wme.c
index cea06e9f26f4..906f00cd6d2f 100644
--- a/net/mac80211/wme.c
+++ b/net/mac80211/wme.c
@@ -160,31 +160,37 @@ u16 ieee80211_select_queue(struct ieee80211_sub_if_data *sdata,
         return ieee80211_downgrade_queue(sdata, skb);
 }
 
+/**
+ * ieee80211_set_qos_hdr - Fill in the QoS header if there is one.
+ *
+ * @sdata: local subif
+ * @skb: packet to be updated
+ */
 void ieee80211_set_qos_hdr(struct ieee80211_sub_if_data *sdata,
                            struct sk_buff *skb)
 {
         struct ieee80211_hdr *hdr = (void *)skb->data;
         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+        u8 *p;
+        u8 ack_policy, tid;
 
-        /* Fill in the QoS header if there is one. */
-        if (ieee80211_is_data_qos(hdr->frame_control)) {
-                u8 *p = ieee80211_get_qos_ctl(hdr);
-                u8 ack_policy, tid;
-
-                tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;
+        if (!ieee80211_is_data_qos(hdr->frame_control))
+                return;
 
-                /* preserve EOSP bit */
-                ack_policy = *p & IEEE80211_QOS_CTL_EOSP;
+        p = ieee80211_get_qos_ctl(hdr);
+        tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;
 
-                if (is_multicast_ether_addr(hdr->addr1) ||
-                    sdata->noack_map & BIT(tid)) {
-                        ack_policy |= IEEE80211_QOS_CTL_ACK_POLICY_NOACK;
-                        info->flags |= IEEE80211_TX_CTL_NO_ACK;
-                }
+        /* preserve EOSP bit */
+        ack_policy = *p & IEEE80211_QOS_CTL_EOSP;
 
-                /* qos header is 2 bytes */
-                *p++ = ack_policy | tid;
-                *p = ieee80211_vif_is_mesh(&sdata->vif) ?
-                        (IEEE80211_QOS_CTL_MESH_CONTROL_PRESENT >> 8) : 0;
+        if (is_multicast_ether_addr(hdr->addr1) ||
+            sdata->noack_map & BIT(tid)) {
+                ack_policy |= IEEE80211_QOS_CTL_ACK_POLICY_NOACK;
+                info->flags |= IEEE80211_TX_CTL_NO_ACK;
         }
+
+        /* qos header is 2 bytes */
+        *p++ = ack_policy | tid;
+        *p = ieee80211_vif_is_mesh(&sdata->vif) ?
+                (IEEE80211_QOS_CTL_MESH_CONTROL_PRESENT >> 8) : 0;
 }