skbuff/mac80211: introduce and use skb_put_zero()

This pattern was introduced a number of times in mac80211 just now,
and since it's present in a number of other places it makes sense
to add a little helper for it.

This just adds the helper and transforms the mac80211 code, a later
patch will transform other places.
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>

include/linux/skbuff.h

@@ -1937,6 +1937,15 @@ static inline unsigned char *__skb_put(struct sk_buff *skb, unsigned int len)
 	return tmp;
 }
 
+static inline unsigned char *skb_put_zero(struct sk_buff *skb, unsigned int len)
+{
+	unsigned char *tmp = skb_put(skb, len);
+
+	memset(tmp, 0, len);
+
+	return tmp;
+}
+
 unsigned char *skb_push(struct sk_buff *skb, unsigned int len);
 static inline unsigned char *__skb_push(struct sk_buff *skb, unsigned int len)
 {

net/mac80211/mesh.c

@@ -744,8 +744,7 @@ ieee80211_mesh_build_beacon(struct ieee80211_if_mesh *ifmsh)
 		int ie_len = 2 + sizeof(struct ieee80211_channel_sw_ie) +
 			     2 + sizeof(struct ieee80211_mesh_chansw_params_ie);
 
-		pos = skb_put(skb, ie_len);
-		memset(pos, 0, ie_len);
+		pos = skb_put_zero(skb, ie_len);
 		*pos++ = WLAN_EID_CHANNEL_SWITCH;
 		*pos++ = 3;
 		*pos++ = 0x0;
@@ -772,8 +771,7 @@ ieee80211_mesh_build_beacon(struct ieee80211_if_mesh *ifmsh)
 		switch (csa->settings.chandef.width) {
 		case NL80211_CHAN_WIDTH_40:
 			ie_len = 2 + sizeof(struct ieee80211_sec_chan_offs_ie);
-			pos = skb_put(skb, ie_len);
-			memset(pos, 0, ie_len);
+			pos = skb_put_zero(skb, ie_len);
 
 			*pos++ = WLAN_EID_SECONDARY_CHANNEL_OFFSET; /* EID */
 			*pos++ = 1;				    /* len */
@@ -789,8 +787,7 @@ ieee80211_mesh_build_beacon(struct ieee80211_if_mesh *ifmsh)
 			/* Channel Switch Wrapper + Wide Bandwidth CSA IE */
 			ie_len = 2 + 2 +
 				 sizeof(struct ieee80211_wide_bw_chansw_ie);
-			pos = skb_put(skb, ie_len);
-			memset(pos, 0, ie_len);
+			pos = skb_put_zero(skb, ie_len);
 
 			*pos++ = WLAN_EID_CHANNEL_SWITCH_WRAPPER; /* EID */
 			*pos++ = 5;				  /* len */

net/mac80211/mesh_plink.c

@@ -264,8 +264,7 @@ static int mesh_plink_frame_tx(struct ieee80211_sub_if_data *sdata,
 		band = sband->band;
 
 		/* capability info */
-		pos = skb_put(skb, 2);
-		memset(pos, 0, 2);
+		pos = skb_put_zero(skb, 2);
 		if (action == WLAN_SP_MESH_PEERING_CONFIRM) {
 			/* AID */
 			pos = skb_put(skb, 2);