iwlwifi: clean up some beacon handling

There's no need to check for NULL before
calling dev_kfree_skb() since it is valid
to call it on NULL -- it becomes a no-op.

There's also no need to initialise the
beacon_skb variable to NULL just after
the memory it is in has been kzalloc'ed.

Some minor whitespace cleanups, and a
lock assertion in a function that needs
the mutex (to access the beacon_skb var)
complete the patch.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>

drivers/net/wireless/iwlwifi/iwl-agn.c

@@ -317,6 +317,8 @@ static u32 iwl_fill_beacon_frame(struct iwl_priv *priv,
 				 struct ieee80211_hdr *hdr,
 				 int left)
 {
+	lockdep_assert_held(&priv->mutex);
+
 	if (!priv->beacon_skb)
 		return 0;
 
@@ -648,12 +650,11 @@ static void iwl_bg_beacon_update(struct work_struct *work)
 	/* Pull updated AP beacon from mac80211. will fail if not in AP mode */
 	beacon = ieee80211_beacon_get(priv->hw, priv->beacon_ctx->vif);
 	if (!beacon) {
-		IWL_ERR(priv, "update beacon failed\n");
+		IWL_ERR(priv, "update beacon failed -- keeping old\n");
 		goto out;
 	}
 
 	/* new beacon skb is allocated every time; dispose previous.*/
-	if (priv->beacon_skb)
 	dev_kfree_skb(priv->beacon_skb);
 
 	priv->beacon_skb = beacon;
@@ -2993,7 +2994,6 @@ static void __iwl_down(struct iwl_priv *priv)
  exit:
 	memset(&priv->card_alive, 0, sizeof(struct iwl_alive_resp));
 
-	if (priv->beacon_skb)
 	dev_kfree_skb(priv->beacon_skb);
 	priv->beacon_skb = NULL;
 
@@ -4131,8 +4131,6 @@ static int iwl_init_drv(struct iwl_priv *priv)
 {
 	int ret;
 
-	priv->beacon_skb = NULL;
-
 	spin_lock_init(&priv->sta_lock);
 	spin_lock_init(&priv->hcmd_lock);
 
@@ -4645,7 +4643,6 @@ static void __devexit iwl_pci_remove(struct pci_dev *pdev)
 
 	iwl_free_isr_ict(priv);
 
-	if (priv->beacon_skb)
 	dev_kfree_skb(priv->beacon_skb);
 
 	ieee80211_free_hw(priv->hw);