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Subject: Re: [PATCH 3/3] mac80211: batch key free synchronize_net()
From: Johannes Berg <johannes@sipsolutions.net>
To: linux-wireless@vger.kernel.org
Date: Thu, 07 Mar 2013 11:29:49 +0100
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On Thu, 2013-03-07 at 11:27 +0100, Johannes Berg wrote:

>  void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
>  {
>  	struct ieee80211_key *key, *tmp;
> +	LIST_HEAD(keys);
>  
>  	cancel_delayed_work_sync(&sdata->dec_tailroom_needed_wk);
>  
> @@ -571,17 +578,61 @@ void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata)
>  
>  	ieee80211_debugfs_key_remove_mgmt_default(sdata);
>  
> -	list_for_each_entry_safe(key, tmp, &sdata->key_list, list)
> -		ieee80211_key_free(key, false);
> +	list_for_each_entry_safe(key, tmp, &sdata->key_list, list) {
> +		ieee80211_key_replace(key->sdata, key->sta,
> +				key->conf.flags & IEEE80211_KEY_FLAG_PAIRWISE,
> +				key, NULL);
> +		list_add_tail(&key->list, &keys);
> +	}
>  
>  	ieee80211_debugfs_key_update_default(sdata);
>  
> +	synchronize_net();
> +	list_for_each_entry_safe(key, tmp, &keys, list)
> +		__ieee80211_key_destroy(key, false);

Since it's likely that there are no keys, I'll change this:

 	ieee80211_debugfs_key_update_default(sdata);
 
-	synchronize_net();
-	list_for_each_entry_safe(key, tmp, &keys, list)
-		__ieee80211_key_destroy(key, false);
+	if (!list_empty(&keys)) {
+		synchronize_net();
+		list_for_each_entry_safe(key, tmp, &keys, list)
+			__ieee80211_key_destroy(key, false);
+	}
 
 	WARN_ON_ONCE(sdata->crypto_tx_tailroom_needed_cnt ||
 		     sdata->crypto_tx_tailroom_pending_dec);


johannes