linux-kernel - Re: [PATCH] net: mac80211: tx.c: be sure of 'sdata->vif.type' must be NL80211_IFTYPE_AP when be in NL80211_IFTYPE

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Message-ID: <5299D306.7070701@gmail.com>
Date:	Sat, 30 Nov 2013 19:59:02 +0800
From:	Chen Gang <gang.chen.5i5j@...il.com>
To:	Johannes Berg <johannes@...solutions.net>
CC:	"John W. Linville" <linville@...driver.com>,
	rkuo <rkuo@...eaurora.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	David Miller <davem@...emloft.net>,
	linux-wireless@...r.kernel.org, netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] net: mac80211: tx.c: be sure of 'sdata->vif.type' must
 be NL80211_IFTYPE_AP when be in NL80211_IFTYPE_AP case

On 11/29/2013 11:38 PM, Johannes Berg wrote:
> 
>> +++ b/net/mac80211/tx.c
>> @@ -1814,8 +1814,9 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
>>  			break;
>>  		/* fall through */
>>  	case NL80211_IFTYPE_AP:
>> -		if (sdata->vif.type == NL80211_IFTYPE_AP)
>> -			chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
>> +		if (sdata->vif.type != NL80211_IFTYPE_AP)
>> +			goto fail_rcu;
>> +		chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
> 
> This change is completely wrong.
> 

Oh, it is.

Hmm... for me, this work flow still can be implemented with a little
clearer way (at least it will avoid related warning):

-------------------------diff begin------------------------------

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index c558b24..7076128 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1810,14 +1810,14 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
 		if (!chanctx_conf)
 			goto fail_rcu;
 		band = chanctx_conf->def.chan->band;
-		if (sta)
-			break;
-		/* fall through */
+		if (!sta)
+			goto try_next;
+		break;
 	case NL80211_IFTYPE_AP:
-		if (sdata->vif.type == NL80211_IFTYPE_AP)
-			chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
+		chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
 		if (!chanctx_conf)
 			goto fail_rcu;
+try_next:
 		fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS);
 		/* DA BSSID SA */
 		memcpy(hdr.addr1, skb->data, ETH_ALEN);



-------------------------diff end--------------------------------


Thanks.
-- 
Chen Gang
--
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