WARNING from mac80211

WARNING from mac80211

[Larry Finger]

Johannes and John,

A regression in recent versions of mac80211 are generating the WARNING at 
net/mac80211/wep.c:101, because the skb headroom is less than WEP_IV_LEN or the 
tailroom is less than WEP_ICV_LEN. My testing indicates that it is a headroom 
problem as the following hack "fixes" it:

Index: wireless-testing-new/net/mac80211/tx.c
===================================================================
--- wireless-testing-new.orig/net/mac80211/tx.c
+++ wireless-testing-new/net/mac80211/tx.c
@@ -1935,6 +1935,8 @@ netdev_tx_t ieee80211_subif_start_xmit(s
                 head_need += IEEE80211_ENCRYPT_HEADROOM;
                 head_need += local->tx_headroom;
                 head_need = max_t(int, 0, head_need);
+               if (head_need < WEP_IV_LEN)
+                       head_need = WEP_IV_LEN;
                 if (ieee80211_skb_resize(local, skb, head_need, true))
                         goto fail;
         }

I'm certain that this is too simple minded, but it at least points to a place to 
look. I have not bisected the problem to see which commit caused the regression, 
but I can if you want.

Larry

Re: WARNING from mac80211

[Johannes Berg]

On Wed, 2011-05-04 at 14:55 -0500, Larry Finger wrote:
> Johannes and John,
> 
> A regression in recent versions of mac80211 are generating the WARNING at 
> net/mac80211/wep.c:101, because the skb headroom is less than WEP_IV_LEN or the 
> tailroom is less than WEP_ICV_LEN. My testing indicates that it is a headroom 
> problem as the following hack "fixes" it:

See also this thread:
http://thread.gmane.org/gmane.linux.kernel.wireless.general/69062/focus=69150

and the resulting patch:
http://article.gmane.org/gmane.linux.kernel.wireless.general/69190
(not sure why it was RFC?)

johannes

Re: WARNING from mac80211

[Larry Finger]

On 05/04/2011 03:02 PM, Johannes Berg wrote:
> On Wed, 2011-05-04 at 14:55 -0500, Larry Finger wrote:
>> Johannes and John,
>>
>> A regression in recent versions of mac80211 are generating the WARNING at
>> net/mac80211/wep.c:101, because the skb headroom is less than WEP_IV_LEN or the
>> tailroom is less than WEP_ICV_LEN. My testing indicates that it is a headroom
>> problem as the following hack "fixes" it:
>
> See also this thread:
> http://thread.gmane.org/gmane.linux.kernel.wireless.general/69062/focus=69150
>
> and the resulting patch:
> http://article.gmane.org/gmane.linux.kernel.wireless.general/69190
> (not sure why it was RFC?)

Thanks. I do remember the thread now that you refreshed my memory. That patch 
does fix my problem.

Larry

Re: WARNING from mac80211

[Johannes Berg]

On Wed, 2011-05-04 at 15:11 -0500, Larry Finger wrote:

> > See also this thread:
> > http://thread.gmane.org/gmane.linux.kernel.wireless.general/69062/focus=69150
> >
> > and the resulting patch:
> > http://article.gmane.org/gmane.linux.kernel.wireless.general/69190
> > (not sure why it was RFC?)
> 
> Thanks. I do remember the thread now that you refreshed my memory. That patch 
> does fix my problem.

Good to know. John should probably merge that patch even though it was
RFC.

johannes

Re: WARNING from mac80211

[Mohammed Shafi]

On Thu, May 5, 2011 at 1:41 AM, Larry Finger <Larry.Finger@lwfinger.net> wrote:
> On 05/04/2011 03:02 PM, Johannes Berg wrote:
>>
>> On Wed, 2011-05-04 at 14:55 -0500, Larry Finger wrote:
>>>
>>> Johannes and John,
>>>
>>> A regression in recent versions of mac80211 are generating the WARNING at
>>> net/mac80211/wep.c:101, because the skb headroom is less than WEP_IV_LEN
>>> or the
>>> tailroom is less than WEP_ICV_LEN. My testing indicates that it is a
>>> headroom
>>> problem as the following hack "fixes" it:
>>
>> See also this thread:
>>
>> http://thread.gmane.org/gmane.linux.kernel.wireless.general/69062/focus=69150
>>
>> and the resulting patch:
>> http://article.gmane.org/gmane.linux.kernel.wireless.general/69190
>> (not sure why it was RFC?)

I will send the patch today :)

thanks,
shafi

>
> Thanks. I do remember the thread now that you refreshed my memory. That
> patch does fix my problem.
>
> Larry
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