Re: rc80211_minstrel.c:70 WARNING with 2.6.34-rc4

[Felix Fietkau <nbd@openwrt.org>]

On 2010-04-19 7:41 PM, Richard Zidlicky wrote:
> 
> Hi,
> 
>> > I am getting tons of these http://www.kerneloops.org/submitresult.php?number=3048061,
>> > appears every packet triggers that.
>> 
>> The warning comes from the function rix_to_ndx() in rc80211_minstrel.c:
>> 
>> /* convert mac80211 rate index to local array index */
>> static inline int
>> rix_to_ndx(struct minstrel_sta_info *mi, int rix)
>> {
>>         int i = rix;
>>         for (i = rix; i >= 0; i--)
>>                 if (mi->r[i].rix == rix)
>>                         break;
>>         WARN_ON(i < 0);
>>         return i;
>> }
>> 
>> > Can provide lots of debugging info.
>> 
>> My impression is that WARN_ON is not warranted in that function, but it
>> would be interesting to know how you got to that point.
> 
> I am using the rt73usb, WEP, adhoc, fixed rate(11M) on both ends:
> 
> wlan0     IEEE 802.11bg  ESSID:"XXXXXXXX"  
>           Mode:Ad-Hoc  Frequency:2.442 GHz  Cell: F6:B2:CB:FC:62:6C   
>           Tx-Power=20 dBm   
>           Retry  long limit:7   RTS thr:off   Fragment thr:off
>           Encryption key:  XXXXXXXXXX
>           Power Management:on
> 
> It is 2.6.34-rc4, no compat-wireless.
> 
> As of unusual circumstances - the  rt73usb driver has some bug that causes
> very high retransmit rates. On the opposite end the ath5k driver complains "cant
> handle jumbo frames".
> I had it perfectly working some time ago but need to figure out which off the many 
> patches did it and apply it to the new kernel. 
> This might stress minstrel more than needed but otoh it was my impression that the
> warning was triggered by every single packet.
> 
> Let me know if you want any more info.
This warning typically shows up, whenever the driver reports a rate to
minstrel in the tx status that is not part of the supported/negotiated
rate set - that's the reason the index lookup above fails.

- Felix