From mboxrd@z Thu Jan  1 00:00:00 1970
From: Oleksij Rempel <linux@rempel-privat.de>
Date: Sat, 18 Oct 2014 12:01:33 +0200
Subject: [ath9k-devel] ath9k-htc: IBSS network crashes after one device
 leaves network
In-Reply-To: <C7367401563A9D46BC5A92B9456C061D48D210@G08CNEXMBPEKD03.g08.fujitsu.local>
References: <C7367401563A9D46BC5A92B9456C061D48D210@G08CNEXMBPEKD03.g08.fujitsu.local>
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To: ath9k-devel@lists.ath9k.org

Am 18.10.2014 um 09:46 schrieb Li, Hongchun:
> I?m building an IBSS network using TP-Link TL-WN722N USB WiFi dongle.
> 
> I find that it is drived by ath9k.

Hi, this adapter is driven by ath9k-htc, at least mostly :)

> 
> Here is a problem I encountered.
> 
> First, I build an IBSS network with more than 8 devices.
> 
> For example, a network consists of 9 devices, N1, N2, ?, N9.
> 
> All devices have same WiFi module.
> 
>  
> 
> When N9 joined network, kernel throws a warning, ?Unable to move IBSS
> STA MAC_ADDR to state 3 (-105)?.
>
> However, the network works correctly. Any node can communicate with each
> other.

Hm.. we should do some thing about it. Not allowed nodes should be
discarded.

>  
> But if I turn off one device, for example N3, the network crashes after
> a few minutes.

Is it crashes only if there is more then 8 devices?

Can you get crash log?

> Ping command fails between any two devices in network.
> 
> Get no warning/error message from kernel.
> 
> After N3 is turned off and network crashes, I turned on N3 and network
> works correctly again.
> 
>  
> 
> I find the number 8 is an macro in device driver code:
> drivers/net/wireless/ath/ath9k/htc.h
> 
> 252 <http://lxr.free-electrons.com/source/drivers/net/wireless/ath/ath9k/htc.h?v=3.11#L252> #define ATH9K_HTC_MAX_STA <http://lxr.free-electrons.com/ident?v=3.11;i=ATH9K_HTC_MAX_STA> 8
> 
> It seems like that when there are more than 8 devices in network, driver
> returns an error ENOBUFS(-105).
> 
>  
> 
> But in linux kernel source: net/mac80211/sta_info.c, I found this,
> 
> 436
> <http://lxr.free-electrons.com/source/net/mac80211/sta_info.c?v=3.11#L436> 
> if (sdata <http://lxr.free-electrons.com/ident?v=3.11;i=sdata>->vif.type
> <http://lxr.free-electrons.com/ident?v=3.11;i=type> ==
> NL80211_IFTYPE_ADHOC) {
> 
> 437
> <http://lxr.free-electrons.com/source/net/mac80211/sta_info.c?v=3.11#L437> 
>       sdata_info
> <http://lxr.free-electrons.com/ident?v=3.11;i=sdata_info>(sdata
> <http://lxr.free-electrons.com/ident?v=3.11;i=sdata>,
> 
> 438
> <http://lxr.free-electrons.com/source/net/mac80211/sta_info.c?v=3.11#L438> 
>                "failed to move IBSS STA %pM to state %d (%d) - keeping
> it anyway\n",
> 
> 439
> <http://lxr.free-electrons.com/source/net/mac80211/sta_info.c?v=3.11#L439> 
>                sta->sta.addr
> <http://lxr.free-electrons.com/ident?v=3.11;i=addr>, state
> <http://lxr.free-electrons.com/ident?v=3.11;i=state> + 1, err
> <http://lxr.free-electrons.com/ident?v=3.11;i=err>);
> 
> 440
> <http://lxr.free-electrons.com/source/net/mac80211/sta_info.c?v=3.11#L440> 
>      err <http://lxr.free-electrons.com/ident?v=3.11;i=err> = 0;
> 
> 441
> <http://lxr.free-electrons.com/source/net/mac80211/sta_info.c?v=3.11#L441> 
> }
> 
> So when it is an ad hoc network, kernel just ignore errors from driver.
> 
> This answers why ibss network work correctly when there are more than 8
> devices.
> 
>  
> 
> But I cannot figure out why the network crashes after one device is
> turned off.
> 
> Does anyone have any idea how to solve this problem?
> 
>  
> 
> Li Chun
> 
>  
> 
> 
> 
> _______________________________________________
> ath9k-devel mailing list
> ath9k-devel at lists.ath9k.org
> https://lists.ath9k.org/mailman/listinfo/ath9k-devel
> 


-- 
Regards,
Oleksij

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