Re: [PATCH] mac80211: fix rates setup on IBSS merge

[Adam Wozniak <awozniak@irobot.com>]

I noticed this a while back and tried (unsuccessfully) to get some 
patches pushed through for it.  Your patch looks cleaner than mine (I 
don't think I understood as much at the time as I do now).

You can look through the linux-wireless archives for some of my old 
posts.  Things to note:

For minstrel, calling rate_control_init() is effectively an update.  A 
workable solution may be to add a minstrel rate_control_update() that 
simply calls init().  I don't *think* PID has an update either, and 
don't forget about the cases where the rate control algorithm is handled 
in the firmware for the device.

Flow control in ieee80211_rx_bss_info() could use some cleanup.  It's 
possible to reach the end and use uninitialized variables.

To solve the problem for my devices, I used a patch to minstrel which 
actually ignores the rates in the beacon, under the assumption that if 
the other STA can't use them, they'll get 0% probability in the rate 
table.  This seems to work well for me.

--Adam

Bruno Randolf wrote:
> when an IBSS merge happened, the supported rates for the newly added station
> were left empty, causing the rate control module to be initialized with only
> the basic rates.
>
> also the section of the ibss code which deals with updating supported rates for
> an already existing station fails to inform the rate control module about the
> new rates. as i don't know how to fix this (minstrel does not have an update
> function), i have just added a comment for now.
>
> Signed-off-by: Bruno Randolf <br1@einfach.org>
> ---
>
>  net/mac80211/ibss.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
> index f3e9424..b840d90 100644
> --- a/net/mac80211/ibss.c
> +++ b/net/mac80211/ibss.c
> @@ -276,6 +276,8 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
>  				    (unsigned long long) sta->sta.supp_rates[band]);
>  #endif
>  			rcu_read_unlock();
> +
> +			/* FIXME: update rate control */
>  		} else {
>  			rcu_read_unlock();
>  			ieee80211_ibss_add_sta(sdata, mgmt->bssid, mgmt->sa,
> @@ -370,6 +372,7 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
>  		       sdata->name, mgmt->bssid);
>  #endif
>  		ieee80211_sta_join_ibss(sdata, bss);
> +		supp_rates = ieee80211_sta_get_rates(local, elems, band);
>  		ieee80211_ibss_add_sta(sdata, mgmt->bssid, mgmt->sa,
>  				       supp_rates, GFP_KERNEL);
>  	}
>
> --
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