Re: [PATCH] mac80211: do not call rate control .tx_status before .rate_init

[Felix Fietkau <nbd@openwrt.org>]

On 2012-02-09 12:01 AM, Pavel Roskin wrote:
> On Wed, 8 Feb 2012 14:44:54 -0500
> "John W. Linville" <linville@tuxdriver.com> wrote:
> 
>> On Wed, Feb 08, 2012 at 08:38:00PM +0100, Felix Fietkau wrote:
>> > On 2012-02-08 8:25 PM, John W. Linville wrote:
>> > > On Wed, Feb 08, 2012 at 07:17:11PM +0100, Felix Fietkau wrote:
>> > >> Most rate control implementations assume .get_rate
>> > >> and .tx_status are only called once the per-station data has
>> > >> been fully initialized. minstrel_ht crashes if this assumption
>> > >> is violated.
>> > >> 
>> > >> Signed-off-by: Felix Fietkau <nbd@openwrt.org>
>> > >> Tested-by: Arend van Spriel <arend@broadcom.com>
>> > >> ---
>> > >>  net/mac80211/rate.h |    2 +-
>> > >>  1 files changed, 1 insertions(+), 1 deletions(-)
>> > >> 
>> > >> diff --git a/net/mac80211/rate.h b/net/mac80211/rate.h
>> > >> index 5fc3135..fbb1efd 100644
>> > >> --- a/net/mac80211/rate.h
>> > >> +++ b/net/mac80211/rate.h
>> > >> @@ -37,7 +37,7 @@ static inline void
>> > >> rate_control_tx_status(struct ieee80211_local *local, struct
>> > >> ieee80211_sta *ista = &sta->sta; void *priv_sta =
>> > >> sta->rate_ctrl_priv; 
>> > >> -	if (!ref)
>> > >> +	if (!ref || !test_sta_flag(sta, WLAN_STA_RATE_CONTROL))
>> > >>  		return;
>> > >>  
>> > >>  	ref->ops->tx_status(ref->priv, sband, ista, priv_sta,
>> > >> skb);
>> > > 
>> > > Any reason not to apply this for 3.3?  Or stable?
>> > I think 3.3 doesn't have that sta flag, the issue was probably
>> > introduced with the 3.4 changes.
>> > I don't remember something like this appearing in earlier versions.
>> 
>> Cool, thanks.
> 
> I believe 3.3 is affected.  At least it looks like the Fedora bug 768639
> (https://bugzilla.redhat.com/show_bug.cgi?id=768639) is caused by
> calling .tx_status at a wrong time.  Fedora kernels use
> compat-wireless-3.3.  I'm going to test the bleeding edge
> compat-wireless with the patch by Felix to see if it fixes things.
> 
> The lack of the WLAN_STA_RATE_CONTROL flag doesn't mean that the old
> behavior was correct.  The flag was introduced to correct that behavior.
> 
> The oldest report is dated 2011-12-17 and it's about Linux 3.2.0-rc5
> with compat-wireless-2011-12-01.
Only .get_rate and .tx_status are affected, wireless-testing commit
e1936e9407138b483e6d1332dd944afec8131f30 adds one of the checks, and my
commit adds the other. Maybe John could merge those two to 3.3.

- Felix