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Date:   Thu, 22 Jun 2023 18:50:38 +0200
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To:     Johannes Berg <johannes@sipsolutions.net>,
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From:   Felix Fietkau <nbd@nbd.name>
Subject: Re: [PATCH] cfg80211: fix sband iftype data lookup for AP_VLAN
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On 22.06.23 18:41, Johannes Berg wrote:
> On Thu, 2023-06-22 at 18:25 +0200, Felix Fietkau wrote:
>> On 22.06.23 18:07, Johannes Berg wrote:
>> > On Thu, 2023-06-22 at 18:05 +0200, Felix Fietkau wrote:
>> > > Since AP_VLAN interfaces are not pushed to the driver, 
>> > > 
>> > That's a mac80211 thing though.
>> > 
>> > > the driver should not
>> > > be expected to register iftype data for them.
>> > > Map them to the regular AP iftype on lookup.
>> > 
>> > And this is in cfg80211 - not sure that seems right?
>> > 
>> > OTOH I'd expect no callers with VLAN here, it doesn't really make sense
>> > since they're not a standalone mode that actually has HE/EHT, but still,
>> > seems odd this way?
>> > 
>> > What's actually calling it? I'm guessing somewhere in mac80211?
>> 
>> Yes, I guess only mac80211 is affected. I put in the cfg80211 prefix
>> because that's what the header file belongs to.
>> 
>> I made the patch in response to this:
>> https://patchwork.kernel.org/project/linux-wireless/patch/20230605152141.17434-4-shayne.chen@mediatek.com/
> 
> OK, sure, that also doesn't really make sense.
> 
>> I found that there are several calls to ieee80211_get_he_iftype_cap and
>> ieee80211_get_eht_iftype_cap, which could be affected by this issue.
>> I thought dealing with this in a single place would be better than playing
>> whac-a-mole by fixing it at the call sites.
>> 
> 
> I replaced almost all of them with ieee80211_get_he_iftype_cap_vif() so
> it shouldn't be that bad? Looks like I forgot some though.

I guess one advantage in using my fix would be that it's way easier to 
backport.
How about using my fix initially (with a changed prefix if you prefer), 
and then replace it once the call sites have been switched over to 
ieee80211_get_he_iftype_cap_vif?

- Felix