Re: [PATCH v3] wifi: mac80211: fix monitor mode frame capture for real chanctx drivers

[Johannes Berg]

Hi Devin,

Please don't nest the threads - it gets confusing quickly.


> +	} else if (local->emulate_chanctx) {
>  		chandef = &local->hw.conf.chandef;
> -	else
> -		goto fail_rcu;
> +	} else {
> +		struct ieee80211_chanctx *ctx;
> +
> +		ctx = list_first_or_null_rcu(&local->chanctx_list,
> +					     struct ieee80211_chanctx, list);
> +		if (!ctx ||
> +		    rcu_access_pointer(ctx->list.next) != &local->chanctx_list)
> +			goto fail_rcu;
> +		chandef = &ctx->conf.def;
> +	}

I'm sure we can basically get rid of the "emulate" check now, because
emulation will always lead to exactly (zero or) one channel context(s)
being present.

And then it's equivalent to my original v2 patch:
https://lore.kernel.org/linux-wireless/20251216111909.25076-2-johannes@xxxxxxxxxxxxxxxx/

(even if that expressed the logic somewhat differently)


And that version was _definitely_ reported to crash. So what changed?
Could you do some investigation if mt76 got bugfixes in this area
perhaps? Or are you just using slightly different devices than Oscar?

johannes