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Message-ID: <d80ae6ae-e1f2-48ef-b18a-29b5ca62e64c@quicinc.com>
Date: Mon, 22 Jan 2024 10:33:28 -0800
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Subject: Re: [PATCH wireless v2] nl80211/cfg80211: add nla_policy for S1G band
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To: Johannes Berg <johannes@sipsolutions.net>, Lin Ma <linma@zju.edu.cn>,
        <davem@davemloft.net>, <edumazet@google.com>, <kuba@kernel.org>,
        <pabeni@redhat.com>, <linux-wireless@vger.kernel.org>,
        <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <kvalo@kernel.org>
References: <20240119151201.8670-1-linma@zju.edu.cn>
 <9e1db7f3-fd18-4b3b-a912-3cf6efd96fed@quicinc.com>
 <590fe2823d934af997c515640733eb8889b0560f.camel@sipsolutions.net>
From: Jeff Johnson <quic_jjohnson@quicinc.com>
In-Reply-To: <590fe2823d934af997c515640733eb8889b0560f.camel@sipsolutions.net>
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On 1/20/2024 12:27 PM, Johannes Berg wrote:
> On Fri, 2024-01-19 at 15:47 -0800, Jeff Johnson wrote:
>>> --- a/net/wireless/nl80211.c
>>> +++ b/net/wireless/nl80211.c
>>> @@ -911,6 +911,7 @@ nl80211_match_band_rssi_policy[NUM_NL80211_BANDS] = {
>>>  	[NL80211_BAND_5GHZ] = { .type = NLA_S32 },
>>>  	[NL80211_BAND_6GHZ] = { .type = NLA_S32 },
>>>  	[NL80211_BAND_60GHZ] = { .type = NLA_S32 },
>>> +	[NL80211_BAND_S1GHZ] = { .type = NLA_S32 },
>>>  	[NL80211_BAND_LC]    = { .type = NLA_S32 },
>>>  };
>>>  
>> something is really suspicious since the NL80211_BAND_* enums are
>> *value* enums, not attribute ID enums, and hence they should never be
>> used in an nla_policy.
> 
> Yeah, that's what it looks like first, but then they do get used
> anyway...
> 
>> what is actually using these as attribute IDs, noting that
>> NL80211_BAND_2GHZ == 0 and hence cannot be used as an attribute ID
> 
> Ohh. Good catch!
> 
>> seems the logic that introduced this policy needs to be revisited.
>>
> 
> Let's just remove it?
> 
> commit 1e1b11b6a1111cd9e8af1fd6ccda270a9fa3eacf
> Author: vamsi krishna <vamsin@codeaurora.org>
> Date:   Fri Feb 1 18:34:51 2019 +0530
> 
>     nl80211/cfg80211: Specify band specific min RSSI thresholds with sched scan
> 
> 
> As far as I can tell nothing is using that in the first place ...
> Certainly not in the kernel, nor wpa_s, nor anything else I could find
> really ...
> 
> We can't completely revert it since we need the attribute number to stay
> allocated, but that's all we cannot remove.

I'm investigating this and will report back.