Re: [PATCH v4 2/3] scan: split full scans by band to enable 6GHz

[Denis Kenzior <denkenz@gmail.com>]

Hi James,

On 8/4/22 17:02, James Prestwood wrote:
> The kernel's regulatory domain updates after some number of beacons
> are processed. This triggers a regulatory domain update (and wiphy
> dump) but only after a scan request. This means a full scan started
> prior to the regdom being set will not include any 6Ghz BSS's even
> if the regdom was unlocked during the scan.
> 
> This can be worked around by splitting up a large scan request into
> multiple requests allowing one of the first commands to trigger a
> regdom update. Once the regdom updates (and wiphy dumps) we are
> hopefully still scanning and could append an additional request to
> scan 6GHz.
> ---
>   src/scan.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++++------
>   1 file changed, 76 insertions(+), 9 deletions(-)
> 

<snip>

> +	/*
> +	 * Otherwise a full spectrum scan will likely open up the 6GHz
> +	 * band. The problem is the regdom update occurs after an
> +	 * individual scan request so a single request isn't going to
> +	 * include potential 6GHz results.
> +	 *
> +	 * Instead we can break this full scan up into individual bands
> +	 * and increase our chances of the regdom updating after one of
> +	 * the earlier requests. If it does update to allow 6GHz an
> +	 * extra 6GHz-only passive scan can be appended to this request
> +	 * at that time.
> +	 */
> +	subsets[0] = scan_freq_set_copy_bands(allowed, BAND_FREQ_2_4_GHZ);
> +	subsets[1] = scan_freq_set_copy_bands(allowed, BAND_FREQ_5_GHZ);

I updated these to use _clone() and ...

> +
> +	scan_freq_set_free(allowed);
> +
> +	for(i = 0; i < L_ARRAY_SIZE(subsets); i++) {
> +		scan_build_next_cmd(sr->cmds, sc, passive, params,
> +					subsets[i]);

added a scan_freq_set_isempty() check here to skip building the command in the 
unlikely event that the set is empty.

> +		scan_freq_set_free(subsets[i]);
> +	}
> +
> +	sr->split = true;
> +}
> +
>   static int scan_request_send_trigger(struct scan_context *sc,
>   					struct scan_request *sr)
>   {

Applied, thanks!

Regards,
-Denis