netdev - Re: [PATCH 08/10] mac80211: Support on-channel scan option.

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Message-ID: <1334202356.3788.7.camel@jlt3.sipsolutions.net>
Date:	Thu, 12 Apr 2012 05:45:56 +0200
From:	Johannes Berg <johannes@...solutions.net>
To:	greearb@...delatech.com
Cc:	linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH 08/10] mac80211: Support on-channel scan option.

On Wed, 2012-04-11 at 10:52 -0700, greearb@...delatech.com wrote:

>  static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
>  				  struct cfg80211_scan_request *req)
> @@ -438,10 +461,43 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
>  	local->scan_req = req;
>  	local->scan_sdata = sdata;
>  
> -	if (local->ops->hw_scan)
> +	if (local->ops->hw_scan) {
>  		__set_bit(SCAN_HW_SCANNING, &local->scanning);
> -	else
> -		__set_bit(SCAN_SW_SCANNING, &local->scanning);
> +	} else {
> +		/* If we are scanning only on the current channel, then
> +		 * we do not need to stop normal activities
> +		 */
> +		if ((req->n_channels == 1) &&
> +		    (req->channels[0]->center_freq ==
> +		     local->hw.conf.channel->center_freq)) {

how about "else if {", then the indentation isn't so deep and you can
have much nicer code in the entire block :)

> +			unsigned long next_delay;

please add a blank line after variable declarations.

> +		}
> +		else {

please read the coding style documentation

> @@ -672,6 +704,12 @@ void ieee80211_scan_work(struct work_struct *work)
>  
>  	sdata = local->scan_sdata;
>  
> +	/* When scanning on-channel, the first-callback means completeed. */

typo "completed"

> +	if (test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning)) {
> +		aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
> +		goto out_complete;
> +	}

how does the onchannel bit get cleared?

Shouldn't you be calling pre/post scan hooks?

I'm a bit divided over this. On the one hand, it seems like a mildly
useful optimisation, on the other though it adds a bunch of complexity
for multi-channel we've been thinking about... Not that we want to
support multi-channel with SW scan anyway, but still.

johannes

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