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Re: [RFC 2/3] cfg80211: Disallow moving out of operating DFS channel in non-ETSI

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On Thursday 26 January 2017 03:06 PM, Johannes Berg wrote:
>
>> +static bool cfg80211_off_channel_oper_allowed(struct wireless_dev
>> *wdev)
>> +{
>> +	if (!cfg80211_beaconing_iface_active(wdev))
>> +		return true;
>> +
>> +	if (!(wdev->chandef.chan->flags & IEEE80211_CHAN_RADAR))
>> +		return true;
>
> That could use some locking assertions. Maybe also in the
> cfg80211_beaconing_iface_active() function you introduced in the
> previous patch.

Ok.

>
>> +	if (!cfg80211_off_channel_oper_allowed(wdev)) {
>> +		struct ieee80211_channel *chan;
>> +
>> +		if (request->n_channels != 1) {
>> +			err = -EBUSY;
>> +			goto out_free;
>> +		}
>> +
>> +		chan = request->channels[0];
>> +		if (chan->center_freq != wdev->chandef.chan-
>>> center_freq) {
>> +			err = -EBUSY;
>> +			goto out_free;
>> +		}
>> +	}
>
> I'm not convinced you even hold the relevant locks here, though off the
> top of my head I'm not even sure which are needed.

Thanks for pointing it, it should be within wdev_lock().

>
>>   	i = 0;
>>   	if (n_ssids) {
>>   		nla_for_each_nested(attr, info-
>>> attrs[NL80211_ATTR_SCAN_SSIDS], tmp) {
>> @@ -9053,6 +9079,7 @@ static int nl80211_remain_on_channel(struct
>> sk_buff *skb,
>>   	struct cfg80211_registered_device *rdev = info->user_ptr[0];
>>   	struct wireless_dev *wdev = info->user_ptr[1];
>>   	struct cfg80211_chan_def chandef;
>> +	const struct cfg80211_chan_def *compat_chandef;
>>   	struct sk_buff *msg;
>>   	void *hdr;
>>   	u64 cookie;
>> @@ -9081,6 +9108,14 @@ static int nl80211_remain_on_channel(struct
>> sk_buff *skb,
>>   	if (err)
>>   		return err;
>>
>> +	if (!(cfg80211_off_channel_oper_allowed(wdev) ||
>> +	      cfg80211_chandef_identical(&wdev->chandef, &chandef)))
>
> I'd prefer to write that as !off_channel && !chandef_identical, seems
> easier to understand here.

Ok.


Thanks,

Vasanth




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