Re: [RFC 5/5] cfg80211: scan before connect if we don't have the bss

[Dave <kilroyd@googlemail.com>]

Johannes Berg wrote:
> On Wed, 2009-08-19 at 20:30 +0100, Dave wrote:
>>> Hmm. What if the bssid isn't set? Then the card might select a different
>>> BSS than the one we have on the scan list.
>> That's correct. For the Agere driver that's also true when bssid is set
>> - we can't specify which AP the firmware connects to.
> 
> Ok. We may want a feature flag for the latter case so we know what's
> going on, and reject a BSSID setting.

I'll look into that.

>>> And it's all racy too -- by the time the driver calls connect_result(),
>>> the BSS might have expired after it was found here now.
>> Agreed, but with a 15s expiry period I wouldn't expect this to be a
>> problem in practice.
> 
> Well, the user could scan, take 12 seconds to pick out the AP manually,
> enter the paramters in another 2.5 seconds, and then it would already
> happen, I think?

As usual, you're right :)

>> Another alternative is for cfg80211_connect_result to trigger the scan
>> if it doesn't have the bss, and only complete the connect when the scan
>> returns. I think I like the sound of this best.

johannes said:
> Good option too, though then it would be useful to pass the channel
> pointer if available to scan only on that channel. Of course, if it
> still can't be found things are really amiss and we should probably
> disconnect and send a failed event to userspace.

Jussi said:
> This sounds best, as with rndis, driver can get currently connected
> bss from device and scan isn't required.

OK, I'll chase this option and see where it goes.


Regards,

Dave.