Re: [PATCH] mac80211: fix oops in ieee80211_scan_state_set_channel()

[Helmut Schaa <helmut.schaa@googlemail.com>]

Am Samstag, 25. Juli 2009 schrieb Pavel Roskin:
> On Sat, 2009-07-25 at 15:06 +0200, Helmut Schaa wrote:
> 
> > Hmm, I'd prefer to keep the decision state as entry and exit point to
> > the scan state machine. The patch below should also fix this issue
> > by returning back to the decision state after every skipped channel.
> 
> The patch is working and I'm fine with it. 

Great, thanks a lot.

> We should fix that in the 
> tree as soon as possible, or it will stand in the way of bisection.

Yes, you're right.

> I forgot to mention that the oops was happening in x86_64 with rt61pci
> and US regulatory domain.  The device only works in the 2.4 GHz range.
> 
> > In the long run I would like to move the channel selection also to
> > the decision state in order to implement various improvements (like
> > scanning multiple channels in a row or reordering the channel list).
> 
> I don't know the code enough, but two things surprised me:
> 
> Lack of SCAN_DONE in mac80211_scan_state.  We exit scanning through the
> "entry point".

I also thought of a separate state SCAN_DONE or something similar but
dropped that idea as the only thing this state would have to do is the
call to ieee80211_scan_completed. So, once the scan is finished we
just stay in SCAN_DECISION as long as the scan state machine gets poked
again by a start_scan call.

> Use of "unsigned long" for bitwise fields, such as queue_stop_reasons
> and scanning.  This reminds me of the good old days where long was
> always 32 bit, but int wasn't.  I think "unsigned int" should be enough,
> and you can annotate it with __bitwise to make sparse catch some
> misuses.

No objections :)

Helmut