There are some places marked
	/* XXX maybe racy? */
and they really are racy because there's no locking.

This patch reworks much of the scan code, and introduces proper
locking for the scan request as well as the internal scanning
(which is necessary for IBSS/managed modes). Helper functions
are added to call the scanning code whenever necessary. The
scan deferring is changed to simply queue the scanning work
instead of trying to start the scan in place, the scanning work
will then take care of the rest.

Also, currently when internal scans are requested for an interface
that is trying to associate, we reject such scans. This was not
intended, the mlme code has provisions to scan twice when it can't
find the BSS to associate with right away; this has never worked
properly. Fix this by not rejecting internal scan requests for an
interface that is associating.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

When the IBSS code wants to scan, but that fails, we can
get stuck in a situation where you can never scan again.
Fix this by properly notifying ourselves when the scan
request has failed.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

There are a few problems in the IBSS code:
 a) it tries to activate interfaces that are down after scanning
 b) it crashes after scanning on an IBSS iface that isn't active
 c) since the ssid_len is used as a flag, need to make it visible
    only after all other settings are set, this helps protect
    against b)

For b), we get a system crash:

wlan0: Creating new IBSS network, BSSID ce:f9:88:76:1e:4d
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<...>] ieee80211_sta_find_ibss+0x294/0x37d [mac80211]
Call Trace:
 [<...>] ieee80211_ibss_notify_scan_completed+0x0/0x88 [mac80211]
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

With the RCU locking here we sleep while in an atomic context,
since we can sleep just use mutex locking for the interface
list instead of RCU. Sorry, seems I didn't get that in my UML
test.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

This converts mac80211 to the new cfg80211 IBSS API, the
wext handling functions are called where appropriate.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Don't call ieee80211_sta_find_ibss() directly, like it's done in STA
mode, so that the commit() call is more harmless respectively has
less site-effects.
Signed-off-by: NAlina Friedrichsen <x-alina@gmx.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

In IBSS mode, the beacon timestamp has to be filled with the
BSS's timestamp when joining, and set to zero when creating
a new BSS.
Signed-off-by: NSujith <Sujith.Manoharan@atheros.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

Give slow hardware some time to do the TSF sync, to not run into an
IBSS merging endless loop in some rarely situations.
Signed-off-by: NAlina Friedrichsen <x-alina@gmx.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

It was not a good idea to do a TSF reset on strange IBSS merges to the same BSSID. For example it will break the TSF sync of ath9k completely and it is unnecessary as all hardware I have tested do a TSF sync to a higher value automatically and IBSS merges are only done to higher TSF values. It only need a TSF reset to accept a lower value, when the IBSS network is changed manually.
Signed-off-by: NAlina Friedrichsen <x-alina@gmx.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

This patch introduces a generic commit() function which initiate a
new network joining process. It should be called after some interface
config changes, so that the changes get applied more cleanly. Currently
set_ssid() and set_bssid() call it. Others can be added in future
patches.

In version 1 the header files was forgotten, sorry.
Signed-off-by: NAlina Friedrichsen <x-alina@gmx.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

This patch splits out the ibss code and data from managed (station) mode.
The reason to do this is to better separate the state machines, and have
the code be contained better so it gets easier to determine what exactly
a given change will affect, that in turn makes it easier to understand.

This is quite some churn, especially because I split sdata->u.sta into
sdata->u.mgd and sdata->u.ibss, but I think it's easier to maintain that
way. I've also shuffled around some code -- null function sending is only
applicable to managed interfaces so put that into that file, some other
functions are needed from various places so put them into util, and also
rearranged the prototypes in ieee80211_i.h accordingly.
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>