Conflicts:
	drivers/net/usb/r8152.c
	drivers/net/xen-netback/netback.c

Both the r8152 and netback conflicts were simple overlapping
changes.

Signed-off-by: David S. Miller <davem@davemloft.net>

In case of AP mode, the beacon interval is already reset to
zero inside cfg80211_stop_ap(), and in the other modes it
isn't relevant. Remove the assignment to remove a potential
race since the assignment isn't properly locked.

Reported-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Commit "nl80211: send event when AP operation is stopped" added an
event to notify user space that an AP interface has been stopped, to
handle cases such as suspend etc. The event is sent regardless
if the stop AP flow was triggered by user space or due to internal state
change.

This might cause issues with wpa_supplicant/hostapd flows that consider
stop AP flow as a synchronous one, e.g., AP/GO channel change in the
absence of CSA support. In such cases, the flow will restart the AP
immediately after the stop AP flow is done, and only handle the stop
AP event after the current flow is done, and as a result stop the AP
again.

Change the current implementation to only send the event in case the
stop AP was triggered due to an internal reason.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Due to the previous commit, when a scan finishes, it is in theory
possible to hit the following sequence:
 1. interface starts being removed
 2. scan is cancelled by driver and cfg80211 is notified
 3. scan done work is scheduled
 4. interface is removed completely, rdev->scan_req is freed,
    event sent to userspace but scan done work remains pending
 5. new scan is requested on another virtual interface
 6. scan done work runs, freeing the still-running scan

To fix this situation, hang on to the scan done message and block
new scans while that is the case, and only send the message from
the work function, regardless of whether the scan_req is already
freed from interface removal. This makes step 5 above impossible
and changes step 6 to be
 5. scan done work runs, sending the scan done message

As this can't work for wext, so we send the message immediately,
but this shouldn't be an issue since we still return -EBUSY.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

When an interface/wdev is removed, any ongoing scan should be
cancelled by the driver. This will make it call cfg80211, which
only queues a work struct. If interface/wdev removal is quick
enough, this can leave the scan request pending and processed
only after the interface is gone, causing a use-after-free.

Fix this by making sure the scan request is not pending after
the interface is destroyed. We can't flush or cancel the work
item due to locking concerns, but when it'll run it shouldn't
find anything to do. This leaves a potential issue, if a new
scan gets requested before the work runs, it prematurely stops
the running scan, potentially causing another crash. I'll fix
that in the next patch.

This was particularly observed with P2P_DEVICE wdevs, likely
because freeing them is quicker than freeing netdevs.

Reported-by: Andrei Otcheretianski <andrei.otcheretianski@intel.com>
Fixes: 4a58e7c38443 ("cfg80211: don't "leak" uncompleted scans")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Unfortunately I forgot this during the merge window, but the
patch seems small enough to go in as a fix. The userspace API
bug that was the reason for disabling it has long been fixed.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Instances of struct device_type are never modified, make them const.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>