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mac80211: correctly close cancelled scans

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__ieee80211_scan_completed is called from a worker. This
means that the following flow is possible.

 * driver calls ieee80211_scan_completed
 * mac80211 cancels the scan (that is already complete)
 * __ieee80211_scan_completed runs

When scan_work will finally run, it will see that the scan
hasn't been aborted and might even trigger another scan on
another band. This leads to a situation where cfg80211's
scan is not done and no further scan can be issued.

Fix this by setting a new flag when a HW scan is being
cancelled so that no other scan will be triggered.

Cc: stable@vger.kernel.org
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Emmanuel Grumbach 2013-09-16 11:12:07 +03:00 committed by Johannes Berg
parent 22c4ceed01
commit a754055a12
2 changed files with 22 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
net/mac80211/ieee80211_i.h
View File

@ -893,6 +893,8 @@ struct tpt_led_trigger {
* that the scan completed.
* @SCAN_ABORTED: Set for our scan work function when the driver reported
* a scan complete for an aborted scan.
* @SCAN_HW_CANCELLED: Set for our scan work function when the scan is being
* cancelled.
*/
enum {
SCAN_SW_SCANNING,
@ -900,6 +902,7 @@ enum {
SCAN_ONCHANNEL_SCANNING,
SCAN_COMPLETED,
SCAN_ABORTED,
SCAN_HW_CANCELLED,
};
/**

19
net/mac80211/scan.c
View File

@ -238,6 +238,9 @@ static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
enum ieee80211_band band;
int i, ielen, n_chans;
if (test_bit(SCAN_HW_CANCELLED, &local->scanning))
return false;
do {
if (local->hw_scan_band == IEEE80211_NUM_BANDS)
return false;
@ -940,7 +943,23 @@ void ieee80211_scan_cancel(struct ieee80211_local *local)
if (!local->scan_req)
goto out;
/*
* We have a scan running and the driver already reported completion,
* but the worker hasn't run yet or is stuck on the mutex - mark it as
* cancelled.
*/
if (test_bit(SCAN_HW_SCANNING, &local->scanning) &&
test_bit(SCAN_COMPLETED, &local->scanning)) {
set_bit(SCAN_HW_CANCELLED, &local->scanning);
goto out;
}
if (test_bit(SCAN_HW_SCANNING, &local->scanning)) {
/*
* Make sure that __ieee80211_scan_completed doesn't trigger a
* scan on another band.
*/
set_bit(SCAN_HW_CANCELLED, &local->scanning);
if (local->ops->cancel_hw_scan)
drv_cancel_hw_scan(local,
rcu_dereference_protected(local->scan_sdata,