mac80211: allow scan to complete from any context
The ieee80211_scan_completed() function was a frequent
source of potential deadlocks, since it is called by
drivers but may call back into drivers, so drivers had
to make sure to call it without any locks held, which
frequently lead to more complex code in drivers. Avoid
that problem by allowing the function to be called in
any context, and queueing the actual work it does.
Also update the documentation for it to indicate this.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 31f233f..d60389b 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -248,13 +248,11 @@
return true;
}
-void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
+static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
{
struct ieee80211_local *local = hw_to_local(hw);
bool was_hw_scan;
- trace_api_scan_completed(local, aborted);
-
mutex_lock(&local->mtx);
/*
@@ -312,6 +310,18 @@
ieee80211_mesh_notify_scan_completed(local);
ieee80211_queue_work(&local->hw, &local->work_work);
}
+
+void ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
+{
+ struct ieee80211_local *local = hw_to_local(hw);
+
+ trace_api_scan_completed(local, aborted);
+
+ set_bit(SCAN_COMPLETED, &local->scanning);
+ if (aborted)
+ set_bit(SCAN_ABORTED, &local->scanning);
+ ieee80211_queue_delayed_work(&local->hw, &local->scan_work, 0);
+}
EXPORT_SYMBOL(ieee80211_scan_completed);
static int ieee80211_start_sw_scan(struct ieee80211_local *local)
@@ -449,7 +459,7 @@
/* if no more bands/channels left, complete scan and advance to the idle state */
if (local->scan_channel_idx >= local->scan_req->n_channels) {
- ieee80211_scan_completed(&local->hw, false);
+ __ieee80211_scan_completed(&local->hw, false);
return 1;
}
@@ -641,6 +651,14 @@
struct ieee80211_sub_if_data *sdata = local->scan_sdata;
unsigned long next_delay = 0;
+ if (test_and_clear_bit(SCAN_COMPLETED, &local->scanning)) {
+ bool aborted;
+
+ aborted = test_and_clear_bit(SCAN_ABORTED, &local->scanning);
+ __ieee80211_scan_completed(&local->hw, aborted);
+ return;
+ }
+
mutex_lock(&local->mtx);
if (!sdata || !local->scan_req) {
mutex_unlock(&local->mtx);
@@ -651,7 +669,7 @@
int rc = drv_hw_scan(local, sdata, local->hw_scan_req);
mutex_unlock(&local->mtx);
if (rc)
- ieee80211_scan_completed(&local->hw, true);
+ __ieee80211_scan_completed(&local->hw, true);
return;
}
@@ -666,7 +684,7 @@
mutex_unlock(&local->mtx);
if (rc)
- ieee80211_scan_completed(&local->hw, true);
+ __ieee80211_scan_completed(&local->hw, true);
return;
}
@@ -676,7 +694,7 @@
* Avoid re-scheduling when the sdata is going away.
*/
if (!ieee80211_sdata_running(sdata)) {
- ieee80211_scan_completed(&local->hw, true);
+ __ieee80211_scan_completed(&local->hw, true);
return;
}
@@ -783,5 +801,5 @@
mutex_unlock(&local->mtx);
if (abortscan)
- ieee80211_scan_completed(&local->hw, true);
+ __ieee80211_scan_completed(&local->hw, true);
}