cfg80211: pmsr: fix abort locking

When we destroy the interface we already hold the wdev->mtx
while calling cfg80211_pmsr_wdev_down(), which assumes this
isn't true and flushes the worker that takes the lock, thus
leading to a deadlock.

Fix this by refactoring the worker and calling its code in
cfg80211_pmsr_wdev_down() directly.

We still need to flush the work later to make sure it's not
still running and will crash, but it will not do anything.

Fixes: 9bb7e0f24e7e ("cfg80211: add peer measurement with FTM initiator API")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 623dfe5..b36ad8e 100644 (file)
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -1068,6 +1068,8 @@ static void __cfg80211_unregister_wdev(struct wireless_dev *wdev, bool sync)
 
        ASSERT_RTNL();
 
+       flush_work(&wdev->pmsr_free_wk);
+
        nl80211_notify_iface(rdev, wdev, NL80211_CMD_DEL_INTERFACE);
 
        list_del_rcu(&wdev->list);

diff --git a/net/wireless/pmsr.c b/net/wireless/pmsr.c
index f2e388e..78c3f56 100644 (file)
--- a/net/wireless/pmsr.c
+++ b/net/wireless/pmsr.c
@@ -529,14 +529,14 @@ free:
 }
 EXPORT_SYMBOL_GPL(cfg80211_pmsr_report);
 
-void cfg80211_pmsr_free_wk(struct work_struct *work)
+static void cfg80211_pmsr_process_abort(struct wireless_dev *wdev)
 {
-       struct wireless_dev *wdev = container_of(work, struct wireless_dev,
-                                                pmsr_free_wk);
        struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
        struct cfg80211_pmsr_request *req, *tmp;
        LIST_HEAD(free_list);
 
+       lockdep_assert_held(&wdev->mtx);
+
        spin_lock_bh(&wdev->pmsr_lock);
        list_for_each_entry_safe(req, tmp, &wdev->pmsr_list, list) {
                if (req->nl_portid)
@@ -546,14 +546,22 @@ void cfg80211_pmsr_free_wk(struct work_struct *work)
        spin_unlock_bh(&wdev->pmsr_lock);
 
        list_for_each_entry_safe(req, tmp, &free_list, list) {
-               wdev_lock(wdev);
                rdev_abort_pmsr(rdev, wdev, req);
-               wdev_unlock(wdev);
 
                kfree(req);
        }
 }
 
+void cfg80211_pmsr_free_wk(struct work_struct *work)
+{
+       struct wireless_dev *wdev = container_of(work, struct wireless_dev,
+                                                pmsr_free_wk);
+
+       wdev_lock(wdev);
+       cfg80211_pmsr_process_abort(wdev);
+       wdev_unlock(wdev);
+}
+
 void cfg80211_pmsr_wdev_down(struct wireless_dev *wdev)
 {
        struct cfg80211_pmsr_request *req;
@@ -567,8 +575,8 @@ void cfg80211_pmsr_wdev_down(struct wireless_dev *wdev)
        spin_unlock_bh(&wdev->pmsr_lock);
 
        if (found)
-               schedule_work(&wdev->pmsr_free_wk);
-       flush_work(&wdev->pmsr_free_wk);
+               cfg80211_pmsr_process_abort(wdev);
+
        WARN_ON(!list_empty(&wdev->pmsr_list));
 }