wireless : use a dedicated workqueue for cfg80211.

This patch moves the works cleanup, scan and events to a cfg80211
dedicated workqueue.

Platform driver like eeepc-laptop ought to use works to rfkill (as
new rfkill does lock in rfkill_unregister and the platform driver is
called from rfkill_switch_all which also lock the same mutex).
This raise a new issue in itself that the work scheduled by the platform
driver to the global worqueue calls wiphy_unregister which flush_work
scan and event works (which thus flush works on the global workqueue inside
a work on the global workqueue) and also put on hold the  wdev_cleanup_work
 (which prevents the dev_put on netdev thus indefinite Usage count error on
wifi device).

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Alban Browaeys <prahal@yahoo.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/net/wireless/core.c b/net/wireless/core.c
index fe6f402a22af..c2a2c563d21a 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -45,6 +45,9 @@ DEFINE_MUTEX(cfg80211_mutex);
 /* for debugfs */
 static struct dentry *ieee80211_debugfs_dir;
 
+/* for the cleanup, scan and event works */
+struct workqueue_struct *cfg80211_wq;
+
 /* requires cfg80211_mutex to be held! */
 struct cfg80211_registered_device *cfg80211_rdev_by_wiphy_idx(int wiphy_idx)
 {
@@ -727,7 +730,7 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb,
                 break;
         case NETDEV_DOWN:
                 dev_hold(dev);
-                schedule_work(&wdev->cleanup_work);
+                queue_work(cfg80211_wq, &wdev->cleanup_work);
                 break;
         case NETDEV_UP:
                 /*
@@ -845,8 +848,14 @@ static int __init cfg80211_init(void)
         if (err)
                 goto out_fail_reg;
 
+        cfg80211_wq = create_singlethread_workqueue("cfg80211");
+        if (!cfg80211_wq)
+                goto out_fail_wq;
+
         return 0;
 
+out_fail_wq:
+        regulatory_exit();
 out_fail_reg:
         debugfs_remove(ieee80211_debugfs_dir);
 out_fail_nl80211:
@@ -868,5 +877,6 @@ static void cfg80211_exit(void)
         wiphy_sysfs_exit();
         regulatory_exit();
         unregister_pernet_device(&cfg80211_pernet_ops);
+        destroy_workqueue(cfg80211_wq);
 }
 module_exit(cfg80211_exit);