cfg80211: allow mgmt_frame_register callback to sleep

This callback is currently not allowed to sleep, which makes it more
difficult to implement proper driver methods in mac80211 than it has
to be. Instead of doing asynchronous work here in mac80211, make it
possible for the callback to sleep by doing some asynchronous work
in cfg80211. This also enables improvements to other drivers, like
ath6kl, that would like to sleep in this callback.

While at it, also fix the code to call the driver on the implicit
unregistration when an interface is removed, and do that also when
a P2P-Device wdev is destroyed (otherwise we leak the structs.)

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

1 files changed, 60 insertions, 15 deletions

diff --git a/net/wireless/mlme.c b/net/wireless/mlme.c
index 7aae329e2b4e..fb44fa3bf4ef 100644
--- a/net/wireless/mlme.c
+++ b/net/wireless/mlme.c
@@ -2,6 +2,7 @@
  * cfg80211 MLME SAP interface
  *
  * Copyright (c) 2009, Jouni Malinen <j@w1.fi>
+ * Copyright (c) 2015		Intel Deutschland GmbH
  */
 
 #include <linux/kernel.h>
@@ -389,6 +390,7 @@ void cfg80211_mlme_down(struct cfg80211_registered_device *rdev,
 
 struct cfg80211_mgmt_registration {
 	struct list_head list;
+	struct wireless_dev *wdev;
 
 	u32 nlportid;
 
@@ -399,6 +401,46 @@ struct cfg80211_mgmt_registration {
 	u8 match[];
 };
 
+static void
+cfg80211_process_mlme_unregistrations(struct cfg80211_registered_device *rdev)
+{
+	struct cfg80211_mgmt_registration *reg;
+
+	ASSERT_RTNL();
+
+	spin_lock_bh(&rdev->mlme_unreg_lock);
+	while ((reg = list_first_entry_or_null(&rdev->mlme_unreg,
+					       struct cfg80211_mgmt_registration,
+					       list))) {
+		list_del(&reg->list);
+		spin_unlock_bh(&rdev->mlme_unreg_lock);
+
+		if (rdev->ops->mgmt_frame_register) {
+			u16 frame_type = le16_to_cpu(reg->frame_type);
+
+			rdev_mgmt_frame_register(rdev, reg->wdev,
+						 frame_type, false);
+		}
+
+		kfree(reg);
+
+		spin_lock_bh(&rdev->mlme_unreg_lock);
+	}
+	spin_unlock_bh(&rdev->mlme_unreg_lock);
+}
+
+void cfg80211_mlme_unreg_wk(struct work_struct *wk)
+{
+	struct cfg80211_registered_device *rdev;
+
+	rdev = container_of(wk, struct cfg80211_registered_device,
+			    mlme_unreg_wk);
+
+	rtnl_lock();
+	cfg80211_process_mlme_unregistrations(rdev);
+	rtnl_unlock();
+}
+
 int cfg80211_mlme_register_mgmt(struct wireless_dev *wdev, u32 snd_portid,
 				u16 frame_type, const u8 *match_data,
 				int match_len)
@@ -449,11 +491,18 @@ int cfg80211_mlme_register_mgmt(struct wireless_dev *wdev, u32 snd_portid,
 	nreg->match_len = match_len;
 	nreg->nlportid = snd_portid;
 	nreg->frame_type = cpu_to_le16(frame_type);
+	nreg->wdev = wdev;
 	list_add(&nreg->list, &wdev->mgmt_registrations);
+	spin_unlock_bh(&wdev->mgmt_registrations_lock);
+
+	/* process all unregistrations to avoid driver confusion */
+	cfg80211_process_mlme_unregistrations(rdev);
 
 	if (rdev->ops->mgmt_frame_register)
 		rdev_mgmt_frame_register(rdev, wdev, frame_type, true);
 
+	return 0;
+
  out:
 	spin_unlock_bh(&wdev->mgmt_registrations_lock);
 
@@ -472,15 +521,12 @@ void cfg80211_mlme_unregister_socket(struct wireless_dev *wdev, u32 nlportid)
 		if (reg->nlportid != nlportid)
 			continue;
 
-		if (rdev->ops->mgmt_frame_register) {
-			u16 frame_type = le16_to_cpu(reg->frame_type);
-
-			rdev_mgmt_frame_register(rdev, wdev,
-						 frame_type, false);
-		}
-
 		list_del(&reg->list);
-		kfree(reg);
+		spin_lock(&rdev->mlme_unreg_lock);
+		list_add_tail(&reg->list, &rdev->mlme_unreg);
+		spin_unlock(&rdev->mlme_unreg_lock);
+
+		schedule_work(&rdev->mlme_unreg_wk);
 	}
 
 	spin_unlock_bh(&wdev->mgmt_registrations_lock);
@@ -496,16 +542,15 @@ void cfg80211_mlme_unregister_socket(struct wireless_dev *wdev, u32 nlportid)
 
 void cfg80211_mlme_purge_registrations(struct wireless_dev *wdev)
 {
-	struct cfg80211_mgmt_registration *reg, *tmp;
+	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
 
 	spin_lock_bh(&wdev->mgmt_registrations_lock);
-
-	list_for_each_entry_safe(reg, tmp, &wdev->mgmt_registrations, list) {
-		list_del(&reg->list);
-		kfree(reg);
-	}
-
+	spin_lock(&rdev->mlme_unreg_lock);
+	list_splice_tail_init(&wdev->mgmt_registrations, &rdev->mlme_unreg);
+	spin_unlock(&rdev->mlme_unreg_lock);
 	spin_unlock_bh(&wdev->mgmt_registrations_lock);
+
+	cfg80211_process_mlme_unregistrations(rdev);
 }
 
 int cfg80211_mlme_mgmt_tx(struct cfg80211_registered_device *rdev,