[PATCH] ieee80211: Fix kernel Oops when module unload

tree b69e983266840983183a00f5ac02c66d5270ca47
parent cdd6372949b76694622ed74fe36e1dd17a92eb71
author Zhu Yi <jketreno@io.(none)> 1124435425 -0500
committer James Ketrenos <jketreno@linux.intel.com> 1127312421 -0500

Fix kernel Oops when module unload.

Export a new function ieee80211_crypt_quiescing from ieee80211. Device
drivers call it to make the host crypto stack enter the quiescence
state, which means "process existing requests, but don't accept new
ones". This is usually called during a driver's host crypto data
structure free (module unload) path.
Signed-off-by: James Ketrenos <jketreno@linux.intel.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

include/net/ieee80211.h

@@ -684,6 +684,7 @@ struct ieee80211_device {
 	struct ieee80211_crypt_data *crypt[WEP_KEYS];
 	int tx_keyidx;		/* default TX key index (crypt[tx_keyidx]) */
 	struct timer_list crypt_deinit_timer;
+	int crypt_quiesced;
 
 	int bcrx_sta_key;	/* use individual keys to override default keys even
 				 * with RX of broad/multicast frames */

include/net/ieee80211_crypt.h

@@ -82,5 +82,6 @@ void ieee80211_crypt_deinit_entries(struct ieee80211_device *, int);
 void ieee80211_crypt_deinit_handler(unsigned long);
 void ieee80211_crypt_delayed_deinit(struct ieee80211_device *ieee,
 				    struct ieee80211_crypt_data **crypt);
+void ieee80211_crypt_quiescing(struct ieee80211_device *ieee);
 
 #endif

net/ieee80211/ieee80211_crypt.c

@@ -44,6 +44,10 @@ void ieee80211_crypt_deinit_entries(struct ieee80211_device *ieee, int force)
 	unsigned long flags;
 
 	spin_lock_irqsave(&ieee->lock, flags);
+
+	if (list_empty(&ieee->crypt_deinit_list))
+		goto unlock;
+
 	for (ptr = ieee->crypt_deinit_list.next, n = ptr->next;
 	     ptr != &ieee->crypt_deinit_list; ptr = n, n = ptr->next) {
 		entry = list_entry(ptr, struct ieee80211_crypt_data, list);
@@ -59,21 +63,35 @@ void ieee80211_crypt_deinit_entries(struct ieee80211_device *ieee, int force)
 		}
 		kfree(entry);
 	}
+      unlock:
+	spin_unlock_irqrestore(&ieee->lock, flags);
+}
+
+/* After this, crypt_deinit_list won't accept new members */
+void ieee80211_crypt_quiescing(struct ieee80211_device *ieee)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ieee->lock, flags);
+	ieee->crypt_quiesced = 1;
 	spin_unlock_irqrestore(&ieee->lock, flags);
 }
 
 void ieee80211_crypt_deinit_handler(unsigned long data)
 {
 	struct ieee80211_device *ieee = (struct ieee80211_device *)data;
+	unsigned long flags;
 
 	ieee80211_crypt_deinit_entries(ieee, 0);
-	if (!list_empty(&ieee->crypt_deinit_list)) {
+
+	spin_lock_irqsave(&ieee->lock, flags);
+	if (!list_empty(&ieee->crypt_deinit_list) && !ieee->crypt_quiesced) {
 		printk(KERN_DEBUG "%s: entries remaining in delayed crypt "
 		       "deletion list\n", ieee->dev->name);
 		ieee->crypt_deinit_timer.expires = jiffies + HZ;
 		add_timer(&ieee->crypt_deinit_timer);
 	}
-
+	spin_unlock_irqrestore(&ieee->lock, flags);
 }
 
 void ieee80211_crypt_delayed_deinit(struct ieee80211_device *ieee,
@@ -93,10 +111,12 @@ void ieee80211_crypt_delayed_deinit(struct ieee80211_device *ieee,
 	 * locking. */
 
 	spin_lock_irqsave(&ieee->lock, flags);
-	list_add(&tmp->list, &ieee->crypt_deinit_list);
-	if (!timer_pending(&ieee->crypt_deinit_timer)) {
-		ieee->crypt_deinit_timer.expires = jiffies + HZ;
-		add_timer(&ieee->crypt_deinit_timer);
+	if (!ieee->crypt_quiesced) {
+		list_add(&tmp->list, &ieee->crypt_deinit_list);
+		if (!timer_pending(&ieee->crypt_deinit_timer)) {
+			ieee->crypt_deinit_timer.expires = jiffies + HZ;
+			add_timer(&ieee->crypt_deinit_timer);
+		}
 	}
 	spin_unlock_irqrestore(&ieee->lock, flags);
 }
@@ -250,6 +270,7 @@ static void __exit ieee80211_crypto_deinit(void)
 EXPORT_SYMBOL(ieee80211_crypt_deinit_entries);
 EXPORT_SYMBOL(ieee80211_crypt_deinit_handler);
 EXPORT_SYMBOL(ieee80211_crypt_delayed_deinit);
+EXPORT_SYMBOL(ieee80211_crypt_quiescing);
 
 EXPORT_SYMBOL(ieee80211_register_crypto_ops);
 EXPORT_SYMBOL(ieee80211_unregister_crypto_ops);

net/ieee80211/ieee80211_module.c

@@ -138,6 +138,7 @@ struct net_device *alloc_ieee80211(int sizeof_priv)
 	init_timer(&ieee->crypt_deinit_timer);
 	ieee->crypt_deinit_timer.data = (unsigned long)ieee;
 	ieee->crypt_deinit_timer.function = ieee80211_crypt_deinit_handler;
+	ieee->crypt_quiesced = 0;
 
 	spin_lock_init(&ieee->lock);
 
@@ -161,6 +162,7 @@ void free_ieee80211(struct net_device *dev)
 
 	int i;
 
+	ieee80211_crypt_quiescing(ieee);
 	del_timer_sync(&ieee->crypt_deinit_timer);
 	ieee80211_crypt_deinit_entries(ieee, 1);