From 9df35800656ecb680d2cc52d5c49c3cb0508a51e Mon Sep 17 00:00:00 2001
From: hartkopp <hartkopp@030b6a49-0b11-0410-94ab-b0dab22257f2>
Date: Sun, 24 Jan 2010 21:35:06 +0000
Subject: [PATCH] Consistently clean up the reference dev->ml_priv when the
 device receiver list is (to be) removed. Cleanly separate
 find_dev_rcv_lists() function for 2.6.26+ as we do not need the fallback.

git-svn-id: svn://svn.berlios.de//socketcan/trunk@1119 030b6a49-0b11-0410-94ab-b0dab22257f2
---
 kernel/2.6/net/can/af_can.c | 38 +++++++++++++++++++++++--------------
 1 file changed, 24 insertions(+), 14 deletions(-)

diff --git a/kernel/2.6/net/can/af_can.c b/kernel/2.6/net/can/af_can.c
index 5f37132..14dbba5 100644
--- a/kernel/2.6/net/can/af_can.c
+++ b/kernel/2.6/net/can/af_can.c
@@ -373,33 +373,34 @@ EXPORT_SYMBOL(can_send);
  * af_can rx path
  */
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,26)
 static struct dev_rcv_lists *find_dev_rcv_lists(struct net_device *dev)
 {
-	struct dev_rcv_lists *d = NULL;
-	struct hlist_node *n;
-
-	/* find receive list for this device */
-
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,26)
 	/*
+	 * find receive list for this device
+	 *
 	 * Since 2.6.26 a new "midlevel private" ml_priv pointer has been
 	 * introduced in struct net_device. We use this pointer to omit the
 	 * linear walk through the can_rx_dev_list. A similar speedup has been
 	 * queued for 2.6.34 mainline but using the new netdev_rcu lists.
+	 * Therefore the can_rx_dev_list is still needed (e.g. in proc.c)
 	 */
 
 	/* dev == NULL is the indicator for the 'all' filterlist */
 	if (!dev)
 		return &can_rx_alldev_list;
-
-	/* do not search in rcu list when we have a direct reference */
-	if (dev->ml_priv)
+	else
 		return (struct dev_rcv_lists *)dev->ml_priv;
-
-	/* fall back to standard behaviour */
-#endif
+}
+#else
+static struct dev_rcv_lists *find_dev_rcv_lists(struct net_device *dev)
+{
+	struct dev_rcv_lists *d = NULL;
+	struct hlist_node *n;
 
 	/*
+	 * find receive list for this device
+	 *
 	 * The hlist_for_each_entry*() macros curse through the list
 	 * using the pointer variable n and set d to the containing
 	 * struct in each list iteration.  Therefore, after list
@@ -417,6 +418,7 @@ static struct dev_rcv_lists *find_dev_rcv_lists(struct net_device *dev)
 
 	return n ? d : NULL;
 }
+#endif
 
 /**
  * find_rcv_list - determine optimal filterlist inside device filter struct
@@ -654,9 +656,12 @@ void can_rx_unregister(struct net_device *dev, canid_t can_id, canid_t mask,
 		can_pstats.rcv_entries--;
 
 	/* remove device structure requested by NETDEV_UNREGISTER */
-	if (d->remove_on_zero_entries && !d->entries)
+	if (d->remove_on_zero_entries && !d->entries) {
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,26)
+		dev->ml_priv = NULL;
+#endif
 		hlist_del_rcu(&d->list);
-	else
+	} else
 		d = NULL;
 
  out:
@@ -934,6 +939,7 @@ static int can_notifier(struct notifier_block *nb, unsigned long msg,
 
 		spin_lock(&can_rcvlists_lock);
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,26)
+		BUG_ON(dev->ml_priv);
 		dev->ml_priv = d;
 #endif
 		hlist_add_head_rcu(&d->list, &can_rx_dev_list);
@@ -1056,6 +1062,10 @@ static __exit void can_exit(void)
 	hlist_del(&can_rx_alldev_list.list);
 	hlist_for_each_entry_safe(d, n, next, &can_rx_dev_list, list) {
 		hlist_del(&d->list);
+		BUG_ON(d->entries);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,26)
+		d->dev->ml_priv = NULL;
+#endif
 		kfree(d);
 	}
 	spin_unlock(&can_rcvlists_lock);
-- 
2.39.2