6lowpan: iphc: add support for stateful compression

This patch introduce support for IPHC stateful address compression. It
will offer the context table via one debugfs entry.
This debugfs has and directory for each cid entry for the context table.
Inside each cid directory there exists the following files:

 - "active": If the entry is added or deleted. The context table is
   original a list implementation, this flag will indicate if the
   context is part of list or not.
 - "prefix": The ipv6 prefix.
 - "prefix_length": The prefix length for the prefix.
 - "compression": The compression flag according RFC6775.

This part should be moved into sysfs after some testing time.

Also the debugfs entry contains a "show" file which is a pretty-printout
for the current context table information.

Reviewed-by: Stefan Schmidt <stefan@osg.samsung.com>
Signed-off-by: Alexander Aring <aar@pengutronix.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

1 files changed, 38 insertions, 1 deletions

diff --git a/net/6lowpan/core.c b/net/6lowpan/core.c
index faf65baed617..34e44c0c0836 100644
--- a/net/6lowpan/core.c
+++ b/net/6lowpan/core.c
@@ -20,7 +20,7 @@
 int lowpan_register_netdevice(struct net_device *dev,
 			      enum lowpan_lltypes lltype)
 {
-	int ret;
+	int i, ret;
 
 	dev->addr_len = EUI64_ADDR_LEN;
 	dev->type = ARPHRD_6LOWPAN;
@@ -29,6 +29,10 @@ int lowpan_register_netdevice(struct net_device *dev,
 
 	lowpan_priv(dev)->lltype = lltype;
 
+	spin_lock_init(&lowpan_priv(dev)->ctx.lock);
+	for (i = 0; i < LOWPAN_IPHC_CTX_TABLE_SIZE; i++)
+		lowpan_priv(dev)->ctx.table[i].id = i;
+
 	ret = register_netdevice(dev);
 	if (ret < 0)
 		return ret;
@@ -68,6 +72,32 @@ void lowpan_unregister_netdev(struct net_device *dev)
 }
 EXPORT_SYMBOL(lowpan_unregister_netdev);
 
+static int lowpan_event(struct notifier_block *unused,
+			unsigned long event, void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	int i;
+
+	if (dev->type != ARPHRD_6LOWPAN)
+		return NOTIFY_DONE;
+
+	switch (event) {
+	case NETDEV_DOWN:
+		for (i = 0; i < LOWPAN_IPHC_CTX_TABLE_SIZE; i++)
+			clear_bit(LOWPAN_IPHC_CTX_FLAG_ACTIVE,
+				  &lowpan_priv(dev)->ctx.table[i].flags);
+		break;
+	default:
+		return NOTIFY_DONE;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block lowpan_notifier = {
+	.notifier_call = lowpan_event,
+};
+
 static int __init lowpan_module_init(void)
 {
 	int ret;
@@ -76,6 +106,12 @@ static int __init lowpan_module_init(void)
 	if (ret < 0)
 		return ret;
 
+	ret = register_netdevice_notifier(&lowpan_notifier);
+	if (ret < 0) {
+		lowpan_debugfs_exit();
+		return ret;
+	}
+
 	request_module_nowait("ipv6");
 
 	request_module_nowait("nhc_dest");
@@ -92,6 +128,7 @@ static int __init lowpan_module_init(void)
 static void __exit lowpan_module_exit(void)
 {
 	lowpan_debugfs_exit();
+	unregister_netdevice_notifier(&lowpan_notifier);
 }
 
 module_init(lowpan_module_init);