ieee802154: 6lowpan: improve packet registration

This patch improves the packet registration handling. Instead of
registration with module init we have a open count variable and
registration the lowpan packet handler when it's needed.

The open count variable should be protected by RTNL.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

1 files changed, 18 insertions, 12 deletions

diff --git a/net/ieee802154/6lowpan_rtnl.c b/net/ieee802154/6lowpan_rtnl.c
index c7e07b8a8f9f..da78fae5b301 100644
--- a/net/ieee802154/6lowpan_rtnl.c
+++ b/net/ieee802154/6lowpan_rtnl.c
@@ -58,6 +58,7 @@
 #include "reassembly.h"
 
 static LIST_HEAD(lowpan_devices);
+static int lowpan_open_count;
 
 /* private device info */
 struct lowpan_dev_info {
@@ -571,11 +572,17 @@ drop:
         return NET_RX_DROP;
 }
 
+static struct packet_type lowpan_packet_type = {
+        .type = htons(ETH_P_IEEE802154),
+        .func = lowpan_rcv,
+};
+
 static int lowpan_newlink(struct net *src_net, struct net_device *dev,
                           struct nlattr *tb[], struct nlattr *data[])
 {
         struct net_device *real_dev;
         struct lowpan_dev_record *entry;
+        int ret;
 
         pr_debug("adding new link\n");
 
@@ -610,9 +617,14 @@ static int lowpan_newlink(struct net *src_net, struct net_device *dev,
         list_add_tail(&entry->list, &lowpan_devices);
         mutex_unlock(&lowpan_dev_info(dev)->dev_list_mtx);
 
-        register_netdevice(dev);
+        ret = register_netdevice(dev);
+        if (ret >= 0) {
+                if (!lowpan_open_count)
+                        dev_add_pack(&lowpan_packet_type);
+                lowpan_open_count++;
+        }
 
-        return 0;
+        return ret;
 }
 
 static void lowpan_dellink(struct net_device *dev, struct list_head *head)
@@ -623,6 +635,10 @@ static void lowpan_dellink(struct net_device *dev, struct list_head *head)
 
         ASSERT_RTNL();
 
+        lowpan_open_count--;
+        if (!lowpan_open_count)
+                dev_remove_pack(&lowpan_packet_type);
+
         mutex_lock(&lowpan_dev_info(dev)->dev_list_mtx);
         list_for_each_entry_safe(entry, tmp, &lowpan_devices, list) {
                 if (entry->ldev == dev) {
@@ -685,11 +701,6 @@ static struct notifier_block lowpan_dev_notifier = {
         .notifier_call = lowpan_device_event,
 };
 
-static struct packet_type lowpan_packet_type = {
-        .type = htons(ETH_P_IEEE802154),
-        .func = lowpan_rcv,
-};
-
 static int __init lowpan_init_module(void)
 {
         int err = 0;
@@ -702,8 +713,6 @@ static int __init lowpan_init_module(void)
         if (err < 0)
                 goto out_frag;
 
-        dev_add_pack(&lowpan_packet_type);
-
         err = register_netdevice_notifier(&lowpan_dev_notifier);
         if (err < 0)
                 goto out_pack;
@@ -711,7 +720,6 @@ static int __init lowpan_init_module(void)
         return 0;
 
 out_pack:
-        dev_remove_pack(&lowpan_packet_type);
         lowpan_netlink_fini();
 out_frag:
         lowpan_net_frag_exit();
@@ -723,8 +731,6 @@ static void __exit lowpan_cleanup_module(void)
 {
         lowpan_netlink_fini();
 
-        dev_remove_pack(&lowpan_packet_type);
-
         lowpan_net_frag_exit();
 
         unregister_netdevice_notifier(&lowpan_dev_notifier);