target/linux/generic/patches-4.3/643-bridge_remove_ipv6_dependency.patch

   1 From: Jonas Gorski <jonas.gorski+openwrt@gmail.com>
   2 Subject: [PATCH] bridge: remove IPv6 depependency of bridge in 2.6.38+
   3
   4 Since 2.6.38 the bridge module has a dependency to IPv6 if IPv6 is
   5 enabled. Since the IPv6 module isn't exactly lightweight and bridge also
   6 only needs a single function from IPv6, it's rather easy to create a
   7 common "lib" module with a RCU pointer to the actual implementation, if
   8 the IPv6 module is loaded (although slightly hackish).
   9
  10 The codepath seems to be only taken when using IPv6, so there should be
  11 no negative side effects when IPv6 isn't loaded. I did not measure how
  12 big the performance impact is.
  13 ---
  14 --- a/include/net/addrconf.h
  15 +++ b/include/net/addrconf.h
  16 @@ -122,6 +122,12 @@ static inline int addrconf_ifid_eui48(u8
  17         return 0;
  18  }
  19
  20 +extern int                     (*ipv6_dev_get_saddr_hook)(struct net *net,
  21 +                                               const struct net_device *dev,
  22 +                                               const struct in6_addr *daddr,
  23 +                                               unsigned int prefs,
  24 +                                               struct in6_addr *saddr);
  25 +
  26  static inline unsigned long addrconf_timeout_fixup(u32 timeout,
  27                                                    unsigned int unit)
  28  {
  29 --- a/net/bridge/Kconfig
  30 +++ b/net/bridge/Kconfig
  31 @@ -6,7 +6,6 @@ config BRIDGE
  32         tristate "802.1d Ethernet Bridging"
  33         select LLC
  34         select STP
  35 -       depends on IPV6 || IPV6=n
  36         ---help---
  37           If you say Y here, then your Linux box will be able to act as an
  38           Ethernet bridge, which means that the different Ethernet segments it
  39 --- a/net/ipv6/Makefile
  40 +++ b/net/ipv6/Makefile
  41 @@ -46,6 +46,7 @@ obj-y += addrconf_core.o exthdrs_core.o
  42  obj-$(CONFIG_INET) += output_core.o protocol.o $(ipv6-offload)
  43
  44  obj-$(subst m,y,$(CONFIG_IPV6)) += inet6_hashtables.o
  45 +obj-$(subst m,y,$(CONFIG_IPV6)) += inet6_stubs.o
  46
  47  ifneq ($(CONFIG_IPV6),)
  48  obj-$(CONFIG_NET_UDP_TUNNEL) += ip6_udp_tunnel.o
  49 --- a/net/ipv6/addrconf.c
  50 +++ b/net/ipv6/addrconf.c
  51 @@ -1509,7 +1509,7 @@ out:
  52         return hiscore_idx;
  53  }
  54
  55 -int ipv6_dev_get_saddr(struct net *net, const struct net_device *dst_dev,
  56 +static int ___ipv6_dev_get_saddr(struct net *net, const struct net_device *dst_dev,
  57                        const struct in6_addr *daddr, unsigned int prefs,
  58                        struct in6_addr *saddr)
  59  {
  60 @@ -1579,7 +1579,6 @@ int ipv6_dev_get_saddr(struct net *net,
  61         in6_ifa_put(hiscore->ifa);
  62         return 0;
  63  }
  64 -EXPORT_SYMBOL(ipv6_dev_get_saddr);
  65
  66  int __ipv6_get_lladdr(struct inet6_dev *idev, struct in6_addr *addr,
  67                       u32 banned_flags)
  68 @@ -5941,6 +5940,9 @@ int __init addrconf_init(void)
  69
  70         ipv6_addr_label_rtnl_register();
  71
  72 +       BUG_ON(ipv6_dev_get_saddr_hook != NULL);
  73 +       rcu_assign_pointer(ipv6_dev_get_saddr_hook, ___ipv6_dev_get_saddr);
  74 +
  75         return 0;
  76  errout:
  77         rtnl_af_unregister(&inet6_ops);
  78 @@ -5960,6 +5962,9 @@ void addrconf_cleanup(void)
  79         struct net_device *dev;
  80         int i;
  81
  82 +       rcu_assign_pointer(ipv6_dev_get_saddr_hook, NULL);
  83 +       synchronize_rcu();
  84 +
  85         unregister_netdevice_notifier(&ipv6_dev_notf);
  86         unregister_pernet_subsys(&addrconf_ops);
  87         ipv6_addr_label_cleanup();
  88 --- /dev/null
  89 +++ b/net/ipv6/inet6_stubs.c
  90 @@ -0,0 +1,33 @@
  91 +/*
  92 + *      This program is free software; you can redistribute it and/or
  93 + *      modify it under the terms of the GNU General Public License
  94 + *      as published by the Free Software Foundation; either version
  95 + *      2 of the License, or (at your option) any later version.
  96 + */
  97 +#include <linux/export.h>
  98 +#include <net/ipv6.h>
  99 +
 100 +int (*ipv6_dev_get_saddr_hook)(struct net *net, const struct net_device *dev,
 101 +                       const struct in6_addr *daddr, unsigned int prefs,
 102 +                       struct in6_addr *saddr);
 103 +
 104 +EXPORT_SYMBOL(ipv6_dev_get_saddr_hook);
 105 +
 106 +int ipv6_dev_get_saddr(struct net *net, const struct net_device *dst_dev,
 107 +                       const struct in6_addr *daddr, unsigned int prefs,
 108 +                       struct in6_addr *saddr)
 109 +{
 110 +       int ret = -EADDRNOTAVAIL;
 111 +       typeof(ipv6_dev_get_saddr_hook) dev_get_saddr;
 112 +
 113 +       rcu_read_lock();
 114 +       dev_get_saddr = rcu_dereference(ipv6_dev_get_saddr_hook);
 115 +
 116 +       if (dev_get_saddr)
 117 +               ret = dev_get_saddr(net, dst_dev, daddr, prefs, saddr);
 118 +
 119 +       rcu_read_unlock();
 120 +       return ret;
 121 +}
 122 +EXPORT_SYMBOL(ipv6_dev_get_saddr);
 123 +