[patch 04/11] net: configure out IGMP support

[patch 04/11] net: configure out IGMP support

[akpm]

From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

tAdd adds the CONFIG_IGMP option which allows to remove support for the
Internet Group Management Protocol, used in multicast.  Multicast is not
necessarly used by applications, particularly on embedded devices.  As
this is a size-reduction option, it depends on CONFIG_EMBEDDED.  It allows
to save ~10 kilobytes of kernel code/data:

   text	   data	    bss	    dec	    hex	filename
1718857	 143672	 221184	2083713	 1fcb81	vmlinux
1708838	 143640	 221184	2073662	 1fa43e	vmlinux.new
 -10019     -32       0  -10051   -2743 +/-

This patch has been originally written by Matt Mackall <mpm@selenic.com>,
and is part of the Linux Tiny project.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/igmp.h       |   20 ++++++++++++++++++++
 init/Kconfig               |    8 ++++++++
 net/ipv4/Makefile          |    3 ++-
 net/ipv4/af_inet.c         |    2 --
 net/ipv4/ip_sockglue.c     |    4 ++++
 net/ipv4/sysctl_net_ipv4.c |    2 ++
 6 files changed, 36 insertions(+), 3 deletions(-)

diff -puN include/linux/igmp.h~configure-out-igmp-support include/linux/igmp.h
--- a/include/linux/igmp.h~configure-out-igmp-support
+++ a/include/linux/igmp.h
@@ -215,6 +215,7 @@ struct ip_mc_list
 #define IGMPV3_QQIC(value) IGMPV3_EXP(0x80, 4, 3, value)
 #define IGMPV3_MRC(value) IGMPV3_EXP(0x80, 4, 3, value)
 
+#ifdef CONFIG_IGMP
 extern int ip_check_mc(struct in_device *dev, __be32 mc_addr, __be32 src_addr, u16 proto);
 extern int igmp_rcv(struct sk_buff *);
 extern int ip_mc_join_group(struct sock *sk, struct ip_mreqn *imr);
@@ -235,6 +236,25 @@ extern void ip_mc_down(struct in_device 
 extern void ip_mc_dec_group(struct in_device *in_dev, __be32 addr);
 extern void ip_mc_inc_group(struct in_device *in_dev, __be32 addr);
 extern void ip_mc_rejoin_group(struct ip_mc_list *im);
+#else /* !CONFIG_IGMP */
+#define ip_check_mc(a, b, c, d) (0)
+#define igmp_rcv(a) (0)
+#define ip_mc_join_group(a, b) (0)
+#define ip_mc_leave_group(a, b) (0)
+#define ip_mc_drop_socket(a)
+#define ip_mc_source(a, b, c, d, e) (0)
+#define ip_mc_msfilter(a, b, c) (0)
+#define ip_mc_msfget(a, b, c, d) (0)
+#define ip_mc_gsfget(a, b, c, d) (0)
+#define ip_mc_sf_allow(a, b, c, d) (0)
+#define ip_mc_init_dev(a)
+#define ip_mc_destroy_dev(a)
+#define ip_mc_up(a)
+#define ip_mc_down(a)
+#define ip_mc_dec_group(a)
+#define ip_mc_inc_group(a)
+#define ip_mc_rejoin_group(a)
+#endif /* CONFIG_IGMP */
 
 #endif
 #endif
diff -puN init/Kconfig~configure-out-igmp-support init/Kconfig
--- a/init/Kconfig~configure-out-igmp-support
+++ a/init/Kconfig
@@ -724,6 +724,14 @@ config SHMEM
 	  option replaces shmem and tmpfs with the much simpler ramfs code,
 	  which may be appropriate on small systems without swap.
 
+config IGMP
+	depends on INET
+	bool "Enable IGMP support" if EMBEDDED && !IP_MULTICAST
+	default y
+	help
+	  Disabling this option removes support for the Internet group
+          management protocol, used for multicast. Saves about 10k.
+
 config VM_EVENT_COUNTERS
 	default y
 	bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
diff -puN net/ipv4/Makefile~configure-out-igmp-support net/ipv4/Makefile
--- a/net/ipv4/Makefile~configure-out-igmp-support
+++ a/net/ipv4/Makefile
@@ -9,13 +9,14 @@ obj-y     := route.o inetpeer.o protocol
 	     tcp.o tcp_input.o tcp_output.o tcp_timer.o tcp_ipv4.o \
 	     tcp_minisocks.o tcp_cong.o \
 	     datagram.o raw.o udp.o udplite.o \
-	     arp.o icmp.o devinet.o af_inet.o  igmp.o \
+	     arp.o icmp.o devinet.o af_inet.o \
 	     fib_frontend.o fib_semantics.o \
 	     inet_fragment.o
 
 obj-$(CONFIG_SYSCTL) += sysctl_net_ipv4.o
 obj-$(CONFIG_IP_FIB_HASH) += fib_hash.o
 obj-$(CONFIG_IP_FIB_TRIE) += fib_trie.o
+obj-$(CONFIG_IGMP) += igmp.o
 obj-$(CONFIG_PROC_FS) += proc.o
 obj-$(CONFIG_IP_MULTIPLE_TABLES) += fib_rules.o
 obj-$(CONFIG_IP_MROUTE) += ipmr.o
diff -puN net/ipv4/af_inet.c~configure-out-igmp-support net/ipv4/af_inet.c
--- a/net/ipv4/af_inet.c~configure-out-igmp-support
+++ a/net/ipv4/af_inet.c
@@ -115,8 +115,6 @@
 #include <linux/mroute.h>
 #endif
 
-extern void ip_mc_drop_socket(struct sock *sk);
-
 /* The inetsw table contains everything that inet_create needs to
  * build a new socket.
  */
diff -puN net/ipv4/ip_sockglue.c~configure-out-igmp-support net/ipv4/ip_sockglue.c
--- a/net/ipv4/ip_sockglue.c~configure-out-igmp-support
+++ a/net/ipv4/ip_sockglue.c
@@ -640,6 +640,7 @@ static int do_ip_setsockopt(struct sock 
 			err = ip_mc_leave_group(sk, &mreq);
 		break;
 	}
+#ifdef CONFIG_IGMP
 	case IP_MSFILTER:
 	{
 		extern int sysctl_igmp_max_msf;
@@ -677,6 +678,7 @@ static int do_ip_setsockopt(struct sock 
 		kfree(msf);
 		break;
 	}
+#endif
 	case IP_BLOCK_SOURCE:
 	case IP_UNBLOCK_SOURCE:
 	case IP_ADD_SOURCE_MEMBERSHIP:
@@ -794,6 +796,7 @@ static int do_ip_setsockopt(struct sock 
 				   greqs.gsr_interface);
 		break;
 	}
+#ifdef CONFIG_IGMP
 	case MCAST_MSFILTER:
 	{
 		extern int sysctl_igmp_max_msf;
@@ -860,6 +863,7 @@ static int do_ip_setsockopt(struct sock 
 		kfree(gsf);
 		break;
 	}
+#endif
 	case IP_ROUTER_ALERT:
 		err = ip_ra_control(sk, val ? 1 : 0, NULL);
 		break;
diff -puN net/ipv4/sysctl_net_ipv4.c~configure-out-igmp-support net/ipv4/sysctl_net_ipv4.c
--- a/net/ipv4/sysctl_net_ipv4.c~configure-out-igmp-support
+++ a/net/ipv4/sysctl_net_ipv4.c
@@ -412,6 +412,7 @@ static struct ctl_table ipv4_table[] = {
 	},
 
 #endif
+#ifdef CONFIG_IGMP
 	{
 		.ctl_name	= NET_IPV4_IGMP_MAX_MSF,
 		.procname	= "igmp_max_msf",
@@ -420,6 +421,7 @@ static struct ctl_table ipv4_table[] = {
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec
 	},
+#endif
 	{
 		.ctl_name	= NET_IPV4_INET_PEER_THRESHOLD,
 		.procname	= "inet_peer_threshold",
_

Re: [patch 04/11] net: configure out IGMP support

[David Miller]

From: akpm@linux-foundation.org
Date: Wed, 30 Jul 2008 12:37:36 -0700

> From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> 
> tAdd adds the CONFIG_IGMP option which allows to remove support for the
> Internet Group Management Protocol, used in multicast.  Multicast is not
> necessarly used by applications, particularly on embedded devices.  As
> this is a size-reduction option, it depends on CONFIG_EMBEDDED.  It allows
> to save ~10 kilobytes of kernel code/data:
> 
>    text	   data	    bss	    dec	    hex	filename
> 1718857	 143672	 221184	2083713	 1fcb81	vmlinux
> 1708838	 143640	 221184	2073662	 1fa43e	vmlinux.new
>  -10019     -32       0  -10051   -2743 +/-
> 
> This patch has been originally written by Matt Mackall <mpm@selenic.com>,
> and is part of the Linux Tiny project.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> Cc: Matt Mackall <mpm@selenic.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

I'm not applying this.

This removes core parts of the BSD socket API from applications.
Like TCP and UDP, multicast capabilities are something applications
can always depend upon being available.

If you want a broken networking implementation, you have the source
code, so you can do it in your own tree.

Re: [patch 04/11] net: configure out IGMP support

[Andrew Morton]

On Wed, 30 Jul 2008 14:45:21 -0700 (PDT)
David Miller <davem@davemloft.net> wrote:

> From: akpm@linux-foundation.org
> Date: Wed, 30 Jul 2008 12:37:36 -0700
> 
> > From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> > 
> > tAdd adds the CONFIG_IGMP option which allows to remove support for the
> > Internet Group Management Protocol, used in multicast.  Multicast is not
> > necessarly used by applications, particularly on embedded devices.  As
> > this is a size-reduction option, it depends on CONFIG_EMBEDDED.  It allows
> > to save ~10 kilobytes of kernel code/data:
> > 
> >    text	   data	    bss	    dec	    hex	filename
> > 1718857	 143672	 221184	2083713	 1fcb81	vmlinux
> > 1708838	 143640	 221184	2073662	 1fa43e	vmlinux.new
> >  -10019     -32       0  -10051   -2743 +/-
> > 
> > This patch has been originally written by Matt Mackall <mpm@selenic.com>,
> > and is part of the Linux Tiny project.
> > 
> > Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> > Cc: Matt Mackall <mpm@selenic.com>
> > Cc: "David S. Miller" <davem@davemloft.net>
> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> 
> I'm not applying this.
> 
> This removes core parts of the BSD socket API from applications.
> Like TCP and UDP, multicast capabilities are something applications
> can always depend upon being available.

That's just a bogus argument.  Embedded device developers have 100%
control over 100% of the applications which run on their devices.  If
they know that their applications don't use multicast then those devices
won't use multicast.   Ever.