This patchs 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
<[email protected]>, and is part of the Linux Tiny project.
Signed-off-by: Thomas Petazzoni <[email protected]>
Signed-off-by: Matt Mackall <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
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(-)
Index: linuxdev/include/linux/igmp.h
===================================================================
--- linuxdev.orig/include/linux/igmp.h
+++ linuxdev/include/linux/igmp.h
@@ -215,6 +215,7 @@
#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_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
Index: linuxdev/init/Kconfig
===================================================================
--- linuxdev.orig/init/Kconfig
+++ linuxdev/init/Kconfig
@@ -748,6 +748,14 @@
Disabling this option removes support for configuring
ethernet device features via ethtool. Saves about 6k.
+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
Index: linuxdev/net/ipv4/Makefile
===================================================================
--- linuxdev.orig/net/ipv4/Makefile
+++ linuxdev/net/ipv4/Makefile
@@ -9,13 +9,14 @@
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
Index: linuxdev/net/ipv4/af_inet.c
===================================================================
--- linuxdev.orig/net/ipv4/af_inet.c
+++ linuxdev/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.
*/
Index: linuxdev/net/ipv4/ip_sockglue.c
===================================================================
--- linuxdev.orig/net/ipv4/ip_sockglue.c
+++ linuxdev/net/ipv4/ip_sockglue.c
@@ -640,6 +640,7 @@
err = ip_mc_leave_group(sk, &mreq);
break;
}
+#ifdef CONFIG_IGMP
case IP_MSFILTER:
{
extern int sysctl_igmp_max_msf;
@@ -677,6 +678,7 @@
kfree(msf);
break;
}
+#endif
case IP_BLOCK_SOURCE:
case IP_UNBLOCK_SOURCE:
case IP_ADD_SOURCE_MEMBERSHIP:
@@ -794,6 +796,7 @@
greqs.gsr_interface);
break;
}
+#ifdef CONFIG_IGMP
case MCAST_MSFILTER:
{
extern int sysctl_igmp_max_msf;
@@ -860,6 +863,7 @@
kfree(gsf);
break;
}
+#endif
case IP_ROUTER_ALERT:
err = ip_ra_control(sk, val ? 1 : 0, NULL);
break;
Index: linuxdev/net/ipv4/sysctl_net_ipv4.c
===================================================================
--- linuxdev.orig/net/ipv4/sysctl_net_ipv4.c
+++ linuxdev/net/ipv4/sysctl_net_ipv4.c
@@ -412,6 +412,7 @@
},
#endif
+#ifdef CONFIG_IGMP
{
.ctl_name = NET_IPV4_IGMP_MAX_MSF,
.procname = "igmp_max_msf",
@@ -420,6 +421,7 @@
.mode = 0644,
.proc_handler = &proc_dointvec
},
+#endif
{
.ctl_name = NET_IPV4_INET_PEER_THRESHOLD,
.procname = "inet_peer_threshold",
--
Thomas Petazzoni, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.
http://free-electrons.com
On Thu, 2008-07-31 at 11:27 +0200, Thomas Petazzoni wrote:
> This patchs 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:
The config option probably lives in net/Kconfig, not init/Kconfig.
And please could you make it clear how this interacts with IP_MULTICAST?
We already have a CONFIG_IP_MULTICAST option, for which the help text
says "For more people, it's safe to say N'. And I think it defaults to
that too. What more does CONFIG_IGMP remove? It's not made clear by the
help text.
--
dwmw2
Le Fri, 01 Aug 2008 20:41:55 +0100,
David Woodhouse <[email protected]> a écrit :
> The config option probably lives in net/Kconfig, not init/Kconfig.
Yes, it could. But AFAIK, until now, all CONFIG_EMBEDDED-related
options have been put in init/Kconfig. But if it's preferred, I can of
course change the patch to move the config option to net/Kconfig.
> And please could you make it clear how this interacts with
> IP_MULTICAST?
>
> We already have a CONFIG_IP_MULTICAST option, for which the help text
> says "For more people, it's safe to say N'. And I think it defaults to
> that too. What more does CONFIG_IGMP remove? It's not made clear by
> the help text.
The interaction of IGMP support with CONFIG_IP_MULTICAST is fairly
unclear to me.
A large portion of igmp.c is already under #ifdef CONFIG_IP_MULTICAST:
all the igmp_*() functions, amongst which is igmp_rcv(), referenced in
igmp_protocol in net/ipv4/af_inet.c, which is compiled-out
when !CONFIG_IP_MULTICAST.
All the proc-related code at the end of the file is only conditionnaly
compiled on CONFIG_PROC_FS, but seems to in fact be only used if both
CONFIG_IP_MULTICAST and CONFIG_PROC_FS are selected:
igmp_mc_proc_init() in net/ipv4/ip_output.c is only called when
CONFIG_IP_MULTICAST and CONFIG_PROC_FS are selected.
Besides that, it's unclear to me why the ip_mc_*() functions are useful
when !CONFIG_IP_MULTICAST, but I'm probably missing something. They are
used to implement setsockopt-operations related to multicast, hooks for
the routing code to handle multicast-related traffic, etc.
Sincerly,
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.
http://free-electrons.com
On Mon, Aug 04, 2008 at 02:48:07PM +0200, Thomas Petazzoni wrote:
> Le Fri, 01 Aug 2008 20:41:55 +0100,
> David Woodhouse <[email protected]> a écrit :
>
> > The config option probably lives in net/Kconfig, not init/Kconfig.
>
> Yes, it could. But AFAIK, until now, all CONFIG_EMBEDDED-related
> options have been put in init/Kconfig.
>...
No, the vast majority is actually outside of init/Kconfig.
> Sincerly,
>
> Thomas
cu
Adrian
--
"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed
On Mon, 2008-08-04 at 14:48 +0200, Thomas Petazzoni wrote:
> Le Fri, 01 Aug 2008 20:41:55 +0100,
> David Woodhouse <[email protected]> a écrit :
>
> > The config option probably lives in net/Kconfig, not init/Kconfig.
>
> Yes, it could. But AFAIK, until now, all CONFIG_EMBEDDED-related
> options have been put in init/Kconfig. But if it's preferred, I can of
> course change the patch to move the config option to net/Kconfig.
It clearly lives in net/Kconfig.
> > And please could you make it clear how this interacts with
> > IP_MULTICAST?
> >
> > We already have a CONFIG_IP_MULTICAST option, for which the help text
> > says "For more people, it's safe to say N'. And I think it defaults to
> > that too. What more does CONFIG_IGMP remove? It's not made clear by
> > the help text.
>
> The interaction of IGMP support with CONFIG_IP_MULTICAST is fairly
> unclear to me.
>
> A large portion of igmp.c is already under #ifdef CONFIG_IP_MULTICAST:
> all the igmp_*() functions, amongst which is igmp_rcv(), referenced in
> igmp_protocol in net/ipv4/af_inet.c, which is compiled-out
> when !CONFIG_IP_MULTICAST.
>
> All the proc-related code at the end of the file is only conditionnaly
> compiled on CONFIG_PROC_FS, but seems to in fact be only used if both
> CONFIG_IP_MULTICAST and CONFIG_PROC_FS are selected:
> igmp_mc_proc_init() in net/ipv4/ip_output.c is only called when
> CONFIG_IP_MULTICAST and CONFIG_PROC_FS are selected.
>
> Besides that, it's unclear to me why the ip_mc_*() functions are useful
> when !CONFIG_IP_MULTICAST, but I'm probably missing something.
Most of them aren't, as far as I can tell.
> They are used to implement setsockopt-operations related to multicast,
> hooks for the routing code to handle multicast-related traffic, etc.
I wonder if those options should return errors now, rather than silently
failing but returning zero. Or maybe that _would_ cause a stock build of
ntpd to fail? Not that it really matters if it _does_, though.
It sounds like 'CONFIG_IGMP' is a bad name for the option, too -- and
the help text is similarly misleading. I think you need to work out how
it all fits together with CONFIG_IP_MULTICAST, fix it up, and resubmit
it.
--
David Woodhouse Open Source Technology Centre
[email protected] Intel Corporation