netlink_proto_init and sock_init

netlink_proto_init and sock_init

[Octavian Purdila]

Hi,

I've noticed that with some exotic build setups (e.g. mingw) 
netlink_proto_init is called before sock_init and subsequently sock_alloc 
runs into a NULL sock_mnt. The following patch seems to fix the problem, but 
I'm not sure if this is the right thing to do, as there are no _initcall_sync 
calls in the kernel yet. 

Thanks,
tavi

PS: please keep me on CC as I am not subscribed to the list.

Author: Octavian Purdila <tavi@cs.pub.ro>
Date:   Thu Dec 27 14:25:31 2007 +0200

    sock_init needs to be called before netlink_proto_init, but both
    sock_init and netlink_proto_init share the same init level
    (core). Move netlink_proto_init to sync core level.

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 1f15821..f69c126 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1845,7 +1845,7 @@ panic:
        panic("netlink_init: Cannot allocate nl_table\n");
 }
 
-core_initcall(netlink_proto_init);
+core_initcall_sync(netlink_proto_init);
 
 EXPORT_SYMBOL(netlink_ack);
 EXPORT_SYMBOL(netlink_run_queue);

Re: netlink_proto_init and sock_init

[David Miller]

From: Octavian Purdila <tavi@cs.pub.ro>
Date: Thu, 27 Dec 2007 14:48:56 +0200

> I've noticed that with some exotic build setups (e.g. mingw) 
> netlink_proto_init is called before sock_init and subsequently sock_alloc 
> runs into a NULL sock_mnt. The following patch seems to fix the problem, but 
> I'm not sure if this is the right thing to do, as there are no _initcall_sync 
> calls in the kernel yet. 

This means that net/netlink/ got linked before net/socket.o, which
should never happen.  net/Makefile reads:

obj-$(CONFIG_NET)		:= socket.o core/
 ...
obj-$(CONFIG_NET)		+= ethernet/ 802/ sched/ netlink/

Which ensures that net/socket.o comes before linking in the
net/netlink/built-in.o object file.

Init call ordering is based upon link ordering, so it looks like
mingw is somehow reordering the object files being linked.

There are many other things that can go wrong if the build environment
does this, please find a way to get your mingw build environment to
not do this.