Subject: Re: [PATCH 2.6.25] netns: struct net content re-work

From: Daniel Lezcano <[email-masked]>
Date: Mon, 10 Dec 2007 18:32:57 +0100

Denis V. Lunev wrote:
> Recently David Miller and Herbert Xu pointed out that struct net becomes
> overbloated and un-maintainable. There are two solutions:
> - provide a pointer to a network subsystem definition from struct net.
>   This costs an additional dereferrence
> - place sub-system definition into the structure itself. This will speedup
>   run-time access at the cost of recompilation time
> 
> The second approach looks better for us. 

Yes, we do not need/want a pointer in this structure and add more 
dereference in the network code.

> Other sub-systems will be converted
> to this approach if this will be accepted :)
> 
> Signed-off-by: Denis V. Lunev <[email-masked]>
> ---
> diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
> index b62e31f..f60e1ce 100644
> --- a/include/net/net_namespace.h
> +++ b/include/net/net_namespace.h
> @@ -8,6 +8,8 @@
>  #include <linux/workqueue.h>
>  #include <linux/list.h>
> 
> +#include <net/netns/unix.h>
> +
>  struct proc_dir_entry;
>  struct net_device;
>  struct sock;
> @@ -46,8 +48,7 @@ struct net {
>  	struct hlist_head	packet_sklist;
> 
>  	/* unix sockets */
> -	int			sysctl_unix_max_dgram_qlen;
> -	struct ctl_table_header	*unix_ctl;
> +	struct netns_unix	unx;

Can you change this from unx to unix ?

If you encapsulate the structure definitions per subsystem, you can drop 
the unix prefix in the variable declaration.

Instead of having:
	netns->unix->unix_ctl
you will have:
	netns->unix->ctl

>  };
> 
>  #ifdef CONFIG_NET
> diff --git a/include/net/netns/unix.h b/include/net/netns/unix.h
> new file mode 100644
> index 0000000..27b4e7f
> --- /dev/null
> +++ b/include/net/netns/unix.h
> @@ -0,0 +1,13 @@
> +/*
> + * Unix network namespace
> + */
> +#ifndef __NETNS_UNIX_H__
> +#define __NETNS_UNIX_H__
> +
> +struct ctl_table_header;
> +struct netns_unix {
> +	int			sysctl_unix_max_dgram_qlen;
> +	struct ctl_table_header	*unix_ctl;
> +};
> +
> +#endif /* __NETNS_UNIX_H__ */

If I follow the logic, we will have a file per subsystem. These files 
will be very small, no ?
IMHO, having the structure defined in net_namespace.h is enough.

> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> index b8a2189..06f7ec8 100644
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -592,7 +592,7 @@ static struct sock * unix_create1(struct net *net, struct socket *sock)
>  				&af_unix_sk_receive_queue_lock_key);
> 
>  	sk->sk_write_space	= unix_write_space;
> -	sk->sk_max_ack_backlog	= net->sysctl_unix_max_dgram_qlen;
> +	sk->sk_max_ack_backlog	= net->unx.sysctl_unix_max_dgram_qlen;
>  	sk->sk_destruct		= unix_sock_destructor;
>  	u	  = unix_sk(sk);
>  	u->dentry = NULL;
> @@ -2138,7 +2138,7 @@ static int unix_net_init(struct net *net)
>  {
>  	int error = -ENOMEM;
> 
> -	net->sysctl_unix_max_dgram_qlen = 10;
> +	net->unx.sysctl_unix_max_dgram_qlen = 10;
>  	if (unix_sysctl_register(net))
>  		goto out;
> 
> diff --git a/net/unix/sysctl_net_unix.c b/net/unix/sysctl_net_unix.c
> index 553ef6a..fbddfb5 100644
> --- a/net/unix/sysctl_net_unix.c
> +++ b/net/unix/sysctl_net_unix.c
> @@ -18,7 +18,7 @@ static ctl_table unix_table[] = {
>  	{
>  		.ctl_name	= NET_UNIX_MAX_DGRAM_QLEN,
>  		.procname	= "max_dgram_qlen",
> -		.data		= &init_net.sysctl_unix_max_dgram_qlen,
> +		.data		= &init_net.unx.sysctl_unix_max_dgram_qlen,
>  		.maxlen		= sizeof(int),
>  		.mode		= 0644,
>  		.proc_handler	= &proc_dointvec
> @@ -40,9 +40,9 @@ int unix_sysctl_register(struct net *net)
>  	if (table == NULL)
>  		goto err_alloc;
> 
> -	table[0].data = &net->sysctl_unix_max_dgram_qlen;
> -	net->unix_ctl = register_net_sysctl_table(net, unix_path, table);
> -	if (net->unix_ctl == NULL)
> +	table[0].data = &net->unx.sysctl_unix_max_dgram_qlen;
> +	net->unx.unix_ctl = register_net_sysctl_table(net, unix_path, table);
> +	if (net->unx.unix_ctl == NULL)
>  		goto err_reg;
> 
>  	return 0;
> @@ -57,8 +57,8 @@ void unix_sysctl_unregister(struct net *net)
>  {
>  	struct ctl_table *table;
> 
> -	table = net->unix_ctl->ctl_table_arg;
> -	unregister_sysctl_table(net->unix_ctl);
> +	table = net->unx.unix_ctl->ctl_table_arg;
> +	unregister_sysctl_table(net->unx.unix_ctl);
>  	kfree(table);
>  }
> 
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