[Devel] Re: [PATCH net-2.6.26 2/6][NETNS][SOCK]: Introduce per-net inuse counters.

[Eric Dumazet]

Pavel Emelyanov a écrit :
> This is probably the most controversial part of the set.
>
> The counters are stored in a per-cpu array on a struct net. To 
> index in this array the prot->inuse is declared as int and used. 
>
> Numbers (indices) to protos are generated with the appropriate 
> enum. I though about using some existing IPPROTO_XXX numbers for
> protocols but they were too large (IPPROTO_RAW is 255) and did 
> not differ for ipv4 and ipv6 (there's no IP6PROTO_RAW, etc).
>
> The sock_prot_inuse_(add|get) now use the net argument to
> get the counter, but this all hides under CONFIG_NET_NS.
>
> The sock_prot_inuse_(init|fini) are no-ops. DEFINE_PROTO_INUSE
> is empty and REF_PROTO_INUSE assigns an index to a proto.
>
>   

Given that :

1) pcounter should really go away from kernel, since Andrew disagree 
with the implementation.

2) the need to enumerate all protocols in your enum, it seems ... ugly :)

3) alloc_percpu(struct net_prot_inuse) per net is nice because we dont 
waste memory (if we had to use percpu_counters for each proto for example)

I suggest to :

1) not use pcounter anymore

2) change 'inuse' field to 'inuse_idx' or 'prot_num' that is 
automatically allocated at proto_register time, instead statically at 
compile time.

Just provide a big enough NET_INUSE_NR (might depend on IPV6 present or 
not, static or module) to take into account all possible protocols.

struct net_prot_inuse {
	int val[NET_INUSE_NR];
};


> Signed-off-by: Pavel Emelyanov <xemul at openvz.org>
>
> ---
>  include/net/net_namespace.h |    3 ++
>  include/net/sock.h          |   35 +++++++++++++++++++++++++++++
>  net/core/sock.c             |   52 +++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 90 insertions(+), 0 deletions(-)
>
> diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
> index f8f3d1a..8a37be1 100644
> --- a/include/net/net_namespace.h
> +++ b/include/net/net_namespace.h
> @@ -18,6 +18,7 @@ struct proc_dir_entry;
>  struct net_device;
>  struct sock;
>  struct ctl_table_header;
> +struct net_prot_inuse;
>  
>  struct net {
>  	atomic_t		count;		/* To decided when the network
> @@ -50,6 +51,8 @@ struct net {
>  	struct ctl_table_header	*sysctl_core_hdr;
>  	int			sysctl_somaxconn;
>  
> +	struct net_prot_inuse	*inuse;
> +
>  	struct netns_packet	packet;
>  	struct netns_unix	unx;
>  	struct netns_ipv4	ipv4;
> diff --git a/include/net/sock.h b/include/net/sock.h
> index a57c58f..84a672c 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -562,8 +562,12 @@ struct proto {
>  
>  	/* Keeping track of sockets in use */
>  #ifdef CONFIG_PROC_FS
> +#ifdef CONFIG_NET_NS
> +	unsigned int		inuse;
> +#else
>  	struct pcounter		inuse;
>  #endif
> +#endif
>  
>  	/* Memory pressure */
>  	void			(*enter_memory_pressure)(void);
> @@ -635,6 +639,36 @@ static inline void sk_refcnt_debug_release(const struct sock *sk)
>  
>  
>  #ifdef CONFIG_PROC_FS
> +#ifdef CONFIG_NET_NS
> +enum {
> +	NET_INUSE_dccp_v4,
> +	NET_INUSE_dccp_v6,
> +	NET_INUSE_raw,
> +	NET_INUSE_tcp,
> +	NET_INUSE_udp,
> +	NET_INUSE_udplite,
> +	NET_INUSE_rawv6,
> +	NET_INUSE_tcpv6,
> +	NET_INUSE_udpv6,
> +	NET_INUSE_udplitev6,
> +	NET_INUSE_sctp,
> +	NET_INUSE_sctpv6,
> +	NET_INUSE_NR,
> +};
> +
> +# define DEFINE_PROTO_INUSE(NAME)
> +# define REF_PROTO_INUSE(NAME) .inuse = NET_INUSE_##NAME,
> +
> +extern void sock_prot_inuse_add(struct net *net, struct proto *prot, int inc);
> +static inline int sock_prot_inuse_init(struct proto *proto)
> +{
> +	return 0;
> +}
> +extern int sock_prot_inuse_get(struct net *net, struct proto *proto);
> +static inline void sock_prot_inuse_free(struct proto *proto)
> +{
> +}
> +#else /* ! CONFIG_NET_NS */
>  # define DEFINE_PROTO_INUSE(NAME) DEFINE_PCOUNTER(NAME)
>  # define REF_PROTO_INUSE(NAME) PCOUNTER_MEMBER_INITIALIZER(NAME, .inuse)
>  /* Called with local bh disabled */
> @@ -655,6 +689,7 @@ static inline void sock_prot_inuse_free(struct proto *proto)
>  {
>  	pcounter_free(&proto->inuse);
>  }
> +#endif /* CONFIG_NET_NS */
>  #else
>  # define DEFINE_PROTO_INUSE(NAME)
>  # define REF_PROTO_INUSE(NAME)
> diff --git a/net/core/sock.c b/net/core/sock.c
> index 3ee9506..743f628 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -2056,6 +2056,58 @@ void proto_unregister(struct proto *prot)
>  EXPORT_SYMBOL(proto_unregister);
>  
>  #ifdef CONFIG_PROC_FS
> +#ifdef CONFIG_NET_NS
> +struct net_prot_inuse {
> +	int val[NET_INUSE_NR];
> +};
> +
> +void sock_prot_inuse_add(struct net *net, struct proto *prot, int val)
> +{
> +	per_cpu_ptr(net->inuse, get_cpu())->val[prot->inuse] += val;
> +	put_cpu();
> +}
> +EXPORT_SYMBOL_GPL(sock_prot_inuse_add);
> +
> +int sock_prot_inuse_get(struct net *net, struct proto *prot)
> +{
> +	int cpu, idx, val;
> +
> +	idx = prot->inuse;
> +	val = 0;
> +	for_each_online_cpu(cpu)
> +		val += per_cpu_ptr(net->inuse, cpu)->val[idx];
> +
> +	return val;
> +}
> +EXPORT_SYMBOL_GPL(sock_prot_inuse_get);
> +
> +static int sock_inuse_init_net(struct net *net)
> +{
> +	net->inuse = alloc_percpu(struct net_prot_inuse);
> +	return net->inuse ? 0 : -ENOMEM;
> +}
> +
> +static void sock_inuse_exit_net(struct net *net)
> +{
> +	free_percpu(net->inuse);
> +}
> +
> +static struct pernet_operations net_inuse_ops = {
> +	.init = sock_inuse_init_net,
> +	.exit = sock_inuse_exit_net,
> +};
> +
> +static __init int net_inuse_init(void)
> +{
> +	if (register_pernet_subsys(&net_inuse_ops))
> +		panic("Cannot initialize net inuse counters");
> +
> +	return 0;
> +}
> +
> +core_initcall(net_inuse_init);
> +#endif
> +
>  static void *proto_seq_start(struct seq_file *seq, loff_t *pos)
>  	__acquires(proto_list_lock)
>  {
>