Re: [PATCH 18/30] netvm: INET reserves.

Daniel Lezcano
2008-10-01T11:38:48Z

> Add reserves for INET.
>
> The two big users seem to be the route cache and ip-fragment cache.
>
> Reserve the route cache under generic RX reserve, its usage is bounded by
> the high reclaim watermark, and thus does not need further accounting.
>
> Reserve the ip-fragement caches under SKB data reserve, these add to the
> SKB RX limit. By ensuring we can at least receive as much data as fits in
> the reassmbly line we avoid fragment attack deadlocks.
>
> Adds to the reserve tree:
>
> total network reserve
> network TX reserve
> protocol TX pages
> network RX reserve
> + IPv6 route cache
> + IPv4 route cache
> SKB data reserve
> + IPv6 fragment cache
> + IPv4 fragment cache
>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> ---
> include/net/inet_frag.h | 7 +++
> include/net/netns/ipv6.h | 4 ++
> net/ipv4/inet_fragment.c | 3 +
> net/ipv4/ip_fragment.c | 89 +++++++++++++++++++++++++++++++++++++++++++++--
> net/ipv4/route.c | 72 +++++++++++++++++++++++++++++++++++++-
> net/ipv6/af_inet6.c | 20 +++++++++-
> net/ipv6/reassembly.c | 88 +++++++++++++++++++++++++++++++++++++++++++++-
> net/ipv6/route.c | 66 ++++++++++++++++++++++++++++++++++
> 8 files changed, 341 insertions(+), 8 deletions(-)
>

Sorry for the delay ...

[ cut ]

I removed a big portion of code because the remarks below apply to the
rest of the code.

> +static int sysctl_intvec_route(struct ctl_table *table,
> + int __user *name, int nlen,
> + void __user *oldval, size_t __user *oldlenp,
> + void __user *newval, size_t newlen)
> +{
> + struct net *net = current->nsproxy->net_ns;

I think you can use the container_of and get rid of using
current->nsproxy->net_ns.

struct net *net = container_of(table->data, struct net,
ipv6.sysctl.ip6_rt_max_size);

Another solution could be to pass directly the sysctl structure pointer
in the table data instead of
".data = &init_net.ipv6.sysctl.ip6_rt_max_size" when initializing the
sysctl table below. But you have to set the right field value yourself.

> + int write = (newval && newlen);
> + int new_size, ret;
> +
> + mutex_lock(&net->ipv6.sysctl.ip6_rt_lock);
> +
> + if (write)
> + table->data = &new_size;
> +
> + ret = sysctl_intvec(table, name, nlen, oldval, oldlenp, newval, newlen);
> +
> + if (!ret && write) {
> + ret = mem_reserve_kmem_cache_set(&net->ipv6.ip6_rt_reserve,
> + net->ipv6.ip6_dst_ops.kmem_cachep, new_size);
> + if (!ret)
> + net->ipv6.sysctl.ip6_rt_max_size = new_size;
> + }
> +
> + if (write)
> + table->data = &net->ipv6.sysctl.ip6_rt_max_size;
> +
> + mutex_unlock(&net->ipv6.sysctl.ip6_rt_lock);
> +
> + return ret;
> +}

Dancing with the table->data looks safe but it is not very nice.
Isn't possible to use a temporary table like in the function
"ipv4_sysctl_local_port_range" ?

> ctl_table ipv6_route_table_template[] = {
> {
> .procname = "flush",
> @@ -2520,7 +2581,8 @@ ctl_table ipv6_route_table_template[] =
> .data = &init_net.ipv6.sysctl.ip6_rt_max_size,
> .maxlen = sizeof(int),
> .mode = 0644,
> - .proc_handler = &proc_dointvec,
> + .proc_handler = &proc_dointvec_route,
> + .strategy = &sysctl_intvec_route,
> },
> {
> .ctl_name = NET_IPV6_ROUTE_GC_MIN_INTERVAL,
> @@ -2608,6 +2670,8 @@ struct ctl_table *ipv6_route_sysctl_init
> table[8].data = &net->ipv6.sysctl.ip6_rt_min_advmss;
> }
>
> + mutex_init(&net->ipv6.sysctl.ip6_rt_lock);
> +
> return table;
> }
> #endif
> Index: linux-2.6/include/net/inet_frag.h
> ===================================================================
> --- linux-2.6.orig/include/net/inet_frag.h
> +++ linux-2.6/include/net/inet_frag.h
> @@ -1,6 +1,9 @@
> #ifndef __NET_FRAG_H__
> #define __NET_FRAG_H__
>
> +#include <linux/reserve.h>
> +#include <linux/mutex.h>
> +
> struct netns_frags {
> int nqueues;
> atomic_t mem;
> @@ -10,6 +13,10 @@ struct netns_frags {
> int timeout;
> int high_thresh;
> int low_thresh;
> +
> + /* reserves */
> + struct mutex lock;
> + struct mem_reserve reserve;
> };
>
> struct inet_frag_queue {
> Index: linux-2.6/net/ipv4/inet_fragment.c
> ===================================================================
> --- linux-2.6.orig/net/ipv4/inet_fragment.c
> +++ linux-2.6/net/ipv4/inet_fragment.c
> @@ -19,6 +19,7 @@
> #include <linux/random.h>
> #include <linux/skbuff.h>
> #include <linux/rtnetlink.h>
> +#include <linux/reserve.h>
>
> #include <net/inet_frag.h>
>
> @@ -74,6 +75,8 @@ void inet_frags_init_net(struct netns_fr
> nf->nqueues = 0;
> atomic_set(&nf->mem, 0);
> INIT_LIST_HEAD(&nf->lru_list);
> + mutex_init(&nf->lock);
> + mem_reserve_init(&nf->reserve, "IP fragement cache", NULL);
> }
> EXPORT_SYMBOL(inet_frags_init_net);
>
> Index: linux-2.6/include/net/netns/ipv6.h
> ===================================================================
> --- linux-2.6.orig/include/net/netns/ipv6.h
> +++ linux-2.6/include/net/netns/ipv6.h
> @@ -24,6 +24,8 @@ struct netns_sysctl_ipv6 {
> int ip6_rt_mtu_expires;
> int ip6_rt_min_advmss;
> int icmpv6_time;
> +
> + struct mutex ip6_rt_lock;
> };
>
> struct netns_ipv6 {
> @@ -55,5 +57,7 @@ struct netns_ipv6 {
> struct sock *ndisc_sk;
> struct sock *tcp_sk;
> struct sock *igmp_sk;
> +
> + struct mem_reserve ip6_rt_reserve;
> };
> #endif
> Index: linux-2.6/net/ipv6/af_inet6.c
> ===================================================================
> --- linux-2.6.orig/net/ipv6/af_inet6.c
> +++ linux-2.6/net/ipv6/af_inet6.c
> @@ -851,6 +851,20 @@ static int inet6_net_init(struct net *ne
> net->ipv6.sysctl.ip6_rt_min_advmss = IPV6_MIN_MTU - 20 - 40;
> net->ipv6.sysctl.icmpv6_time = 1*HZ;
>
> + mem_reserve_init(&net->ipv6.ip6_rt_reserve, "IPv6 route cache",
> + &net_rx_reserve);
> + /*
> + * XXX: requires that net->ipv6.ip6_dst_ops is already set-up
> + * but afaikt its impossible to order the various
> + * pernet_subsys calls so that this one is done after
> + * ip6_route_net_init().
> + */

As this code seems related to the routes, is there a particular reason
to not put it at the end of "ip6_route_net_init" function ? You will be
sure "net->ipv6.ip6_dst_ops is already set-up", no ?

> + err = mem_reserve_kmem_cache_set(&net->ipv6.ip6_rt_reserve,
> + net->ipv6.ip6_dst_ops.kmem_cachep,
> + net->ipv6.sysctl.ip6_rt_max_size);
> + if (err)
> + goto reserve_fail;
> +
> #ifdef CONFIG_PROC_FS
> err = udp6_proc_init(net);
> if (err)
> @@ -861,8 +875,8 @@ static int inet6_net_init(struct net *ne
> err = ac6_proc_init(net);
> if (err)
> goto proc_ac6_fail;
> -out:
> #endif
> +out:
> return err;
>
> #ifdef CONFIG_PROC_FS
> @@ -870,8 +884,10 @@ proc_ac6_fail:
> tcp6_proc_exit(net);
> proc_tcp6_fail:
> udp6_proc_exit(net);
> - goto out;
> #endif
> +reserve_fail:
> + mem_reserve_disconnect(&net->ipv6.ip6_rt_reserve);

Idem.

> + goto out;
> }
>
> static void inet6_net_exit(struct net *net)

Isn't "mem_reserve_disconnect" missing here ? (but going to
ip6_route_net_exit)

I hope this review helped :)

Thanks
--Daniel