[PATCH] netfilter: xtables: stackptr should be percpu
From: Eric Dumazet <hidden>
Date: 2010-05-31 13:13:37
Also in:
lkml, netfilter-devel
Subsystem:
netfilter, networking [general], the rest · Maintainers:
Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Le lundi 31 mai 2010 à 13:51 +0200, Jan Engelhardt a écrit :
On Monday 2010-05-31 13:06, Xiaotian Feng wrote:quoted
In xt_register_table, xt_jumpstack_alloc is called first, later xt_replace_table is used. But in xt_replace_table, xt_jumpstack_alloc will be used again. Then the memory allocated by previous xt_jumpstack_alloc will be leaked. We can simply remove the previous xt_jumpstack_alloc because there aren't any users of newinfo between xt_jumpstack_alloc and xt_replace_table.Indeed that seems to be so.
An official "Acked-by: ..." would be fine Jan :) BTW I noticed a _big_ slowdown of iptables lately, and located the reason. All cpus share a single cache line for their 'stackptr' storage, introduced in commit f3c5c1bfd4 This is a stable candidate (2.6.34) Note : We also should use alloc_percpu() for jumpstack but this is not a critical thing and can be a net-next patch. [PATCH] netfilter: xtables: stackptr should be percpu commit f3c5c1bfd4 (netfilter: xtables: make ip_tables reentrant) introduced a performance regression, because stackptr array is shared by all cpus, adding cache line ping pongs. (16 cpus share a 64 bytes cache line) Fix this using alloc_percpu() Signed-off-by: Eric Dumazet <redacted> --- include/linux/netfilter/x_tables.h | 2 +- net/ipv4/netfilter/ip_tables.c | 2 +- net/ipv6/netfilter/ip6_tables.c | 2 +- net/netfilter/x_tables.c | 13 +++---------- 4 files changed, 6 insertions(+), 13 deletions(-)
diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h
index c00cc0c..24e5d01 100644
--- a/include/linux/netfilter/x_tables.h
+++ b/include/linux/netfilter/x_tables.h@@ -397,7 +397,7 @@ struct xt_table_info { * @stacksize jumps (number of user chains) can possibly be made. */ unsigned int stacksize; - unsigned int *stackptr; + unsigned int __percpu *stackptr; void ***jumpstack; /* ipt_entry tables: one per CPU */ /* Note : this field MUST be the last one, see XT_TABLE_INFO_SZ */
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 63958f3..4b6c5ca 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c@@ -336,7 +336,7 @@ ipt_do_table(struct sk_buff *skb, cpu = smp_processor_id(); table_base = private->entries[cpu]; jumpstack = (struct ipt_entry **)private->jumpstack[cpu]; - stackptr = &private->stackptr[cpu]; + stackptr = per_cpu_ptr(private->stackptr, cpu); origptr = *stackptr; e = get_entry(table_base, private->hook_entry[hook]);
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 6f517bd..9d2d68f 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c@@ -363,7 +363,7 @@ ip6t_do_table(struct sk_buff *skb, cpu = smp_processor_id(); table_base = private->entries[cpu]; jumpstack = (struct ip6t_entry **)private->jumpstack[cpu]; - stackptr = &private->stackptr[cpu]; + stackptr = per_cpu_ptr(private->stackptr, cpu); origptr = *stackptr; e = get_entry(table_base, private->hook_entry[hook]);
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index 445de70..7e8a93d 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c@@ -699,10 +699,8 @@ void xt_free_table_info(struct xt_table_info *info) vfree(info->jumpstack); else kfree(info->jumpstack); - if (sizeof(unsigned int) * nr_cpu_ids > PAGE_SIZE) - vfree(info->stackptr); - else - kfree(info->stackptr); + + free_percpu(info->stackptr); kfree(info); }
@@ -753,14 +751,9 @@ static int xt_jumpstack_alloc(struct xt_table_info *i) unsigned int size; int cpu; - size = sizeof(unsigned int) * nr_cpu_ids; - if (size > PAGE_SIZE) - i->stackptr = vmalloc(size); - else - i->stackptr = kmalloc(size, GFP_KERNEL); + i->stackptr = alloc_percpu(unsigned int); if (i->stackptr == NULL) return -ENOMEM; - memset(i->stackptr, 0, size); size = sizeof(void **) * nr_cpu_ids; if (size > PAGE_SIZE)