Le lundi 31 mai 2010 à 13:51 +0200, Jan Engelhardt a écrit :
> On Monday 2010-05-31 13:06, Xiaotian Feng wrote:
>
> >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 <eric.dumazet@xxxxxxxxx>
---
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)
--
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