On Wed, May 26, 2010 at 7:54 PM, Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:
>
> Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
> ---
> diff --git a/net/netfilter/xt_statistic.c b/net/netfilter/xt_statistic.c
> index 96e62b8..0114d2b 100644
> --- a/net/netfilter/xt_statistic.c
> +++ b/net/netfilter/xt_statistic.c
> @@ -18,8 +18,8 @@
> #include <linux/netfilter/x_tables.h>
>
> struct xt_statistic_priv {
> - uint32_t count;
> -};
> + atomic_t count;
> +} ____cacheline_aligned_in_smp;
>
> MODULE_LICENSE("GPL");
> MODULE_AUTHOR("Patrick McHardy <kaber@xxxxxxxxx>");
> @@ -27,13 +27,12 @@ MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)");
> MODULE_ALIAS("ipt_statistic");
> MODULE_ALIAS("ip6t_statistic");
>
> -static DEFINE_SPINLOCK(nth_lock);
> -
> static bool
> statistic_mt(const struct sk_buff *skb, struct xt_action_param *par)
> {
> const struct xt_statistic_info *info = par->matchinfo;
> bool ret = info->flags & XT_STATISTIC_INVERT;
> + int nval, oval;
>
> switch (info->mode) {
> case XT_STATISTIC_MODE_RANDOM:
> @@ -41,12 +40,14 @@ statistic_mt(const struct sk_buff *skb, struct xt_action_param *par)
> ret = !ret;
> break;
> case XT_STATISTIC_MODE_NTH:
> - spin_lock_bh(&nth_lock);
> - if (info->master->count++ == info->u.nth.every) {
> - info->master->count = 0;
> + do {
> + oval = atomic_read(&info->master->count);
> + nval = oval + 1;
> + if (nval == info->u.nth.every)
> + nval = 0;
these lines should be:
if (oval == info->u.nth.every)
nval = 0;
else
nval = oval + 1;
> + } while (atomic_cmpxchg(&info->master->count, oval, nval) != oval);
> + if (nval == 0)
> ret = !ret;
> - }
> - spin_unlock_bh(&nth_lock);
> break;
> }
>
> @@ -64,7 +65,7 @@ static int statistic_mt_check(const struct xt_mtchk_param *par)
> info->master = kzalloc(sizeof(*info->master), GFP_KERNEL);
> if (info->master == NULL)
> return -ENOMEM;
> - info->master->count = info->u.nth.count;
> + atomic_set(&info->master->count, info->u.nth.count);
>
> return 0;
> }
>
>
> --
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>
--
Regards，
Changli Gao(xiaosuo@xxxxxxxxx)
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