From: Stephen Hemminger <shemminger@vyatta•com>
To: David Miller <davem@davemloft•net>
Cc: netdev@vger•kernel.org
Subject: [PATCH 5/6] netfilter: use sequence number synchronization for counters
Date: Fri, 30 Jan 2009 13:57:05 -0800 [thread overview]
Message-ID: <20090130215729.536716172@vyatta.com> (raw)
In-Reply-To: 20090130215700.965611970@vyatta.com
[-- Attachment #1: counters-seqcount.patch --]
[-- Type: text/plain, Size: 1330 bytes --]
Change how synchronization is done on the iptables counters. Use seqcount
wrapper instead of depending on reader/writer lock.
Signed-off-by: Stephen Hemminger <shemminger@vyatta•com>
--- a/net/netfilter/x_tables.c 2009-01-30 09:15:52.648542116 -0800
+++ b/net/netfilter/x_tables.c 2009-01-30 09:17:03.669061821 -0800
@@ -577,18 +577,36 @@ int xt_compat_target_to_user(struct xt_e
EXPORT_SYMBOL_GPL(xt_compat_target_to_user);
#endif
+static DEFINE_PER_CPU(seqcount_t, xt_counter_sequence);
+
+/* Update the counters on the current CPU. preempt must be disabled. */
void xt_add_counter(struct xt_counters *c, unsigned b, unsigned p)
{
+ seqcount_t *seq = &__get_cpu_var(xt_counter_sequence);
+
+ write_seqcount_begin(seq);
c->bcnt += b;
c->pcnt += p;
+ write_seqcount_end(seq);
}
EXPORT_SYMBOL_GPL(xt_add_counter);
+/* Fetch counters on other CPU. */
void xt_sum_counter(struct xt_counters *t, int cpu,
const struct xt_counters *c)
{
- t->pcnt += c->pcnt;
- t->bcnt += c->bcnt;
+ seqcount_t *seq = &per_cpu(xt_counter_sequence, cpu);
+ unsigned start;
+ struct xt_counters v;
+
+ /* Atomic fetch of counter value */
+ do {
+ start = read_seqcount_begin(seq);
+ v = *c;
+ } while (read_seqcount_retry(seq, start));
+
+ t->pcnt += v.pcnt;
+ t->bcnt += v.bcnt;
}
EXPORT_SYMBOL_GPL(xt_sum_counter);
--
next prev parent reply other threads:[~2009-01-30 21:58 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-30 21:57 [PATCH 0/6] iptables: eliminate read/write lock (v0.4) Stephen Hemminger
2009-01-30 21:57 ` [PATCH 1/6] netfilter: change elements in x_tables Stephen Hemminger
2009-01-30 21:57 ` [PATCH 2/6] netfilter: remove unneeded initializations Stephen Hemminger
2009-01-30 21:57 ` [PATCH 3/6] ebtables: " Stephen Hemminger
2009-01-30 21:57 ` [PATCH 4/6] netfilter: abstract xt_counters Stephen Hemminger
2009-02-01 12:25 ` Eric Dumazet
2009-02-02 23:33 ` [PATCH 3/3] iptables: lock free counters (alternate version) Stephen Hemminger
2009-02-03 19:00 ` Eric Dumazet
2009-02-03 19:19 ` Eric Dumazet
2009-02-03 19:32 ` Paul E. McKenney
2009-02-03 20:20 ` Eric Dumazet
2009-02-03 20:44 ` Stephen Hemminger
2009-02-03 21:05 ` Eric Dumazet
2009-02-03 21:10 ` Paul E. McKenney
2009-02-03 21:22 ` Stephen Hemminger
2009-02-03 21:27 ` Rick Jones
2009-02-03 23:11 ` Paul E. McKenney
2009-02-03 23:18 ` Stephen Hemminger
2009-01-30 21:57 ` Stephen Hemminger [this message]
2009-01-30 21:57 ` [PATCH 6/6] netfilter: convert x_tables to use RCU Stephen Hemminger
2009-01-31 17:27 ` Eric Dumazet
-- strict thread matches above, loose matches on Subject: below --
2009-01-29 19:12 [PATCH 0/6] iptables: read/write lock elimination (v0.4) Stephen Hemminger
2009-01-29 19:12 ` [PATCH 5/6] netfilter: use sequence number synchronization for counters Stephen Hemminger
2009-01-30 8:03 ` Eric Dumazet
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