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authorEric Dumazet <eric.dumazet@gmail.com>2011-01-10 20:11:38 +0100
committerPablo Neira Ayuso <pablo@netfilter.org>2011-01-10 20:11:38 +0100
commit83723d60717f8da0f53f91cf42a845ed56c09662 (patch)
tree9d32edc2c6dc4849e63d422f8dad42606b2f984f /include
parent45b9f509b7f5d2d792b3c03b78ddc8ec543e921b (diff)
netfilter: x_tables: dont block BH while reading counters
Using "iptables -L" with a lot of rules have a too big BH latency. Jesper mentioned ~6 ms and worried of frame drops. Switch to a per_cpu seqlock scheme, so that taking a snapshot of counters doesnt need to block BH (for this cpu, but also other cpus). This adds two increments on seqlock sequence per ipt_do_table() call, its a reasonable cost for allowing "iptables -L" not block BH processing. Reported-by: Jesper Dangaard Brouer <hawk@comx.dk> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> CC: Patrick McHardy <kaber@trash.net> Acked-by: Stephen Hemminger <shemminger@vyatta.com> Acked-by: Jesper Dangaard Brouer <hawk@comx.dk> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/netfilter/x_tables.h10
1 files changed, 5 insertions, 5 deletions
diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h
index 742bec05144..6712e713b29 100644
--- a/include/linux/netfilter/x_tables.h
+++ b/include/linux/netfilter/x_tables.h
@@ -472,7 +472,7 @@ extern void xt_free_table_info(struct xt_table_info *info);
* necessary for reading the counters.
*/
struct xt_info_lock {
- spinlock_t lock;
+ seqlock_t lock;
unsigned char readers;
};
DECLARE_PER_CPU(struct xt_info_lock, xt_info_locks);
@@ -497,7 +497,7 @@ static inline void xt_info_rdlock_bh(void)
local_bh_disable();
lock = &__get_cpu_var(xt_info_locks);
if (likely(!lock->readers++))
- spin_lock(&lock->lock);
+ write_seqlock(&lock->lock);
}
static inline void xt_info_rdunlock_bh(void)
@@ -505,7 +505,7 @@ static inline void xt_info_rdunlock_bh(void)
struct xt_info_lock *lock = &__get_cpu_var(xt_info_locks);
if (likely(!--lock->readers))
- spin_unlock(&lock->lock);
+ write_sequnlock(&lock->lock);
local_bh_enable();
}
@@ -516,12 +516,12 @@ static inline void xt_info_rdunlock_bh(void)
*/
static inline void xt_info_wrlock(unsigned int cpu)
{
- spin_lock(&per_cpu(xt_info_locks, cpu).lock);
+ write_seqlock(&per_cpu(xt_info_locks, cpu).lock);
}
static inline void xt_info_wrunlock(unsigned int cpu)
{
- spin_unlock(&per_cpu(xt_info_locks, cpu).lock);
+ write_sequnlock(&per_cpu(xt_info_locks, cpu).lock);
}
/*