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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2011-01-10 20:11:38 +0100 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2011-01-10 20:11:38 +0100 |
| commit | 83723d60717f8da0f53f91cf42a845ed56c09662 (patch) | |
| tree | 9d32edc2c6dc4849e63d422f8dad42606b2f984f /include/linux/netfilter | |
| parent | 45b9f509b7f5d2d792b3c03b78ddc8ec543e921b (diff) | |
| download | linux-83723d60717f8da0f53f91cf42a845ed56c09662.tar.gz linux-83723d60717f8da0f53f91cf42a845ed56c09662.tar.bz2 linux-83723d60717f8da0f53f91cf42a845ed56c09662.zip | |
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/linux/netfilter')
| -rw-r--r-- | include/linux/netfilter/x_tables.h | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h index 742bec051440..6712e713b299 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); } /* |