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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2011-04-04 17:04:03 +0200 |
|---|---|---|
| committer | Patrick McHardy <kaber@trash.net> | 2011-04-04 17:04:03 +0200 |
| commit | 7f5c6d4f665bb57a19a34ce1fb16cc708c04f219 (patch) | |
| tree | e804faa506bbf9edcfd1fdadb2ab3749f58836cd /net/ipv6 | |
| parent | 8f7b01a178b8e6a7b663a1bbaa1710756d67b69b (diff) | |
| download | linux-7f5c6d4f665bb57a19a34ce1fb16cc708c04f219.tar.bz2 | |
netfilter: get rid of atomic ops in fast path
We currently use a percpu spinlock to 'protect' rule bytes/packets
counters, after various attempts to use RCU instead.
Lately we added a seqlock so that get_counters() can run without
blocking BH or 'writers'. But we really only need the seqcount in it.
Spinlock itself is only locked by the current/owner cpu, so we can
remove it completely.
This cleanups api, using correct 'writer' vs 'reader' semantic.
At replace time, the get_counters() call makes sure all cpus are done
using the old table.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Diffstat (limited to 'net/ipv6')
| -rw-r--r-- | net/ipv6/netfilter/ip6_tables.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c index 0b2af9b85cec..ec7cf579cdd4 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -340,6 +340,7 @@ ip6t_do_table(struct sk_buff *skb, unsigned int *stackptr, origptr, cpu; const struct xt_table_info *private; struct xt_action_param acpar; + unsigned int addend; /* Initialization */ indev = in ? in->name : nulldevname; @@ -358,7 +359,8 @@ ip6t_do_table(struct sk_buff *skb, IP_NF_ASSERT(table->valid_hooks & (1 << hook)); - xt_info_rdlock_bh(); + local_bh_disable(); + addend = xt_write_recseq_begin(); private = table->private; cpu = smp_processor_id(); table_base = private->entries[cpu]; @@ -442,7 +444,9 @@ ip6t_do_table(struct sk_buff *skb, } while (!acpar.hotdrop); *stackptr = origptr; - xt_info_rdunlock_bh(); + + xt_write_recseq_end(addend); + local_bh_enable(); #ifdef DEBUG_ALLOW_ALL return NF_ACCEPT; @@ -899,7 +903,7 @@ get_counters(const struct xt_table_info *t, unsigned int i; for_each_possible_cpu(cpu) { - seqlock_t *lock = &per_cpu(xt_info_locks, cpu).lock; + seqcount_t *s = &per_cpu(xt_recseq, cpu); i = 0; xt_entry_foreach(iter, t->entries[cpu], t->size) { @@ -907,10 +911,10 @@ get_counters(const struct xt_table_info *t, unsigned int start; do { - start = read_seqbegin(lock); + start = read_seqcount_begin(s); bcnt = iter->counters.bcnt; pcnt = iter->counters.pcnt; - } while (read_seqretry(lock, start)); + } while (read_seqcount_retry(s, start)); ADD_COUNTER(counters[i], bcnt, pcnt); ++i; @@ -1325,6 +1329,7 @@ do_add_counters(struct net *net, const void __user *user, unsigned int len, int ret = 0; const void *loc_cpu_entry; struct ip6t_entry *iter; + unsigned int addend; #ifdef CONFIG_COMPAT struct compat_xt_counters_info compat_tmp; @@ -1381,13 +1386,13 @@ do_add_counters(struct net *net, const void __user *user, unsigned int len, i = 0; /* Choose the copy that is on our node */ curcpu = smp_processor_id(); - xt_info_wrlock(curcpu); + addend = xt_write_recseq_begin(); loc_cpu_entry = private->entries[curcpu]; xt_entry_foreach(iter, loc_cpu_entry, private->size) { ADD_COUNTER(iter->counters, paddc[i].bcnt, paddc[i].pcnt); ++i; } - xt_info_wrunlock(curcpu); + xt_write_recseq_end(addend); unlock_up_free: local_bh_enable(); |