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>
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index a9adf4c..52959ef 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -762,8 +762,8 @@
EXPORT_SYMBOL_GPL(xt_compat_unlock);
#endif
-DEFINE_PER_CPU(struct xt_info_lock, xt_info_locks);
-EXPORT_PER_CPU_SYMBOL_GPL(xt_info_locks);
+DEFINE_PER_CPU(seqcount_t, xt_recseq);
+EXPORT_PER_CPU_SYMBOL_GPL(xt_recseq);
static int xt_jumpstack_alloc(struct xt_table_info *i)
{
@@ -1362,10 +1362,7 @@
int rv;
for_each_possible_cpu(i) {
- struct xt_info_lock *lock = &per_cpu(xt_info_locks, i);
-
- seqlock_init(&lock->lock);
- lock->readers = 0;
+ seqcount_init(&per_cpu(xt_recseq, i));
}
xt = kmalloc(sizeof(struct xt_af) * NFPROTO_NUMPROTO, GFP_KERNEL);
