- instances_lock becomes a spinlock
- lockless lookups
While nfnetlink_log probably not performance critical, using less
rwlocks in our code is always welcomed...
Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
---
net/netfilter/nfnetlink_log.c | 49 +++++++++++++++++---------------
1 file changed, 27 insertions(+), 22 deletions(-)
diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c
index fc9a211..8ec23ec 100644
--- a/net/netfilter/nfnetlink_log.c
+++ b/net/netfilter/nfnetlink_log.c
@@ -66,9 +66,10 @@ struct nfulnl_instance {
u_int16_t group_num; /* number of this queue */
u_int16_t flags;
u_int8_t copy_mode;
+ struct rcu_head rcu;
};
-static DEFINE_RWLOCK(instances_lock);
+static DEFINE_SPINLOCK(instances_lock);
static atomic_t global_seq;
#define INSTANCE_BUCKETS 16
@@ -88,7 +89,7 @@ __instance_lookup(u_int16_t group_num)
struct nfulnl_instance *inst;
head = &instance_table[instance_hashfn(group_num)];
- hlist_for_each_entry(inst, pos, head, hlist) {
+ hlist_for_each_entry_rcu(inst, pos, head, hlist) {
if (inst->group_num == group_num)
return inst;
}
@@ -106,22 +107,26 @@ instance_lookup_get(u_int16_t group_num)
{
struct nfulnl_instance *inst;
- read_lock_bh(&instances_lock);
+ rcu_read_lock_bh();
inst = __instance_lookup(group_num);
if (inst)
instance_get(inst);
- read_unlock_bh(&instances_lock);
+ rcu_read_unlock_bh();
return inst;
}
+static void nfulnl_instance_free_rcu(struct rcu_head *head)
+{
+ kfree(container_of(head, struct nfulnl_instance, rcu));
+ module_put(THIS_MODULE);
+}
+
static void
instance_put(struct nfulnl_instance *inst)
{
- if (inst && atomic_dec_and_test(&inst->use)) {
- kfree(inst);
- module_put(THIS_MODULE);
- }
+ if (inst && atomic_dec_and_test(&inst->use))
+ call_rcu_bh(&inst->rcu, nfulnl_instance_free_rcu);
}
static void nfulnl_timer(unsigned long data);
@@ -132,7 +137,7 @@ instance_create(u_int16_t group_num, int pid)
struct nfulnl_instance *inst;
int err;
- write_lock_bh(&instances_lock);
+ spin_lock_bh(&instances_lock);
if (__instance_lookup(group_num)) {
err = -EEXIST;
goto out_unlock;
@@ -169,12 +174,12 @@ instance_create(u_int16_t group_num, int pid)
hlist_add_head(&inst->hlist,
&instance_table[instance_hashfn(group_num)]);
- write_unlock_bh(&instances_lock);
+ spin_unlock_bh(&instances_lock);
return inst;
out_unlock:
- write_unlock_bh(&instances_lock);
+ spin_unlock_bh(&instances_lock);
return ERR_PTR(err);
}
@@ -200,9 +205,9 @@ __instance_destroy(struct nfulnl_instance *inst)
static inline void
instance_destroy(struct nfulnl_instance *inst)
{
- write_lock_bh(&instances_lock);
+ spin_lock_bh(&instances_lock);
__instance_destroy(inst);
- write_unlock_bh(&instances_lock);
+ spin_unlock_bh(&instances_lock);
}
static int
@@ -672,7 +677,7 @@ nfulnl_rcv_nl_event(struct notifier_block *this,
int i;
/* destroy all instances for this pid */
- write_lock_bh(&instances_lock);
+ spin_lock_bh(&instances_lock);
for (i = 0; i < INSTANCE_BUCKETS; i++) {
struct hlist_node *tmp, *t2;
struct nfulnl_instance *inst;
@@ -684,7 +689,7 @@ nfulnl_rcv_nl_event(struct notifier_block *this,
__instance_destroy(inst);
}
}
- write_unlock_bh(&instances_lock);
+ spin_unlock_bh(&instances_lock);
}
return NOTIFY_DONE;
}
@@ -861,19 +866,19 @@ static struct hlist_node *get_first(struct iter_state *st)
for (st->bucket = 0; st->bucket < INSTANCE_BUCKETS; st->bucket++) {
if (!hlist_empty(&instance_table[st->bucket]))
- return instance_table[st->bucket].first;
+ return rcu_dereference_bh(instance_table[st->bucket].first);
}
return NULL;
}
static struct hlist_node *get_next(struct iter_state *st, struct hlist_node *h)
{
- h = h->next;
+ h = rcu_dereference_bh(h->next);
while (!h) {
if (++st->bucket >= INSTANCE_BUCKETS)
return NULL;
- h = instance_table[st->bucket].first;
+ h = rcu_dereference_bh(instance_table[st->bucket].first);
}
return h;
}
@@ -890,9 +895,9 @@ static struct hlist_node *get_idx(struct iter_state *st, loff_t pos)
}
static void *seq_start(struct seq_file *seq, loff_t *pos)
- __acquires(instances_lock)
+ __acquires(rcu_bh)
{
- read_lock_bh(&instances_lock);
+ rcu_read_lock_bh();
return get_idx(seq->private, *pos);
}
@@ -903,9 +908,9 @@ static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
}
static void seq_stop(struct seq_file *s, void *v)
- __releases(instances_lock)
+ __releases(rcu_bh)
{
- read_unlock_bh(&instances_lock);
+ rcu_read_unlock_bh();
}
static int seq_show(struct seq_file *s, void *v)
--
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