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platform_kernel-5.15
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af_key: locking change 

Get rid of custom locking that was using wait queue, lock, and atomic
to basically build a queued mutex.  Use RCU for read side.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
stephen hemminger 2010-02-22 07:57:19 +00:00 committed by David S. Miller
parent 808f5114a9
commit 7f6b9dbd5a
1 changed files with 16 additions and 60 deletions
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76
net/key/af_key.c
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@ -41,9 +41,7 @@ struct netns_pfkey {
struct hlist_head table; struct hlist_head table;
atomic_t socks_nr; atomic_t socks_nr;
}; };
static DECLARE_WAIT_QUEUE_HEAD(pfkey_table_wait); static DEFINE_MUTEX(pfkey_mutex);
static DEFINE_RWLOCK(pfkey_table_lock);
static atomic_t pfkey_table_users = ATOMIC_INIT(0);
struct pfkey_sock { struct pfkey_sock {
/* struct sock must be the first member of struct pfkey_sock */ /* struct sock must be the first member of struct pfkey_sock */
@ -108,50 +106,6 @@ static void pfkey_sock_destruct(struct sock *sk)
atomic_dec(&net_pfkey->socks_nr); atomic_dec(&net_pfkey->socks_nr);
} }
static void pfkey_table_grab(void)
{
write_lock_bh(&pfkey_table_lock);
if (atomic_read(&pfkey_table_users)) {
DECLARE_WAITQUEUE(wait, current);
add_wait_queue_exclusive(&pfkey_table_wait, &wait);
for(;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (atomic_read(&pfkey_table_users) == 0)
break;
write_unlock_bh(&pfkey_table_lock);
schedule();
write_lock_bh(&pfkey_table_lock);
}
__set_current_state(TASK_RUNNING);
remove_wait_queue(&pfkey_table_wait, &wait);
}
}
static __inline__ void pfkey_table_ungrab(void)
{
write_unlock_bh(&pfkey_table_lock);
wake_up(&pfkey_table_wait);
}
static __inline__ void pfkey_lock_table(void)
{
/* read_lock() synchronizes us to pfkey_table_grab */
read_lock(&pfkey_table_lock);
atomic_inc(&pfkey_table_users);
read_unlock(&pfkey_table_lock);
}
static __inline__ void pfkey_unlock_table(void)
{
if (atomic_dec_and_test(&pfkey_table_users))
wake_up(&pfkey_table_wait);
}
static const struct proto_ops pfkey_ops; static const struct proto_ops pfkey_ops;
static void pfkey_insert(struct sock *sk) static void pfkey_insert(struct sock *sk)
@ -159,16 +113,16 @@ static void pfkey_insert(struct sock *sk)
struct net *net = sock_net(sk); struct net *net = sock_net(sk);
struct netns_pfkey *net_pfkey = net_generic(net, pfkey_net_id); struct netns_pfkey *net_pfkey = net_generic(net, pfkey_net_id);
pfkey_table_grab(); mutex_lock(&pfkey_mutex);
sk_add_node(sk, &net_pfkey->table); sk_add_node_rcu(sk, &net_pfkey->table);
pfkey_table_ungrab(); mutex_unlock(&pfkey_mutex);
} }
static void pfkey_remove(struct sock *sk) static void pfkey_remove(struct sock *sk)
{ {
pfkey_table_grab(); mutex_lock(&pfkey_mutex);
sk_del_node_init(sk); sk_del_node_init_rcu(sk);
pfkey_table_ungrab(); mutex_unlock(&pfkey_mutex);
} }
static struct proto key_proto = { static struct proto key_proto = {
@ -223,6 +177,8 @@ static int pfkey_release(struct socket *sock)
sock_orphan(sk); sock_orphan(sk);
sock->sk = NULL; sock->sk = NULL;
skb_queue_purge(&sk->sk_write_queue); skb_queue_purge(&sk->sk_write_queue);
synchronize_rcu();
sock_put(sk); sock_put(sk);
return 0; return 0;
@ -277,8 +233,8 @@ static int pfkey_broadcast(struct sk_buff *skb, gfp_t allocation,
if (!skb) if (!skb)
return -ENOMEM; return -ENOMEM;
pfkey_lock_table(); rcu_read_lock();
sk_for_each(sk, node, &net_pfkey->table) { sk_for_each_rcu(sk, node, &net_pfkey->table) {
struct pfkey_sock *pfk = pfkey_sk(sk); struct pfkey_sock *pfk = pfkey_sk(sk);
int err2; int err2;
@ -309,7 +265,7 @@ static int pfkey_broadcast(struct sk_buff *skb, gfp_t allocation,
if ((broadcast_flags & BROADCAST_REGISTERED) && err) if ((broadcast_flags & BROADCAST_REGISTERED) && err)
err = err2; err = err2;
} }
pfkey_unlock_table(); rcu_read_unlock();
if (one_sk != NULL) if (one_sk != NULL)
err = pfkey_broadcast_one(skb, &skb2, allocation, one_sk); err = pfkey_broadcast_one(skb, &skb2, allocation, one_sk);
@ -3702,8 +3658,8 @@ static void *pfkey_seq_start(struct seq_file *f, loff_t *ppos)
struct net *net = seq_file_net(f); struct net *net = seq_file_net(f);
struct netns_pfkey *net_pfkey = net_generic(net, pfkey_net_id); struct netns_pfkey *net_pfkey = net_generic(net, pfkey_net_id);
read_lock(&pfkey_table_lock); rcu_read_lock();
return seq_hlist_start_head(&net_pfkey->table, *ppos); return seq_hlist_start_head_rcu(&net_pfkey->table, *ppos);
} }
static void *pfkey_seq_next(struct seq_file *f, void *v, loff_t *ppos) static void *pfkey_seq_next(struct seq_file *f, void *v, loff_t *ppos)
@ -3711,12 +3667,12 @@ static void *pfkey_seq_next(struct seq_file *f, void *v, loff_t *ppos)
struct net *net = seq_file_net(f); struct net *net = seq_file_net(f);
struct netns_pfkey *net_pfkey = net_generic(net, pfkey_net_id); struct netns_pfkey *net_pfkey = net_generic(net, pfkey_net_id);
return seq_hlist_next(v, &net_pfkey->table, ppos); return seq_hlist_next_rcu(v, &net_pfkey->table, ppos);
} }
static void pfkey_seq_stop(struct seq_file *f, void *v) static void pfkey_seq_stop(struct seq_file *f, void *v)
{ {
read_unlock(&pfkey_table_lock); rcu_read_unlock();
} }
static const struct seq_operations pfkey_seq_ops = { static const struct seq_operations pfkey_seq_ops = {