GitHub-Mirror/Star64_linux
2
0
Fork 0
mirror of https://github.com/Fishwaldo/Star64_linux.git synced 2025-07-23 07:12:09 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

net: sk_dst_cache RCUification

Browse source 
With latest CONFIG_PROVE_RCU stuff, I felt more comfortable to make this
work.

sk->sk_dst_cache is currently protected by a rwlock (sk_dst_lock)

This rwlock is readlocked for a very small amount of time, and dst
entries are already freed after RCU grace period. This calls for RCU
again :)

This patch converts sk_dst_lock to a spinlock, and use RCU for readers.

__sk_dst_get() is supposed to be called with rcu_read_lock() or if
socket locked by user, so use appropriate rcu_dereference_check()
condition (rcu_read_lock_held() || sock_owned_by_user(sk))

This patch avoids two atomic ops per tx packet on UDP connected sockets,
for example, and permits sk_dst_lock to be much less dirtied.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-04-08 23:03:29 +00:00 • committed by David S. Miller
parent 7a161ea924
commit b6c6712a42
11 changed files with 60 additions and 61 deletions
Download patch file Download diff file Expand all files Collapse all files

8
net/core/sock.c
View file

@ -364,11 +364,11 @@ EXPORT_SYMBOL(sk_reset_txq);
struct dst_entry *__sk_dst_check(struct sock *sk, u32 cookie)
{
struct dst_entry *dst = sk->sk_dst_cache;
struct dst_entry *dst = __sk_dst_get(sk);
if (dst && dst->obsolete && dst->ops->check(dst, cookie) == NULL) {
sk_tx_queue_clear(sk);
sk->sk_dst_cache = NULL;
rcu_assign_pointer(sk->sk_dst_cache, NULL);
dst_release(dst);
return NULL;
}
@ -1157,7 +1157,7 @@ struct sock *sk_clone(const struct sock *sk, const gfp_t priority)
skb_queue_head_init(&newsk->sk_async_wait_queue);
#endif
rwlock_init(&newsk->sk_dst_lock);
spin_lock_init(&newsk->sk_dst_lock);
rwlock_init(&newsk->sk_callback_lock);
lockdep_set_class_and_name(&newsk->sk_callback_lock,
af_callback_keys + newsk->sk_family,
@ -1898,7 +1898,7 @@ void sock_init_data(struct socket *sock, struct sock *sk)
} else
sk->sk_sleep = NULL;
rwlock_init(&sk->sk_dst_lock);
spin_lock_init(&sk->sk_dst_lock);
rwlock_init(&sk->sk_callback_lock);
lockdep_set_class_and_name(&sk->sk_callback_lock,
af_callback_keys + sk->sk_family,