Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit fc01538f authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

inet: simplify timewait refcounting 



timewait sockets have a complex refcounting logic.
Once we realize it should be similar to established and
syn_recv sockets, we can use sk_nulls_del_node_init_rcu()
and remove inet_twsk_unhash()

In particular, deferred inet_twsk_put() added in commit
13475a30 ("tcp: connect() race with timewait reuse")
looks unecessary : When removing a timewait socket from
ehash or bhash, caller must own a reference on the socket
anyway.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3fd2f1b9

include/net/inet_hashtables.h

+2 −2
Original line number Diff line number Diff line
@@ -205,8 +205,8 @@ void inet_put_port(struct sock *sk); 


void inet_hashinfo_init(struct inet_hashinfo *h);



int __inet_hash_nolisten(struct sock *sk, struct inet_timewait_sock *tw);

int __inet_hash(struct sock *sk, struct inet_timewait_sock *tw);

void __inet_hash_nolisten(struct sock *sk, struct sock *osk);

void __inet_hash(struct sock *sk, struct sock *osk);

void inet_hash(struct sock *sk);

void inet_unhash(struct sock *sk);

include/net/inet_timewait_sock.h

+2 −4
Original line number Diff line number Diff line
@@ -100,9 +100,7 @@ static inline struct inet_timewait_sock *inet_twsk(const struct sock *sk) 
void inet_twsk_free(struct inet_timewait_sock *tw);

void inet_twsk_put(struct inet_timewait_sock *tw);



int inet_twsk_unhash(struct inet_timewait_sock *tw);



int inet_twsk_bind_unhash(struct inet_timewait_sock *tw,

void inet_twsk_bind_unhash(struct inet_timewait_sock *tw,

			   struct inet_hashinfo *hashinfo);



struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk,

net/ipv4/inet_hashtables.c

+10 −21
Original line number Diff line number Diff line
@@ -343,7 +343,6 @@ static int __inet_check_established(struct inet_timewait_death_row *death_row, 
	struct sock *sk2;

	const struct hlist_nulls_node *node;

	struct inet_timewait_sock *tw = NULL;

	int twrefcnt = 0;



	spin_lock(lock);
@@ -371,12 +370,10 @@ static int __inet_check_established(struct inet_timewait_death_row *death_row, 
	WARN_ON(!sk_unhashed(sk));

	__sk_nulls_add_node_rcu(sk, &head->chain);

	if (tw) {

		twrefcnt = inet_twsk_unhash(tw);

		sk_nulls_del_node_init_rcu((struct sock *)tw);

		NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);

	}

	spin_unlock(lock);

	if (twrefcnt)

		inet_twsk_put(tw);

	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);



	if (twp) {
@@ -384,7 +381,6 @@ static int __inet_check_established(struct inet_timewait_death_row *death_row, 
	} else if (tw) {

		/* Silly. Should hash-dance instead... */

		inet_twsk_deschedule(tw);



		inet_twsk_put(tw);

	}

	return 0;
@@ -403,13 +399,12 @@ static u32 inet_sk_port_offset(const struct sock *sk) 
					  inet->inet_dport);

}



int __inet_hash_nolisten(struct sock *sk, struct inet_timewait_sock *tw)

void __inet_hash_nolisten(struct sock *sk, struct sock *osk)

{

	struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;

	struct hlist_nulls_head *list;

	struct inet_ehash_bucket *head;

	spinlock_t *lock;

	int twrefcnt = 0;



	WARN_ON(!sk_unhashed(sk));
@@ -420,23 +415,22 @@ int __inet_hash_nolisten(struct sock *sk, struct inet_timewait_sock *tw) 


	spin_lock(lock);

	__sk_nulls_add_node_rcu(sk, list);

	if (tw) {

		WARN_ON(sk->sk_hash != tw->tw_hash);

		twrefcnt = inet_twsk_unhash(tw);

	if (osk) {

		WARN_ON(sk->sk_hash != osk->sk_hash);

		sk_nulls_del_node_init_rcu(osk);

	}

	spin_unlock(lock);

	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);

	return twrefcnt;

}

EXPORT_SYMBOL_GPL(__inet_hash_nolisten);



int __inet_hash(struct sock *sk, struct inet_timewait_sock *tw)

void __inet_hash(struct sock *sk, struct sock *osk)

{

	struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;

	struct inet_listen_hashbucket *ilb;



	if (sk->sk_state != TCP_LISTEN)

		return __inet_hash_nolisten(sk, tw);

		return __inet_hash_nolisten(sk, osk);



	WARN_ON(!sk_unhashed(sk));

	ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
@@ -445,7 +439,6 @@ int __inet_hash(struct sock *sk, struct inet_timewait_sock *tw) 
	__sk_nulls_add_node_rcu(sk, &ilb->head);

	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);

	spin_unlock(&ilb->lock);

	return 0;

}

EXPORT_SYMBOL(__inet_hash);
@@ -492,7 +485,6 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, 
	struct inet_bind_bucket *tb;

	int ret;

	struct net *net = sock_net(sk);

	int twrefcnt = 1;



	if (!snum) {

		int i, remaining, low, high, port;
@@ -560,19 +552,16 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, 
		inet_bind_hash(sk, tb, port);

		if (sk_unhashed(sk)) {

			inet_sk(sk)->inet_sport = htons(port);

			twrefcnt += __inet_hash_nolisten(sk, tw);

			__inet_hash_nolisten(sk, (struct sock *)tw);

		}

		if (tw)

			twrefcnt += inet_twsk_bind_unhash(tw, hinfo);

			inet_twsk_bind_unhash(tw, hinfo);

		spin_unlock(&head->lock);



		if (tw) {

			inet_twsk_deschedule(tw);

			while (twrefcnt) {

				twrefcnt--;

			inet_twsk_put(tw);

		}

		}



		ret = 0;

		goto out;

net/ipv4/inet_timewait_sock.c

+6 −36
Original line number Diff line number Diff line
@@ -17,28 +17,6 @@ 
#include <net/ip.h>





/**

 *	inet_twsk_unhash - unhash a timewait socket from established hash

 *	@tw: timewait socket

 *

 *	unhash a timewait socket from established hash, if hashed.

 *	ehash lock must be held by caller.

 *	Returns 1 if caller should call inet_twsk_put() after lock release.

 */

int inet_twsk_unhash(struct inet_timewait_sock *tw)

{

	if (hlist_nulls_unhashed(&tw->tw_node))

		return 0;



	hlist_nulls_del_rcu(&tw->tw_node);

	sk_nulls_node_init(&tw->tw_node);

	/*

	 * We cannot call inet_twsk_put() ourself under lock,

	 * caller must call it for us.

	 */

	return 1;

}



/**

 *	inet_twsk_bind_unhash - unhash a timewait socket from bind hash

 *	@tw: timewait socket
@@ -48,35 +26,29 @@ int inet_twsk_unhash(struct inet_timewait_sock *tw) 
 *	bind hash lock must be held by caller.

 *	Returns 1 if caller should call inet_twsk_put() after lock release.

 */

int inet_twsk_bind_unhash(struct inet_timewait_sock *tw,

void inet_twsk_bind_unhash(struct inet_timewait_sock *tw,

			  struct inet_hashinfo *hashinfo)

{

	struct inet_bind_bucket *tb = tw->tw_tb;



	if (!tb)

		return 0;

		return;



	__hlist_del(&tw->tw_bind_node);

	tw->tw_tb = NULL;

	inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);

	/*

	 * We cannot call inet_twsk_put() ourself under lock,

	 * caller must call it for us.

	 */

	return 1;

	__sock_put((struct sock *)tw);

}



/* Must be called with locally disabled BHs. */

static void inet_twsk_kill(struct inet_timewait_sock *tw)

{

	struct inet_hashinfo *hashinfo = tw->tw_dr->hashinfo;

	struct inet_bind_hashbucket *bhead;

	int refcnt;

	/* Unlink from established hashes. */

	spinlock_t *lock = inet_ehash_lockp(hashinfo, tw->tw_hash);

	struct inet_bind_hashbucket *bhead;



	spin_lock(lock);

	refcnt = inet_twsk_unhash(tw);

	sk_nulls_del_node_init_rcu((struct sock *)tw);

	spin_unlock(lock);



	/* Disassociate with bind bucket. */
@@ -84,11 +56,9 @@ static void inet_twsk_kill(struct inet_timewait_sock *tw) 
			hashinfo->bhash_size)];



	spin_lock(&bhead->lock);

	refcnt += inet_twsk_bind_unhash(tw, hashinfo);

	inet_twsk_bind_unhash(tw, hashinfo);

	spin_unlock(&bhead->lock);



	BUG_ON(refcnt >= atomic_read(&tw->tw_refcnt));

	atomic_sub(refcnt, &tw->tw_refcnt);

	atomic_dec(&tw->tw_dr->tw_count);

	inet_twsk_put(tw);

}

net/ipv6/inet6_hashtables.c

+1 −5
Original line number Diff line number Diff line
@@ -207,7 +207,6 @@ static int __inet6_check_established(struct inet_timewait_death_row *death_row, 
	struct sock *sk2;

	const struct hlist_nulls_node *node;

	struct inet_timewait_sock *tw = NULL;

	int twrefcnt = 0;



	spin_lock(lock);
@@ -234,12 +233,10 @@ static int __inet6_check_established(struct inet_timewait_death_row *death_row, 
	WARN_ON(!sk_unhashed(sk));

	__sk_nulls_add_node_rcu(sk, &head->chain);

	if (tw) {

		twrefcnt = inet_twsk_unhash(tw);

		sk_nulls_del_node_init_rcu((struct sock *)tw);

		NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);

	}

	spin_unlock(lock);

	if (twrefcnt)

		inet_twsk_put(tw);

	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);



	if (twp) {
@@ -247,7 +244,6 @@ static int __inet6_check_established(struct inet_timewait_death_row *death_row, 
	} else if (tw) {

		/* Silly. Should hash-dance instead... */

		inet_twsk_deschedule(tw);



		inet_twsk_put(tw);

	}

	return 0;