Commit c3718936 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

ipv6: anycast: complete RCU handling of struct ifacaddr6 



struct ifacaddr6 are already freed after RCU grace period.

Add __rcu qualifier to aca_next pointer, and idev->ac_list

Add relevant rcu_assign_pointer() and dereference accessors.

ipv6_chk_acast_dev() no longer needs to acquire idev->lock.

/proc/net/anycast6 is now purely RCU protected, it no
longer acquires idev->lock.

Similarly in6_dump_addrs() can use RCU protection to iterate
through anycast addresses. It was relying on a mixture of RCU
and RTNL but next patches will get rid of RTNL there.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarJiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20240223201054.220534-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 5c237967

include/net/if_inet6.h

+2 −2
Original line number Diff line number Diff line
@@ -144,7 +144,7 @@ struct ipv6_ac_socklist { 
struct ifacaddr6 {

	struct in6_addr		aca_addr;

	struct fib6_info	*aca_rt;

	struct ifacaddr6	*aca_next;

	struct ifacaddr6 __rcu	*aca_next;

	struct hlist_node	aca_addr_lst;

	int			aca_users;

	refcount_t		aca_refcnt;
@@ -196,7 +196,7 @@ struct inet6_dev { 
	spinlock_t		mc_report_lock;	/* mld query report lock */

	struct mutex		mc_lock;	/* mld global lock */



	struct ifacaddr6	*ac_list;

	struct ifacaddr6 __rcu	*ac_list;

	rwlock_t		lock;

	refcount_t		refcnt;

	__u32			if_flags;

net/ipv6/addrconf.c

+2 −2
Original line number Diff line number Diff line
@@ -5314,8 +5314,8 @@ static int in6_dump_addrs(struct inet6_dev *idev, struct sk_buff *skb, 
	case ANYCAST_ADDR:

		fillargs->event = RTM_GETANYCAST;

		/* anycast address */

		for (ifaca = idev->ac_list; ifaca;

		     ifaca = ifaca->aca_next, ip_idx++) {

		for (ifaca = rcu_dereference(idev->ac_list); ifaca;

		     ifaca = rcu_dereference(ifaca->aca_next), ip_idx++) {

			if (ip_idx < s_ip_idx)

				continue;

			err = inet6_fill_ifacaddr(skb, ifaca, fillargs);

net/ipv6/anycast.c

+23 −38
Original line number Diff line number Diff line
@@ -296,7 +296,8 @@ int __ipv6_dev_ac_inc(struct inet6_dev *idev, const struct in6_addr *addr) 
		goto out;

	}



	for (aca = idev->ac_list; aca; aca = aca->aca_next) {

	for (aca = rtnl_dereference(idev->ac_list); aca;

	     aca = rtnl_dereference(aca->aca_next)) {

		if (ipv6_addr_equal(&aca->aca_addr, addr)) {

			aca->aca_users++;

			err = 0;
@@ -317,13 +318,13 @@ int __ipv6_dev_ac_inc(struct inet6_dev *idev, const struct in6_addr *addr) 
		goto out;

	}



	aca->aca_next = idev->ac_list;

	idev->ac_list = aca;



	/* Hold this for addrconf_join_solict() below before we unlock,

	 * it is already exposed via idev->ac_list.

	 */

	aca_get(aca);

	aca->aca_next = idev->ac_list;

	rcu_assign_pointer(idev->ac_list, aca);



	write_unlock_bh(&idev->lock);



	ipv6_add_acaddr_hash(net, aca);
@@ -350,7 +351,8 @@ int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr) 


	write_lock_bh(&idev->lock);

	prev_aca = NULL;

	for (aca = idev->ac_list; aca; aca = aca->aca_next) {

	for (aca = rtnl_dereference(idev->ac_list); aca;

	     aca = rtnl_dereference(aca->aca_next)) {

		if (ipv6_addr_equal(&aca->aca_addr, addr))

			break;

		prev_aca = aca;
@@ -364,9 +366,9 @@ int __ipv6_dev_ac_dec(struct inet6_dev *idev, const struct in6_addr *addr) 
		return 0;

	}

	if (prev_aca)

		prev_aca->aca_next = aca->aca_next;

		rcu_assign_pointer(prev_aca->aca_next, aca->aca_next);

	else

		idev->ac_list = aca->aca_next;

		rcu_assign_pointer(idev->ac_list, aca->aca_next);

	write_unlock_bh(&idev->lock);

	ipv6_del_acaddr_hash(aca);

	addrconf_leave_solict(idev, &aca->aca_addr);
@@ -392,8 +394,8 @@ void ipv6_ac_destroy_dev(struct inet6_dev *idev) 
	struct ifacaddr6 *aca;



	write_lock_bh(&idev->lock);

	while ((aca = idev->ac_list) != NULL) {

		idev->ac_list = aca->aca_next;

	while ((aca = rtnl_dereference(idev->ac_list)) != NULL) {

		rcu_assign_pointer(idev->ac_list, aca->aca_next);

		write_unlock_bh(&idev->lock);



		ipv6_del_acaddr_hash(aca);
@@ -420,11 +422,10 @@ static bool ipv6_chk_acast_dev(struct net_device *dev, const struct in6_addr *ad 


	idev = __in6_dev_get(dev);

	if (idev) {

		read_lock_bh(&idev->lock);

		for (aca = idev->ac_list; aca; aca = aca->aca_next)

		for (aca = rcu_dereference(idev->ac_list); aca;

		     aca = rcu_dereference(aca->aca_next))

			if (ipv6_addr_equal(&aca->aca_addr, addr))

				break;

		read_unlock_bh(&idev->lock);

		return aca != NULL;

	}

	return false;
@@ -477,53 +478,43 @@ bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev, 
struct ac6_iter_state {

	struct seq_net_private p;

	struct net_device *dev;

	struct inet6_dev *idev;

};



#define ac6_seq_private(seq)	((struct ac6_iter_state *)(seq)->private)



static inline struct ifacaddr6 *ac6_get_first(struct seq_file *seq)

{

	struct ifacaddr6 *im = NULL;

	struct ac6_iter_state *state = ac6_seq_private(seq);

	struct net *net = seq_file_net(seq);

	struct ifacaddr6 *im = NULL;



	state->idev = NULL;

	for_each_netdev_rcu(net, state->dev) {

		struct inet6_dev *idev;



		idev = __in6_dev_get(state->dev);

		if (!idev)

			continue;

		read_lock_bh(&idev->lock);

		im = idev->ac_list;

		if (im) {

			state->idev = idev;

		im = rcu_dereference(idev->ac_list);

		if (im)

			break;

	}

		read_unlock_bh(&idev->lock);

	}

	return im;

}



static struct ifacaddr6 *ac6_get_next(struct seq_file *seq, struct ifacaddr6 *im)

{

	struct ac6_iter_state *state = ac6_seq_private(seq);

	struct inet6_dev *idev;



	im = im->aca_next;

	im = rcu_dereference(im->aca_next);

	while (!im) {

		if (likely(state->idev != NULL))

			read_unlock_bh(&state->idev->lock);



		state->dev = next_net_device_rcu(state->dev);

		if (!state->dev) {

			state->idev = NULL;

		if (!state->dev)

			break;

		}

		state->idev = __in6_dev_get(state->dev);

		if (!state->idev)

		idev = __in6_dev_get(state->dev);

		if (!idev)

			continue;

		read_lock_bh(&state->idev->lock);

		im = state->idev->ac_list;

		im = rcu_dereference(idev->ac_list);

	}

	return im;

}
@@ -555,12 +546,6 @@ static void *ac6_seq_next(struct seq_file *seq, void *v, loff_t *pos) 
static void ac6_seq_stop(struct seq_file *seq, void *v)

	__releases(RCU)

{

	struct ac6_iter_state *state = ac6_seq_private(seq);



	if (likely(state->idev != NULL)) {

		read_unlock_bh(&state->idev->lock);

		state->idev = NULL;

	}

	rcu_read_unlock();

}