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Commit f726214d authored by Guillaume Nault's avatar Guillaume Nault Committed by David S. Miller
Browse files

l2tp: hold reference on tunnels printed in l2tp/tunnels debugfs file 



Use l2tp_tunnel_get_nth() instead of l2tp_tunnel_find_nth(), to be safe
against concurrent tunnel deletion.

Use the same mechanism as in l2tp_ppp.c for dropping the reference
taken by l2tp_tunnel_get_nth(). That is, drop the reference just
before looking up the next tunnel. In case of error, drop the last
accessed tunnel in l2tp_dfs_seq_stop().

That was the last use of l2tp_tunnel_find_nth().

Fixes: 0ad66140 ("l2tp: Add debugfs files for dumping l2tp debug info")
Signed-off-by: default avatarGuillaume Nault <g.nault@alphalink.fr>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0e0c3fee

net/l2tp/l2tp_core.c

+0 −20
Original line number Diff line number Diff line
@@ -355,26 +355,6 @@ int l2tp_session_register(struct l2tp_session *session, 
}

EXPORT_SYMBOL_GPL(l2tp_session_register);



struct l2tp_tunnel *l2tp_tunnel_find_nth(const struct net *net, int nth)

{

	struct l2tp_net *pn = l2tp_pernet(net);

	struct l2tp_tunnel *tunnel;

	int count = 0;



	rcu_read_lock_bh();

	list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {

		if (++count > nth) {

			rcu_read_unlock_bh();

			return tunnel;

		}

	}



	rcu_read_unlock_bh();



	return NULL;

}

EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth);



/*****************************************************************************

 * Receive data handling

 *****************************************************************************/

net/l2tp/l2tp_core.h

+0 −1
Original line number Diff line number Diff line
@@ -222,7 +222,6 @@ struct l2tp_session *l2tp_session_get(const struct net *net, 
struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);

struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,

						const char *ifname);

struct l2tp_tunnel *l2tp_tunnel_find_nth(const struct net *net, int nth);



int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,

		       u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,

net/l2tp/l2tp_debugfs.c

+13 −2
Original line number Diff line number Diff line
@@ -47,7 +47,11 @@ struct l2tp_dfs_seq_data { 


static void l2tp_dfs_next_tunnel(struct l2tp_dfs_seq_data *pd)

{

	pd->tunnel = l2tp_tunnel_find_nth(pd->net, pd->tunnel_idx);

	/* Drop reference taken during previous invocation */

	if (pd->tunnel)

		l2tp_tunnel_dec_refcount(pd->tunnel);



	pd->tunnel = l2tp_tunnel_get_nth(pd->net, pd->tunnel_idx);

	pd->tunnel_idx++;

}
@@ -96,7 +100,14 @@ static void *l2tp_dfs_seq_next(struct seq_file *m, void *v, loff_t *pos) 


static void l2tp_dfs_seq_stop(struct seq_file *p, void *v)

{

	/* nothing to do */

	struct l2tp_dfs_seq_data *pd = v;



	if (!pd || pd == SEQ_START_TOKEN)

		return;



	/* Drop reference taken by last invocation of l2tp_dfs_next_tunnel() */

	if (pd->tunnel)

		l2tp_tunnel_dec_refcount(pd->tunnel);

}



static void l2tp_dfs_seq_tunnel_show(struct seq_file *m, void *v)