3.16.60-rc1 review patch. If anyone has any objections, please let me know.
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From: Guillaume Nault g.nault@alphalink.fr
commit f726214d9b23e5fce8c11937577a289a3202498f upstream.
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: 0ad6614048cf ("l2tp: Add debugfs files for dumping l2tp debug info") Signed-off-by: Guillaume Nault g.nault@alphalink.fr Signed-off-by: David S. Miller davem@davemloft.net [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- net/l2tp/l2tp_core.c | 20 -------------------- net/l2tp/l2tp_core.h | 1 - net/l2tp/l2tp_debugfs.c | 15 +++++++++++++-- 3 files changed, 13 insertions(+), 23 deletions(-)
--- a/net/l2tp/l2tp_core.c +++ b/net/l2tp/l2tp_core.c @@ -415,26 +415,6 @@ err_tlock: } EXPORT_SYMBOL_GPL(l2tp_session_register);
-struct l2tp_tunnel *l2tp_tunnel_find_nth(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 *****************************************************************************/ --- a/net/l2tp/l2tp_core.h +++ b/net/l2tp/l2tp_core.h @@ -242,7 +242,6 @@ struct l2tp_session *l2tp_session_get_nt struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, const char *ifname, bool do_ref); -struct l2tp_tunnel *l2tp_tunnel_find_nth(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, --- a/net/l2tp/l2tp_debugfs.c +++ b/net/l2tp/l2tp_debugfs.c @@ -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 se
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)