commit 834944073301e85001c3ed9913027ca47c6f889b
author Guillaume Nault <g.nault@alphalink.fr> Wed Apr 25 19:54:14 2018 +0200
committer David S. Miller <davem@davemloft.net> Fri Apr 27 11:06:35 2018 -0400
tree deb655628c17910683936af73a8b510992404ff2
parent 3e5cf362c34b14c8d01d19d4b821fb35e1779862

l2tp: consistent reference counting in procfs and debufs

The 'pppol2tp' procfs and 'l2tp/tunnels' debugfs files handle reference
counting of sessions differently than for tunnels.

For consistency, use the same mechanism for handling both sessions and
tunnels. That is, drop the reference on the previous session just
before looking up the next one (rather than in .show()). If necessary
(if dump stops before *_next_session() returns NULL), drop the last
reference in .stop().

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/l2tp/l2tp_debugfs.c

diff --git a/net/l2tp/l2tp_debugfs.c b/net/l2tp/l2tp_debugfs.c
index 7f1e842..e87686f 100644
--- a/net/l2tp/l2tp_debugfs.c
+++ b/net/l2tp/l2tp_debugfs.c
@@ -57,6 +57,10 @@ static void l2tp_dfs_next_tunnel(struct l2tp_dfs_seq_data *pd)
 
 static void l2tp_dfs_next_session(struct l2tp_dfs_seq_data *pd)
 {
+	/* Drop reference taken during previous invocation */
+	if (pd->session)
+		l2tp_session_dec_refcount(pd->session);
+
 	pd->session = l2tp_session_get_nth(pd->tunnel, pd->session_idx);
 	pd->session_idx++;
 
@@ -105,11 +109,16 @@ static void l2tp_dfs_seq_stop(struct seq_file *p, void *v)
 	if (!pd || pd == SEQ_START_TOKEN)
 		return;
 
-	/* Drop reference taken by last invocation of l2tp_dfs_next_tunnel() */
+	/* Drop reference taken by last invocation of l2tp_dfs_next_session()
+	 * or l2tp_dfs_next_tunnel().
+	 */
+	if (pd->session) {
+		l2tp_session_dec_refcount(pd->session);
+		pd->session = NULL;
+	}
 	if (pd->tunnel) {
 		l2tp_tunnel_dec_refcount(pd->tunnel);
 		pd->tunnel = NULL;
-		pd->session = NULL;
 	}
 }
 
@@ -250,13 +259,10 @@ static int l2tp_dfs_seq_show(struct seq_file *m, void *v)
 		goto out;
 	}
 
-	/* Show the tunnel or session context */
-	if (!pd->session) {
+	if (!pd->session)
 		l2tp_dfs_seq_tunnel_show(m, pd->tunnel);
-	} else {
+	else
 		l2tp_dfs_seq_session_show(m, pd->session);
-		l2tp_session_dec_refcount(pd->session);
-	}
 
 out:
 	return 0;

net/l2tp/l2tp_ppp.c

diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 1fd9e14..f951c76 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -1576,6 +1576,10 @@ static void pppol2tp_next_tunnel(struct net *net, struct pppol2tp_seq_data *pd)
 
 static void pppol2tp_next_session(struct net *net, struct pppol2tp_seq_data *pd)
 {
+	/* Drop reference taken during previous invocation */
+	if (pd->session)
+		l2tp_session_dec_refcount(pd->session);
+
 	pd->session = l2tp_session_get_nth(pd->tunnel, pd->session_idx);
 	pd->session_idx++;
 
@@ -1624,11 +1628,16 @@ static void pppol2tp_seq_stop(struct seq_file *p, void *v)
 	if (!pd || pd == SEQ_START_TOKEN)
 		return;
 
-	/* Drop reference taken by last invocation of pppol2tp_next_tunnel() */
+	/* Drop reference taken by last invocation of pppol2tp_next_session()
+	 * or pppol2tp_next_tunnel().
+	 */
+	if (pd->session) {
+		l2tp_session_dec_refcount(pd->session);
+		pd->session = NULL;
+	}
 	if (pd->tunnel) {
 		l2tp_tunnel_dec_refcount(pd->tunnel);
 		pd->tunnel = NULL;
-		pd->session = NULL;
 	}
 }
 
@@ -1723,14 +1732,10 @@ static int pppol2tp_seq_show(struct seq_file *m, void *v)
 		goto out;
 	}
 
-	/* Show the tunnel or session context.
-	 */
-	if (!pd->session) {
+	if (!pd->session)
 		pppol2tp_seq_tunnel_show(m, pd->tunnel);
-	} else {
+	else
 		pppol2tp_seq_session_show(m, pd->session);
-		l2tp_session_dec_refcount(pd->session);
-	}
 
 out:
 	return 0;