linux-kernel - [PATCH 3/4] net: add ref_tracker_dir_debugfs() calls for netns refcount tracking

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Message-Id: <20250414-reftrack-dbgfs-v1-3-f03585832203@kernel.org>
Date: Mon, 14 Apr 2025 10:45:48 -0400
From: Jeff Layton <jlayton@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Simon Horman <horms@...nel.org>
Cc: Qasim Ijaz <qasdev00@...il.com>, Nathan Chancellor <nathan@...nel.org>, 
 Andrew Lunn <andrew@...n.ch>, linux-kernel@...r.kernel.org, 
 netdev@...r.kernel.org, Jeff Layton <jlayton@...nel.org>
Subject: [PATCH 3/4] net: add ref_tracker_dir_debugfs() calls for netns
 refcount tracking

After assigning the inode number to the namespace, use it to create a
unique name for each netns refcount tracker and register the debugfs
files for them.

The init_net is registered early in the boot process before the
ref_tracker dir is created, so add a late_initcall() to register its
files.

Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
 net/core/net_namespace.c | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 4303f2a4926243e2c0ff0c0387383cd8e0658019..6ffd8aa05c38512e26572d6eada96a36e4aa1ef3 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -761,12 +761,44 @@ struct net *get_net_ns_by_pid(pid_t pid)
 }
 EXPORT_SYMBOL_GPL(get_net_ns_by_pid);

+#ifdef CONFIG_NET_NS_REFCNT_TRACKER
+static void net_ns_net_debugfs(struct net *net)
+{
+	char name[32];
+	size_t len;
+
+	len = snprintf(name, sizeof(name), "net-%u-refcnt", net->ns.inum);
+	if (len < sizeof(name))
+		ref_tracker_dir_debugfs(&net->refcnt_tracker, name);
+
+	len = snprintf(name, sizeof(name), "net-%u-notrefcnt", net->ns.inum);
+	if (len < sizeof(name))
+		ref_tracker_dir_debugfs(&net->notrefcnt_tracker, name);
+}
+
+static int __init init_net_debugfs(void)
+{
+	net_ns_net_debugfs(&init_net);
+	return 0;
+}
+late_initcall(init_net_debugfs);
+#else
+static void net_ns_net_debugfs(struct net *net)
+{
+}
+#endif
+
 static __net_init int net_ns_net_init(struct net *net)
 {
+	int ret;
+
 #ifdef CONFIG_NET_NS
 	net->ns.ops = &netns_operations;
 #endif
-	return ns_alloc_inum(&net->ns);
+	ret = ns_alloc_inum(&net->ns);
+	if (!ret)
+		net_ns_net_debugfs(net);
+	return ret;
 }

 static __net_exit void net_ns_net_exit(struct net *net)

-- 
2.49.0