netdev - [PATCH net-next 08/19] drop_monitor: add net device refcount tracker

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Date:   Wed,  1 Dec 2021 19:21:28 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev <netdev@...r.kernel.org>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH net-next 08/19] drop_monitor: add net device refcount tracker

From: Eric Dumazet <edumazet@...gle.com>

We want to track all dev_hold()/dev_put() to ease leak hunting.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/net/devlink.h   | 3 +++
 net/core/drop_monitor.c | 4 ++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/net/devlink.h b/include/net/devlink.h
index 043fcec8b0aadf041aba35b8339c93ac9336b551..09b75fdfa74e268aaeb05ec640fd76ec5ba777ac 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -670,7 +670,10 @@ struct devlink_health_reporter_ops {
 struct devlink_trap_metadata {
 	const char *trap_name;
 	const char *trap_group_name;
+
 	struct net_device *input_dev;
+	netdevice_tracker dev_tracker;
+
 	const struct flow_action_cookie *fa_cookie;
 	enum devlink_trap_type trap_type;
 };
diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
index 49442cae6f69d5e9d93d00b53ab8f5a0563c1d37..dff13c208c1dafac26c3180a37e6e3be5f8fa744 100644
--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -850,7 +850,7 @@ net_dm_hw_metadata_copy(const struct devlink_trap_metadata *metadata)
 	}
 
 	hw_metadata->input_dev = metadata->input_dev;
-	dev_hold(hw_metadata->input_dev);
+	dev_hold_track(hw_metadata->input_dev, &hw_metadata->dev_tracker, GFP_ATOMIC);
 
 	return hw_metadata;
 
@@ -866,7 +866,7 @@ net_dm_hw_metadata_copy(const struct devlink_trap_metadata *metadata)
 static void
 net_dm_hw_metadata_free(const struct devlink_trap_metadata *hw_metadata)
 {
-	dev_put(hw_metadata->input_dev);
+	dev_put_track(hw_metadata->input_dev, &hw_metadata->dev_tracker);
 	kfree(hw_metadata->fa_cookie);
 	kfree(hw_metadata->trap_name);
 	kfree(hw_metadata->trap_group_name);
-- 
2.34.0.rc2.393.gf8c9666880-goog