netdev - [PATCH v3 net-next 08/23] drop_monitor: add net device refcount tracker

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Date:   Sat,  4 Dec 2021 20:22:02 -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>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: [PATCH v3 net-next 08/23] 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   | 4 ++++
 net/core/drop_monitor.c | 6 +++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/net/devlink.h b/include/net/devlink.h
index 043fcec8b0aadf041aba35b8339c93ac9336b551..3276a29f2b814cda1fdce80f52c126c1cd444272 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -664,13 +664,17 @@ struct devlink_health_reporter_ops {
  * @trap_name: Trap name.
  * @trap_group_name: Trap group name.
  * @input_dev: Input netdevice.
+ * @dev_tracker: refcount tracker for @input_dev.
  * @fa_cookie: Flow action user cookie.
  * @trap_type: Trap type.
  */
 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..3d0ab2eec91667bdfac93878a046fc727fc22b99 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;
 
@@ -864,9 +864,9 @@ 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)
+net_dm_hw_metadata_free(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);
-- 
2.34.1.400.ga245620fadb-goog