linux-kernel - [PATCH 5.10 012/105] net: move net_set_todo inside rollback

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Date:   Wed, 27 Jul 2022 18:09:58 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Edwin Peer <edwin.peer@...adcom.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Fedor Pchelkin <pchelkin@...ras.ru>
Subject: [PATCH 5.10 012/105] net: move net_set_todo inside rollback_registered()

From: Fedor Pchelkin <pchelkin@...ras.ru>

From: Jakub Kicinski <kuba@...nel.org>

commit 2014beea7eb165c745706b13659a0f1d0a9a2a61 upstream.

Commit 93ee31f14f6f ("[NET]: Fix free_netdev on register_netdev
failure.") moved net_set_todo() outside of rollback_registered()
so that rollback_registered() can be used in the failure path of
register_netdevice() but without risking a double free.

Since commit cf124db566e6 ("net: Fix inconsistent teardown and
release of private netdev state."), however, we have a better
way of handling that condition, since destructors don't call
free_netdev() directly.

After the change in commit c269a24ce057 ("net: make free_netdev()
more lenient with unregistering devices") we can now move
net_set_todo() back.

Reviewed-by: Edwin Peer <edwin.peer@...adcom.com>
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Fedor Pchelkin <pchelkin@...ras.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/core/dev.c |   11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -9595,8 +9595,10 @@ static void rollback_registered_many(str
 
 	synchronize_net();
 
-	list_for_each_entry(dev, head, unreg_list)
+	list_for_each_entry(dev, head, unreg_list) {
 		dev_put(dev);
+		net_set_todo(dev);
+	}
 }
 
 static void rollback_registered(struct net_device *dev)
@@ -10147,7 +10149,6 @@ int register_netdevice(struct net_device
 		/* Expect explicit free_netdev() on failure */
 		dev->needs_free_netdev = false;
 		rollback_registered(dev);
-		net_set_todo(dev);
 		goto out;
 	}
 	/*
@@ -10755,8 +10756,6 @@ void unregister_netdevice_queue(struct n
 		list_move_tail(&dev->unreg_list, head);
 	} else {
 		rollback_registered(dev);
-		/* Finish processing unregister after unlock */
-		net_set_todo(dev);
 	}
 }
 EXPORT_SYMBOL(unregister_netdevice_queue);
@@ -10770,12 +10769,8 @@ EXPORT_SYMBOL(unregister_netdevice_queue
  */
 void unregister_netdevice_many(struct list_head *head)
 {
-	struct net_device *dev;
-
 	if (!list_empty(head)) {
 		rollback_registered_many(head);
-		list_for_each_entry(dev, head, unreg_list)
-			net_set_todo(dev);
 		list_del(head);
 	}
 }