netdev - [PATCH net-next v4 1/9] net: free_netdev: exit earlier if dummy

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Message-ID: <20240409125738.1824983-2-leitao@debian.org>
Date: Tue,  9 Apr 2024 05:57:15 -0700
From: Breno Leitao <leitao@...ian.org>
To: aleksander.lobakin@...el.com,
	kuba@...nel.org,
	davem@...emloft.net,
	pabeni@...hat.com,
	edumazet@...gle.com,
	elder@...nel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org,
	nbd@....name,
	sean.wang@...iatek.com,
	Mark-MC.Lee@...iatek.com,
	lorenzo@...nel.org,
	taras.chornyi@...ision.eu,
	ath11k@...ts.infradead.org,
	ath10k@...ts.infradead.org,
	linux-wireless@...r.kernel.org,
	geomatsi@...il.com,
	kvalo@...nel.org
Cc: quic_jjohnson@...cinc.com,
	leon@...nel.org,
	dennis.dalessandro@...nelisnetworks.com,
	linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org,
	bpf@...r.kernel.org,
	Jiri Pirko <jiri@...nulli.us>,
	Simon Horman <horms@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH net-next v4 1/9] net: free_netdev: exit earlier if dummy

For dummy devices, exit earlier at free_netdev() instead of executing
the whole function. This is necessary, because dummy devices are
special, and shouldn't have the second part of the function executed.

Otherwise reg_state, which is NETREG_DUMMY for dummy devices, will be
overwritten and there will be no way to identify that this is a dummy
device. Also, this device do not need the final put_device(), since
dummy devices are not registered (through register_netdevice()), where
the device reference is increased (at netdev_register_kobject() ->
device_add()).

Suggested-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 net/core/dev.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 92f5bddbc2de..bf0a335781aa 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -11051,7 +11051,8 @@ void free_netdev(struct net_device *dev)
 	dev->xdp_bulkq = NULL;
 
 	/*  Compatibility with error handling in drivers */
-	if (dev->reg_state == NETREG_UNINITIALIZED) {
+	if (dev->reg_state == NETREG_UNINITIALIZED ||
+	    dev->reg_state == NETREG_DUMMY) {
 		netdev_freemem(dev);
 		return;
 	}
-- 
2.43.0