[PATCH 6.6.y] net: free_netdev: exit earlier if dummy

[Dust Li <dust.li@linux.alibaba.com>]

From: Breno Leitao <leitao@debian.org>

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, 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@kernel.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Dust Li <dust.li@linux.alibaba.com>
---
 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 f9436563a2e84..0d88d285c713f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -11093,7 +11093,8 @@ 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;
 	}
-- 
2.43.7