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SubjectRe: [PATCH 1/2] can: bcm: registration process optimization in bcm_module_init()
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On 08.09.22 05:04, Ziyang Xuan wrote:
> Now, register_netdevice_notifier() and register_pernet_subsys() are both
> after can_proto_register(). It can create CAN_BCM socket and process socket
> once can_proto_register() successfully, so it is possible missing notifier
> event or proc node creation because notifier or bcm proc directory is not
> registered or created yet. Although this is a low probability scenario, it
> is not impossible.
>
> Move register_pernet_subsys() and register_netdevice_notifier() to the
> front of can_proto_register(). In addition, register_pernet_subsys() and
> register_netdevice_notifier() may fail, check their results are necessary.
>
> Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
> ---
> net/can/bcm.c | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/net/can/bcm.c b/net/can/bcm.c
> index e60161bec850..e2783156bfd1 100644
> --- a/net/can/bcm.c
> +++ b/net/can/bcm.c
> @@ -1744,15 +1744,27 @@ static int __init bcm_module_init(void)
>
> pr_info("can: broadcast manager protocol\n");
>
> + err = register_pernet_subsys(&canbcm_pernet_ops);
> + if (err)
> + return err;

Analogue to your patch for the CAN_RAW socket here (which has been
applied to can-next right now) ...

https://lore.kernel.org/linux-can/7af9401f0d2d9fed36c1667b5ac9b8df8f8b87ee.1661584485.git.william.xuanziyang@huawei.com/T/#u

... I'm not sure whether this is the right sequence to acquire the
different resources here.

E.g. in ipsec_pfkey_init() in af_key.c

https://elixir.bootlin.com/linux/v5.19.7/source/net/key/af_key.c#L3887

proto_register() is executed before register_pernet_subsys()

Which seems to be more natural to me.

Best regards,
Oliver

> +
> + err = register_netdevice_notifier(&canbcm_notifier);
> + if (err)
> + goto register_notifier_failed;
> +
> err = can_proto_register(&bcm_can_proto);
> if (err < 0) {
> printk(KERN_ERR "can: registration of bcm protocol failed\n");
> - return err;
> + goto register_proto_failed;
> }
>
> - register_pernet_subsys(&canbcm_pernet_ops);
> - register_netdevice_notifier(&canbcm_notifier);
> return 0;
> +
> +register_proto_failed:
> + unregister_netdevice_notifier(&canbcm_notifier);
> +register_notifier_failed:
> + unregister_pernet_subsys(&canbcm_pernet_ops);
> + return err;
> }
>
> static void __exit bcm_module_exit(void)

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