On 09.09.2022 17:04:06, Oliver Hartkopp wrote: > > > On 09.09.22 05:58, Ziyang Xuan (William) wrote: > > > > > > > > > On 9/8/22 13:14, Ziyang Xuan (William) wrote: > > > > > Just another reference which make it clear that the reordering of function calls in your patch is likely not correct: > > > > > > > > > > https://elixir.bootlin.com/linux/v5.19.7/source/net/packet/af_packet.c#L4734 > > > > > > > > > > static int __init packet_init(void) > > > > > { > > > > > int rc; > > > > > > > > > > rc = proto_register(&packet_proto, 0); > > > > > if (rc) > > > > > goto out; > > > > > rc = sock_register(&packet_family_ops); > > > > > if (rc) > > > > > goto out_proto; > > > > > rc = register_pernet_subsys(&packet_net_ops); > > > > > if (rc) > > > > > goto out_sock; > > > > > rc = register_netdevice_notifier(&packet_netdev_notifier); > > > > > if (rc) > > > > > goto out_pernet; > > > > > > > > > > return 0; > > > > > > > > > > out_pernet: > > > > > unregister_pernet_subsys(&packet_net_ops); > > > > > out_sock: > > > > > sock_unregister(PF_PACKET); > > > > > out_proto: > > > > > proto_unregister(&packet_proto); > > > > > out: > > > > > return rc; > > > > > } > > > > > > > > Yes，all these socket operations need time, most likely, register_netdevice_notifier() and register_pernet_subsys() had been done. > > But it maybe not for some reasons, for example, cpu# that runs {raw,bcm}_module_init() is stuck temporary, > > or pernet_ops_rwsem lock competition in register_netdevice_notifier() and register_pernet_subsys(). > > > > If the condition which I pointed happens, I think my solution can solve. > > > > No, I don't think so. > > We need to maintain the exact order which is depicted in the af_packet.c > code from above as the notifier call references the sock pointer. The notifier calls bcm_notifier() first, which will loop over the bcm_notifier_list. The list is empty if there are no sockets open, yet. So from my point of view this change looks fine. IMHO it's better to make a series where all these notifiers are moved in front of the respective socket proto_register(). regards, Marc -- Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung West/Dortmund | Phone: +49-231-2826-924 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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