- DaveM Hi Kirill,
On 03/05/2018 04:22 PM, Kirill Tkhai wrote: > Thanks for the explanation, and module unloading should be nice. Just to > clarify, > I worry not about rules, but about netdevices. > > unshare -n ip link add type vcan > > This command creates net ns, adds vcan there and exits. Then net ns is > destroyed. > Since vcan has rtnl_link_ops, it unregistered by default_device_exit_batch(). > Real can devices are moved to init_net in default_device_exit(), as they don't > have rtnl_link_ops set. In fact most of the real CAN drivers have rtnl_link_ops: https://elixir.bootlin.com/linux/latest/source/drivers/net/can/dev.c#L1162 https://elixir.bootlin.com/linux/latest/source/drivers/net/can/dev.c#L1225 Just slcan.c which is something like slip.c is missing these feature. AFAIK real CAN netdevices are created in init_net at system startup, and you can move them to a netns later. When we already have rtnl_link_ops in the real CAN drivers - what happens to them when the namespace is destroyed? Are they still moved to init_net, or do we need to add some default handler in the current rtnl_link_ops setup? > So, for_each_netdev_rcu() cycle in can_pernet_exit() should be useless (there > are > no can devices in the list of net's devices). This looks so for me, please say > what devices are there if my assumption is wrong. See above? >>> Since can_pernet_ops is pernet subsys, it's executed after >>> default_device_exit() >>> from default_device_ops pernet device, as devices exit methods are executed >>> first >>> (see net/core/net_namespace.c). >> >> Hm - a device exit fires the NETDEV_UNREGISTER notifier which removes the >> user-generated filters (e.g. in raw_notifier() in net/can/raw.c). >> Finally the can_dev_rcv_lists structure is free'd in af_can.c. >> >> Marc Kleine-Budde recently proposed a patch to create the can_dev_rcv_lists >> at >> netdevice creation time (-> the space is allocated by alloc_netdev() and >> removed by free_netdev()). This would remove the handling (allocate & free) >> of >> ml_priv by af_can.c. Would this rework fix the described issue? > > Could you please give me a link to the patches? I can't find them in > patchwork. There was a patchset of 14 patches from Marc where some of the refactoring & renaming already made it into mainline - but the patches to move the can_dev_rcv_lists data structure into the network device space have not been pushed: https://marc.info/?l=linux-can&m=150169588319315&w=2 https://marc.info/?l=linux-can&r=1&b=201708&w=2 This patch & documentation describes Marc's proposed idea best: https://marc.info/?l=linux-can&m=150169589619340&w=2 Best regards, Oliver
