On 17.01.25 14:00, Alexandra Winter wrote: > > > On 17.01.25 03:13, Dust Li wrote: >>>>> Modular Approach: I've made the ism_loopback an independent kernel >>>>> module since dynamic enable/disable functionality is not yet supported >>>>> in SMC. Using insmod and rmmod for module management could provide the >>>>> flexibility needed in practical scenarios. >>> >>> With this proposal ism_loopback is just another ism device and SMC-D will >>> handle removal just like ism_client.remove(ism_dev) of other ism devices. >>> >>> But I understand that net/smc/ism_loopback.c today does not provide enable/disable, >>> which is a big disadvantage, I agree. The ism layer is prepared for dynamic >>> removal by ism_dev_unregister(). In case of this RFC that would only happen >>> in case of rmmod ism. Which should be improved. >>> One way to do that would be a separate ism_loopback kernel module, like you say. >>> Today ism_loopback is only 10k LOC, so I'd be fine with leaving it in the ism module. >>> I also think it is a great way for testing any ISM client, so it has benefit for >>> anybody using the ism module. >>> Another way would be e.g. an 'enable' entry in the sysfs of the loopback device. >>> (Once we agree if and how to represent ism devices in genera in sysfs). >> This works for me as well. I think it would be better to implement this >> within the common ISM layer, rather than duplicating the code in each >> device. Similar to how it's done in netdevice. >> >> Best regards, >> Dust > > > Is there a specific example for enable/disable in the netdevice code, you have in mind? > Or do you mean in general how netdevice provides a common layer? > Yes, everything that is common for all devices should be provided by the network layer. Dust for some reason, you did not 'Reply-all': Dust Li wrote: > I think dev_close()/dev_open() are the high-level APIs, while > ndo_stop()/ndo_open() are the underlying device operations that we > can reference. I hear you, it can be beneficial to have a way for upper layers to enable/disable an ism device. But all this is typically a tricky area. The device driver can also have reasons to enable/disable a device, then hardware could do that or even hotplug a device. Error recovery on different levels may want to run a disable/enable sequence as a reset, etc. And all this has potential for deadlocks. All this is rather trivial for ism-loopback, as there is not much of a lower layer. ism-vpci already has 'HW' / device driver configure on/off and device add/remove. For a future ism-virtio, the Hipervisor may want to add/remove devices. I wonder what could be the simplest definition of an enable/disable for the ism layer, that we can start with? More sophisticated functionality can always be added later. Maybe support for add/remove ism-device by the device driver is sufficient as starting point?
