On Thu, 2024-04-04 at 21:12 +0800, Wen Gu wrote: > > On 2024/4/4 19:42, Niklas Schnelle wrote: > > On Thu, 2024-04-04 at 17:32 +0800, Wen Gu wrote: > > > > > > On 2024/4/4 00:25, Gerd Bayer wrote: > > > > On Sun, 2024-03-24 at 21:55 +0800, Wen Gu wrote: > > > > > This implements some operations that loopback-ism does not support > > > > > currently: > > > > > - vlan operations, since there is no strong use-case for it. > > > > > - signal_event operations, since there is no event to be processed > > > > > by the loopback-ism device. > > > > > > > > Hi Wen, > > > > > > > > I wonder if the these operations that are not supported by loopback-ism > > > > should rather be marked "optional" in the struct smcd_ops, and the > > > > calling code should call these only when they are implemented. > > > > > > > > Of course this would mean more changes to net/smc/smc_core.c - but > > > > loopback-ism could omit these "boiler-plate" functions. > > > > > > > > > > Hi Gerd. > > > > > > Thank you for the thoughts! I agree that checks like 'if(smcd->ops->xxx)' > > > can avoid the device driver from implementing unsupported operations. But I > > > am afraid that which operations need to be defined as 'optional' may differ > > > from different device perspectives (e.g. for loopback-ism they are vlan-related > > > opts and signal_event). So I perfer to simply let the smc protocol assume > > > that all operations have been implemented, and let drivers to decide which > > > ones are unsupported in implementation. What do you think? > > > > > > Thanks! > > > > > > > I agree with Gerd, in my opinion it is better to document ops as > > optional and then allow their function pointers to be NULL and check > > for that. Acting like they are supported and then they turn out to be > > nops to me seems to contradict the principle of least surprises. I also > > think we can find a subset of mandatory ops without which SMC-D is > > impossible and then everything else should be optional. > > I see. If we all agree to classify smcd_ops into mandatory and optional ones, > I'll add a patch to mark the optional ops and check if they are implemented. Keep in mind I don't speak for the SMC maintainers but that does sound reasonable to me. > > > > > As a first guess I think the following options may be mandatory: > > > > * query_remote_gid() > > * register_dmb()/unregister_dmb() > > * move_data() > > For this one could argue that either move_data() or > > attach_dmb()/detach_dmb() is required though personally I would > > prefer to always have move_data() as a fallback and simple API > > * supports_v2() > > * get_local_gid() > > * get_chid() > > * get_dev() > I agree with this classification. Just one point, maybe we can take > supports_v2() as an optional ops, like support_dmb_nocopy()? e.g. if > it is not implemented, we treat it as an ISMv1. > > Thanks! Interpreting a NULL supports_v2() as not supporting v2 sounds reasonable to me.
