On Fri, Jul 26, 2024 at 04:15:03PM +0100, Jonathan Cameron wrote: > On Mon, 24 Jun 2024 19:47:27 -0300 > Jason Gunthorpe <jgg@xxxxxxxxxx> wrote: > > > Userspace will need to know some details about the fwctl interface being > > used to locate the correct userspace code to communicate with the > > kernel. Provide a simple device_type enum indicating what the kernel > > driver is. > > As below - maybe consider a UUID? > Would let you decouple allocating those with upstreaming drivers. > We'll just get annoying races on the enum otherwise as multiple > drivers get upstreamed that use this. I view the coupling as a feature - controlling uABI number assignment is one of the subtle motivations the kernel community has typically used to encourage upstream participation. > > static dev_t fwctl_dev; > > static DEFINE_IDA(fwctl_ida); > > > > +DEFINE_FREE(kfree_errptr, void *, if (!IS_ERR_OR_NULL(_T)) kfree(_T)); > > Why need for a new one? That's the same as the one in slab.h from > 6.9 onwards. Before that it was > if (_T) > > I was going to suggest promoting this to slab.h and then found > the normal implementation had been improved since I last checked. Same, now it is improved it can go away. > > +/** > > + * struct fwctl_info - ioctl(FWCTL_INFO) > > + * @size: sizeof(struct fwctl_info) > > + * @flags: Must be 0 > > + * @out_device_type: Returns the type of the device from enum fwctl_device_type > > Maybe a UUID? Avoid need to synchronize that list for ever. > > > + * @device_data_len: On input the length of the out_device_data memory. On > > + * output the size of the kernel's device_data which may be larger or > > + * smaller than the input. Maybe 0 on input. > > + * @out_device_data: Pointer to a memory of device_data_len bytes. Kernel will > > + * fill the entire memory, zeroing as required. > > Why do we need device in names of these two? I'm not sure I understand this question? out_device_type returns the "name" out_device_data returns a struct of data, the layout of the struct is defined by out_device_type Jason
