On Fri, Aug 11, 2023 at 02:40:45PM -0400, Alistair Francis wrote: > On Thu, Aug 10, 2023 at 9:04???PM Damien Le Moal <dlemoal@xxxxxxxxxx> wrote: > > > This uses pci_sysfs_init() instead of the ->is_visible() function as > > > is_visible only applies to the attributes under the group. Which > > > means that every PCIe device will see a `doe_protos` directory, no > > > matter if DOE is supported at all on the device. > > > > > > On top of that ->is_visible() is only called > > > (fs/sysfs/group.c:create_files()) if there are sub attrs, which we > > > don't necessary have. There are no static attrs, instead they are > > > all generated dynamically. > > > > You said that the kernel caches the protocols supported. So it should > > not be hard to allocate one attribute for each of the supported protocols > > when these are discovered, no ? > > I couldn't figure out a way to get this to work. You end up with a > race between the sysfs group being created and the attributes being > created. The DOE features are probed before the sysfs init creates the > group. If you look at device_add_attrs() in drivers/base/core.c, you'll notice it calls device_add_groups() for the class, type and dev->groups. pci_dev_attr_groups[] is assigned through the type. What you want to do is amend pci_alloc_dev() to allocate enough space for a struct attribute_group, in addition to struct pci_dev, then assign it to dev->groups in that same function. Define a macro for the size. Initially you'll need two struct attribute_group elements, one for your DOE element plus one for the terminating zero element. If there are DOE mailboxes, let ->is_visible of the DOE group return true and use "doe" as its ->name to make attributes appear in a "doe" subdirectory. Finally allocate and fill a struct struct attribute[] array with all the protocols found in all the mailboxes. Thanks, Lukas
