On Sat, Aug 12, 2023 at 4:26 AM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > On Sat, Aug 12, 2023 at 10:15:26AM +0200, Lukas Wunner wrote: > > On Thu, Aug 10, 2023 at 11:34:11AM -0400, Alistair Francis wrote: > > > On Thu, Aug 10, 2023 at 3:34???AM Lukas Wunner <lukas@xxxxxxxxx> wrote: > > > > On Wed, Aug 09, 2023 at 07:28:51PM -0400, Alistair Francis wrote: > > > > > --- a/drivers/pci/pci-sysfs.c > > > > > +++ b/drivers/pci/pci-sysfs.c > > > > > @@ -1226,6 +1227,12 @@ static int pci_create_resource_files(struct pci_dev *pdev) > > > > > int i; > > > > > int retval; > > > > > > > > > > +#ifdef CONFIG_PCI_DOE > > > > > + retval = doe_sysfs_init(pdev); > > > > > + if (retval) > > > > > + return retval; > > > > > +#endif > > > > > + > > > > > > > > The preferred way to expose PCI sysfs attributes nowadays is to add them > > > > to pci_dev_attr_groups[] and use the ->is_visible callback to check > > > > whether they're applicable to a particular pci_dev. The alternative > > > > via pci_create_resource_files() has race conditions which I think > > > > still haven't been fixed. Bjorn recommended the ->is_visible approach > > > > in response to the most recent attempt to fix the race: > > > > > > > > https://lore.kernel.org/linux-pci/20230427161458.GA249886@bhelgaas/ > > > > > > The is_visible doen't seem to work in this case. > > > > > > AFAIK 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. > > > > internal_create_group() in fs/sysfs/group.c does this: > > > > if (grp->name) { > > ... > > kn = kernfs_create_dir_ns(kobj->sd, grp->name, ... > > > > So I'm under the impression that if you set the ->name member of > > struct attribute_group, the attributes in that group appear under > > a directory of that name. > > > > In fact, the kernel-doc for struct attribute_group claims as much: > > > > * struct attribute_group - data structure used to declare an attribute group. > > * @name: Optional: Attribute group name > > * If specified, the attribute group will be created in > > * a new subdirectory with this name. > > > > So I don't quite understand why you think that "every PCIe device will > > see a `doe_protos` directory, no matter if DOE is supported"? > > > > Am I missing something? > > I think the issue might be that the directory will be created even if no > attributes are present in it due to the is_visable() check not returning > any valid files? Yes, that's what I'm seeing. I see the directory for all PCIe devices This is a WIP that I had: https://github.com/alistair23/linux/commit/61925cd174c31386eaa7e51e3a1be606b38f847c > > If so, I had a patch somewhere around here where I was trying to fix > that up: > https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git/commit/?h=debugfs_cleanup&id=f670945dfbaf353fe068544c31e3fa45575da5b5 > but it didn't seem to work properly and kept crashing. I didn't spend > much time on looking into it, but if this is an issue, I can work on > fixing this properly. That patch sounds like it would fix the issue of empty directories that I'm seeing. Do you mind fixing it up properly? Then I just need to address the race condition and we can switch to using .is_visible() Alistair > > thanks, > > greg k-h
