[+cc Greg, sorry for the ill-formed sysfs question below]
On Wed, Aug 25, 2021 at 09:22:52PM +0000, Krzysztof Wilczyński wrote:
> This helper aims to replace functions pci_create_resource_files() and
> pci_create_attr() that are currently involved in the PCI resource sysfs
> objects dynamic creation and set up once the.
>
> After the conversion to use static sysfs objects when exposing the PCI
> BAR address space this helper is to be called from the .is_bin_visible()
> callback for each of the PCI resources attributes.
>
> Signed-off-by: Krzysztof Wilczyński <kw@xxxxxxxxx>
> ---
> drivers/pci/pci-sysfs.c | 40 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 40 insertions(+)
>
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index b70f61fbcd4b..c94ab9830932 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -1237,6 +1237,46 @@ static int pci_create_resource_files(struct pci_dev *pdev)
> }
> return 0;
> }
> +
> +static umode_t pci_dev_resource_attr_is_visible(struct kobject *kobj,
> + struct bin_attribute *attr,
> + int bar, bool write_combine)
> +{
> + struct pci_dev *pdev = to_pci_dev(kobj_to_dev(kobj));
> + resource_size_t resource_size = pci_resource_len(pdev, bar);
> + unsigned long flags = pci_resource_flags(pdev, bar);
> +
> + if (!resource_size)
> + return 0;
> +
> + if (write_combine) {
> + if (arch_can_pci_mmap_wc() && (flags &
> + (IORESOURCE_MEM | IORESOURCE_PREFETCH)) ==
> + (IORESOURCE_MEM | IORESOURCE_PREFETCH))
> + attr->mmap = pci_mmap_resource_wc;
Is it legal to update attr here in an .is_visible() method? Is attr
the single static struct bin_attribute here, or is it a per-device
copy?
I'm assuming the static bin_attribute is a template and when we add a
device that uses it, we alloc a new copy so each device has its own
size, mapping function, etc.
If that's the case, we only want to update the *copy*, not the
template. I don't see an alloc before the call in create_files(),
so I'm worried that this .is_visible() method might get the template,
in which case we'd be updating ->mmap for *all* devices.
> + else
> + return 0;
> + } else {
> + if (flags & IORESOURCE_MEM) {
> + attr->mmap = pci_mmap_resource_uc;
> + } else if (flags & IORESOURCE_IO) {
> + attr->read = pci_read_resource_io;
> + attr->write = pci_write_resource_io;
> + if (arch_can_pci_mmap_io())
> + attr->mmap = pci_mmap_resource_uc;
> + } else {
> + return 0;
> + }
> + }
> +
> + attr->size = resource_size;
> + if (attr->mmap)
> + attr->f_mapping = iomem_get_mapping;
> +
> + attr->private = (void *)(unsigned long)bar;
> +
> + return attr->attr.mode;
> +}
> #else /* !(defined(HAVE_PCI_MMAP) || defined(ARCH_GENERIC_PCI_MMAP_RESOURCE)) */
> int __weak pci_create_resource_files(struct pci_dev *dev) { return 0; }
> void __weak pci_remove_resource_files(struct pci_dev *dev) { return; }
> --
> 2.32.0
>
