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PCI/sysfs: Return -EINVAL for unsupported I/O BAR mmap

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Currently, mmap() of a resourceN file for an I/O BAR fails with -ENODEV on
architectures where arch_can_pci_mmap_io() is 0, such as x86, because the
attribute has no mmap callback there and the error comes from the generic
kernfs dispatch.

This is a side effect of commit e854d8b2a8 ("PCI: Add
arch_can_pci_mmap_io() on architectures which can mmap() I/O space"),
which removed the mmap callback from the I/O resource attribute on
these architectures.  Previously the request reached the architecture
mmap code and failed with -EINVAL, and the same commit deliberately
kept -EINVAL for the identical operation on the procfs interface, so
the two PCI userspace interfaces have disagreed ever since.

Add a pci_mmap_resource_io_unsupported() callback that
returns -EINVAL and use it as the mmap handler of the I/O resource
attribute when arch_can_pci_mmap_io() is 0, so the failure is
produced deliberately by PCI code, consistent with the procfs
interface and with the behaviour before e854d8b2a8.

Architectures where arch_can_pci_mmap_io() is non-zero keep the real
pci_mmap_resource_uc() handler and are unaffected.  The mmap() fails
either way.  Only the reported error changes from -ENODEV to -EINVAL.

Fixes: e854d8b2a8 ("PCI: Add arch_can_pci_mmap_io() on architectures which can mmap() I/O space")
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20260720204624.1503794-1-kwilczynski@kernel.org
This commit is contained in:
Krzysztof Wilczyński 2026-07-20 20:46:24 +00:00 committed by Bjorn Helgaas
parent b14b2bab88
commit bad94d3d18
1 changed files with 10 additions and 1 deletions
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11
drivers/pci/pci-sysfs.c
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@ -1274,7 +1274,16 @@ static loff_t pci_llseek_resource(struct file *filep,
.llseek = pci_llseek_resource, \
.mmap = pci_mmap_resource_uc,
#else
# define __PCI_RESOURCE_IO_MMAP_ATTRS
static int pci_mmap_resource_io_unsupported(struct file *filp,
struct kobject *kobj,
const struct bin_attribute *attr,
struct vm_area_struct *vma)
{
return -EINVAL;
}
# define __PCI_RESOURCE_IO_MMAP_ATTRS \
.mmap = pci_mmap_resource_io_unsupported,
#endif
#define pci_dev_resource_io_attr(_bar) \