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

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 e854d8b2a82e ("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 e854d8b2a82e.

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: e854d8b2a82e ("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

0 files changed, 0 insertions, 0 deletions