Re: [PATCH v6 1/4] lib/pci_iomap.c: fix cleanup bug in pci_iounmap()

[Philipp Stanner]

On Wed, 2024-01-31 at 15:09 -0600, Bjorn Helgaas wrote:
> On Wed, Jan 31, 2024 at 10:00:20AM +0100, Philipp Stanner wrote:
> > The #ifdef for the ioport-ranges accidentally also guards
> > iounmap(),
> > potentially compiling an empty function. This would cause the
> > mapping to
> > be leaked.
> > 
> > Move the guard so that iounmap() will always be part of the
> > function.
> 
> I tweaked the subject and commit log to be more explicit about what
> the bug is.  Let me know if I got it wrong:

Mostly correct IMO

> 
>   pci_iounmap(): Fix MMIO mapping leak
> 
>   The #ifdef ARCH_HAS_GENERIC_IOPORT_MAP accidentally also guards
> iounmap(),
>   which means MMIO mappings are leaked.

nit: I wasn't entirely sure when they are actually leaked, just that
they _could_ be leaked. To know for sure we'd need to search who sets
ARCH_WANTS_GENERIC_PCI_IOUNMAP without setting
ARCH_HAS_GENERIC_IOPORT_MAP.

I think your formulation should be fine, though, since it's definitely
a bug.

P.

> 
>   Move the guard so we call iounmap() for MMIO mappings.
> 
> Bjorn
>