[PATCH v2 3/3] asm-generic/io.h: Fix !CONFIG_GENERIC_IOMAP pci_iounmap() implementation

[Catalin Marinas]

On Wed, Sep 16, 2020 at 12:06:58PM +0100, Lorenzo Pieralisi wrote:
> For arches that do not select CONFIG_GENERIC_IOMAP, the current
> pci_iounmap() function does nothing causing obvious memory leaks
> for mapped regions that are backed by MMIO physical space.
> 
> In order to detect if a mapped pointer is IO vs MMIO, a check must made
> available to the pci_iounmap() function so that it can actually detect
> whether the pointer has to be unmapped.
> 
> In configurations where CONFIG_HAS_IOPORT_MAP && !CONFIG_GENERIC_IOMAP,
> a mapped port is detected using an ioport_map() stub defined in
> asm-generic/io.h.
> 
> Use the same logic to implement a stub (ie __pci_ioport_unmap()) that
> detects if the passed in pointer in pci_iounmap() is IO vs MMIO to
> iounmap conditionally and call it in pci_iounmap() fixing the issue.
> 
> Leave __pci_ioport_unmap() as a NOP for all other config options.
> 
> Reported-by: George Cherian <george.cherian at marvell.com>
> Link: https://lore.kernel.org/lkml/20200905024811.74701-1-yangyingliang@huawei.com
> Link: https://lore.kernel.org/lkml/20200824132046.3114383-1-george.cherian@marvell.com
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
> Cc: Arnd Bergmann <arnd at arndb.de>
> Cc: George Cherian <george.cherian at marvell.com>
> Cc: Will Deacon <will at kernel.org>
> Cc: Bjorn Helgaas <bhelgaas at google.com>
> Cc: Catalin Marinas <catalin.marinas at arm.com>
> Cc: Yang Yingliang <yangyingliang at huawei.com>
> ---
>  include/asm-generic/io.h | 39 +++++++++++++++++++++++++++------------
>  1 file changed, 27 insertions(+), 12 deletions(-)

This works for me. The only question I have is whether pci_iomap.h is
better than io.h for __pci_ioport_unmap(). These headers are really
confusing.

Either way:

Reviewed-by: Catalin Marinas <catalin.marinas at arm.com>