[PATCH v3 0/3] asm-generic/io.h: Silence -Wnull-pointer-arithmetic warning on PCI_IOBASE

From: Niklas Schnelle
Date: Wed Apr 21 2021 - 07:18:29 EST


Hi,

This is version 3 of my attempt to get rid of a clang -Wnull-pointer-arithmetic
warning for the use of PCI_IOBASE in asm-generic/io.h. This was originally
found on s390 but should apply to all platforms leaving PCI_IOBASE undefined
while making use of the inb() and friends helpers from asm-generic/io.h.

This applies cleanly and was compile tested on top of v5.12-rc8 for the
previously broken ARC and nds32 architectures.

I did boot test this only on x86_64 and s390x the former implements inb()
itself while the latter would emit a WARN_ONCE() but no drivers using inb().

Thanks,
Niklas

Changes since v2:
- Improved comment for SPARC PCI_IOBASE definition as suggested by David Laight
- Added a patch for ARC which is missing the asm/bug.h include for WARN_ONCE()
(kernel test robot)
- Added ifdefs to ioport_map() and __pci_ioport_map() since apparently at least
test configs enable CONFIG_HAS_IOPORT_MAP even on architectures which leave
PCI_IOBASE unset (kernel test robot for nds32 and ARC).

Changes since v1:
- Added patch to explicitly set PCI_IOBASE to 0 on sparc as suggested by Arnd
Bergmann
- Instead of working around the warning with a uintptr_t PCI_IOBASE make inb()
and friends explicitly WARN_ONCE() and return 0xff... (Arnd Bergmann)

Niklas Schnelle (3):
sparc: explicitly set PCI_IOBASE to 0
ARC: io.h: Include asm/bug.h
asm-generic/io.h: Silence -Wnull-pointer-arithmetic warning on
PCI_IOBASE

arch/arc/include/asm/io.h | 1 +
arch/sparc/include/asm/io.h | 8 +++++
include/asm-generic/io.h | 64 ++++++++++++++++++++++++++++++++++---
3 files changed, 69 insertions(+), 4 deletions(-)

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2.25.1