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(-) -- 2.25.1