Re: [pci:controller/xilinx-xdma] BUILD REGRESSION 8d786149d78c7784144c7179e25134b6530b714b

[Bjorn Helgaas <helgaas@kernel.org>]

[+cc powerpc, clang folks]

On Sat, Oct 28, 2023 at 08:22:54PM +0800, kernel test robot wrote:
> tree/branch: https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git controller/xilinx-xdma
> branch HEAD: 8d786149d78c7784144c7179e25134b6530b714b  PCI: xilinx-xdma: Add Xilinx XDMA Root Port driver
> 
> Error/Warning ids grouped by kconfigs:
> 
> clang_recent_errors
> `-- powerpc-pmac32_defconfig
>     |-- arch-powerpc-sysdev-grackle.c:error:unused-function-grackle_set_stg-Werror-Wunused-function
>     |-- arch-powerpc-xmon-xmon.c:error:unused-function-get_output_lock-Werror-Wunused-function
>     `-- arch-powerpc-xmon-xmon.c:error:unused-function-release_output_lock-Werror-Wunused-function

This report is close to useless.  It doesn't show the complete error
message, it doesn't show how to reproduce the issue, and the pci -next
branch (including controller/xilinx-xdma) doesn't reference any of
these functions:

  $ git grep -E "grackle_set_stg|get_output_lock|release_output_lock" | cat
  arch/powerpc/sysdev/grackle.c:static inline void grackle_set_stg(struct pci_controller* bp, int enable)
  arch/powerpc/sysdev/grackle.c:	grackle_set_stg(hose, 1);
  arch/powerpc/xmon/xmon.c:static void get_output_lock(void)
  arch/powerpc/xmon/xmon.c:static void release_output_lock(void)
  arch/powerpc/xmon/xmon.c:static inline void get_output_lock(void) {}
  arch/powerpc/xmon/xmon.c:static inline void release_output_lock(void) {}
  arch/powerpc/xmon/xmon.c:		get_output_lock();
  arch/powerpc/xmon/xmon.c:		release_output_lock();
  arch/powerpc/xmon/xmon.c:			get_output_lock();
  arch/powerpc/xmon/xmon.c:			release_output_lock();
  arch/powerpc/xmon/xmon.c:		get_output_lock();
  arch/powerpc/xmon/xmon.c:		release_output_lock();
  arch/powerpc/xmon/xmon.c:		get_output_lock();
  arch/powerpc/xmon/xmon.c:		release_output_lock();

That said, the unused functions do look legit:

grackle_set_stg() is a static function and the only call is under
"#if 0".

Same with get_output_lock() and release_output_lock(): they're static
and always defined in xmon.c, but only called if either CONFIG_SMP or
CONFIG_DEBUG_FS.

But they're certainly not related to controller/xilinx-xdma, so I'm
going to ignore them.

Bjorn

P.S. Nathan & Nick, I cc'd you because of this earlier report that
also mentioned grackle_set_stg():
https://lore.kernel.org/lkml/202308121120.u2d3YPVt-lkp@intel.com/