Re: [PATCH 2/2] x86, sched: Fix the undefined reference building error of init_freq_invariance_cppc

[Huang Rui <ray.huang@amd.com>]

On Fri, Jan 07, 2022 at 01:46:04AM +0800, Rafael J. Wysocki wrote:
> On Thu, Jan 6, 2022 at 6:12 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
> >
> > On Thu, Jan 6, 2022 at 8:43 AM Huang Rui <ray.huang@amd.com> wrote:
> > >
> > > The init_freq_invariance_cppc function is implemented in smpboot and depends on
> > > CONFIG_SMP.
> > >
> > >   MODPOST vmlinux.symvers
> > >   MODINFO modules.builtin.modinfo
> > >   GEN     modules.builtin
> > >   LD      .tmp_vmlinux.kallsyms1
> > > ld: drivers/acpi/cppc_acpi.o: in function `acpi_cppc_processor_probe':
> > > /home/ray/brahma3/linux/drivers/acpi/cppc_acpi.c:819: undefined reference to `init_freq_invariance_cppc'
> > > make: *** [Makefile:1161: vmlinux] Error 1
> > >
> > > See https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flkml%2F484af487-7511-647e-5c5b-33d4429acdec%40infradead.org%2F&amp;data=04%7C01%7Cray.huang%40amd.com%7Cde64292b38394cf2cac508d9d13c701c%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637770879795785268%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=BtO45nsVaYM%2BBytS%2B5GOPQuIadaiUEnzzaSmydsl0Jo%3D&amp;reserved=0.
> > >
> > > Fixes: 41ea667227ba ("x86, sched: Calculate frequency invariance for AMD systems")
> > > Reported-by: kernel test robot <lkp@intel.com>
> > > Reported-by: Randy Dunlap <rdunlap@infradead.org>
> > > Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> > > Signed-off-by: Huang Rui <ray.huang@amd.com>
> > > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > > Cc: Borislav Petkov <bp@alien8.de>
> > > Cc: Ingo Molnar <mingo@kernel.org>
> > > Cc: Peter Zijlstra <peterz@infradead.org>
> > > Cc: x86@kernel.org
> > > Cc: stable@vger.kernel.org
> > > ---
> > >  arch/x86/include/asm/topology.h | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
> > > index cc164777e661..2f0b6be8eaab 100644
> > > --- a/arch/x86/include/asm/topology.h
> > > +++ b/arch/x86/include/asm/topology.h
> > > @@ -221,7 +221,7 @@ static inline void arch_set_max_freq_ratio(bool turbo_disabled)
> > >  }
> > >  #endif
> > >
> > > -#ifdef CONFIG_ACPI_CPPC_LIB
> > > +#if defined(CONFIG_ACPI_CPPC_LIB) && defined(CONFIG_SMP)
> > >  void init_freq_invariance_cppc(void);
> > >  #define init_freq_invariance_cppc init_freq_invariance_cppc
> >
> > Why don't you check CONFIG_SMP instead of this symbol in cppc_acpi.c?
> > That file depends on CONFIG_ACPI_CPPC_LIB anyway.
> 
> Scratch that, it needs to compile on non-x86 too.
> 
> The $subject patch is cleaner than all of the alternatives I have
> considered, so I'm going to apply it.
> 
> However, I'm not really happy with the dependencies between CPPC and
> smpboot.c going both ways.

Thanks, for urgent fix for linux-next, I think we can use this patch at
this moment.
Let me think out a better way to handle the dependencies next step. :-)

Thanks,
Ray