Date:   Fri, 28 Aug 2020 17:39:22 -0700
From:   Atish Patra <atishp@...shpatra.org>
To:     Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc:     Atish Patra <atish.patra@....com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Zong Li <zong.li@...ive.com>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Will Deacon <will@...nel.org>, linux-arch@...r.kernel.org,
        Rob Herring <robh@...nel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Ganapatrao Kulkarni <gkulkarni@...ium.com>,
        Steven Price <steven.price@....com>,
        Greentime Hu <greentime.hu@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Arnd Bergmann <arnd@...db.de>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Nick Hu <nickhu@...estech.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Anup Patel <Anup.Patel@....com>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mike Rapoport <rppt@...nel.org>
Subject: Re: [RFC/RFT PATCH 2/6] arm64, numa: Change the numa init function
 name to be generic

On Fri, Aug 28, 2020 at 2:37 AM Jonathan Cameron
<Jonathan.Cameron@...wei.com> wrote:
>
> On Fri, 14 Aug 2020 14:47:21 -0700
> Atish Patra <atish.patra@....com> wrote:
>
> > As we are using generic numa implementation code, modify the init function
> > name to indicate that generic implementation.
> >
> > Signed-off-by: Atish Patra <atish.patra@....com>
> > ---
> >  arch/arm64/mm/init.c       | 4 ++--
> >  drivers/base/arch_numa.c   | 8 ++++++--
> >  include/asm-generic/numa.h | 4 ++--
> >  3 files changed, 10 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> > index 481d22c32a2e..93b660229e1d 100644
> > --- a/arch/arm64/mm/init.c
> > +++ b/arch/arm64/mm/init.c
> > @@ -418,10 +418,10 @@ void __init bootmem_init(void)
> >       max_pfn = max_low_pfn = max;
> >       min_low_pfn = min;
> >
> > -     arm64_numa_init();
> > +     arch_numa_init();
> >
> >       /*
> > -      * must be done after arm64_numa_init() which calls numa_init() to
> > +      * must be done after arch_numa_init() which calls numa_init() to
> >        * initialize node_online_map that gets used in hugetlb_cma_reserve()
> >        * while allocating required CMA size across online nodes.
> >        */
> > diff --git a/drivers/base/arch_numa.c b/drivers/base/arch_numa.c
> > index 73f8b49d485c..83341c807240 100644
> > --- a/drivers/base/arch_numa.c
> > +++ b/drivers/base/arch_numa.c
> > @@ -13,7 +13,9 @@
> >  #include <linux/module.h>
> >  #include <linux/of.h>
> >
> > +#ifdef CONFIG_ARM64
> >  #include <asm/acpi.h>
> > +#endif
>
> This highlights an issue.  We really don't want to define 'generic' arch
> code then match on individual architectures if at all possible.
>

I agree.

> I'm also not sure we need to.
>
> The arm64_acpi_numa_init() code is just a light wrapper around the
> standard acpi_init() call so should work fine on riscv (once ACPI
> support is ready).
>
> Can we pull that function into here

Sure. We can move the arm64_acpi_numa_init to here and rename it to
arch_acpi_numa_init.
We can keep arch_acpi_numa_init and the acpi.h included under CONFIG_ACPI_NUMA.
If RISC-V becomes ACPI ready one day, they always need to enable
CONFIG_ACPI_NUMA and reuse the generic functions.

> or perhaps a generic arch_numa_acpi.c?
>
There has not been much discussion about ACPI for RISC-V. So moving
the arm64 acpi code now to generic code would be premature
in my opinion. Currently, we don't even know how ACPI will look like
for RISC-V.

> There is probably a bit of a dance needed around acpi_disabled
> though as that can be defined in entirely different places
> depending on whether acpi is enabled or not.
> Possibly just adding an
>
> extern int acpi_disabled to include/linux/acpi.h when acpi is enabled
> will be sufficient (if ugly)?
>

We don't need to do that now unless we are moving arm64 ACPI code
implementation to generic code.
If ACPI is not enabled, it is already defined as a macro in
include/linux/acpi.h.

>
> >  #include <asm/sections.h>
> >
> >  struct pglist_data *node_data[MAX_NUMNODES] __read_mostly;
> > @@ -445,16 +447,18 @@ static int __init dummy_numa_init(void)
> >  }
> >
> >  /**
> > - * arm64_numa_init() - Initialize NUMA
> > + * arch_numa_init() - Initialize NUMA
> >   *
> >   * Try each configured NUMA initialization method until one succeeds. The
> >   * last fallback is dummy single node config encomapssing whole memory.
> >   */
> > -void __init arm64_numa_init(void)
> > +void __init arch_numa_init(void)
> >  {
> >       if (!numa_off) {
> > +#ifdef CONFIG_ARM64
> >               if (!acpi_disabled && !numa_init(arm64_acpi_numa_init))
> >                       return;
> > +#endif
> >               if (acpi_disabled && !numa_init(of_numa_init))
> >                       return;
> >       }
> > diff --git a/include/asm-generic/numa.h b/include/asm-generic/numa.h
> > index 0635c0724b7c..309eca8c0b5d 100644
> > --- a/include/asm-generic/numa.h
> > +++ b/include/asm-generic/numa.h
> > @@ -27,7 +27,7 @@ static inline const struct cpumask *cpumask_of_node(int node)
> >  }
> >  #endif
> >
> > -void __init arm64_numa_init(void);
> > +void __init arch_numa_init(void);
> >  int __init numa_add_memblk(int nodeid, u64 start, u64 end);
> >  void __init numa_set_distance(int from, int to, int distance);
> >  void __init numa_free_distance(void);
> > @@ -41,7 +41,7 @@ void numa_remove_cpu(unsigned int cpu);
> >  static inline void numa_store_cpu_info(unsigned int cpu) { }
> >  static inline void numa_add_cpu(unsigned int cpu) { }
> >  static inline void numa_remove_cpu(unsigned int cpu) { }
> > -static inline void arm64_numa_init(void) { }
> > +static inline void arch_numa_init(void) { }
> >  static inline void early_map_cpu_to_node(unsigned int cpu, int nid) { }
> >
> >  #endif       /* CONFIG_NUMA */
>
>
>
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-- 
Regards,
Atish

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