linux-kernel - Re: [RFT/RFC PATCH v3 4/5] arm: Use common cpu

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Message-ID: <20190415153147.GB28623@e107155-lin>
Date:   Mon, 15 Apr 2019 16:31:47 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Atish Patra <atish.patra@....com>
Cc:     linux-kernel@...r.kernel.org, Albert Ou <aou@...s.berkeley.edu>,
        Anup Patel <anup@...infault.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        devicetree@...r.kernel.org,
        Dmitriy Cherkasov <dmitriy@...-tech.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        Jeremy Linton <jeremy.linton@....com>,
        Johan Hovold <johan@...nel.org>,
        linux-riscv@...ts.infradead.org,
        Mark Rutland <mark.rutland@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Otto Sabart <ottosabart@...erm.com>,
        Palmer Dabbelt <palmer@...ive.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Will Deacon <will.deacon@....com>
Subject: Re: [RFT/RFC PATCH v3 4/5] arm: Use common cpu_topology

On Wed, Mar 20, 2019 at 04:48:05PM -0700, Atish Patra wrote:
> Currently, ARM32 and ARM64 uses different data structures to
> represent their cpu toplogies. Since, we are moving the ARM64
> topology to common code to be used by other architectures, we
> can reuse that for ARM32 as well.
>
> Signed-off-by: Atish Patra <atish.patra@....com>
> ---
>  arch/arm/include/asm/topology.h | 22 +---------------------
>  arch/arm/kernel/topology.c      | 10 +++++-----
>  include/linux/arch_topology.h   | 10 +++++++++-
>  3 files changed, 15 insertions(+), 27 deletions(-)
>

[...]

> diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h
> index d4e76e0a..7c850611 100644
> --- a/include/linux/arch_topology.h
> +++ b/include/linux/arch_topology.h
> @@ -36,17 +36,25 @@ unsigned long topology_get_freq_scale(int cpu)
>  struct cpu_topology {
>  	int thread_id;
>  	int core_id;
> +#ifdef CONFIG_ARM_CPU_TOPOLOGY
> +	int socket_id;

Sorry, but I can't find any reason why we need to do this ifdef dance
here, especially for socket_id vs package_id ? Other's I can understand
as there are new, but I am sure we can find a way and get away with
#ifdefery here completely.

> +#else
>  	int package_id;
>  	int llc_id;
> +	cpumask_t llc_sibling;
> +#endif
>  	cpumask_t thread_sibling;
>  	cpumask_t core_sibling;
> -	cpumask_t llc_sibling;
>  };
>
>  #ifdef CONFIG_GENERIC_ARCH_TOPOLOGY
>  extern struct cpu_topology cpu_topology[NR_CPUS];
>
> +#ifdef CONFIG_ARM_CPU_TOPOLOGY
> +#define topology_physical_package_id(cpu)	(cpu_topology[cpu].socket_id)
> +#else
>  #define topology_physical_package_id(cpu)	(cpu_topology[cpu].package_id)
> +#endif

Since all callsites must use topology_physical_package_id, we should be
able to rename socket_id to package_id easily.

--
Regards,
Sudeep