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References: <20190612044506.16392-1-nathanl@linux.ibm.com>
 <20190612044506.16392-2-nathanl@linux.ibm.com>
In-Reply-To: <20190612044506.16392-2-nathanl@linux.ibm.com>
From: Gautham R Shenoy <ego.lkml@gmail.com>
Date: Fri, 14 Jun 2019 11:25:09 +0530
Message-ID: <CAHZ_5Wx12GBbBw1caWa8c31XOE3pVSOTHAYdJ37mdheFjn58Kw@mail.gmail.com>
Subject: Re: [PATCH 1/3] powerpc/cacheinfo: add cacheinfo_teardown,
 cacheinfo_rebuild
To: Nathan Lynch <nathanl@linux.ibm.com>, ego@linux.vnet.ibm.com
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On Wed, Jun 12, 2019 at 10:15 AM Nathan Lynch <nathanl@linux.ibm.com> wrote:
>
> Allow external callers to force the cacheinfo code to release all its
> references to cache nodes, e.g. before processing device tree updates
> post-migration, and to rebuild the hierarchy afterward.
>
> CPU online/offline must be blocked by callers; enforce this.
>
> Fixes: 410bccf97881 ("powerpc/pseries: Partition migration in the kernel")
> Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>

Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
> ---
>  arch/powerpc/kernel/cacheinfo.c | 21 +++++++++++++++++++++
>  arch/powerpc/kernel/cacheinfo.h |  4 ++++
>  2 files changed, 25 insertions(+)
>
> diff --git a/arch/powerpc/kernel/cacheinfo.c b/arch/powerpc/kernel/cacheinfo.c
> index 862e2890bd3d..42c559efe060 100644
> --- a/arch/powerpc/kernel/cacheinfo.c
> +++ b/arch/powerpc/kernel/cacheinfo.c
> @@ -896,4 +896,25 @@ void cacheinfo_cpu_offline(unsigned int cpu_id)
>         if (cache)
>                 cache_cpu_clear(cache, cpu_id);
>  }
> +
> +void cacheinfo_teardown(void)
> +{
> +       unsigned int cpu;
> +
> +       lockdep_assert_cpus_held();
> +
> +       for_each_online_cpu(cpu)
> +               cacheinfo_cpu_offline(cpu);
> +}
> +
> +void cacheinfo_rebuild(void)
> +{
> +       unsigned int cpu;
> +
> +       lockdep_assert_cpus_held();
> +
> +       for_each_online_cpu(cpu)
> +               cacheinfo_cpu_online(cpu);
> +}
> +
>  #endif /* (CONFIG_PPC_PSERIES && CONFIG_SUSPEND) || CONFIG_HOTPLUG_CPU */
> diff --git a/arch/powerpc/kernel/cacheinfo.h b/arch/powerpc/kernel/cacheinfo.h
> index 955f5e999f1b..52bd3fc6642d 100644
> --- a/arch/powerpc/kernel/cacheinfo.h
> +++ b/arch/powerpc/kernel/cacheinfo.h
> @@ -6,4 +6,8 @@
>  extern void cacheinfo_cpu_online(unsigned int cpu_id);
>  extern void cacheinfo_cpu_offline(unsigned int cpu_id);
>
> +/* Allow migration/suspend to tear down and rebuild the hierarchy. */
> +extern void cacheinfo_teardown(void);
> +extern void cacheinfo_rebuild(void);
> +
>  #endif /* _PPC_CACHEINFO_H */
> --
> 2.20.1
>


-- 
Thanks and Regards
gautham.