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Subject: Re: svn commit: r250294 - head/sys/arm/arm
From: Adrian Chadd <adrian@freebsd.org>
To: Grzegorz Bernacki <gber@freebsd.org>
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.. is this really the only way to do this reliably?



adrian

On 6 May 2013 07:27, Grzegorz Bernacki <gber@freebsd.org> wrote:
> Author: gber
> Date: Mon May  6 14:27:46 2013
> New Revision: 250294
> URL: http://svnweb.freebsd.org/changeset/base/250294
>
> Log:
>   Avoid calling pcpu_init() simultaneously.
>
>   pcpu_init() updates queue, so cannot be called by multiple cores
>   at the same time
>
>   Obtained from:        Semihalf
>
> Modified:
>   head/sys/arm/arm/mp_machdep.c
>
> Modified: head/sys/arm/arm/mp_machdep.c
> ==============================================================================
> --- head/sys/arm/arm/mp_machdep.c       Mon May  6 14:12:36 2013        (r250293)
> +++ head/sys/arm/arm/mp_machdep.c       Mon May  6 14:27:46 2013        (r250294)
> @@ -173,8 +173,15 @@ init_secondary(int cpu)
>
>         pc = &__pcpu[cpu];
>         set_pcpu(pc);
> -       pcpu_init(pc, cpu, sizeof(struct pcpu));
>
> +       /*
> +        * pcpu_init() updates queue, so it should not be executed in parallel
> +        * on several cores
> +        */
> +       while(mp_naps < (cpu - 1))
> +               ;
> +
> +       pcpu_init(pc, cpu, sizeof(struct pcpu));
>         dpcpu_init(dpcpu[cpu - 1], cpu);
>
>         /* Provide stack pointers for other processor modes. */