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Re: [PATCH 4/12] arch/mips: remove references to cpu_*_map.

To: Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH 4/12] arch/mips: remove references to cpu_*_map.
From: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Date: Wed, 15 Feb 2012 14:50:02 +0530
Cc: Ralf Baechle <ralf@linux-mips.org>, linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, Venkatesh Pallipadi <venki@google.com>, "akpm@linux-foundation.org" <akpm@linux-foundation.org>
In-reply-to: <1329281884.26321.rusty@rustcorp.com.au>
References: <1329281884.26321.rusty@rustcorp.com.au>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mozilla/5.0 (X11; Linux i686; rv:9.0) Gecko/20111222 Thunderbird/9.0
On 02/15/2012 10:28 AM, Rusty Russell wrote:

> From: Rusty Russell <rusty@rustcorp.com.au>
> 
> This has been obsolescent for a while; time for the final push.
> 
> Also took the chance to get rid of old cpus_* in favor of cpumask_*.
> 
> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
> Cc: Ralf Baechle <ralf@linux-mips.org>
> Cc: linux-mips@linux-mips.org
> ---
[...]


> diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
> --- a/arch/mips/kernel/smp.c
> +++ b/arch/mips/kernel/smp.c
> @@ -148,7 +148,7 @@ static void stop_this_cpu(void *dummy)
>       /*
>        * Remove this CPU:
>        */
> -     cpu_clear(smp_processor_id(), cpu_online_map);
> +     set_cpu_online(smp_processor_id(), false);
>       for (;;) {
>               if (cpu_wait)
>                       (*cpu_wait)();          /* Wait if available. */
> @@ -174,7 +174,7 @@ void __init smp_prepare_cpus(unsigned in
>       mp_ops->prepare_cpus(max_cpus);
>       set_cpu_sibling_map(0);
>  #ifndef CONFIG_HOTPLUG_CPU
> -     init_cpu_present(&cpu_possible_map);
> +     init_cpu_present(cpu_possible_mask);
>  #endif
>  }
>  
> @@ -248,7 +248,7 @@ int __cpuinit __cpu_up(unsigned int cpu)
>       while (!cpu_isset(cpu, cpu_callin_map))
>               udelay(100);
>  
> -     cpu_set(cpu, cpu_online_map);
> +     set_cpu_online(cpu, true);
>  
>       return 0;
>  }
> @@ -320,13 +320,12 @@ void flush_tlb_mm(struct mm_struct *mm)
>       if ((atomic_read(&mm->mm_users) != 1) || (current->mm != mm)) {
>               smp_on_other_tlbs(flush_tlb_mm_ipi, mm);
>       } else {
> -             cpumask_t mask = cpu_online_map;
>               unsigned int cpu;
>  
> -             cpu_clear(smp_processor_id(), mask);
> -             for_each_cpu_mask(cpu, mask)
> -                     if (cpu_context(cpu, mm))
> +             for_each_online_cpu(cpu) {
> +                     if (cpu != smp_processor_id() && cpu_context(cpu, mm))
>                               cpu_context(cpu, mm) = 0;
> +             }


Strictly speaking, this one is not a mere cleanup. It causes a subtle change in
behaviour: earlier, it used to iterate over a local copy of cpu_online_mask, 
which
wouldn't change. However, with this patch, it will iterate directly over
cpu_online_mask, which can change underneath. (The preempt_disable() won't stop
new CPUs from coming in.. it only prevents CPUs from going offline, that too
provided that we use stop_machine stuff for CPU offline, which we do currently.)

>       }
>       local_flush_tlb_mm(mm);
>  
> @@ -360,13 +359,12 @@ void flush_tlb_range(struct vm_area_stru
>  
>               smp_on_other_tlbs(flush_tlb_range_ipi, &fd);
>       } else {
> -             cpumask_t mask = cpu_online_map;
>               unsigned int cpu;
>  
> -             cpu_clear(smp_processor_id(), mask);
> -             for_each_cpu_mask(cpu, mask)
> -                     if (cpu_context(cpu, mm))
> +             for_each_online_cpu(cpu) {
> +                     if (cpu != smp_processor_id() && cpu_context(cpu, mm))
>                               cpu_context(cpu, mm) = 0;
> +             }
>       }


Same here.

>       local_flush_tlb_range(vma, start, end);
>       preempt_enable();
> @@ -407,13 +405,12 @@ void flush_tlb_page(struct vm_area_struc
>  
>               smp_on_other_tlbs(flush_tlb_page_ipi, &fd);
>       } else {
> -             cpumask_t mask = cpu_online_map;
>               unsigned int cpu;
>  
> -             cpu_clear(smp_processor_id(), mask);
> -             for_each_cpu_mask(cpu, mask)
> -                     if (cpu_context(cpu, vma->vm_mm))
> +             for_each_online_cpu(cpu) {
> +                     if (cpu != smp_processor_id() && cpu_context(cpu, 
> vma->vm_mm))
>                               cpu_context(cpu, vma->vm_mm) = 0;
> +             }
>       }


And here too.

>       local_flush_tlb_page(vma, page);
>       preempt_enable();
> diff --git a/arch/mips/kernel/smtc.c b/arch/mips/kernel/smtc.c
> --- a/arch/mips/kernel/smtc.c
> +++ b/arch/mips/kernel/smtc.c
> @@ -292,7 +292,7 @@ static void smtc_configure_tlb(void)
>   * possibly leave some TCs/VPEs as "slave" processors.
>   *
>   * Use c0_MVPConf0 to find out how many TCs are available, setting up
> - * cpu_possible_map and the logical/physical mappings.
> + * cpu_possible_mask and the logical/physical mappings.
>   */
>  
>  int __init smtc_build_cpu_map(int start_cpu_slot)
> diff --git a/arch/mips/mm/c-octeon.c b/arch/mips/mm/c-octeon.c
> --- a/arch/mips/mm/c-octeon.c
> +++ b/arch/mips/mm/c-octeon.c
> @@ -81,9 +81,9 @@ static void octeon_flush_icache_all_core
>       if (vma)
>               mask = *mm_cpumask(vma->vm_mm);
>       else
> -             mask = cpu_online_map;
> -     cpu_clear(cpu, mask);
> -     for_each_cpu_mask(cpu, mask)
> +             mask = *cpu_online_mask;
> +     cpumask_clear(&mask, cpu);


This should be cpumask_clear_cpu(cpu, &mask);

> +     for_each_cpu(cpu, &mask)
>               octeon_send_ipi_single(cpu, SMP_ICACHE_FLUSH);
>  
>       preempt_enable();
 

Regards,
Srivatsa S. Bhat


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