linux-kernel - Re: [4.4-rc6-rt1 PATCH 0/2] ARM: am437x: boot test report

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Date:	Fri, 15 Jan 2016 13:35:33 +0200
From:	Grygorii Strashko <grygorii.strashko@...com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
CC:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Sekhar Nori <nsekhar@...com>, <linux-rt-users@...r.kernel.org>,
	linux-arm <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [4.4-rc6-rt1 PATCH 0/2] ARM: am437x: boot test report

Hi Russell,

On 01/14/2016 11:30 PM, Russell King - ARM Linux wrote:
> On Thu, Jan 14, 2016 at 10:11:09PM +0200, Grygorii Strashko wrote:
>> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
>> index deabc36..b9b4f9c 100644
>> --- a/arch/arm/mm/highmem.c
>> +++ b/arch/arm/mm/highmem.c
>> @@ -167,7 +167,7 @@ void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p)
>>           * Clear @prev's kmap_atomic mappings
>>           */
>>          for (i = 0; i < prev_p->kmap_idx; i++) {
>> -               int idx = i + KM_TYPE_NR * smp_processor_id();
>> +               int idx = FIX_KMAP_BEGIN + i + KM_TYPE_NR * smp_processor_id();
>>   
>>                  set_fixmap_pte(idx, __pte(0));
>>          }
>> @@ -175,7 +175,7 @@ void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p)
>>           * Restore @next_p's kmap_atomic mappings
>>           */
>>          for (i = 0; i < next_p->kmap_idx; i++) {
>> -               int idx = i + KM_TYPE_NR * smp_processor_id();
>> +               int idx = FIX_KMAP_BEGIN + i + KM_TYPE_NR * smp_processor_id();
>>   
>>                  if (!pte_none(next_p->kmap_pte[i]))
>>                          set_fixmap_pte(idx, next_p->kmap_pte[i]);
> 
> This looks like it introduces the 4th and 5th copies of the same
> calcuation, so can I suggest that we do this to prevent this kind
> of error?
> 
> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
> index d02f8187b1cc..61f0d5941116 100644
> --- a/arch/arm/mm/highmem.c
> +++ b/arch/arm/mm/highmem.c
> @@ -34,6 +34,11 @@ static inline pte_t get_fixmap_pte(unsigned long vaddr)
>   	return *ptep;
>   }
>   
> +static unsigned int fixmap_idx(int type)
> +{
> +	return FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
> +}
> +


This looks very reasonable - I'll updated and re-send.
Would you agree if I'll add your Signed-off-by: in final patch?

Thanks for review.


[...]


-- 
regards,
-grygorii