[PATCH] writeback: Simplify wb_stat_sum

[PATCH] writeback: Simplify wb_stat_sum

[Nikolay Borisov]

wb_stat_sum disables interrupts and calls __wb_stat_sum which eventually calls
__percpu_counter_sum. However, the percpu routine is already irq-safe. Simplify
the code a bit by making wb_stat_sum directly call percpu_counter_sum_positive
and not disable interrupts. Also remove the now-uneeded __wb_stat_sum which was
just a wrapper over percpu_counter_sum_positive

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---
 include/linux/backing-dev.h | 15 +--------------
 1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index e9c967b86054..854e1bdd0b2a 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -84,22 +84,9 @@ static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
 	return percpu_counter_read_positive(&wb->stat[item]);
 }
 
-static inline s64 __wb_stat_sum(struct bdi_writeback *wb,
-				enum wb_stat_item item)
-{
-	return percpu_counter_sum_positive(&wb->stat[item]);
-}
-
 static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)
 {
-	s64 sum;
-	unsigned long flags;
-
-	local_irq_save(flags);
-	sum = __wb_stat_sum(wb, item);
-	local_irq_restore(flags);
-
-	return sum;
+	return percpu_counter_sum_positive(&wb->stat[item]);
 }
 
 extern void wb_writeout_inc(struct bdi_writeback *wb);
-- 
2.7.4

Re: [PATCH] writeback: Simplify wb_stat_sum

[Nikolay Borisov]

[CC'ing Andrew since he seems to be taking those patches through -mm ]

On 23.06.2017 18:11, Nikolay Borisov wrote:
> wb_stat_sum disables interrupts and calls __wb_stat_sum which eventually calls
> __percpu_counter_sum. However, the percpu routine is already irq-safe. Simplify
> the code a bit by making wb_stat_sum directly call percpu_counter_sum_positive
> and not disable interrupts. Also remove the now-uneeded __wb_stat_sum which was
> just a wrapper over percpu_counter_sum_positive
> 
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>
> ---
>  include/linux/backing-dev.h | 15 +--------------
>  1 file changed, 1 insertion(+), 14 deletions(-)
> 
> diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
> index e9c967b86054..854e1bdd0b2a 100644
> --- a/include/linux/backing-dev.h
> +++ b/include/linux/backing-dev.h
> @@ -84,22 +84,9 @@ static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
>  	return percpu_counter_read_positive(&wb->stat[item]);
>  }
>  
> -static inline s64 __wb_stat_sum(struct bdi_writeback *wb,
> -				enum wb_stat_item item)
> -{
> -	return percpu_counter_sum_positive(&wb->stat[item]);
> -}
> -
>  static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)
>  {
> -	s64 sum;
> -	unsigned long flags;
> -
> -	local_irq_save(flags);
> -	sum = __wb_stat_sum(wb, item);
> -	local_irq_restore(flags);
> -
> -	return sum;
> +	return percpu_counter_sum_positive(&wb->stat[item]);
>  }
>  
>  extern void wb_writeout_inc(struct bdi_writeback *wb);
>