Re: [RFC][PATCH 1/4] res_counter set_limit and -EBUSY.

[Pavel Emelyanov <xemul-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>]

KAMEZAWA Hiroyuki wrote:
> Add an interface to set limit. This is necessary to memory resource controller
> because it shrinks usage at set limit.
> 
> (*) Other controller may not need this interface to shrink usage because
>     shrinking is not necessary or impossible.
> 
> This is an enhancement.
> named as res_counter-limit-change-ebusy.patch
> 
> Changelog v1->v2
>   - fixed white space bug.
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org>

Acked-by: Pavel Emelyanov <xemul-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>

> 
>  include/linux/res_counter.h |   15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> Index: linux-2.6.26-rc8-mm1/include/linux/res_counter.h
> ===================================================================
> --- linux-2.6.26-rc8-mm1.orig/include/linux/res_counter.h
> +++ linux-2.6.26-rc8-mm1/include/linux/res_counter.h
> @@ -176,4 +176,19 @@ static inline bool res_counter_can_add(s
>  	return ret;
>  }
>  
> +static inline int res_counter_set_limit(struct res_counter *cnt,
> +	unsigned long long limit)
> +{
> +	unsigned long flags;
> +	int ret = -EBUSY;
> +
> +	spin_lock_irqsave(&cnt->lock, flags);
> +	if (cnt->usage < limit) {
> +		cnt->limit = limit;
> +		ret = 0;
> +	}
> +	spin_unlock_irqrestore(&cnt->lock, flags);
> +	return ret;
> +}
> +
>  #endif
> 
>