Re: [RFC][PATCH 1/2] add res_counter_usage_safe

[David Rientjes <rientjes@google.com>]

On Thu, 28 Jun 2012, Kamezawa Hiroyuki wrote:

> diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
> index 7d7fbe2..a6f8cc5 100644
> --- a/include/linux/res_counter.h
> +++ b/include/linux/res_counter.h
> @@ -226,4 +226,6 @@ res_counter_set_soft_limit(struct res_counter *cnt,
>  	return 0;
>  }
>  
> +u64 res_counter_usage_safe(struct res_counter *cnt);
> +
>  #endif
> diff --git a/kernel/res_counter.c b/kernel/res_counter.c
> index ad581aa..e84149b 100644
> --- a/kernel/res_counter.c
> +++ b/kernel/res_counter.c
> @@ -171,6 +171,21 @@ u64 res_counter_read_u64(struct res_counter *counter, int member)
>  }
>  #endif
>  
> +/*
> + * Returns usage. If usage > limit, limit is returned.
> + * This is useful not to break user experiance if the excess
> + * is temporal.

s/temporal/temporary/

> + */
> +u64 res_counter_usage_safe(struct res_counter *counter)
> +{
> +	u64 usage, limit;
> +
> +	limit = res_counter_read_u64(counter, RES_LIMIT);
> +	usage = res_counter_read_u64(counter, RES_USAGE);
> +
> +	return min(usage, limit);
> +}
> +
>  int res_counter_memparse_write_strategy(const char *buf,
>  					unsigned long long *res)
>  {
> diff --git a/net/ipv4/tcp_memcontrol.c b/net/ipv4/tcp_memcontrol.c
> index b6f3583..a73dce6 100644
> --- a/net/ipv4/tcp_memcontrol.c
> +++ b/net/ipv4/tcp_memcontrol.c
> @@ -180,7 +180,7 @@ static u64 tcp_read_usage(struct mem_cgroup *memcg)
>  		return atomic_long_read(&tcp_memory_allocated) << PAGE_SHIFT;
>  
>  	tcp = tcp_from_cgproto(cg_proto);
> -	return res_counter_read_u64(&tcp->tcp_memory_allocated, RES_USAGE);
> +	return res_counter_usage_safe(&tcp->tcp_memory_allocated);
>  }
>  
>  static u64 tcp_cgroup_read(struct cgroup *cont, struct cftype *cft)

Acked-by: David Rientjes <rientjes@google.com>

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