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Date: Mon, 23 Mar 2009 04:21:23 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: bharata@linux.vnet.ibm.com
Cc: linux-kernel@vger.kernel.org, Balaji Rao <balajirrao@gmail.com>,
       Dhaval Giani <dhaval@linux.vnet.ibm.com>,
       Balbir Singh <balbir@linux.vnet.ibm.com>,
       Li Zefan <lizf@cn.fujitsu.com>, Paul Menage <menage@google.com>,
       Ingo Molnar <mingo@elte.hu>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
       KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [PATCH -tip] cpuacct: per-cgroup utime/stime statistics - v4
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On Mon, 23 Mar 2009 10:05:38 +0530 Bharata B Rao <bharata@linux.vnet.ibm.com> wrote:

> +static int cpuacct_stats_show(struct cgroup *cgrp, struct cftype *cft,
> +		struct cgroup_map_cb *cb)
> +{
> +	struct cpuacct *ca = cgroup_ca(cgrp);
> +	int i;
> +
> +	for (i = 0; i < CPUACCT_STAT_NSTATS; i++) {
> +		s64 val = percpu_counter_read(&ca->cpustat[i]);
> +		val = cputime_to_clock_t(val);
> +		cb->fill(cb, cpuacct_stat_desc[i], val);
> +	}
> +	return 0;
> +}

I'd have expected `val' to have type clock_t.  But clock_t is 32-bit on
32-bit x86.

Is it correct to pass a 64-bit value to a function which takes a 32-bit
value and to then copy the 32-bit return value into a 64-bit variable?