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Date: Fri, 06 Jul 2007 14:24:00 -0700
From: Balbir Singh <balbir@linux.vnet.ibm.com>
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To: Dave Hansen <haveblue@us.ibm.com>
CC: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Pavel Emelianov <xemul@openvz.org>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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       Eric W Biederman <ebiederm@xmission.com>,
       Linux Containers <containers@lists.osdl.org>,
       Paul Menage <menage@google.com>
Subject: Re: [-mm PATCH 1/8] Memory controller resource counters (v2)
References: <20070706052029.11677.16964.sendpatchset@balbir-laptop> <20070706052043.11677.56208.sendpatchset@balbir-laptop> <1183742642.10287.151.camel@localhost>  <468EAE3E.4050802@linux.vnet.ibm.com> <1183756205.10287.212.camel@localhost>
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Dave Hansen wrote:
> On Fri, 2007-07-06 at 14:03 -0700, Balbir Singh wrote:
>>>> +ssize_t res_counter_read(struct res_counter *cnt, int member,
>>>> +            const char __user *userbuf, size_t nbytes, loff_t
>> *pos)
>>>> +{
>>>> +    unsigned long *val;
>>>> +    char buf[64], *s;
>>>> +
>>>> +    s = buf;
>>>> +    val = res_counter_member(cnt, member);
>>>> +    s += sprintf(s, "%lu\n", *val);
>>>> +    return simple_read_from_buffer((void __user *)userbuf, nbytes,
>>>> +                    pos, buf, s - buf);
>>>> +}
>>> Why do we need that cast?  
>>>
>> u mean the __user? If I remember correctly it's a attribute for
>> sparse.
> 
> The userbuf is already __user.  This just appears to be making a 'const
> char *' into a 'void *'.  I wondered what the reason for that part is.
> 

Aah.. yes.. good point. I'll look into it.

> -- Dave
> 
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-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL