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Subject: Re: [-mm PATCH 1/8] Memory controller resource counters (v2)
From: Dave Hansen <haveblue@us.ibm.com>
To: balbir@linux.vnet.ibm.com
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
       Andrew Morton <akpm@linux-foundation.org>,
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Date: Fri, 06 Jul 2007 14:10:05 -0700
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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.

-- Dave