linux-kernel - Re: [PATCH] bitmap: bitmap_parse takes a kernel buffer instead of a user buffer

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Message-ID: <4748.10.24.192.177.1159984635.squirrel@linux.intel.com>
Date:	Wed, 4 Oct 2006 10:57:15 -0700 (PDT)
From:	"Inaky Perez-Gonzalez" <inaky@...ux.intel.com>
To:	"Joe Korty" <joe.korty@...r.com>
Cc:	"Andrew Morton" <akpm@...l.org>,
	"Reinette Chatre" <reinette.chatre@...ux.intel.com>,
	linux-kernel@...r.kernel.org,
	"Inaky Perez-Gonzalez" <inaky@...ux.intel.com>,
	"Paul Jackson" <pj@....com>
Subject: Re: [PATCH] bitmap: bitmap_parse takes a kernel buffer instead of 
     a user buffer


Joe Korty wrote:
> On Wed, Oct 04, 2006 at 09:40:29AM -0700, Andrew Morton wrote:
>> I think we can do a version which omits the kmalloc altogether:
>
>> 			if (__get_user(c, ubuf++))
>> 				return -EFAULT;
>>
>> (Note the s/get_user/__get_user/)
>
> Nice.  This eliminates the bulk of the get_user() overhead.  And
> it can be merged into Inaky's enum solution too, for something
> that is both simple and efficient.

Then bitmap_parse_user() will need a quick access_ok() check
before calling down on __bitmap_parse(). Nice.

-- 
Inaky
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