linux-kernel - Re: new architectures, time_t __kernel_long

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Message-ID: <50D3EE1A.7020703@zytor.com>
Date:	Thu, 20 Dec 2012 21:05:30 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Al Viro <viro@...IV.linux.org.uk>
CC:	Arnd Bergmann <arnd@...db.de>, linux-arch@...r.kernel.org,
	Vineet.Gupta1@...opsys.com, linux-kernel@...r.kernel.org,
	James Hogan <james.hogan@...tec.com>
Subject: Re: new architectures, time_t __kernel_long_t

On 12/20/2012 09:02 PM, Al Viro wrote:
> On Thu, Dec 20, 2012 at 09:00:27PM -0800, H. Peter Anvin wrote:
>> On 12/20/2012 08:57 PM, Al Viro wrote:
>>> On Wed, Nov 14, 2012 at 12:18:01PM +0000, Arnd Bergmann wrote:
>>>
>>>> The other types that are used as 64 bit on x32 are ino_t, nlink_t,
>>>> size_t, ssize_t, ptrdiff_t, and off_t.
>>>
>>> *Kernel-side* we should not give a damn about the userland nlink_t, period.
>>> Making it architecture-dependent had been a bad mistake that essentially
>>> made nlink_t useless for the kernel.  That mistake had been fixed; please,
>>> do not bring it back.  If some userland structure needs to include a field
>>> encoding nlink_t values, please use an explicitly-sized type when refering
>>> to it kernel-side.
>>>
>>
>> We should never use userland types per se.  We can use __kernel_*_t
>> typedefs to make the kernel headers neater if it makes sense, but that
>> is often not even necessary.
>
> ... as long as we do not have typedef __kernel_foo_t foo_t in linux/types.h.
>

In the case of things like nlink_t and dev_t I would suggest we 
explicitly call out the types as kernel and user.  I would suggest 
knlink_t and unlink_t but the latter made me want to stab my eyes out 
due to its confusion potential, so I wonder if we should establish a new 
convention with _kt (kernel type) and _ut (user type) suffixes, so 
nlink_kt and nlink_ut, alternatively one could consider k_nlink_t and 
u_nlink_t.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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