linux-kernel - Re: [PATCH] m68k, exec: remove redundant set_fs(USER

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Message-ID: <BANLkTikdD8rwUhEXzkgj5qEN7a3E=BoDgQ@mail.gmail.com>
Date:	Wed, 15 Jun 2011 17:49:39 +0200
From:	Mathias Krause <minipli@...glemail.com>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-m68k@...ts.linux-m68k.org, linux-kernel@...r.kernel.org,
	Greg Ungerer <gerg@...inux.org>
Subject: Re: [PATCH] m68k, exec: remove redundant set_fs(USER_DS)

On Wed, Jun 15, 2011 at 4:40 PM, Geert Uytterhoeven
<geert@...ux-m68k.org> wrote:
> On Fri, Jun 10, 2011 at 15:09, Mathias Krause <minipli@...glemail.com> wrote:
>> The address limit is already set in flush_old_exec() so those calls to
>> set_fs(USER_DS) are redundant.
>>
>> Signed-off-by: Mathias Krause <minipli@...glemail.com>
>> Cc: Greg Ungerer <gerg@...inux.org>
>> ---
>>
>> Note: I'm not sure about the assignment to current->thread.fs in
>> flush_thread() -- shouldn't this be done in set_fs() itself?
>
> set_fs() is used to temporary set the address space to be used from the
> kernel.
> current->thread.fs is the address space that will be used when the
> thread returns
> to userspace.
> So I think it's correct.
>
> For nommu, thread.fs is set, but not really used.

Thanks for the explanation. So only the set_fs() is redundant.

Mathias
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