linux-kernel - Re: [PATCH] sparc, exec: remove redundant addr

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Message-Id: <09961391-F83F-4499-A0A3-00AA5C2028CE@googlemail.com>
Date:	Mon, 13 Jun 2011 22:28:20 +0200
From:	Mathias Krause <minipli@...glemail.com>
To:	David Miller <davem@...emloft.net>
Cc:	akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
	sparclinux@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sparc, exec: remove redundant addr_limit assignment

On 12.06.2011, at 01:08 David Miller wrote:
> From: Mathias Krause <minipli@...glemail.com>
> Date: Fri, 10 Jun 2011 15:10:53 +0200
> 
>> The address limit is already set in flush_old_exec() so this
>> assignment of USER_DS is redundant.
>> 
>> Signed-off-by: Mathias Krause <minipli@...glemail.com>
> ...
>> @@ -368,9 +368,6 @@ void flush_thread(void)
>> 
>> 	/* Clear FPU register state. */
>> 	t->fpsaved[0] = 0;
>> -	
>> -	if (get_thread_current_ds() != ASI_AIUS)
>> -		set_fs(USER_DS);
>> }
> 
> Yeah but now you're doing it unconditionally, the guard is here
> because the %asi register write which set_fs() does is extremely
> expensive on sparc64 and %99.99999 of the time we can avoid it.

As Linus already pointed out, that set_fs() was never called because
we already had (and still have) an unconditional set_fs() in the arch
independent code. So this patch just removes some dead code.

Mathias
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