netdev - Re: [PATCH 1/2] ipmr: delete redundant variable

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <48874B48.8060001@cn.fujitsu.com>
Date:	Wed, 23 Jul 2008 23:16:24 +0800
From:	Wang Chen <wangchen@...fujitsu.com>
To:	Ingo Oeser <netdev@...eo.de>
CC:	"David S. Miller" <davem@...emloft.net>,
	NETDEV <netdev@...r.kernel.org>
Subject: Re: [PATCH 1/2] ipmr: delete redundant variable

Ingo Oeser said the following on 2008-7-23 20:05:
> Hi Wand Chen,
> 
> Wang Chen schrieb:
>> But "accessing entry of table by index" is always allowed,
>> right?
>> If the complier makes such pointer which spills a register with
>> the multiply/shift, the simple code as following is bug too:
>> i = table[100].field;
>> But it shouldn't, right :)
> 
> I'm NOT telling you, that your transformation is introducing a BUG.
> It is semantically perfectly equivalent.
> 
> I'm trying to tell you, that it might not led to the same or better 
> performance and might thus be not worth it.
> 

Agree. I also think the accessing by index might lead to worse performance.
But in this code, we don't care performance, since it only be called when
device is unregistered. :)

> But please check the generated assembly yourself on a CISC and RISC
> machine to get an idea of the effects. It will be a nice learning 
> experience I enjoyed myself already.
> 

Sure. I am doing it.

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html