Message-ID: <3BC1B831.1060601@wipro.com>
Date: Mon, 08 Oct 2001 19:59:05 +0530
From: "BALBIR SINGH" <balbir.singh@wipro.com>
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To: linux-kernel@vger.kernel.org
Subject: [RFC] I still see people using cli()
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I saw the latest patch for 2.4.10 and saw that people are still blindly
copying the code in serial.c (au1000), though it uses save_flags() and cli().
Is somebody looking to replace these with either spinlocks or __cli() where
applicable, I do not mind spending sometime looking into these issues.

I would request people to look at the global-spin-lock document at lse.sf.net
before doing any locking. Also please look at kernel-locking.tmpl (using db2pdf
or db2ps). Please understand how locking works and then use this in your code.

Imagine a driver using save_flags(); cli(); and essentially serializing an entire
SMP system. Please do not do this until extremely necessary.

BTW, that brings me to another issue, once the kernel becomes preemptibel, what
are the locking issues? how are semaphores and spin-locks affected? Has anybody
defined or come up with the rules/document yet?

I hope, I have understood these issues  :-D 

Comments, flames
Balbir Singh.


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