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Re: [PATCH] Replace completions with semaphores

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From: Bart Van Assche
Subject: Re: [PATCH] Replace completions with semaphores
Date: Tuesday, April 15, 2008 - 6:15 am

On Tue, Apr 15, 2008 at 10:44 AM, Peter Zijlstra <peterz@infradead.org> wrote:

I agree that lockdep is a real help for kernel developers. But please
keep in mind that locking order checking has its limitations. While
locking order checking can detect certain very important classes of
deadlocks, it can't detect all classes of possible deadlocks. Consider
e.g. the example mentioned by Roland Dreier, where semaphores are used
to count the number of elements in a queue. Deadlocks triggered by
waiting for a certain semaphore value can't be detected by
lockdep-style algorithms. And renaming semaphores into something else
won't help.

Bart.
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Messages in current thread:
[PATCH] Replace completions with semaphores, Matthew Wilcox, (Fri Apr 11, 2:00 pm)
Re: [PATCH] Replace completions with semaphores, Daniel Walker, (Fri Apr 11, 11:43 pm)
Re: [PATCH] Replace completions with semaphores, Ingo Oeser, (Sat Apr 12, 3:31 am)
Re: [PATCH] Replace completions with semaphores, Peter Zijlstra, (Sat Apr 12, 5:24 am)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Sat Apr 12, 10:26 am)
Re: [PATCH] Replace completions with semaphores, Daniel Walker, (Sat Apr 12, 11:01 am)
Re: [PATCH] Replace completions with semaphores, Peter Zijlstra, (Sat Apr 12, 11:05 am)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Sat Apr 12, 12:04 pm)
Re: [PATCH] Replace completions with semaphores, Peter Zijlstra, (Sat Apr 12, 12:16 pm)
Re: [PATCH] Replace completions with semaphores, Roland Dreier, (Sat Apr 12, 12:53 pm)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Sat Apr 12, 1:47 pm)
Re: [PATCH] Replace completions with semaphores, Ingo Molnar, (Sun Apr 13, 12:05 am)
Re: [PATCH] Replace completions with semaphores, Ingo Molnar, (Sun Apr 13, 12:08 am)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Sun Apr 13, 5:52 am)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Sun Apr 13, 5:57 am)
Re: [PATCH] Replace completions with semaphores, Bart Van Assche, (Sun Apr 13, 6:55 am)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Sun Apr 13, 7:22 am)
Re: [PATCH] Replace completions with semaphores, Bart Van Assche, (Sun Apr 13, 7:55 am)
Re: [PATCH] Replace completions with semaphores, Ingo Molnar, (Mon Apr 14, 8:39 am)
Re: [PATCH] Replace completions with semaphores, Ingo Molnar, (Mon Apr 14, 8:41 am)
Re: [PATCH] Replace completions with semaphores, Roland Dreier, (Mon Apr 14, 8:58 am)
Re: [PATCH] Replace completions with semaphores, Peter Zijlstra, (Mon Apr 14, 9:32 am)
Re: [PATCH] Replace completions with semaphores, Jens Axboe, (Mon Apr 14, 9:54 am)
Re: [PATCH] Replace completions with semaphores, Arjan van de Ven, (Mon Apr 14, 9:56 am)
Re: API documentation (was [PATCH] Replace completions wit ..., Jonathan Corbet, (Mon Apr 14, 10:12 am)
Re: API documentation (was [PATCH] Replace completions wit ..., Peter Zijlstra, (Mon Apr 14, 10:33 am)
Re: [PATCH] Replace completions with semaphores, Andi Kleen, (Mon Apr 14, 10:46 am)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Mon Apr 14, 10:46 am)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Mon Apr 14, 10:50 am)
Re: [PATCH] Replace completions with semaphores, Peter Zijlstra, (Mon Apr 14, 10:54 am)
Re: [PATCH] Replace completions with semaphores, Daniel Walker, (Mon Apr 14, 11:09 am)
Re: API documentation (was [PATCH] Replace completions wit ..., Bart Van Assche, (Mon Apr 14, 11:38 am)
Re: [PATCH] Replace completions with semaphores, Andi Kleen, (Mon Apr 14, 12:16 pm)
Re: [PATCH] Replace completions with semaphores, Alan Cox, (Mon Apr 14, 12:16 pm)
Re: [PATCH] Replace completions with semaphores, Bart Van Assche, (Mon Apr 14, 11:18 pm)
Re: [PATCH] Replace completions with semaphores, Peter Zijlstra, (Mon Apr 14, 11:46 pm)
Re: [PATCH] Replace completions with semaphores, Bart Van Assche, (Tue Apr 15, 12:17 am)
Re: [PATCH] Replace completions with semaphores, Peter Zijlstra, (Tue Apr 15, 1:44 am)
Re: [PATCH] Replace completions with semaphores, Bart Van Assche, (Tue Apr 15, 6:15 am)
Re: [PATCH] Replace completions with semaphores, Linus Torvalds, (Tue Apr 15, 9:09 am)
Re: [PATCH] Replace completions with semaphores, Andi Kleen, (Tue Apr 15, 9:27 am)
Re: [PATCH] Replace completions with semaphores, Linus Torvalds, (Tue Apr 15, 9:57 am)
Re: [PATCH] Replace completions with semaphores, Ingo Molnar, (Tue Apr 15, 10:05 am)
Re: [PATCH] Replace completions with semaphores, Andi Kleen, (Tue Apr 15, 10:15 am)
Re: [PATCH] Replace completions with semaphores, Linus Torvalds, (Tue Apr 15, 10:26 am)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Tue Apr 15, 10:41 am)
Re: [PATCH] Replace completions with semaphores, Linus Torvalds, (Tue Apr 15, 11:14 am)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Tue Apr 15, 11:50 am)
Re: [PATCH] Replace completions with semaphores, Ingo Molnar, (Wed Apr 16, 5:37 am)
Re: [PATCH] Replace completions with semaphores, Andi Kleen, (Wed Apr 16, 5:50 am)
Killable stat/readdir, Matthew Wilcox, (Wed Apr 16, 5:59 am)
Re: [PATCH] Replace completions with semaphores, Ingo Oeser, (Wed Apr 16, 9:07 am)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Wed Apr 16, 9:16 am)
Re: [PATCH] Replace completions with semaphores, Oliver Neukum, (Wed Apr 16, 9:31 am)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Wed Apr 16, 9:34 am)
Re: [PATCH] Replace completions with semaphores, Oliver Neukum, (Wed Apr 16, 9:42 am)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Wed Apr 16, 9:44 am)
Re: [PATCH] Replace completions with semaphores, Roland Dreier, (Wed Apr 16, 9:47 am)
Re: [PATCH] Replace completions with semaphores, Arjan van de Ven, (Wed Apr 16, 9:50 am)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Wed Apr 16, 9:58 am)
Re: [PATCH] Replace completions with semaphores, Arjan van de Ven, (Wed Apr 16, 10:08 am)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Wed Apr 16, 10:12 am)
Re: [PATCH] Replace completions with semaphores, Matthew Wilcox, (Wed Apr 16, 11:10 am)