Re: [BUG] long freezes on thinkpad t60

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From: Linus Torvalds
Date: Thursday, June 21, 2007 - 1:14 pm

On Thu, 21 Jun 2007, Ingo Molnar wrote:

But this is a perfect example of exactly what I'm talking about:

 THAT CODE IS HORRIBLY BUGGY!

It's not the spinlocks that are broken, it's that damn code.


What a piece of crap. 

Anybody who ever waits for a lock by busy-looping over it is BUGGY, 
dammit!

The only correct way to wait for a lock is:

  (a) try it *once* with an atomic r-m-w 
  (b) loop over just _reading_ it (and something that implies a memory 
      barrier, _not_ "__delay()". Use "cpu_relax()" or "smp_rmb()")
  (c) rinse and repeat.

and code like the above should just be shot on sight.

So don't blame the spinlocks or the hardware for crap code.

		Linus
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Messages in current thread:
[BUG] long freezes on thinkpad t60, Miklos Szeredi, (Thu May 24, 5:04 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu May 24, 5:54 am)
Re: [BUG] long freezes on thinkpad t60, Miklos Szeredi, (Thu May 24, 7:03 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu May 24, 7:10 am)
Re: [BUG] long freezes on thinkpad t60, Miklos Szeredi, (Thu May 24, 7:28 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu May 24, 7:42 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu May 24, 7:44 am)
Re: [BUG] long freezes on thinkpad t60, Miklos Szeredi, (Thu May 24, 10:09 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu May 24, 2:01 pm)
Re: [BUG] long freezes on thinkpad t60, Henrique de Moraes H ..., (Thu May 24, 3:08 pm)
Re: [BUG] long freezes on thinkpad t60, Kok, Auke, (Thu May 24, 3:13 pm)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu May 24, 11:58 pm)
Re: [BUG] long freezes on thinkpad t60, Miklos Szeredi, (Fri May 25, 2:51 am)
Re: [BUG] long freezes on thinkpad t60, Miklos Szeredi, (Thu Jun 14, 9:04 am)
Re: [BUG] long freezes on thinkpad t60, Chuck Ebbert, (Fri Jun 15, 2:25 pm)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Sat Jun 16, 3:37 am)
Re: [BUG] long freezes on thinkpad t60, Miklos Szeredi, (Sun Jun 17, 2:46 pm)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Sun Jun 17, 11:43 pm)
Re: [BUG] long freezes on thinkpad t60, Miklos Szeredi, (Mon Jun 18, 12:24 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Mon Jun 18, 1:12 am)
Re: [BUG] long freezes on thinkpad t60, Andrew Morton, (Mon Jun 18, 1:20 am)
Re: [BUG] long freezes on thinkpad t60, Miklos Szeredi, (Mon Jun 18, 1:25 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Mon Jun 18, 1:31 am)
Re: [BUG] long freezes on thinkpad t60, Miklos Szeredi, (Mon Jun 18, 1:34 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Mon Jun 18, 2:18 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Mon Jun 18, 2:38 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Mon Jun 18, 2:44 am)
Re: [BUG] long freezes on thinkpad t60, Miklos Szeredi, (Mon Jun 18, 3:18 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Mon Jun 18, 5:36 am)
Re: [BUG] long freezes on thinkpad t60, Miklos Szeredi, (Mon Jun 18, 6:10 am)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Mon Jun 18, 9:34 am)
Re: [BUG] long freezes on thinkpad t60, Miklos Szeredi, (Mon Jun 18, 10:41 am)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Mon Jun 18, 10:48 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Mon Jun 18, 11:00 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Mon Jun 18, 11:02 am)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Mon Jun 18, 11:25 am)
Re: [BUG] long freezes on thinkpad t60, Ravikiran G Thirumalai, (Mon Jun 18, 9:22 pm)
Re: [BUG] long freezes on thinkpad t60, Jarek Poplawski, (Wed Jun 20, 2:36 am)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Wed Jun 20, 10:34 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu Jun 21, 12:30 am)
Re: [BUG] long freezes on thinkpad t60, Jarek Poplawski, (Thu Jun 21, 12:38 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu Jun 21, 1:39 am)
Re: [BUG] long freezes on thinkpad t60, Jarek Poplawski, (Thu Jun 21, 4:09 am)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Thu Jun 21, 8:50 am)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Thu Jun 21, 9:01 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu Jun 21, 9:08 am)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Thu Jun 21, 9:32 am)
Re: [BUG] long freezes on thinkpad t60, Chuck Ebbert, (Thu Jun 21, 9:44 am)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Thu Jun 21, 10:31 am)
Re: [BUG] long freezes on thinkpad t60, Eric Dumazet, (Thu Jun 21, 11:29 am)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Thu Jun 21, 11:44 am)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Thu Jun 21, 12:35 pm)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu Jun 21, 12:56 pm)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu Jun 21, 1:09 pm)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Thu Jun 21, 1:10 pm)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu Jun 21, 1:12 pm)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Thu Jun 21, 1:14 pm)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu Jun 21, 1:16 pm)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu Jun 21, 1:18 pm)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu Jun 21, 1:23 pm)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu Jun 21, 1:30 pm)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Thu Jun 21, 1:36 pm)
Re: [BUG] long freezes on thinkpad t60, Eric Dumazet, (Thu Jun 21, 1:36 pm)
[patch] spinlock debug: make looping nicer, Ingo Molnar, (Thu Jun 21, 1:42 pm)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Thu Jun 21, 1:48 pm)
Re: [patch] spinlock debug: make looping nicer, Linus Torvalds, (Thu Jun 21, 1:58 pm)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Thu Jun 21, 2:06 pm)
Re: [patch] spinlock debug: make looping nicer, Ingo Molnar, (Thu Jun 21, 2:15 pm)
Re: [patch] spinlock debug: make looping nicer, Jarek Poplawski, (Fri Jun 22, 12:00 am)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Fri Jun 22, 1:17 am)
Re: [BUG] long freezes on thinkpad t60, Jarek Poplawski, (Fri Jun 22, 3:38 am)
Re: [BUG] long freezes on thinkpad t60, Miklos Szeredi, (Sat Jun 23, 3:36 am)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Sat Jun 23, 9:39 am)
Re: [BUG] long freezes on thinkpad t60, Jarek Poplawski, (Sun Jun 24, 11:45 pm)
Re: [BUG] long freezes on thinkpad t60, Nick Piggin, (Tue Jun 26, 1:42 am)
Re: [BUG] long freezes on thinkpad t60, Jarek Poplawski, (Tue Jun 26, 3:56 am)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Tue Jun 26, 10:23 am)
Re: [BUG] long freezes on thinkpad t60, Nick Piggin, (Tue Jun 26, 10:23 pm)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Tue Jun 26, 11:04 pm)
Re: [BUG] long freezes on thinkpad t60, Nick Piggin, (Tue Jun 26, 11:20 pm)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Wed Jun 27, 12:47 pm)
Re: [BUG] long freezes on thinkpad t60, Ingo Molnar, (Wed Jun 27, 1:10 pm)
Re: [BUG] long freezes on thinkpad t60, Davide Libenzi, (Wed Jun 27, 1:17 pm)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Wed Jun 27, 3:11 pm)
Re: [BUG] long freezes on thinkpad t60, Davide Libenzi, (Wed Jun 27, 4:30 pm)
Re: [BUG] long freezes on thinkpad t60, Linus Torvalds, (Wed Jun 27, 5:46 pm)
Re: [BUG] long freezes on thinkpad t60, Davide Libenzi, (Wed Jun 27, 8:03 pm)
Re: [BUG] long freezes on thinkpad t60, Nick Piggin, (Mon Jul 2, 12:06 am)