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From: Andrew Morton <akpm@osdl.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: mingo@elte.hu, markh@compro.net, linux-kernel@vger.kernel.org,
	dwalker@mvista.com, tglx@linutronix.de
Subject: Re: 3c59x vortex_timer rt hack (was: rt20 patch question)
Date: Fri, 12 May 2006 07:49:29 -0700	[thread overview]
Message-ID: <20060512074929.031d4eaf.akpm@osdl.org> (raw)
In-Reply-To: <Pine.LNX.4.58.0605121036150.30264@gandalf.stny.rr.com>

Steven Rostedt <rostedt@goodmis.org> wrote:
>
>  Use this patch instead.  It needs an irq disable.  But, believe it or not,
>  on SMP this is actually better.  If the irq is shared (as it is in Mark's
>  case), we don't stop the irq of other devices from being handled on
>  another CPU (unfortunately for Mark, he pinned all interrupts to one CPU).
> 
>  Andrew,
> 
>  should this be changed in mainline too?

I suppose so - we're taking the lock with spin_lock_bh(), but it can also
be taken by this CPU from the interrupt, so it'll deadlock.  But lo!  We've
done disable_irq(), so the interrupt won't be happening.

So yes, doing spin_lock_irq() (irqrestore isn't needed in a timer handler)
instead of disable_irq() in vortex_timer() looks OK.

One does wonder how long we'll hold off interrupts though.


  parent reply	other threads:[~2006-05-12 14:52 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-05-09 12:23 rt20 patch question Mark Hounschell
2006-05-09 14:38 ` Daniel Walker
2006-05-09 14:58   ` Mark Hounschell
2006-05-09 15:53     ` Daniel Walker
2006-05-10 12:39     ` Steven Rostedt
2006-05-10 13:06       ` Mark Hounschell
2006-05-10 14:10         ` Steven Rostedt
2006-05-10 15:33           ` Mark Hounschell
2006-05-10 16:17             ` Steven Rostedt
2006-05-10 18:30               ` Mark Hounschell
2006-05-10 18:49                 ` Steven Rostedt
2006-05-10 19:28                   ` Mark Hounschell
2006-05-11 11:25                     ` Mark Hounschell
2006-05-11 12:01                       ` Steven Rostedt
2006-05-11 12:22                         ` Steven Rostedt
2006-05-11 13:02                           ` Mark Hounschell
2006-05-11 13:14                             ` Steven Rostedt
2006-05-11 13:26                               ` Mark Hounschell
2006-05-11 13:53                                 ` Steven Rostedt
2006-05-11 14:57                                   ` Mark Hounschell
2006-05-12  6:47                                     ` Steven Rostedt
2006-05-12  7:33                                       ` Sébastien Dugué
2006-05-12  8:18                                         ` Mark Hounschell
2006-05-12  9:08                                       ` Mark Hounschell
2006-05-12  9:20                                         ` Steven Rostedt
2006-05-10 20:33                 ` Steven Rostedt
2006-05-12  8:16                   ` Ingo Molnar
2006-05-12  8:45                     ` Steven Rostedt
2006-05-12  9:16                       ` Ingo Molnar
2006-05-12  9:21                       ` Ingo Molnar
2006-05-12 12:38                         ` Mark Hounschell
2006-05-12 13:18                           ` Steven Rostedt
2006-05-12 13:38                             ` Mark Hounschell
2006-05-12 13:43                             ` Mark Hounschell
2006-05-12 14:05                               ` Steven Rostedt
2006-05-12 14:36                                 ` Mark Hounschell
2006-05-12 14:51                                   ` Steven Rostedt
2006-05-12 13:16                         ` 3c59x vortex_timer rt hack (was: rt20 patch question) Steven Rostedt
2006-05-12 13:36                           ` Ingo Molnar
2006-05-12 13:46                             ` Steven Rostedt
2006-05-12 14:16                           ` Andrew Morton
2006-05-12 14:32                             ` Steven Rostedt
2006-05-12 14:39                               ` Steven Rostedt
2006-05-12 14:43                                 ` Ingo Molnar
2006-05-12 14:49                                 ` Andrew Morton [this message]
2006-05-12 15:04                                   ` Steven Rostedt
2006-05-12 16:53                                     ` 3c59x vortex_timer rt hack Mark Hounschell
2006-05-12 15:22                                   ` 3c59x vortex_timer rt hack (was: rt20 patch question) Steven Rostedt
2006-05-12 15:23                                     ` Andrew Morton
2006-05-12 15:36                                       ` Steven Rostedt
2006-05-12 16:03                                         ` Andrew Morton
2006-05-12 16:11                                           ` Steven Rostedt
2006-05-12 16:27                                             ` Andrew Morton
2006-05-12 16:38                                               ` Steven Rostedt
2006-05-10 18:45             ` rt20 patch question Steven Rostedt

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