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Date: Thu, 29 Jun 2006 13:25:41 +0100
From: Russell King <rmk+lkml@arm.linux.org.uk>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Esben Nielsen <nielsen.esben@googlemail.com>,
       Milan Svoboda <msvoboda@ra.rockwell.com>,
       LKML <linux-kernel@vger.kernel.org>,
       Deepak Saxena <dsaxena@plexity.net>, Ingo Molnar <mingo@elte.hu>,
       Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [BUG] Linux-2.6.17-rt3 on arm ixdp465
Message-ID: <20060629122541.GB9709@flint.arm.linux.org.uk>
Mail-Followup-To: Steven Rostedt <rostedt@goodmis.org>,
	Esben Nielsen <nielsen.esben@googlemail.com>,
	Milan Svoboda <msvoboda@ra.rockwell.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Deepak Saxena <dsaxena@plexity.net>, Ingo Molnar <mingo@elte.hu>,
	Thomas Gleixner <tglx@linutronix.de>
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On Thu, Jun 29, 2006 at 08:09:24AM -0400, Steven Rostedt wrote:
> 
> 
> On Thu, 29 Jun 2006, Esben Nielsen wrote:
> 
> >
> > On Thu, 29 Jun 2006, Milan Svoboda wrote:
> >
> >
> > It seems that dma_unmap_single() on arm contains
> >  	local_irq_save(flags);
> >
> >  	unmap_single(dev, dma_addr, size, dir);
> >
> >  	local_irq_restore(flags);
> >
> 
> Yeah I saw this too.
> 
> > I don't know the dma code on arm. It doesn't look like a per-cpu code but it
> > seems to me that it is not SMP safe and therefore not preempt-realtime
> > safe, either.
> >
> > The hard thing is to figure out which datastructures exactly is protected
> > by those irq-disable and put in a spinlock..
> >
> > I added Deepak Saxena on CC as he seems to be the last one who touched the
> > file.
> >
> 
> Well, the following patch may not be the best but I don't see it being any
> worse than what is already there.  I don't have any arm platforms or even
> an arm compiler, so I haven't even tested this patch with a compile.  But
> it should be at least a temporary fix.

Guys, look at what's in the latest -git from Linus.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core