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Date: Wed, 03 Oct 2001 14:13:30 -0700
From: Jun Sun <jsun@mvista.com>
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To: Ralf Baechle <ralf@oss.sgi.com>
CC: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>, linux-mips@oss.sgi.com
Subject: Re: CVS Update@oss.sgi.com: linux
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Ralf Baechle wrote:
> 
> On Wed, Oct 03, 2001 at 01:02:56PM +0200, Maciej W. Rozycki wrote:
> 
> > > Modified files:
> > >     arch/mips/kernel: scall_o32.S sysmips.c
> > >
> > > Log message:
> > >     Barf.
> >
> >  The new mips_atomic_set() doesn't mask interrupts in the non-ll/sc case.
> > Thus it may fail to keep coherency.  Is it intentional?
> 
> Yes.  Assuming do_page_fault did it's job successfully the address which
> has been passed as argument to sysmips() is now writable and thus we
> won't take any pagefaults.
> 
> There are two remaining failure scenarios which probably are't very
> interesting for practical usage.  It's when an interrupt is accessing
> the same address.  This could be fixed by disabling interrupts.
> The other case is missaligned words.
> 

And a third one - when you enable kernel preemption with the preemptable
kernel patch. :-)


Jun