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Subject[PATCH] linux-2.6.0-test2_mtrr-race-fix_A0
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On Wed, 2003-08-06 at 11:02, john stultz wrote:
> On Wed, 2003-08-06 at 11:05, Mark Haverkamp wrote:
> > On Wed, 2003-08-06 at 10:15, john stultz wrote:
> > >
> > > Well, let me look at it again and see if I can come up with a proper
> > > fix.
> > I added an extra sync up from the caller after the last gate change so
> > it is the last one to touch the automatic data.
>
> Ah, you beat me to it!
>
> I'm actually testing the very same change (comments differ a touch, but
> that's ok).
>
> Looks good. If everyone is happy I'd say resubmit it to Andrew.
>
> thanks
> -john

I'd like to submit this patch for inclusion. It adds an extra sync up
in set_mtrr and ipi_handler to make sure that set_mtrr is the last to
touch the automatic set_mtrr_data.


===== arch/i386/kernel/cpu/mtrr/main.c 1.29 vs edited =====
--- 1.29/arch/i386/kernel/cpu/mtrr/main.c Tue Jul 15 10:08:48 2003
+++ edited/arch/i386/kernel/cpu/mtrr/main.c Wed Aug 6 10:46:00 2003
@@ -169,6 +169,7 @@
cpu_relax();
barrier();
}
+ atomic_dec(&data->count);
local_irq_restore(flags);
}

@@ -256,8 +257,18 @@
cpu_relax();
barrier();
}
- local_irq_restore(flags);
+ atomic_set(&data.count, num_booting_cpus() - 1);
atomic_set(&data.gate,0);
+
+ /*
+ * Wait here for everyone to have seen the gate change
+ * So we're the last ones to touch 'data'
+ */
+ while(atomic_read(&data.count)) {
+ cpu_relax();
+ barrier();
+ }
+ local_irq_restore(flags);
}

/**

--
Mark Haverkamp <markh@osdl.org>

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