[PATCH] ppc64: Fix cpu_up race

[Srivatsa Vaddagiri <vatsa@in.ibm.com>]

On Thu, Jul 29, 2004 at 03:30:11PM +1000, Anton Blanchard wrote:
>  
> > I think Anton pushed this to ameslab. I presume there should be some mechanism
> > for ameslab stuff to be included mainline. If there is such mechanism, then
> > I dont want to push the patch myself.
> 
> It looks good, could you send it directly to akpm, ccing me?

Andrew,
	Patch below fixes a cpu_up race in PPC64. Please apply.


Signed-off-by : Srivatsa Vaddagiri <vatsa@in.ibm.com>
Signed-off-by : Anton Blanchard <anton@samba.org>


---

 linux-2.6.8-rc2-vatsa/arch/ppc64/kernel/smp.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletion(-)

diff -puN arch/ppc64/kernel/smp.c~ppc64_cpu_up_fix arch/ppc64/kernel/smp.c
--- linux-2.6.8-rc2/arch/ppc64/kernel/smp.c~ppc64_cpu_up_fix	2004-07-30 10:33:55.000000000 +0530
+++ linux-2.6.8-rc2-vatsa/arch/ppc64/kernel/smp.c	2004-07-30 10:34:02.000000000 +0530
@@ -927,7 +927,11 @@ int __devinit __cpu_up(unsigned int cpu)
 
 	if (smp_ops->give_timebase)
 		smp_ops->give_timebase();
-	cpu_set(cpu, cpu_online_map);
+
+	/* Wait until cpu puts itself in the online map */
+	while (!cpu_online(cpu))
+		cpu_relax();
+
 	return 0;
 }
 
@@ -963,6 +967,10 @@ int __devinit start_secondary(void *unus
 #endif
 #endif
 
+	spin_lock(&call_lock);
+	cpu_set(cpu, cpu_online_map);
+	spin_unlock(&call_lock);
+
 	local_irq_enable();
 
 	return cpu_idle(NULL);

_

-- 


Thanks and Regards,
Srivatsa Vaddagiri,
Linux Technology Center,
IBM Software Labs,
Bangalore, INDIA - 560017