[10/89] powerpc/4xx: Fix regression in SMP on 476

From: Greg KH
Date: Thu Jun 16 2011 - 03:00:30 EST

2.6.39-stable review patch. If anyone has any objections, please let us know.


From: kerstin jonsson <kerstin.jonsson@xxxxxxxxxxxx>

commit c560bbceaf6b06e52f1ef20131b76a3fdc0a2c19 upstream.

commit c56e58537d504706954a06570b4034c04e5b7500 breaks SMP support in PPC_47x chip.
secondary_ti must be set to current thread info before callin kick_cpu or else
start_secondary_47x will jump into void when trying to return to c-code.
In the current setup secondary_ti is initialized before the CPU idle task is started
and only the boot core will start. I am not sure this is the correct solution, but it
makes SMP possible in my chip.
Note! The HOTPLUG support probably need some fixing to, There is no trampoline code
available in head_44x.S - start_secondary_resume?

Signed-off-by: Kerstin Jonsson <kerstin.jonsson@xxxxxxxxxxxx>
Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

arch/powerpc/kernel/smp.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -410,8 +410,6 @@ int __cpuinit __cpu_up(unsigned int cpu)
int rc, c;

- secondary_ti = current_set[cpu];
if (smp_ops == NULL ||
(smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu)))
return -EINVAL;
@@ -421,6 +419,8 @@ int __cpuinit __cpu_up(unsigned int cpu)
if (rc)
return rc;

+ secondary_ti = current_set[cpu];
/* Make sure callin-map entry is 0 (can be leftover a CPU
* hotplug

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