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Subject[patch 84/83] powerpc: Use cpu_thread_in_core in smp_init for of_spin_map
From: Milton Miller <miltonm@bga.com>

commit 6a75a6b8e85e92cc774d42a4e113c76c30b5a539 upstream.

We used to assume that even numbered threads were the primary
threads, ie those that would be listed and started as a cpu from
open firmware. Replace a left over is even (% 2) check with a check
for it being a primary thread and update the comments.

Tested with a debug print on pseries, identical code found for cell.

Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/powerpc/platforms/cell/smp.c | 10 +++-------
arch/powerpc/platforms/pseries/smp.c | 13 ++++---------
2 files changed, 7 insertions(+), 16 deletions(-)

--- a/arch/powerpc/platforms/cell/smp.c
+++ b/arch/powerpc/platforms/cell/smp.c
@@ -54,8 +54,8 @@
#endif

/*
- * The primary thread of each non-boot processor is recorded here before
- * smp init.
+ * The Primary thread of each non-boot processor was started from the OF client
+ * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
*/
static cpumask_t of_spin_map;

@@ -208,11 +208,7 @@ void __init smp_init_cell(void)
/* Mark threads which are still spinning in hold loops. */
if (cpu_has_feature(CPU_FTR_SMT)) {
for_each_present_cpu(i) {
- if (i % 2 == 0)
- /*
- * Even-numbered logical cpus correspond to
- * primary threads.
- */
+ if (cpu_thread_in_core(i) == 0)
cpu_set(i, of_spin_map);
}
} else {
--- a/arch/powerpc/platforms/pseries/smp.c
+++ b/arch/powerpc/platforms/pseries/smp.c
@@ -52,8 +52,8 @@


/*
- * The primary thread of each non-boot processor is recorded here before
- * smp init.
+ * The Primary thread of each non-boot processor was started from the OF client
+ * interface by prom_hold_cpus and is spinning on secondary_hold_spinloop.
*/
static cpumask_t of_spin_map;

@@ -191,8 +191,7 @@ static void __devinit smp_pSeries_kick_c
static int smp_pSeries_cpu_bootable(unsigned int nr)
{
/* Special case - we inhibit secondary thread startup
- * during boot if the user requests it. Odd-numbered
- * cpus are assumed to be secondary threads.
+ * during boot if the user requests it.
*/
if (system_state < SYSTEM_RUNNING &&
cpu_has_feature(CPU_FTR_SMT) &&
@@ -229,11 +228,7 @@ static void __init smp_init_pseries(void
/* Mark threads which are still spinning in hold loops. */
if (cpu_has_feature(CPU_FTR_SMT)) {
for_each_present_cpu(i) {
- if (i % 2 == 0)
- /*
- * Even-numbered logical cpus correspond to
- * primary threads.
- */
+ if (cpu_thread_in_core(i) == 0)
cpu_set(i, of_spin_map);
}
} else {

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