powerpc CONFIG_PREEMPT fixes

Hello!

This series provides fixes for a couple of CONFIG_PREEMPT problems on Power:

1. The hpte_need_flush() function accesses per-CPU variables without
protection.
2. The rtas_event_scan() function needs to use raw_smp_processor_id()
to get a starting point to avoid debugging splats.

There are probably a few more where these came from. ;-)

Thanx, Paul

The hpte_need_flush() function accesses the ppc64_tlb_batch per-CPU variable with preemption enabled, a bug that this patch fixes. Perhaps crudely.

---
 arch/powerpc/include/asm/pgtable-ppc64.h |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

index 2b09cd5..6ed08ab 100644
@@ -228,8 +228,11 @@ static inline unsigned long pte_update(struct mm_struct *mm,
 		assert_pte_locked(mm, addr);
 
 #ifdef CONFIG_PPC_STD_MMU_64
-	if (old & _PAGE_HASHPTE)
+	if (old & _PAGE_HASHPTE) {
+		preempt_disable();
 		hpte_need_flush(mm, addr, ptep, old, huge);
+		preempt_enable();
+	}
 #endif
 
 	return old;

1.7.3.2

The rtas_event_scan() function uses smp_processor_id() to select a starting point in cpu_online_mask, and does so under the protection of get_online_cpus(). This might not select the current processor in any case, so switch to raw_smp_processor_id().

---
 arch/powerpc/kernel/rtasd.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

index 049dbec..7980ec0 100644
@@ -412,7 +412,8 @@ static void rtas_event_scan(struct work_struct *w)
 
 	get_online_cpus();
 
-	cpu = cpumask_next(smp_processor_id(), cpu_online_mask);
+	/* raw_ OK because just using CPU as starting point. */
+	cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask);
         if (cpu >= nr_cpu_ids) {
 		cpu = cpumask_first(cpu_online_mask);
 

1.7.3.2