[v5,39/45] powerpc: Use get/put_online_cpus_atomic() to prevent CPU offline

Commit Message

Srivatsa S. Bhat Jan. 22, 2013, 7:43 a.m. UTC

Once stop_machine() is gone from the CPU offline path, we won't be able to
depend on preempt_disable() or local_irq_disable() to prevent CPUs from
going offline from under us.

Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going offline,
while invoking from atomic context.

Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: [e-mail]
Signed-off-by: Srivatsa S. Bhat <[e-mail]>
---

 arch/powerpc/mm/mmu_context_nohash.c |    2 ++
 1 file changed, 2 insertions(+)


--
To unsubscribe from this list: send the line "unsubscribe linux-pm" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

diff --git a/arch/powerpc/mm/mmu_context_nohash.c b/arch/powerpc/mm/mmu_context_nohash.c
index e779642..29f58cf 100644
--- a/arch/powerpc/mm/mmu_context_nohash.c
+++ b/arch/powerpc/mm/mmu_context_nohash.c
@@ -196,6 +196,7 @@  void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next)
 
 	/* No lockless fast path .. yet */
 	raw_spin_lock(&context_lock);
+	get_online_cpus_atomic();
 
 	pr_hard("[%d] activating context for mm @%p, active=%d, id=%d",
 		cpu, next, next->context.active, next->context.id);
@@ -279,6 +280,7 @@  void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next)
 	/* Flick the MMU and release lock */
 	pr_hardcont(" -> %d\n", id);
 	set_context(id, next->pgd);
+	put_online_cpus_atomic();
 	raw_spin_unlock(&context_lock);
 }