[PATCH v5 39/45] powerpc: Use get/put_online_cpus_atomic() to prevent CPU offline
From: Srivatsa S. Bhat <hidden>
Date: 2013-01-22 07:45:59
Also in:
linux-arch, linux-pm, linuxppc-dev, lkml, netdev
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
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 <benh@kernel.crashing.org> Cc: Paul Mackerras <redacted> Cc: linuxppc-dev at lists.ozlabs.org Signed-off-by: Srivatsa S. Bhat <redacted> --- arch/powerpc/mm/mmu_context_nohash.c | 2 ++ 1 file changed, 2 insertions(+)
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); }