[PATCH v5 40/45] sh: Use get/put_online_cpus_atomic() to prevent CPU offline

["Srivatsa S. Bhat" <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>]

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: Paul Mundt <lethal@xxxxxxxxxxxx>
Cc: linux-sh@xxxxxxxxxxxxxxx
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
---

 arch/sh/kernel/smp.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/sh/kernel/smp.c b/arch/sh/kernel/smp.c
index 2062aa8..232fabe 100644
--- a/arch/sh/kernel/smp.c
+++ b/arch/sh/kernel/smp.c
@@ -357,7 +357,7 @@ static void flush_tlb_mm_ipi(void *mm)
  */
 void flush_tlb_mm(struct mm_struct *mm)
 {
-	preempt_disable();
+	get_online_cpus_atomic();
 
 	if ((atomic_read(&mm->mm_users) != 1) || (current->mm != mm)) {
 		smp_call_function(flush_tlb_mm_ipi, (void *)mm, 1);
@@ -369,7 +369,7 @@ void flush_tlb_mm(struct mm_struct *mm)
 	}
 	local_flush_tlb_mm(mm);
 
-	preempt_enable();
+	put_online_cpus_atomic();
 }
 
 struct flush_tlb_data {
@@ -390,7 +390,7 @@ void flush_tlb_range(struct vm_area_struct *vma,
 {
 	struct mm_struct *mm = vma->vm_mm;
 
-	preempt_disable();
+	get_online_cpus_atomic();
 	if ((atomic_read(&mm->mm_users) != 1) || (current->mm != mm)) {
 		struct flush_tlb_data fd;
 
@@ -405,7 +405,7 @@ void flush_tlb_range(struct vm_area_struct *vma,
 				cpu_context(i, mm) = 0;
 	}
 	local_flush_tlb_range(vma, start, end);
-	preempt_enable();
+	put_online_cpus_atomic();
 }
 
 static void flush_tlb_kernel_range_ipi(void *info)
@@ -433,7 +433,7 @@ static void flush_tlb_page_ipi(void *info)
 
 void flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
 {
-	preempt_disable();
+	get_online_cpus_atomic();
 	if ((atomic_read(&vma->vm_mm->mm_users) != 1) ||
 	    (current->mm != vma->vm_mm)) {
 		struct flush_tlb_data fd;
@@ -448,7 +448,7 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
 				cpu_context(i, vma->vm_mm) = 0;
 	}
 	local_flush_tlb_page(vma, page);
-	preempt_enable();
+	put_online_cpus_atomic();
 }
 
 static void flush_tlb_one_ipi(void *info)

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