[PATCH v6 31/46] alpha/smp: 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.

Also, remove the non-ASCII character present in this file!

Cc: linux-alpha@xxxxxxxxxxxxxxx
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
---

 arch/alpha/kernel/smp.c |   19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/arch/alpha/kernel/smp.c b/arch/alpha/kernel/smp.c
index 9603bc2..9213d5d 100644
--- a/arch/alpha/kernel/smp.c
+++ b/arch/alpha/kernel/smp.c
@@ -498,7 +498,6 @@ smp_cpus_done(unsigned int max_cpus)
 	       ((bogosum + 2500) / (5000/HZ)) % 100);
 }
 
-
 void
 smp_percpu_timer_interrupt(struct pt_regs *regs)
 {
@@ -682,7 +681,7 @@ ipi_flush_tlb_mm(void *x)
 void
 flush_tlb_mm(struct mm_struct *mm)
 {
-	preempt_disable();
+	get_online_cpus_atomic();
 
 	if (mm == current->active_mm) {
 		flush_tlb_current(mm);
@@ -694,7 +693,7 @@ flush_tlb_mm(struct mm_struct *mm)
 				if (mm->context[cpu])
 					mm->context[cpu] = 0;
 			}
-			preempt_enable();
+			put_online_cpus_atomic();
 			return;
 		}
 	}
@@ -703,7 +702,7 @@ flush_tlb_mm(struct mm_struct *mm)
 		printk(KERN_CRIT "flush_tlb_mm: timed out\n");
 	}
 
-	preempt_enable();
+	put_online_cpus_atomic();
 }
 EXPORT_SYMBOL(flush_tlb_mm);
 
@@ -731,7 +730,7 @@ flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
 	struct flush_tlb_page_struct data;
 	struct mm_struct *mm = vma->vm_mm;
 
-	preempt_disable();
+	get_online_cpus_atomic();
 
 	if (mm == current->active_mm) {
 		flush_tlb_current_page(mm, vma, addr);
@@ -743,7 +742,7 @@ flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
 				if (mm->context[cpu])
 					mm->context[cpu] = 0;
 			}
-			preempt_enable();
+			put_online_cpus_atomic();
 			return;
 		}
 	}
@@ -756,7 +755,7 @@ flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
 		printk(KERN_CRIT "flush_tlb_page: timed out\n");
 	}
 
-	preempt_enable();
+	put_online_cpus_atomic();
 }
 EXPORT_SYMBOL(flush_tlb_page);
 
@@ -787,7 +786,7 @@ flush_icache_user_range(struct vm_area_struct *vma, struct page *page,
 	if ((vma->vm_flags & VM_EXEC) == 0)
 		return;
 
-	preempt_disable();
+	get_online_cpus_atomic();
 
 	if (mm == current->active_mm) {
 		__load_new_mm_context(mm);
@@ -799,7 +798,7 @@ flush_icache_user_range(struct vm_area_struct *vma, struct page *page,
 				if (mm->context[cpu])
 					mm->context[cpu] = 0;
 			}
-			preempt_enable();
+			put_online_cpus_atomic();
 			return;
 		}
 	}
@@ -808,5 +807,5 @@ flush_icache_user_range(struct vm_area_struct *vma, struct page *page,
 		printk(KERN_CRIT "flush_icache_page: timed out\n");
 	}
 
-	preempt_enable();
+	put_online_cpus_atomic();
 }

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