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Subject[PATCH v6 38/46] mn10300: Use get/put_online_cpus_atomic() to prevent CPU offline
Date
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: David Howells <dhowells@redhat.com>
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Cc: linux-am33-list@redhat.com
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
---

arch/mn10300/kernel/smp.c | 2 ++
arch/mn10300/mm/cache-smp.c | 5 +++++
arch/mn10300/mm/tlb-smp.c | 15 +++++++++------
3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/arch/mn10300/kernel/smp.c b/arch/mn10300/kernel/smp.c
index 5d7e152..9dfa172 100644
--- a/arch/mn10300/kernel/smp.c
+++ b/arch/mn10300/kernel/smp.c
@@ -349,9 +349,11 @@ void send_IPI_allbutself(int irq)
{
cpumask_t cpumask;

+ get_online_cpus_atomic();
cpumask_copy(&cpumask, cpu_online_mask);
cpumask_clear_cpu(smp_processor_id(), &cpumask);
send_IPI_mask(&cpumask, irq);
+ put_online_cpus_atomic();
}

void arch_send_call_function_ipi_mask(const struct cpumask *mask)
diff --git a/arch/mn10300/mm/cache-smp.c b/arch/mn10300/mm/cache-smp.c
index 2d23b9e..47ca1c9 100644
--- a/arch/mn10300/mm/cache-smp.c
+++ b/arch/mn10300/mm/cache-smp.c
@@ -13,6 +13,7 @@
#include <linux/mman.h>
#include <linux/threads.h>
#include <linux/interrupt.h>
+#include <linux/cpu.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/processor.h>
@@ -94,6 +95,8 @@ void smp_cache_call(unsigned long opr_mask,
smp_cache_mask = opr_mask;
smp_cache_start = start;
smp_cache_end = end;
+
+ get_online_cpus_atomic();
cpumask_copy(&smp_cache_ipi_map, cpu_online_mask);
cpumask_clear_cpu(smp_processor_id(), &smp_cache_ipi_map);

@@ -102,4 +105,6 @@ void smp_cache_call(unsigned long opr_mask,
while (!cpumask_empty(&smp_cache_ipi_map))
/* nothing. lockup detection does not belong here */
mb();
+
+ put_online_cpus_atomic();
}
diff --git a/arch/mn10300/mm/tlb-smp.c b/arch/mn10300/mm/tlb-smp.c
index 3e57faf..d47304d 100644
--- a/arch/mn10300/mm/tlb-smp.c
+++ b/arch/mn10300/mm/tlb-smp.c
@@ -23,6 +23,7 @@
#include <linux/sched.h>
#include <linux/profile.h>
#include <linux/smp.h>
+#include <linux/cpu.h>
#include <asm/tlbflush.h>
#include <asm/bitops.h>
#include <asm/processor.h>
@@ -105,6 +106,7 @@ static void flush_tlb_others(cpumask_t cpumask, struct mm_struct *mm,
BUG_ON(cpumask_empty(&cpumask));
BUG_ON(cpumask_test_cpu(smp_processor_id(), &cpumask));

+ get_online_cpus_atomic();
cpumask_and(&tmp, &cpumask, cpu_online_mask);
BUG_ON(!cpumask_equal(&cpumask, &tmp));

@@ -134,6 +136,7 @@ static void flush_tlb_others(cpumask_t cpumask, struct mm_struct *mm,
flush_mm = NULL;
flush_va = 0;
spin_unlock(&tlbstate_lock);
+ put_online_cpus_atomic();
}

/**
@@ -144,7 +147,7 @@ void flush_tlb_mm(struct mm_struct *mm)
{
cpumask_t cpu_mask;

- preempt_disable();
+ get_online_cpus_atomic();
cpumask_copy(&cpu_mask, mm_cpumask(mm));
cpumask_clear_cpu(smp_processor_id(), &cpu_mask);

@@ -152,7 +155,7 @@ void flush_tlb_mm(struct mm_struct *mm)
if (!cpumask_empty(&cpu_mask))
flush_tlb_others(cpu_mask, mm, FLUSH_ALL);

- preempt_enable();
+ put_online_cpus_atomic();
}

/**
@@ -163,7 +166,7 @@ void flush_tlb_current_task(void)
struct mm_struct *mm = current->mm;
cpumask_t cpu_mask;

- preempt_disable();
+ get_online_cpus_atomic();
cpumask_copy(&cpu_mask, mm_cpumask(mm));
cpumask_clear_cpu(smp_processor_id(), &cpu_mask);

@@ -171,7 +174,7 @@ void flush_tlb_current_task(void)
if (!cpumask_empty(&cpu_mask))
flush_tlb_others(cpu_mask, mm, FLUSH_ALL);

- preempt_enable();
+ put_online_cpus_atomic();
}

/**
@@ -184,7 +187,7 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long va)
struct mm_struct *mm = vma->vm_mm;
cpumask_t cpu_mask;

- preempt_disable();
+ get_online_cpus_atomic();
cpumask_copy(&cpu_mask, mm_cpumask(mm));
cpumask_clear_cpu(smp_processor_id(), &cpu_mask);

@@ -192,7 +195,7 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long va)
if (!cpumask_empty(&cpu_mask))
flush_tlb_others(cpu_mask, mm, va);

- preempt_enable();
+ put_online_cpus_atomic();
}

/**


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