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Subject[PATCH v6 36/46] m32r: 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: Hirokazu Takata <takata@linux-m32r.org>
Cc: linux-m32r@ml.linux-m32r.org
Cc: linux-m32r-ja@ml.linux-m32r.org
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
---

arch/m32r/kernel/smp.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/m32r/kernel/smp.c b/arch/m32r/kernel/smp.c
index ce7aea3..0dad4d7 100644
--- a/arch/m32r/kernel/smp.c
+++ b/arch/m32r/kernel/smp.c
@@ -151,7 +151,7 @@ void smp_flush_cache_all(void)
cpumask_t cpumask;
unsigned long *mask;

- preempt_disable();
+ get_online_cpus_atomic();
cpumask_copy(&cpumask, cpu_online_mask);
cpumask_clear_cpu(smp_processor_id(), &cpumask);
spin_lock(&flushcache_lock);
@@ -162,7 +162,7 @@ void smp_flush_cache_all(void)
while (flushcache_cpumask)
mb();
spin_unlock(&flushcache_lock);
- preempt_enable();
+ put_online_cpus_atomic();
}

void smp_flush_cache_all_interrupt(void)
@@ -250,7 +250,7 @@ void smp_flush_tlb_mm(struct mm_struct *mm)
unsigned long *mmc;
unsigned long flags;

- preempt_disable();
+ get_online_cpus_atomic();
cpu_id = smp_processor_id();
mmc = &mm->context[cpu_id];
cpumask_copy(&cpu_mask, mm_cpumask(mm));
@@ -268,7 +268,7 @@ void smp_flush_tlb_mm(struct mm_struct *mm)
if (!cpumask_empty(&cpu_mask))
flush_tlb_others(cpu_mask, mm, NULL, FLUSH_ALL);

- preempt_enable();
+ put_online_cpus_atomic();
}

/*==========================================================================*
@@ -715,10 +715,12 @@ static void send_IPI_allbutself(int ipi_num, int try)
{
cpumask_t cpumask;

+ get_online_cpus_atomic();
cpumask_copy(&cpumask, cpu_online_mask);
cpumask_clear_cpu(smp_processor_id(), &cpumask);

send_IPI_mask(&cpumask, ipi_num, try);
+ put_online_cpus_atomic();
}

/*==========================================================================*
@@ -750,6 +752,7 @@ static void send_IPI_mask(const struct cpumask *cpumask, int ipi_num, int try)
if (num_cpus <= 1) /* NO MP */
return;

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

@@ -760,6 +763,7 @@ static void send_IPI_mask(const struct cpumask *cpumask, int ipi_num, int try)
}

send_IPI_mask_phys(&physid_mask, ipi_num, try);
+ put_online_cpus_atomic();
}

/*==========================================================================*


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