[PATCH 36/45] ia64: smp, tlb: Use get/put_online_cpus_atomic() to prevent CPU offline

[Srivatsa S. Bhat]

Once stop_machine() is gone from the CPU offline path, we won't be able
to depend on disabling preemption 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: Tony Luck <tony.l...@intel.com>
Cc: Fenghua Yu <fenghua...@intel.com>
Cc: linux-i...@vger.kernel.org
Signed-off-by: Srivatsa S. Bhat <srivatsa.b...@linux.vnet.ibm.com>
---

 arch/ia64/kernel/smp.c |   12 ++++++------
 arch/ia64/mm/tlb.c     |    4 ++--
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/ia64/kernel/smp.c b/arch/ia64/kernel/smp.c
index 9fcd4e6..25991ba 100644
--- a/arch/ia64/kernel/smp.c
+++ b/arch/ia64/kernel/smp.c
@@ -24,6 +24,7 @@
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/smp.h>
+#include <linux/cpu.h>
 #include <linux/kernel_stat.h>
 #include <linux/mm.h>
 #include <linux/cache.h>
@@ -259,8 +260,7 @@ smp_flush_tlb_cpumask(cpumask_t xcpumask)
        cpumask_t cpumask = xcpumask;
        int mycpu, cpu, flush_mycpu = 0;
 
-       preempt_disable();
-       mycpu = smp_processor_id();
+       mycpu = get_online_cpus_atomic();
 
        for_each_cpu_mask(cpu, cpumask)
                counts[cpu] = local_tlb_flush_counts[cpu].count & 0xffff;
@@ -280,7 +280,7 @@ smp_flush_tlb_cpumask(cpumask_t xcpumask)
                while(counts[cpu] == (local_tlb_flush_counts[cpu].count & 
0xffff))
                        udelay(FLUSH_DELAY);
 
-       preempt_enable();
+       put_online_cpus_atomic();
 }
 
 void
@@ -293,12 +293,12 @@ void
 smp_flush_tlb_mm (struct mm_struct *mm)
 {
        cpumask_var_t cpus;
-       preempt_disable();
+       get_online_cpus_atomic();
        /* this happens for the common case of a single-threaded fork():  */
        if (likely(mm == current->active_mm && atomic_read(&mm->mm_users) == 1))
        {
                local_finish_flush_tlb_mm(mm);
-               preempt_enable();
+               put_online_cpus_atomic();
                return;
        }
        if (!alloc_cpumask_var(&cpus, GFP_ATOMIC)) {
@@ -313,7 +313,7 @@ smp_flush_tlb_mm (struct mm_struct *mm)
        local_irq_disable();
        local_finish_flush_tlb_mm(mm);
        local_irq_enable();
-       preempt_enable();
+       put_online_cpus_atomic();
 }
 
 void arch_send_call_function_single_ipi(int cpu)
diff --git a/arch/ia64/mm/tlb.c b/arch/ia64/mm/tlb.c
index ed61297..8c55ef5 100644
--- a/arch/ia64/mm/tlb.c
+++ b/arch/ia64/mm/tlb.c
@@ -87,11 +87,11 @@ wrap_mmu_context (struct mm_struct *mm)
         * can't call flush_tlb_all() here because of race condition
         * with O(1) scheduler [EF]
         */
-       cpu = get_cpu(); /* prevent preemption/migration */
+       cpu = get_online_cpus_atomic(); /* prevent preemption/migration */
        for_each_online_cpu(i)
                if (i != cpu)
                        per_cpu(ia64_need_tlb_flush, i) = 1;
-       put_cpu();
+       put_online_cpus_atomic();
        local_flush_tlb_all();
 }
 

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/