evie/android_kernel_oneplus_msm8998
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[IA64] eliminate race condition in smp_flush_tlb_mm

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A race condition exists within smp_call_function_many() when called from
smp_flush_tlb_mm().  On rare occasions the cpu_vm_mask can be cleared
while smp_call_function_many is executing, occasionally resulting in a
hung process.

Make a copy of the mask prior to calling smp_call_function_many().

Signed-off-by: Dimitri Sivanich <sivanich@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Dimitri Sivanich 2010-12-28 13:34:42 -06:00 • committed by Tony Luck
parent 90a8a73c06
commit 75c1c91cb9
1 changed files with 10 additions and 3 deletions
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13
arch/ia64/kernel/smp.c
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@ -293,6 +293,7 @@ smp_flush_tlb_all (void)
void void
smp_flush_tlb_mm (struct mm_struct *mm) smp_flush_tlb_mm (struct mm_struct *mm)
{ {
cpumask_var_t cpus;
preempt_disable(); preempt_disable();
/* this happens for the common case of a single-threaded fork(): */ /* this happens for the common case of a single-threaded fork(): */
if (likely(mm == current->active_mm && atomic_read(&mm->mm_users) == 1)) if (likely(mm == current->active_mm && atomic_read(&mm->mm_users) == 1))
@ -301,9 +302,15 @@ smp_flush_tlb_mm (struct mm_struct *mm)
preempt_enable(); preempt_enable();
return; return;
} }
if (!alloc_cpumask_var(&cpus, GFP_ATOMIC)) {
smp_call_function_many(mm_cpumask(mm), smp_call_function((void (*)(void *))local_finish_flush_tlb_mm,
(void (*)(void *))local_finish_flush_tlb_mm, mm, 1); mm, 1);
} else {
cpumask_copy(cpus, mm_cpumask(mm));
smp_call_function_many(cpus,
(void (*)(void *))local_finish_flush_tlb_mm, mm, 1);
free_cpumask_var(cpus);
}
local_irq_disable(); local_irq_disable();
local_finish_flush_tlb_mm(mm); local_finish_flush_tlb_mm(mm);
local_irq_enable(); local_irq_enable();