quoted

? ? ? ?atomic_set(&data->refs, cpumask_weight(data->cpumask));
+ ? ? ? if (unlikely(!atomic_read(&data->refs))) {
+ ? ? ? ? ? ? ? csd_unlock(&data->csd);
+ ? ? ? ? ? ? ? return;
+ ? ? ? }

I don't think this is save, if the mask get cleaned after having cpu
set to valid value and before calculating the next_cpu, the code with
go to the fast path (smp_call_function_single)

I was wrong, this is actually not a problem, taking the fast path will
not hang the process.

quoted

An alternative would be to copy the cpumask to a local variable in
on_each_cpu_mask(), though the workaround above would cover other cases
that we haven't spotted yet. Also, the smp_call_function_many()
description doesn't state that the cpumask should not be modified.

diff --git a/arch/arm/kernel/smp_tlb.c b/arch/arm/kernel/smp_tlb.c
index 8f57f32..1717dec 100644
--- a/arch/arm/kernel/smp_tlb.c
+++ b/arch/arm/kernel/smp_tlb.c

@@ -16,10 +16,13 @@

?static void on_each_cpu_mask(void (*func)(void *), void *info, int wait,
? ? ? ?const struct cpumask *mask)
?{
+ ? ? ? struct cpumask call_mask;
+
? ? ? ?preempt_disable();

+ ? ? ? cpumask_copy(&call_mask, mask);
? ? ? ?smp_call_function_many(mask, func, info, wait);

?I'll check this one, but the mask here should be call_mask.

quoted

- ? ? ? if (cpumask_test_cpu(smp_processor_id(), mask))
+ ? ? ? if (cpumask_test_cpu(smp_processor_id(), &call_mask))
? ? ? ? ? ? ? ?func(info);

this patch increases my system instability, for some reason, the
call_function_data data get corrupted when the
generic_smp_call_function_interrupt() is running.
saeed