On Fri 2016-03-25 14:34:52, Josh Poimboeuf wrote:
> This is a horrible way to detect whether a task has been preempted.
> Come up with something better: task flag? or is there already an
> existing mechanism?
What about using kallsyms_lookup_size_offset() to check the address.
It is more heavyweight but less hacky. The following code seems
to work for me:
bool in_preempt_schedule_irq(unsigned long addr)
{
static unsigned long size;
if (unlikely(!size)) {
int ret;
ret = kallsyms_lookup_size_offset(
(unsigned long)preempt_schedule_irq,
size, NULL);
/*
* Warn when the function is used without kallsyms or
* when it is unable to locate preempt_schedule_irq().
* Be conservative and always return true in this case.
*/
if (WARN_ON(!ret))
size = -1L;
}
return (addr - (unsigned long)preempt_schedule_irq <= size);
}
Best Regards,
Petr
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