On Wed, Apr 06, 2016 at 03:06:19PM +0200, Petr Mladek wrote:
> 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);
> }
Yeah, that would definitely be better. Though still somewhat hacky.
--
Josh
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