On Thursday 14 February 2013, Haojian Zhuang wrote:
> On 14 February 2013 23:57, Arnd Bergmann <a...@arndb.de> wrote:
> > On Thursday 14 February 2013, Haojian Zhuang wrote:
> >> If you can change it into code in below, it could work. Otherwise, it
> >> always fails.
> >> driver_deferred_probe_enable = true;
> >> driver_deferred_probe_trigger();
> >> + deferred_probe_work_func(NULL);
> >> return 0;
> >>
> >> Because deferred_probe_work_func() depends on that deferred_probe is added
> >> into deferred_probe_active_list. If driver_deferred_probe_trigger() isn't
> >> called
> >> first, the deferred uart probe can't be added into active list. So even
> >> you call
> >> work_func at here, it doesn't help.
> >>
> >
> > Would that not cause two instances of the work function to run at the same
> > time?
> > That sounds like a source for a lot of problems.
> >
> > Arnd
>
> Two instances of the work function? I'm sorry that I don't
> understanding your meaning.
> Could you help explain your question?
I mean you end up calling the work function directly, while it gets run as part
of the work queue on a different CPU at the same time. I just noticed that
there is actually locking in place in deferred_probe_work_func that prevents
any actual bugs, but you are still adding extra overhead here.
Maybe just add
flush_workqueue(deferred_wq);
here?
Arnd
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