Re: [PATCH] driver core: add wait event for deferred probe

From: Grant Likely
Date: Thu Feb 14 2013 - 12:42:47 EST

On Thu, 14 Feb 2013 15:57:18 +0000, Arnd Bergmann <arnd@xxxxxxxx> 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.

Yes. Even ignoring the problems with device drivers not handling
multithreaded probing well, the current deferred probe wouldn't handle
it well. I could make it support multithreading, but I don't see a whole
lot of value there.


Grant Likely, B.Sc, P.Eng.
Secret Lab Technologies, Ltd.
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