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Re: lockdep: incorrect deadlock warning with two GPIO expanders

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: lockdep: incorrect deadlock warning with two GPIO expanders
Date 2016-09-15 15:40 +0200
Message-ID <shF3r-7Ca-13@gated-at.bofh.it> (permalink)
References (3 earlier) <sgBuW-58A-37@gated-at.bofh.it> <sgV0B-1M6-19@gated-at.bofh.it> <shzKp-4a4-17@gated-at.bofh.it> <shEh4-75Z-29@gated-at.bofh.it> <shETM-7yO-13@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Thu, Sep 15, 2016 at 03:20:58PM +0200, Bartosz Golaszewski wrote:
> 2016-09-15 14:41 GMT+02:00 Linus Walleij <linus.walleij@linaro.org>:
> >> So can't you walk up that and see if you encounter the exact same driver
> >> again?
> >>
> >> Something like:
> >>
> >>         for (nr = 0, parent = dev->parent; parent; parent = parent->parent) {
> >>                 if (parent->device_driver == &pca953x_driver.driver)
> >>                         nr++;
> >>         }
> >
> > Oh clever. Of course.
> >
> > Bartosz can you try out this approach?
> >
> 
> I think it may be more complicated than that, depending on the hw
> topology, but the general idea seems reasonable. I'll try this.

Yeah, I figured there might be more to it.

In any case, if this fails, we can always punt and simply count the
total number of instances of this driver on the system and go with that.

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Thread

lockdep: incorrect deadlock warning with two GPIO expanders Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-09-12 14:00 +0200
  Re: lockdep: incorrect deadlock warning with two GPIO expanders Peter Zijlstra <peterz@infradead.org> - 2016-09-12 14:10 +0200
    Re: lockdep: incorrect deadlock warning with two GPIO expanders Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-09-12 17:20 +0200
      Re: lockdep: incorrect deadlock warning with two GPIO expanders Peter Zijlstra <peterz@infradead.org> - 2016-09-12 17:40 +0200
        Re: lockdep: incorrect deadlock warning with two GPIO expanders Linus Walleij <linus.walleij@linaro.org> - 2016-09-13 14:30 +0200
          Re: lockdep: incorrect deadlock warning with two GPIO expanders Peter Zijlstra <peterz@infradead.org> - 2016-09-15 10:00 +0200
            Re: lockdep: incorrect deadlock warning with two GPIO expanders Linus Walleij <linus.walleij@linaro.org> - 2016-09-15 14:50 +0200
              Re: lockdep: incorrect deadlock warning with two GPIO expanders Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-09-15 15:30 +0200
                Re: lockdep: incorrect deadlock warning with two GPIO expanders Peter Zijlstra <peterz@infradead.org> - 2016-09-15 15:40 +0200
                Re: lockdep: incorrect deadlock warning with two GPIO expanders Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-09-15 16:20 +0200
                Re: lockdep: incorrect deadlock warning with two GPIO expanders Peter Zijlstra <peterz@infradead.org> - 2016-09-15 16:40 +0200
                Re: lockdep: incorrect deadlock warning with two GPIO expanders Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-09-15 17:30 +0200
                Re: lockdep: incorrect deadlock warning with two GPIO expanders Peter Zijlstra <peterz@infradead.org> - 2016-09-16 13:00 +0200
                Re: lockdep: incorrect deadlock warning with two GPIO expanders Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-09-16 13:20 +0200
                Re: lockdep: incorrect deadlock warning with two GPIO expanders Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-09-16 14:10 +0200
              Re: lockdep: incorrect deadlock warning with two GPIO expanders Bartosz Golaszewski <bgolaszewski@baylibre.com> - 2016-09-16 16:30 +0200

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