Re: [PATCH] driver core: unbind consumers before locking parent on device unbind

From	Lucas Stach <l.stach@pengutronix.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH] driver core: unbind consumers before locking parent on device unbind
Date	2017-02-17 19:50 +0100
Message-ID	<tbVLs-7V6-13@gated-at.bofh.it> (permalink)
References	<tbVBM-7Rv-21@gated-at.bofh.it> <tbVLs-7V6-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Am Freitag, den 17.02.2017, 10:42 -0800 schrieb Greg Kroah-Hartman:
> On Fri, Feb 17, 2017 at 07:36:29PM +0100, Lucas Stach wrote:
> > On forced unbind the parent lock is taken, as the device might be a USB
> > device. The device to be unbound might have active consumers, which
> > must be unbound before calling device_release_driver(), otherwise this
> > function might deadlock when trying to take the parent lock during
> > consumer unbind.
> 
> Really?  What type of device does this fail on today?

Regular devices on a MMIO bus. __device_release_driver() will take the
parent lock unconditionally when it unbinds consumer devices. So if the
forced unbound device is on the same bus as the consumer we will
deadlock right there.

Regards,
Lucas

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[PATCH] driver core: unbind consumers before locking parent on device unbind Lucas Stach <l.stach@pengutronix.de> - 2017-02-17 19:40 +0100
  Re: [PATCH] driver core: unbind consumers before locking parent on  device unbind Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-02-17 19:50 +0100
    Re: [PATCH] driver core: unbind consumers before locking parent on  device unbind Lucas Stach <l.stach@pengutronix.de> - 2017-02-17 19:50 +0100

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