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Re: [PATCH 5/5] input: twl6040-vibra: remove mutex

From "H. Nikolaus Schaller" <hns@goldelico.com>
Newsgroups linux.kernel
Subject Re: [PATCH 5/5] input: twl6040-vibra: remove mutex
Date 2016-04-19 10:10 +0200
Message-ID <rpyTp-3C4-21@gated-at.bofh.it> (permalink)
References <rpnuV-2F6-7@gated-at.bofh.it> <rpnuW-2F6-31@gated-at.bofh.it> <rpoU1-422-7@gated-at.bofh.it> <rpyA1-3dt-5@gated-at.bofh.it> <rpyTo-3C4-7@gated-at.bofh.it>
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> Am 19.04.2016 um 10:01 schrieb Dmitry Torokhov <dmitry.torokhov@gmail.com>:
> 
> On Tue, Apr 19, 2016 at 09:49:01AM +0200, H. Nikolaus Schaller wrote:
>> 
>>> Am 18.04.2016 um 23:20 schrieb Dmitry Torokhov <dmitry.torokhov@gmail.com>:
>>> 
>>> On Mon, Apr 18, 2016 at 09:55:41PM +0200, H. Nikolaus Schaller wrote:
>>>> The mutex does not seem to be needed.
>>> 
>>> twl6040_vibra_suspend() and vibra_play_work() may run concurrently, no?
>> 
>> Hm. I don't know about the rule that would give an answer to this question...
> 
> Sorry, that was actually a statement, not really a question.

Indeed. In doubt about the answer we should take measures for the worst case.

> It is
> possible (although very unlikely) that userspace posts play request and
> workqueue will not run until after suspend callback.
> 
> Thinking about it some more I wonder if we better do what
> twl6040_vibra_close() does and cancel the work before shutting off the
> device, so that there is no chance of work executing after suspend
> callback and reenabling the device. This way we can indeed remove the
> mutex.

Ok, I am fine with this.

Will post an update ASAP.

BR and thanks,
Nikolaus

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[PATCH 0/5] fixes for twl6040-vibra "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-04-18 22:00 +0200
  [PATCH 5/5] input: twl6040-vibra: remove mutex "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-04-18 22:00 +0200
    Re: [PATCH 5/5] input: twl6040-vibra: remove mutex Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2016-04-18 23:30 +0200
      Re: [PATCH 5/5] input: twl6040-vibra: remove mutex "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-04-19 09:50 +0200
        Re: [PATCH 5/5] input: twl6040-vibra: remove mutex Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2016-04-19 10:10 +0200
          Re: [PATCH 5/5] input: twl6040-vibra: remove mutex "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-04-19 10:10 +0200
            Re: [Letux-kernel] [PATCH 5/5] input: twl6040-vibra: remove mutex "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-04-20 11:30 +0200
              Re: [Letux-kernel] [PATCH 5/5] input: twl6040-vibra: remove mutex Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2016-04-20 20:00 +0200
                Re: [Letux-kernel] [PATCH 5/5] input: twl6040-vibra: remove mutex "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-04-20 20:20 +0200
                Re: [Letux-kernel] [PATCH 5/5] input: twl6040-vibra: remove mutex Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2016-04-20 20:20 +0200
                Re: [Letux-kernel] [PATCH 5/5] input: twl6040-vibra: remove mutex "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-04-20 21:10 +0200
  [PATCH 3/5] input: twl6040-vibra: fix NULL pointer dereference by removing workqueue "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-04-18 22:00 +0200
    Re: [PATCH 3/5] input: twl6040-vibra: fix NULL pointer dereference  by removing workqueue Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2016-04-18 23:50 +0200
  [PATCH 2/5] input: twl6040-vibra: add handler to unregister input if module is removed "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-04-18 22:00 +0200
    Re: [PATCH 2/5] input: twl6040-vibra: add handler to unregister  input if module is removed Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2016-04-18 23:20 +0200
      Re: [PATCH 2/5] input: twl6040-vibra: add handler to unregister input if module is removed "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-04-19 09:40 +0200
        Re: [PATCH 2/5] input: twl6040-vibra: add handler to unregister  input if module is removed Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2016-04-19 10:00 +0200
          Re: [PATCH 2/5] input: twl6040-vibra: add handler to unregister input if module is removed "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-04-19 10:10 +0200
            Re: [PATCH 2/5] input: twl6040-vibra: add handler to unregister  input if module is removed Dmitry Torokhov <dmitry.torokhov@gmail.com> - 2016-04-19 19:00 +0200
              Re: [PATCH 2/5] input: twl6040-vibra: add handler to unregister input if module is removed "H. Nikolaus Schaller" <hns@goldelico.com> - 2016-04-20 11:20 +0200

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