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Groups > linux.kernel > #1425135

Re: initialize a mutex into locked state?

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On Fri, Jun 17, 2016 at 10:14:10AM -0400, Oleg Drokin wrote:
> 
> On Jun 17, 2016, at 4:25 AM, Peter Zijlstra wrote:
> 
> > On Wed, Jun 15, 2016 at 02:23:35PM -0400, Oleg Drokin wrote:
> >> Hello!
> >> 
> >>  To my surprise I found out that it's not possible to initialise a mutex into
> >>  a locked state.
> >>  I discussed it with Arjan and apparently there's no fundamental reason
> >>  not to allow this.
> > 
> > There is. A mutex _must_ have an owner. If you can initialize it in
> > locked state, you could do so statically, ie. outside of the context of
> > a task.
> 
> What's wrong with disallowing only static initializers, but allowing dynamic ones?
> Then there is a clear owner.

At which point, what wrong with the simple:

	mutex_init(&m);
	mutex_lock(&m);

Sequence? Its obvious, has clear semantics and doesn't extend the API.

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Thread

initialize a mutex into locked state? Oleg Drokin <green@linuxhacker.ru> - 2016-06-15 20:30 +0200
  Re: initialize a mutex into locked state? Peter Zijlstra <peterz@infradead.org> - 2016-06-17 10:30 +0200
    Re: initialize a mutex into locked state? Oleg Drokin <green@linuxhacker.ru> - 2016-06-17 16:20 +0200
      Re: initialize a mutex into locked state? Peter Zijlstra <peterz@infradead.org> - 2016-06-17 16:20 +0200
        Re: initialize a mutex into locked state? Oleg Drokin <green@linuxhacker.ru> - 2016-06-17 16:30 +0200
          Re: initialize a mutex into locked state? Peter Zijlstra <peterz@infradead.org> - 2016-06-17 16:40 +0200
            Re: initialize a mutex into locked state? Oleg Drokin <green@linuxhacker.ru> - 2016-06-17 16:50 +0200
              Re: initialize a mutex into locked state? Jeff Layton <jlayton@poochiereds.net> - 2016-06-17 16:50 +0200
                Re: initialize a mutex into locked state? Oleg Drokin <green@linuxhacker.ru> - 2016-06-17 17:00 +0200
                Re: initialize a mutex into locked state? Arjan van de Ven <arjan@linux.intel.com> - 2016-06-17 17:00 +0200
              Re: initialize a mutex into locked state? Peter Zijlstra <peterz@infradead.org> - 2016-06-17 17:10 +0200
          Re: initialize a mutex into locked state? Oleg Drokin <green@linuxhacker.ru> - 2016-06-17 16:50 +0200

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