Re: [Qemu-devel] [PATCH 2/5] lock-guard: add scoped lock implementation

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Mon, Dec 11, 2017 at 07:51:43AM -0600, Eric Blake wrote:
> On 12/11/2017 04:16 AM, Stefan Hajnoczi wrote:
> 
> >>> I don't understand the need for the qemu_lock_guard_is_taken(&name)
> >>> condition, why not do the following?
> >>>
> >>>   for (QEMU_LOCK_GUARD(type, name, lock);
> >>>        ;
> >>>        qemu_lock_guard_unlock(&name))
> >>
> >> Because that would be an infinite loop. :)
> > 
> > Sorry, I mean for (...; false; ...).  Is there any reason to do
> > qemu_lock_guard_is_taken(&name)?
> 
> You need the loop to execute at least once ;)
> 
> But I proposed an alternative that doesn't need is_taken, by:
> 
> for (bool name##done = false, QEMU_LOCK_GUARD(type, name, lock);
>      ! name##done; name##done = true)
> 
> if we still like the form that declares a for-loop scope.

Okay guys, for loops are hard.  I give up programming.

Stefan

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