From: Johannes Sixt <j6t@kdbg.org>
Date: Wed, 13 Jan 2010 18:40:43 GMT
Subject: Re: [PATCH 1/5] MSVC: Windows-native implementation for subset of Pthreads API
Message-ID: <201001131940.43868.j6t@kdbg.org>
In-Reply-To: <20100113125312.GD10586@dpotapov.dyndns.org>

On Mittwoch, 13. Januar 2010, Dmitry Potapov wrote:
> On Tue, Jan 12, 2010 at 10:13:38PM +0100, Johannes Sixt wrote:
> > In particular, it doesn't say that it is atomic WRT reads such as we have
> >
> > here:
> > > >> +     /* we're done waiting, so make sure we decrease waiters count
> > > >> */ +     EnterCriticalSection(&cond->waiters_lock);
> > > >> +     --cond->waiters;
> > > >> +     LeaveCriticalSection(&cond->waiters_lock);
>
> and these lines should be replaced with
>
>   InterlockedDecrement(&cond->waiters)

Ah, yes, of course. I quoted the wrong section, sorry. By "atomic WRT reads" I 
meant this snippet:

>> +     EnterCriticalSection(&cond->waiters_lock);
>> +     have_waiters = cond->waiters > 0;
>> +     LeaveCriticalSection(&cond->waiters_lock);

Is there "InterlockedRead()"? I suppose no, but I would get confirmation that 
a simple memory mov instruction is atomic WRT Interlocked* functions.

-- Hannes