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Date: Wed, 15 Dec 2021 00:55:56 +0100
From: qwx@sciops.net
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X-Bullshit: responsive object-oriented realtime dependency HTML over ORM factory-oriented realtime generator 
Subject: Re: [9front] aux/wacom: possible race
Reply-To: 9front@9front.org
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On Mon Dec  6 02:57:05 +0100 2021, qwx@sciops.net wrote:
> Hello,
> 
> I've been playing with aux/wacom and aux/tablet on x61t.
> aux/tablet often crashes with a `no concurrent reads, please'
> error mid-drawing.  From what I can tell both of these
> programs are early 9front additions.  Has anyone else seen
> these errors?
> 
> I think that the issue is that nothing prevents the .req
> field of each Reader from being modified at the same time
> as a read(2) comes in, so at some point a new read could
> check the field before sendout() can clear it.  The patch
> below seems to work.
> 
> What do you think?
> 
> Thanks,
> qwx

After testing, the errors no longer occur.  I believe
that this is the right fix, and have pushed it.

Cheers!
qwx