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Subject: Re: [PATCH 1/1] futex: remove duplicated code
To: Will Deacon <will.deacon@arm.com>
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References: <20170515130742.18357-1-jslaby@suse.cz>
 <20170515131644.GA3605@arm.com>
From: Jiri Slaby <jslaby@suse.cz>
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Date: Wed, 17 May 2017 10:01:29 +0200
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On 05/15/2017, 03:16 PM, Will Deacon wrote:
> Whilst I think this is a good idea, the code in question actually results
> in undefined behaviour per the C spec and is reported by UBSAN.

Hi, yes, I know -- this patch was the 1st from the series of 3 which I
sent a long time ago to fix that up too. But I remember your patch, so I
sent only this one this time.

> See my
> patch fixing arm64 here (which I'd forgotten about):
> 
> https://www.spinics.net/lists/linux-arch/msg38564.html
> 
> But, as stated in the thread above, I think we should go a step further
> and remove FUTEX_OP_{OR,ANDN,XOR,OPARG_SHIFT} altogether. They don't
> appear to be used by userspace, and this whole thing is a total mess.
> 
> Any thoughts?

Ok, I am all for that. I think the only question is who is going to do
the work and submit it :)? Do I understand correctly to eliminate all
these functions and the path into the kernel? But won't this break API
-- are there really no users of this interface?

thanks,
-- 
js
suse labs