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Date: Fri, 7 Jul 2017 10:06:21 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: David Laight <David.Laight@ACULAB.COM>,
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Subject: Re: [PATCH v2 0/9] Remove spin_unlock_wait()
Message-ID: <20170707080621.dmhw2ryes7n3kgag@gmail.com>
References: <20170629235918.GA6445@linux.vnet.ibm.com>
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* Peter Zijlstra <peterz@infradead.org> wrote:

> > It might even be that this is the defined semantics of spin_unlock_wait().
> 
> As is, spin_unlock_wait() is somewhat ill defined. IIRC it grew from an 
> optimization by Oleg and subsequently got used elsewhere. And it being the 
> subtle bugger it is, there were bugs.

I believe the historical, original spin_unlock_wait() came from early SMP 
optimizations of the networking code - and then spread elsewhere, step by step. 
All but one of the networking uses went away since then - so I don't think there's 
any original usecase left.

Thanks,

	Ingo