Re: Commit 81a43adae3b9 (locking/mutex: Use acquire/release semantics) causing failures on arm64 (ThunderX)

[Peter Zijlstra]

On Mon, Dec 14, 2015 at 06:49:31PM +0000, One Thousand Gnomes wrote:
> 
> But seriously are there any cases we actually care about this for osq ?

So I think what PaulMck is worried about is that one would expect things
like:

	mutex_lock();
	MMIO(++var);
	mutex_unlock();

(the same example Linus gave but with a mutex instead of a spinlock) to
just work.

Now, I haven't checked the code, but I'm not sure we ever rely on osq to
provide the mutex ACQUIRE barrier, since we always need to acquire the
mutex variable itself after we've acquired the osq 'lock'.

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