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Date: Thu, 14 Jun 2018 16:46:59 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Hellstrom <thellstrom@vmware.com>
Cc: Matthew Wilcox <willy@infradead.org>,
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Subject: Re: [PATCH v2 1/2] locking: Implement an algorithm choice for
 Wound-Wait mutexes
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On Thu, Jun 14, 2018 at 03:43:04PM +0200, Thomas Hellstrom wrote:
> It's intended to be enforced by storing the algorithm choice in the
> WW_MUTEX_CLASS which must be common for an acquire context and the
> ww_mutexes it acquires. However, I don't think there is a check that that
> holds. I guess we could add it as a DEBUG_MUTEX test in ww_mutex_lock().

There is ww_mutex_lock_acquired():

	DEBUG_LOCKS_WARN_ON(ww_ctx->ww_class != ww->ww_class)

which should trigger if you try and be clever.