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From: Daniel Vetter <daniel@ffwll.ch>
To: Chris Wilson <chris@chris-wilson.co.uk>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
	Mika Kuoppala <mika.kuoppala@intel.com>,
	Daniel Vetter <daniel.vetter@intel.com>
Subject: Re: [PATCH] drm/i915: Remove bogus locking check in the hangcheck code
Date: Tue, 3 Feb 2015 12:09:47 +0100	[thread overview]
Message-ID: <20150203110947.GI14009@phenom.ffwll.local> (raw)
In-Reply-To: <20150203105027.GB26272@nuc-i3427.alporthouse.com>

On Tue, Feb 03, 2015 at 10:50:27AM +0000, Chris Wilson wrote:
> On Tue, Feb 03, 2015 at 11:49:00AM +0100, Daniel Vetter wrote:
> > Aside: It is possible to check whether a given task doesn't hold a
> > lock, but only when lockdep is enabled, using the lockdep_assert_held
> > stuff.
> 
> Bah. That's what I said, but a certain Daniel insists on using WARN_ON().

That is for the inverse check which warns when the lock is not taking,
i.e. WARN_ON(!mutex_is_locked). lockdep_assert_held would be more
accurate but also won't work at all if disabled. We run single-threaded by
accident often enough that the reduced practical coverage trumps the
reduced theoretical coverage imo.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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  reply	other threads:[~2015-02-03 11:08 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-03 10:49 [PATCH] drm/i915: Remove bogus locking check in the hangcheck code Daniel Vetter
2015-02-03 10:50 ` Chris Wilson
2015-02-03 11:09   ` Daniel Vetter [this message]
2015-02-03 11:00 ` Chris Wilson
2015-02-03 11:14   ` Daniel Vetter
2015-02-03 11:17     ` Chris Wilson
2015-02-03 13:57 ` shuang.he

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