linux-kernel - Re: [Linaro-mm-sig] [PATCH v4 3/4] mutex: Add ww tests to lib/locking-selftest.c. v4

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Date:	Wed, 29 May 2013 09:22:41 +0200
From:	Daniel Vetter <daniel.vetter@...ll.ch>
To:	Maarten Lankhorst <maarten.lankhorst@...onical.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-arch@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>,
	x86@...nel.org, dri-devel <dri-devel@...ts.freedesktop.org>,
	"linaro-mm-sig@...ts.linaro.org" <linaro-mm-sig@...ts.linaro.org>,
	rob clark <robclark@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>,
	"linux-media@...r.kernel.org" <linux-media@...r.kernel.org>
Subject: Re: [Linaro-mm-sig] [PATCH v4 3/4] mutex: Add ww tests to
 lib/locking-selftest.c. v4

On Tue, May 28, 2013 at 11:12 PM, Maarten Lankhorst
<maarten.lankhorst@...onical.com> wrote:
>>> +static void ww_test_spin_nest_unlocked(void)
>>> +{
>>> +    raw_spin_lock_nest_lock(&lock_A, &o.base);
>>> +    U(A);
>>> +}
>> I don't quite see the point of this one here ...
> It's a lockdep test that was missing. o.base is not locked. So lock_A is being nested into an unlocked lock, resulting in a lockdep error.

Sounds like a different patch then ...

>>> +
>>> +static void ww_test_unneeded_slow(void)
>>> +{
>>> +    int ret;
>>> +
>>> +    WWAI(&t);
>>> +
>>> +    ww_mutex_lock_slow(&o, &t);
>>> +}
>> I think checking the _slow debug stuff would be neat, i.e.
>> - fail/success tests for properly unlocking all held locks
>> - fail/success tests for lock_slow acquiring the right lock.
>>
>> Otherwise I didn't spot anything that seems missing in these self-tests
>> here.
>>
> Yes it would be nice, doing so is left as an excercise for the reviewer, who failed to raise this point sooner. ;-)

Hm, I guess I've volunteered myself to look into this a bit ;-)
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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