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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 9 Oct 2018 09:36:52 -0400 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp22034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w99Dap8n63045736 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 9 Oct 2018 13:36:51 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BBFFEB2065; Tue, 9 Oct 2018 09:34:54 -0400 (EDT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8F02CB205F; Tue, 9 Oct 2018 09:34:54 -0400 (EDT) Received: from paulmck-ThinkPad-W541 (unknown [9.85.157.198]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Tue, 9 Oct 2018 09:34:54 -0400 (EDT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id A511C16C4242; Tue, 9 Oct 2018 06:36:50 -0700 (PDT) Date: Tue, 9 Oct 2018 06:36:50 -0700 From: "Paul E. McKenney" To: Will Deacon Cc: Lance Roy , linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar Subject: Re: [PATCH 12/16] locking/mutex: Replace spin_is_locked() with lockdep Reply-To: paulmck@linux.ibm.com References: <20181003053902.6910-1-ldr709@gmail.com> <20181003053902.6910-13-ldr709@gmail.com> <20181009121809.GG6248@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181009121809.GG6248@arm.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18100913-0064-0000-0000-0000035CA7A4 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009848; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000267; SDB=6.01100154; UDB=6.00569182; IPR=6.00880202; MB=3.00023679; MTD=3.00000008; XFM=3.00000015; UTC=2018-10-09 13:36:53 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18100913-0065-0000-0000-00003AEBEEA7 Message-Id: <20181009133650.GO2674@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-10-09_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=2 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=874 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1810090135 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 09, 2018 at 01:18:10PM +0100, Will Deacon wrote: > On Tue, Oct 02, 2018 at 10:38:58PM -0700, Lance Roy wrote: > > lockdep_assert_held() is better suited to checking locking requirements, > > since it won't get confused when someone else holds the lock. This is > > also a step towards possibly removing spin_is_locked(). > > > > Signed-off-by: Lance Roy > > Cc: Peter Zijlstra > > Cc: Ingo Molnar > > Cc: Will Deacon > > --- > > kernel/locking/mutex-debug.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/kernel/locking/mutex-debug.c b/kernel/locking/mutex-debug.c > > index 9aa713629387..771d4ca96dda 100644 > > --- a/kernel/locking/mutex-debug.c > > +++ b/kernel/locking/mutex-debug.c > > @@ -36,7 +36,7 @@ void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter) > > > > void debug_mutex_wake_waiter(struct mutex *lock, struct mutex_waiter *waiter) > > { > > - SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock)); > > + lockdep_assert_held(&lock->wait_lock); > > DEBUG_LOCKS_WARN_ON(list_empty(&lock->wait_list)); > > DEBUG_LOCKS_WARN_ON(waiter->magic != waiter); > > DEBUG_LOCKS_WARN_ON(list_empty(&waiter->list)); > > @@ -51,7 +51,7 @@ void debug_mutex_free_waiter(struct mutex_waiter *waiter) > > void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter, > > struct task_struct *task) > > { > > - SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock)); > > + lockdep_assert_held(&lock->wait_lock); > > I think it's a good idea to replace debug usage of spin_is_locked() with > calls to lockdep, but I wonder whether that means that DEBUG_MUTEXES should > select LOCKDEP so that we don't lose coverage? > > What do you think? Makes sense to me! But given that this was accepted into -tip, I have dropped it from my tree. Thanx, Paul