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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 29 Apr 2019 15:51:13 +0100 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp23032.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x3TEnu9b36110556 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 29 Apr 2019 14:49:56 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B7E5FB2075; Mon, 29 Apr 2019 14:49:56 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 96435B206B; Mon, 29 Apr 2019 14:49:56 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.85.213.184]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Mon, 29 Apr 2019 14:49:56 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id 4CBD616C0F1D; Mon, 29 Apr 2019 07:49:56 -0700 (PDT) Date: Mon, 29 Apr 2019 07:49:56 -0700 From: "Paul E. McKenney" To: Johan Hovold Cc: Peter Zijlstra , Nicholas Piggin , LKMM Maintainers -- Akira Yokosawa , Andrea Parri , Boqun Feng , David Howells , Daniel Lustig , Jade Alglave , Kernel development list , Luc Maranget , Alan Stern , Will Deacon Subject: Re: [PATCH] Documentation: atomic_t.txt: Explain ordering provided by smp_mb__{before,after}_atomic() Reply-To: paulmck@linux.ibm.com References: <20190419180017.GP4038@hirez.programming.kicks-ass.net> <20190419182620.GF14111@linux.ibm.com> <1555719429.t9n8gkf70y.astroid@bobo.none> <20190420085440.GK14111@linux.ibm.com> <20190423123209.GR4038@hirez.programming.kicks-ass.net> <20190423133010.GK3923@linux.ibm.com> <20190429092430.GF26546@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190429092430.GF26546@localhost> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 19042914-0072-0000-0000-00000422B2C2 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00011017; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000285; SDB=6.01196110; UDB=6.00627248; IPR=6.00976960; MB=3.00026647; MTD=3.00000008; XFM=3.00000015; UTC=2019-04-29 14:51:16 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19042914-0073-0000-0000-00004C02CF28 Message-Id: <20190429144956.GQ3923@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-04-29_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904290104 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 29, 2019 at 11:24:30AM +0200, Johan Hovold wrote: > On Tue, Apr 23, 2019 at 06:30:10AM -0700, Paul E. McKenney wrote: > > On Tue, Apr 23, 2019 at 02:32:09PM +0200, Peter Zijlstra wrote: > > > On Sat, Apr 20, 2019 at 01:54:40AM -0700, Paul E. McKenney wrote: > > > > > And lock acquisition??? acm_read_bulk_callback(). > > > > > > I think it goes with the set_bit() earlier, but what do I know. > > > > Quite possibly! In that case it should be smp_mb__after_atomic(), > > and it would be nice if it immediately followed the set_bit(). > > I noticed this one last week as well. The set_bit() had been incorrectly > moved and without noticing the smp_mb__before_atomic(). I've submitted a > patch to restore it and to fix a related issue to due missing barriers: > > https://lkml.kernel.org/r/20190425160540.10036-5-johan@kernel.org Good to know, thank you! Thanx, Paul