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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 11 Jan 2019 21:44:48 -0000 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 x0BLilgU22872300 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 11 Jan 2019 21:44:47 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id F20CDB2068; Fri, 11 Jan 2019 21:44:46 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C0BFDB205F; Fri, 11 Jan 2019 21:44:46 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.70.82.88]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Fri, 11 Jan 2019 21:44:46 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id D3B5F16C648C; Fri, 11 Jan 2019 13:44:46 -0800 (PST) Date: Fri, 11 Jan 2019 13:44:46 -0800 From: "Paul E. McKenney" To: Andrea Parri Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, mingo@kernel.org, stern@rowland.harvard.edu, parri.andrea@gmail.com, will.deacon@arm.com, peterz@infradead.org, boqun.feng@gmail.com, npiggin@gmail.com, dhowells@redhat.com, j.alglave@ucl.ac.uk, luc.maranget@inria.fr, willy@infradead.org Subject: Re: [PATCH RFC LKMM 7/7] tools/memory-model: Dynamically check SRCU lock-to-unlock matching Reply-To: paulmck@linux.ibm.com References: <20190109210706.GA27268@linux.ibm.com> <20190109210748.29074-7-paulmck@linux.ibm.com> <20190110094131.GA11647@andrea> <20190110144049.GK1215@linux.ibm.com> <20190110232045.GA3908@andrea> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190110232045.GA3908@andrea> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 19011121-0040-0000-0000-000004B090E8 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010387; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000274; SDB=6.01145097; UDB=6.00593882; IPR=6.00925367; MB=3.00025090; MTD=3.00000008; XFM=3.00000015; UTC=2019-01-11 21:44:51 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19011121-0041-0000-0000-000008BB9760 Message-Id: <20190111214446.GL1215@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-01-11_11:,, 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-1901110171 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 11, 2019 at 12:20:45AM +0100, Andrea Parri wrote: > > > I'm not all that exited about spreading version requirements in the > > > source: we report this requirement in our README, and apparently we > > > already struggle to keep this information up-to-date. So what about > > > squashing something like the below (assume that 7.52 will be released > > > by the time this patch hit mainline; if this won't be the case, we > > > may consider using the development version 7.51+6)? notice that this > > > also removes an (obsolete, at this point) comment from lock.cat. > > > > Sounds like a very good point to me! > > > > Should have pointers in the various files to the README file? Or maybe > > get people used to using scripting that checks versions? Or maybe > > after answering questions for some time, people will get used to > > checking versions? > > As discussed off-list: I have no strong opinion on this regard, well, > except that I think we ought to fix the README, somehow (consider my > diff below as a first proposal). Akira actually preceded me on this > and suggested another solution [1]. > > Andrea > > [1] http://lkml.kernel.org/r/04d15c18-d210-e3da-01e2-483eff135cb7@gmail.com My concern with this approach is that it seems to me to implicitly promise that herd will provide backwards compatibility, which is a real pain to test, let alone to provide. Yes, the latest version of herd probably supports latest mainline, but will five-years-from-now herd work correctly on the .bell, .cat, and .def files from current mainline? Thanx, Paul > > > Andrea > > > > > > diff --git a/tools/memory-model/README b/tools/memory-model/README > > > index 9d7d4f23503fd..b362a41358fa1 100644 > > > --- a/tools/memory-model/README > > > +++ b/tools/memory-model/README > > > @@ -20,8 +20,8 @@ that litmus test to be exercised within the Linux kernel. > > > REQUIREMENTS > > > ============ > > > > > > -Version 7.49 of the "herd7" and "klitmus7" tools must be downloaded > > > -separately: > > > +Version 7.52 or higher of the "herd7" and "klitmus7" tools must be > > > +downloaded separately: > > > > > > https://github.com/herd/herdtools7 > > > > > > diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat > > > index 95bf45f1215fc..8dcb37835b613 100644 > > > --- a/tools/memory-model/linux-kernel.cat > > > +++ b/tools/memory-model/linux-kernel.cat > > > @@ -1,7 +1,5 @@ > > > // SPDX-License-Identifier: GPL-2.0+ > > > (* > > > - * Requires herd version 7.51+6 or higher. > > > - * > > > * Copyright (C) 2015 Jade Alglave , > > > * Copyright (C) 2016 Luc Maranget for Inria > > > * Copyright (C) 2017 Alan Stern , > > > diff --git a/tools/memory-model/lock.cat b/tools/memory-model/lock.cat > > > index 305ded17e7411..a059d1a6d8a29 100644 > > > --- a/tools/memory-model/lock.cat > > > +++ b/tools/memory-model/lock.cat > > > @@ -6,9 +6,6 @@ > > > > > > (* > > > * Generate coherence orders and handle lock operations > > > - * > > > - * Warning: spin_is_locked() crashes herd7 versions strictly before 7.48. > > > - * spin_is_locked() is functional from herd7 version 7.49. > > > *) > > > > > > include "cross.cat" > > > > > > > > > > > > > + * > > > > * Copyright (C) 2015 Jade Alglave , > > > > * Copyright (C) 2016 Luc Maranget for Inria > > > > * Copyright (C) 2017 Alan Stern , > > > > diff --git a/tools/memory-model/linux-kernel.def b/tools/memory-model/linux-kernel.def > > > > index 1d6a120cde14..0c3f0ef486f4 100644 > > > > --- a/tools/memory-model/linux-kernel.def > > > > +++ b/tools/memory-model/linux-kernel.def > > > > @@ -49,7 +49,7 @@ synchronize_rcu_expedited() { __fence{sync-rcu}; } > > > > > > > > // SRCU > > > > srcu_read_lock(X) __srcu{srcu-lock}(X) > > > > -srcu_read_unlock(X,Y) { __srcu{srcu-unlock}(X); } > > > > +srcu_read_unlock(X,Y) { __srcu{srcu-unlock}(X,Y); } > > > > synchronize_srcu(X) { __srcu{sync-srcu}(X); } > > > > > > > > // Atomic > > > > -- > > > > 2.17.1 > > > > > > > > > >