From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE32FC7618F for ; Tue, 16 Jul 2019 18:28:48 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 3EF6A2173C for ; Tue, 16 Jul 2019 18:28:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3EF6A2173C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-16476-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 19995 invoked by uid 550); 16 Jul 2019 18:28:42 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 19973 invoked from network); 16 Jul 2019 18:28:41 -0000 Date: Tue, 16 Jul 2019 11:28:16 -0700 From: "Paul E. McKenney" To: "Joel Fernandes (Google)" Cc: linux-kernel@vger.kernel.org, Oleg Nesterov , Alexey Kuznetsov , Bjorn Helgaas , Borislav Petkov , c0d1n61at3@gmail.com, "David S. Miller" , edumazet@google.com, Greg Kroah-Hartman , Hideaki YOSHIFUJI , "H. Peter Anvin" , Ingo Molnar , Jonathan Corbet , Josh Triplett , keescook@chromium.org, kernel-hardening@lists.openwall.com, kernel-team@android.com, Lai Jiangshan , Len Brown , linux-acpi@vger.kernel.org, linux-doc@vger.kernel.org, linux-pci@vger.kernel.org, linux-pm@vger.kernel.org, Mathieu Desnoyers , neilb@suse.com, netdev@vger.kernel.org, Pavel Machek , peterz@infradead.org, "Rafael J. Wysocki" , Rasmus Villemoes , rcu@vger.kernel.org, Steven Rostedt , Tejun Heo , Thomas Gleixner , will@kernel.org, "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" Subject: Re: [PATCH v2 3/9] rcu/sync: Remove custom check for reader-section References: <20190712170024.111093-1-joel@joelfernandes.org> <20190712170024.111093-4-joel@joelfernandes.org> <20190716182642.GB22819@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190716182642.GB22819@linux.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 19071618-0072-0000-0000-00000449AC27 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00011440; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000286; SDB=6.01233103; UDB=6.00649716; IPR=6.01014415; MB=3.00027748; MTD=3.00000008; XFM=3.00000015; UTC=2019-07-16 18:28:26 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19071618-0073-0000-0000-00004CB9F7A1 Message-Id: <20190716182816.GA23249@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-07-16_04:,, 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-1907160226 On Tue, Jul 16, 2019 at 11:26:42AM -0700, Paul E. McKenney wrote: > On Fri, Jul 12, 2019 at 01:00:18PM -0400, Joel Fernandes (Google) wrote: > > The rcu/sync code was doing its own check whether we are in a reader > > section. With RCU consolidating flavors and the generic helper added in > > this series, this is no longer need. We can just use the generic helper > > and it results in a nice cleanup. > > > > Cc: Oleg Nesterov > > Signed-off-by: Joel Fernandes (Google) > > This needs to be forward-ported to current mainline. (Or, I believe > equivalently for this file, to branch "dev" of -rcu.) > > Especially given that you have Oleg's Ack, I would be happy to > take the forward-ported version. Never mind, I am one version behind. Apologies for the noise! Thanx, Paul > > --- > > Please note: Only build and boot tested this particular patch so far. > > > > include/linux/rcu_sync.h | 5 ++--- > > kernel/rcu/sync.c | 22 ---------------------- > > 2 files changed, 2 insertions(+), 25 deletions(-) > > > > diff --git a/include/linux/rcu_sync.h b/include/linux/rcu_sync.h > > index 6fc53a1345b3..c954f1efc919 100644 > > --- a/include/linux/rcu_sync.h > > +++ b/include/linux/rcu_sync.h > > @@ -39,9 +39,8 @@ extern void rcu_sync_lockdep_assert(struct rcu_sync *); > > */ > > static inline bool rcu_sync_is_idle(struct rcu_sync *rsp) > > { > > -#ifdef CONFIG_PROVE_RCU > > - rcu_sync_lockdep_assert(rsp); > > -#endif > > + RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(), > > + "suspicious rcu_sync_is_idle() usage"); > > return !rsp->gp_state; /* GP_IDLE */ > > } > > > > diff --git a/kernel/rcu/sync.c b/kernel/rcu/sync.c > > index a8304d90573f..535e02601f56 100644 > > --- a/kernel/rcu/sync.c > > +++ b/kernel/rcu/sync.c > > @@ -10,37 +10,25 @@ > > #include > > #include > > > > -#ifdef CONFIG_PROVE_RCU > > -#define __INIT_HELD(func) .held = func, > > -#else > > -#define __INIT_HELD(func) > > -#endif > > - > > static const struct { > > void (*sync)(void); > > void (*call)(struct rcu_head *, void (*)(struct rcu_head *)); > > void (*wait)(void); > > -#ifdef CONFIG_PROVE_RCU > > - int (*held)(void); > > -#endif > > } gp_ops[] = { > > [RCU_SYNC] = { > > .sync = synchronize_rcu, > > .call = call_rcu, > > .wait = rcu_barrier, > > - __INIT_HELD(rcu_read_lock_held) > > }, > > [RCU_SCHED_SYNC] = { > > .sync = synchronize_rcu, > > .call = call_rcu, > > .wait = rcu_barrier, > > - __INIT_HELD(rcu_read_lock_sched_held) > > }, > > [RCU_BH_SYNC] = { > > .sync = synchronize_rcu, > > .call = call_rcu, > > .wait = rcu_barrier, > > - __INIT_HELD(rcu_read_lock_bh_held) > > }, > > }; > > > > @@ -49,16 +37,6 @@ enum { CB_IDLE = 0, CB_PENDING, CB_REPLAY }; > > > > #define rss_lock gp_wait.lock > > > > -#ifdef CONFIG_PROVE_RCU > > -void rcu_sync_lockdep_assert(struct rcu_sync *rsp) > > -{ > > - RCU_LOCKDEP_WARN(!gp_ops[rsp->gp_type].held(), > > - "suspicious rcu_sync_is_idle() usage"); > > -} > > - > > -EXPORT_SYMBOL_GPL(rcu_sync_lockdep_assert); > > -#endif > > - > > /** > > * rcu_sync_init() - Initialize an rcu_sync structure > > * @rsp: Pointer to rcu_sync structure to be initialized > > -- > > 2.22.0.510.g264f2c817a-goog > >