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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 16 Jul 2019 19:26:44 +0100 Received: from b01ledav003.gho.pok.ibm.com (b01ledav003.gho.pok.ibm.com [9.57.199.108]) by b01cxnp22036.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x6GIQh3r15860536 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 16 Jul 2019 18:26:43 GMT Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BE3B7B2066; Tue, 16 Jul 2019 18:26:42 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 70B34B2068; Tue, 16 Jul 2019 18:26:42 +0000 (GMT) Received: from paulmck-ThinkPad-W541 (unknown [9.80.225.134]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Tue, 16 Jul 2019 18:26:42 +0000 (GMT) Received: by paulmck-ThinkPad-W541 (Postfix, from userid 1000) id 7609D16C8EBE; Tue, 16 Jul 2019 11:26:42 -0700 (PDT) Date: Tue, 16 Jul 2019 11:26:42 -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 Reply-To: paulmck@linux.ibm.com References: <20190712170024.111093-1-joel@joelfernandes.org> <20190712170024.111093-4-joel@joelfernandes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190712170024.111093-4-joel@joelfernandes.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 19071618-2213-0000-0000-000003AF9AB3 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=6.01014414; MB=3.00027748; MTD=3.00000008; XFM=3.00000015; UTC=2019-07-16 18:26:52 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19071618-2214-0000-0000-00005F427600 Message-Id: <20190716182642.GB22819@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-1907160225 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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. 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 >