From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946089AbdEYWW2 (ORCPT ); Thu, 25 May 2017 18:22:28 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:53280 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S939256AbdEYWAL (ORCPT ); Thu, 25 May 2017 18:00:11 -0400 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 17/88] checkpatch: Remove checks for expedited grace periods Date: Thu, 25 May 2017 14:58:50 -0700 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20170525215934.GA11578@linux.vnet.ibm.com> References: <20170525215934.GA11578@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17052522-0056-0000-0000-00000371398E X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007117; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000212; SDB=6.00865574; UDB=6.00429833; IPR=6.00645396; BA=6.00005375; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015583; XFM=3.00000015; UTC=2017-05-25 22:00:08 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17052522-0057-0000-0000-000007A76E8F Message-Id: <1495749601-21574-17-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-05-25_17:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1705250401 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There was a time when the expedited grace-period primitives (synchronize_rcu_expedited(), synchronize_rcu_bh_expedited(), and synchronize_sched_expedited()) used rather antisocial kernel facilities like try_stop_cpus(). However, they have since been housebroken to use only single-CPU IPIs, and typically cause less disturbance than a scheduling-clock interrupt. Furthermore, this disturbance can be eliminated entirely using NO_HZ_FULL on the one hand or the rcupdate.rcu_normal boot parameter on the other. This commit therefore removes checkpatch's complaints about use of the expedited RCU primitives. Signed-off-by: Paul E. McKenney --- scripts/checkpatch.pl | 17 ----------------- 1 file changed, 17 deletions(-) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 4b9569fa931b..c7e4d73fe1ce 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -5533,23 +5533,6 @@ sub process { } } -# Check for expedited grace periods that interrupt non-idle non-nohz -# online CPUs. These expedited can therefore degrade real-time response -# if used carelessly, and should be avoided where not absolutely -# needed. It is always OK to use synchronize_rcu_expedited() and -# synchronize_sched_expedited() at boot time (before real-time applications -# start) and in error situations where real-time response is compromised in -# any case. Note that synchronize_srcu_expedited() does -not- interrupt -# other CPUs, so don't warn on uses of synchronize_srcu_expedited(). -# Of course, nothing comes for free, and srcu_read_lock() and -# srcu_read_unlock() do contain full memory barriers in payment for -# synchronize_srcu_expedited() non-interruption properties. - if ($line =~ /\b(synchronize_rcu_expedited|synchronize_sched_expedited)\(/) { - WARN("EXPEDITED_RCU_GRACE_PERIOD", - "expedited RCU grace periods should be avoided where they can degrade real-time response\n" . $herecurr); - - } - # check of hardware specific defines if ($line =~ m@^.\s*\#\s*if.*\b(__i386__|__powerpc64__|__sun__|__s390x__)\b@ && $realfile !~ m@include/asm-@) { CHK("ARCH_DEFINES", -- 2.5.2