From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751788AbdANJPm (ORCPT ); Sat, 14 Jan 2017 04:15:42 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:47455 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751735AbdANJNe (ORCPT ); Sat, 14 Jan 2017 04:13:34 -0500 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, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 11/20] sched,rcu: Make cond_resched() provide RCU quiescent state Date: Sat, 14 Jan 2017 01:13:12 -0800 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20170114091255.GA20854@linux.vnet.ibm.com> References: <20170114091255.GA20854@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17011409-0004-0000-0000-0000114A2B68 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006431; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000199; SDB=6.00807466; UDB=6.00393077; IPR=6.00584804; BA=6.00005055; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00013919; XFM=3.00000011; UTC=2017-01-14 09:13:31 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17011409-0005-0000-0000-00007C2A5E69 Message-Id: <1484385201-22227-11-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-01-14_01:,, 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=8.0.1-1612050000 definitions=main-1701140136 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is some confusion as to which of cond_resched() or cond_resched_rcu_qs() should be added to long in-kernel loops. This commit therefore eliminates the decision by adding RCU quiescent states to cond_resched(). Warning: This is a prototype. For example, it does not correctly handle Tasks RCU. Which is OK for the moment, given that no one actually uses Tasks RCU yet. Reported-by: Michal Hocko Not-yet-signed-off-by: Paul E. McKenney Cc: Peter Zijlstra --- include/linux/sched.h | 3 ++- kernel/sched/core.c | 1 + 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 4d1905245c7a..1531c48f56e2 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -3352,10 +3352,11 @@ static inline int signal_pending_state(long state, struct task_struct *p) * cond_resched_lock() will drop the spinlock before scheduling, * cond_resched_softirq() will enable bhs before scheduling. */ +void rcu_all_qs(void); #ifndef CONFIG_PREEMPT extern int _cond_resched(void); #else -static inline int _cond_resched(void) { return 0; } +static inline int _cond_resched(void) { rcu_all_qs(); return 0; } #endif #define cond_resched() ({ \ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c56fb57f2991..b442f8918eb9 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4907,6 +4907,7 @@ int __sched _cond_resched(void) preempt_schedule_common(); return 1; } + rcu_all_qs(); return 0; } EXPORT_SYMBOL(_cond_resched); -- 2.5.2