From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751290AbdJDVue (ORCPT ); Wed, 4 Oct 2017 17:50:34 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:39722 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750951AbdJDVuc (ORCPT ); Wed, 4 Oct 2017 17:50:32 -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, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 4/4] rcu: Suppress RCU CPU stall warnings while dumping trace Date: Wed, 4 Oct 2017 14:50:25 -0700 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20171004215006.GA12792@linux.vnet.ibm.com> References: <20171004215006.GA12792@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 17100421-0044-0000-0000-0000039A6119 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007844; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000233; SDB=6.00926540; UDB=6.00466105; IPR=6.00706752; BA=6.00005620; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00017395; XFM=3.00000015; UTC=2017-10-04 21:50:30 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17100421-0045-0000-0000-000007C9702E Message-Id: <1507153825-14136-4-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-10-04_10:,, 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=8.0.1-1707230000 definitions=main-1710040302 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, RCU emits Suppress RCU CPU stall warnings during its automatically initiated ftrace_dump() calls after detecting an error condition, which can result in excessively excessive console output and lost trace events. This commit therefore suppresses RCU CPU stall warnings across any of these ftrace_dump() calls. Signed-off-by: Paul E. McKenney --- kernel/rcu/rcu.h | 17 +++++++++++++++++ kernel/rcu/update.c | 1 + 2 files changed, 18 insertions(+) diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index b8729eb09a5d..59c471de342a 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -203,6 +203,21 @@ static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head) extern int rcu_cpu_stall_suppress; int rcu_jiffies_till_stall_check(void); +#define rcu_ftrace_dump_stall_suppress() \ +do { \ + if (!rcu_cpu_stall_suppress) \ + rcu_cpu_stall_suppress = 3; \ +} while (0) + +#define rcu_ftrace_dump_stall_unsuppress() \ +do { \ + if (rcu_cpu_stall_suppress == 3) \ + rcu_cpu_stall_suppress = 0; \ +} while (0) + +#else /* #endif #ifdef CONFIG_RCU_STALL_COMMON */ +#define rcu_ftrace_dump_stall_suppress() +#define rcu_ftrace_dump_stall_unsuppress() #endif /* #ifdef CONFIG_RCU_STALL_COMMON */ /* @@ -222,7 +237,9 @@ do { \ if (!atomic_read(&___rfd_beenhere) && \ !atomic_xchg(&___rfd_beenhere, 1)) { \ tracing_off(); \ + rcu_ftrace_dump_stall_suppress(); \ ftrace_dump(oops_dump_mode); \ + rcu_ftrace_dump_stall_unsuppress(); \ } \ } while (0) diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index 5033b66d2753..3dc8efb16dc7 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -494,6 +494,7 @@ EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read); #endif int rcu_cpu_stall_suppress __read_mostly; /* 1 = suppress stall warnings. */ +EXPORT_SYMBOL_GPL(rcu_cpu_stall_suppress); static int rcu_cpu_stall_timeout __read_mostly = CONFIG_RCU_CPU_STALL_TIMEOUT; module_param(rcu_cpu_stall_suppress, int, 0644); -- 2.5.2