From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:56766 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751393AbcJDPFi (ORCPT ); Tue, 4 Oct 2016 11:05:38 -0400 Subject: Patch "rcuperf: Don't treat gp_exp mis-setting as a WARN" has been added to the 4.7-stable tree To: boqun.feng@gmail.com, gregkh@linuxfoundation.org, paulmck@linux.vnet.ibm.com Cc: , From: Date: Tue, 04 Oct 2016 17:04:24 +0200 Message-ID: <14755934641552@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled rcuperf: Don't treat gp_exp mis-setting as a WARN to the 4.7-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: rcuperf-don-t-treat-gp_exp-mis-setting-as-a-warn.patch and it can be found in the queue-4.7 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From af06d4f74a7d2132c805339bfd5ab771b5706f42 Mon Sep 17 00:00:00 2001 From: Boqun Feng Date: Wed, 25 May 2016 09:25:33 +0800 Subject: rcuperf: Don't treat gp_exp mis-setting as a WARN From: Boqun Feng commit af06d4f74a7d2132c805339bfd5ab771b5706f42 upstream. 0day found a boot warning triggered in rcu_perf_writer() on !SMP kernel: WARN_ON(rcu_gp_is_normal() && gp_exp); , the root cause of which is trying to measure expedited grace periods(by setting gp_exp to true by default) when all the grace periods are normal(TINY RCU only has normal grace periods). However, such a mis-setting would only result in failing to measure the performance for a specific kind of grace periods, therefore using a WARN_ON to check this is a little overkilling. We could handle this inside rcuperf module via some error messages to tell users about the mis-settings. Therefore this patch removes the WARN_ON in rcu_perf_writer() and handles those checkings in rcu_perf_init() with plain if() code. Moreover, this patch changes the default value of gp_exp to 1) align with rcutorture tests and 2) make the default setting work for all RCU implementations by default. Suggested-by: Paul E. McKenney Signed-off-by: Boqun Feng Fixes: http://lkml.kernel.org/r/57411b10.mFvG0+AgcrMXGtcj%fengguang.wu@intel.com Signed-off-by: Paul E. McKenney Signed-off-by: Greg Kroah-Hartman --- kernel/rcu/rcuperf.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) --- a/kernel/rcu/rcuperf.c +++ b/kernel/rcu/rcuperf.c @@ -58,7 +58,7 @@ MODULE_AUTHOR("Paul E. McKenney