From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161709AbbKSVSj (ORCPT ); Thu, 19 Nov 2015 16:18:39 -0500 Received: from e33.co.us.ibm.com ([32.97.110.151]:35934 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161683AbbKSVSh (ORCPT ); Thu, 19 Nov 2015 16:18:37 -0500 X-IBM-Helo: d03dlp01.boulder.ibm.com X-IBM-MailFrom: paulmck@linux.vnet.ibm.com X-IBM-RcptTo: kernel-janitors@vger.kernel.org;linux-kernel@vger.kernel.org Date: Thu, 19 Nov 2015 13:18:52 -0800 From: "Paul E. McKenney" To: Dan Carpenter Cc: Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: Re: [patch -next] rcu: off by one in gp_state_getname() Message-ID: <20151119211852.GS5184@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20151119193408.GA24110@mwanda> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151119193408.GA24110@mwanda> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15111921-0009-0000-0000-00000FE68A51 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 19, 2015 at 10:34:09PM +0300, Dan Carpenter wrote: > It should be >= ARRAY_SIZE() instead of > ARRAY_SIZE(). > > Fixes: 6231da675578 ('rcu: Print symbolic name for ->gp_state') > Signed-off-by: Dan Carpenter Good catch! I folded this into the original commit with attribution, please see below. Thanx, Paul > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 6a5e1c4..6559b3c 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -1203,7 +1203,7 @@ static void record_gp_stall_check_time(struct rcu_state *rsp) > */ > static char *gp_state_getname(short gs) > { > - if (gs < 0 || gs > ARRAY_SIZE(gp_state_names)) > + if (gs < 0 || gs >= ARRAY_SIZE(gp_state_names)) > return "???"; > return gp_state_names[gs]; > } ------------------------------------------------------------------------ commit 31bf937d2dcbe71a329e5bc6c7726f3a5949089a Author: Paul E. McKenney Date: Tue Nov 17 14:39:26 2015 -0800 rcu: Print symbolic name for ->gp_state Currently, ->gp_state is printed as an integer, which slows debugging. This commit therefore prints a symbolic name in addition to the integer. Signed-off-by: Paul E. McKenney [ Updated to fix relational operator called out by Daniel Carpenter. ] diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index e768fc64583f..6559b3cb5ea6 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1199,6 +1199,16 @@ static void record_gp_stall_check_time(struct rcu_state *rsp) } /* + * Convert a ->gp_state value to a character string. + */ +static char *gp_state_getname(short gs) +{ + if (gs < 0 || gs >= ARRAY_SIZE(gp_state_names)) + return "???"; + return gp_state_names[gs]; +} + +/* * Complain about starvation of grace-period kthread. */ static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp) @@ -1209,10 +1219,11 @@ static void rcu_check_gp_kthread_starvation(struct rcu_state *rsp) j = jiffies; gpa = READ_ONCE(rsp->gp_activity); if (j - gpa > 2 * HZ) { - pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x s%d ->state=%#lx\n", + pr_err("%s kthread starved for %ld jiffies! g%lu c%lu f%#x %s(%d) ->state=%#lx\n", rsp->name, j - gpa, rsp->gpnum, rsp->completed, - rsp->gp_flags, rsp->gp_state, + rsp->gp_flags, + gp_state_getname(rsp->gp_state), rsp->gp_state, rsp->gp_kthread ? rsp->gp_kthread->state : ~0); if (rsp->gp_kthread) sched_show_task(rsp->gp_kthread); diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index 6cbec31f99d6..5c70b09a85d4 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -546,6 +546,15 @@ struct rcu_state { #define RCU_GP_DOING_FQS 4 /* Wait done for force-quiescent-state time. */ #define RCU_GP_CLEANUP 5 /* Grace-period cleanup started. */ #define RCU_GP_CLEANED 6 /* Grace-period cleanup complete. */ +static char * const gp_state_names[] = { + "RCU_GP_IDLE", + "RCU_GP_WAIT_GPS", + "RCU_GP_DONE_GPS", + "RCU_GP_WAIT_FQS", + "RCU_GP_DOING_FQS", + "RCU_GP_CLEANUP", + "RCU_GP_CLEANED", +}; extern struct list_head rcu_struct_flavors;