Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753358AbbLFB5M (ORCPT ); Sat, 5 Dec 2015 20:57:12 -0500 Received: from relay5-d.mail.gandi.net ([217.70.183.197]:36314 "EHLO relay5-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752050AbbLFB5K (ORCPT ); Sat, 5 Dec 2015 20:57:10 -0500 X-Originating-IP: 50.39.163.18 Date: Sat, 5 Dec 2015 17:56:56 -0800 From: Josh Triplett To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, 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 Subject: Re: [PATCH tip/core/rcu 6/8] rcutorture: Print symbolic name for ->gp_state Message-ID: <20151206015656.GA29594@x> References: <20151205002331.GA27249@linux.vnet.ibm.com> <1449275032-28206-6-git-send-email-paulmck@linux.vnet.ibm.com> <20151205010421.GC27128@cloud> <20151206015436.GM28602@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151206015436.GM28602@linux.vnet.ibm.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3951 Lines: 92 On Sat, Dec 05, 2015 at 05:54:36PM -0800, Paul E. McKenney wrote: > On Fri, Dec 04, 2015 at 05:04:21PM -0800, Josh Triplett wrote: > > On Fri, Dec 04, 2015 at 04:23:50PM -0800, Paul E. McKenney wrote: > > > 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 Dan Carpenter. ] > > > --- > > > kernel/rcu/tree.c | 15 +++++++++++++-- > > > kernel/rcu/tree.h | 9 +++++++++ > > > 2 files changed, 22 insertions(+), 2 deletions(-) > > > > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > > > index 7b78c88e19a3..491c99a73996 100644 > > > --- a/kernel/rcu/tree.c > > > +++ b/kernel/rcu/tree.c > > > @@ -1187,6 +1187,16 @@ 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) > > > > Same comment about "const char *" > > Good point, fixed! > > > > +{ > > > + 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) > > > @@ -1197,10 +1207,11 @@ 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 f32bebb6bc90..f0304988e3f8 100644 > > > --- a/kernel/rcu/tree.h > > > +++ b/kernel/rcu/tree.h > > > @@ -544,6 +544,15 @@ 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[] = { > > > > Same comment about "const char * const", but also, should this really go > > in a header file? Do any circumstances exist where this header could > > get included in more than one source file in a given build? If so, > > multiple copies of this array could potentially end up in the binary, if > > the compiler fails to merge them. > > I added the const. > > However, I left the array in the .h file. The issue is that the #defines > really have to be in the tree.h file. Given that, if I move the array > elsewhere, they will very likely drift out of sync. So this sounds like > a job for the compiler/linker... > > Ah, but there is another approach. It turns out that tree.h in included > only from tree.c and tree_trace.c. And tree_trace.c defines a CPP symbol > RCU_TREE_NONCORE that is used elsewhere in tree.h to keep tree_trace.c's > mitts off a number of attractive but dangerous functions. So I just put > the array under "#ifndef RCU_TREE_NONCORE". > > Fair enough? Fair enough. Reviewed-by: Josh Triplett -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/