[tip: core/rcu] rcutorture: Output number of elapsed grace periods

["tip-bot2 for Joel Fernandes (Google)" <tip-bot2@linutronix.de>]

The following commit has been merged into the core/rcu branch of tip:

Commit-ID:     959954df0ca7da2111c3fb67a666681798d15b9d
Gitweb:        https://git.kernel.org/tip/959954df0ca7da2111c3fb67a666681798d15b9d
Author:        Joel Fernandes (Google) <joel@joelfernandes.org>
AuthorDate:    Thu, 18 Jun 2020 16:29:55 -04:00
Committer:     Paul E. McKenney <paulmck@kernel.org>
CommitterDate: Mon, 24 Aug 2020 18:45:31 -07:00

rcutorture: Output number of elapsed grace periods

This commit adds code to print the grace-period number at the start
of the test along with both the grace-period number and the number of
elapsed grace periods at the end of the test.  Note that variants of
RCU)without the notion of a grace-period number (for example, Tiny RCU)
just print zeroes.

[ paulmck: Adjust commit log. ]
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 kernel/rcu/rcutorture.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index db37861..c8206ff 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -172,6 +172,7 @@ static long n_barrier_successes; /* did rcu_barrier test succeed? */
 static unsigned long n_read_exits;
 static struct list_head rcu_torture_removed;
 static unsigned long shutdown_jiffies;
+static unsigned long start_gp_seq;
 
 static int rcu_torture_writer_state;
 #define RTWS_FIXED_DELAY	0
@@ -2469,8 +2470,9 @@ rcu_torture_cleanup(void)
 
 	rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
 	srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
-	pr_alert("%s:  End-test grace-period state: g%lu f%#x\n",
-		 cur_ops->name, gp_seq, flags);
+	pr_alert("%s:  End-test grace-period state: g%ld f%#x total-gps=%ld\n",
+		 cur_ops->name, (long)gp_seq, flags,
+		 rcutorture_seq_diff(gp_seq, start_gp_seq));
 	torture_stop_kthread(rcu_torture_stats, stats_task);
 	torture_stop_kthread(rcu_torture_fqs, fqs_task);
 	if (rcu_torture_can_boost())
@@ -2594,6 +2596,8 @@ rcu_torture_init(void)
 	long i;
 	int cpu;
 	int firsterr = 0;
+	int flags = 0;
+	unsigned long gp_seq = 0;
 	static struct rcu_torture_ops *torture_ops[] = {
 		&rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
 		&busted_srcud_ops, &tasks_ops, &tasks_rude_ops,
@@ -2636,6 +2640,11 @@ rcu_torture_init(void)
 			nrealreaders = 1;
 	}
 	rcu_torture_print_module_parms(cur_ops, "Start of test");
+	rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
+	srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
+	start_gp_seq = gp_seq;
+	pr_alert("%s:  Start-test grace-period state: g%ld f%#x\n",
+		 cur_ops->name, (long)gp_seq, flags);
 
 	/* Set up the freelist. */