From 1e6bfbb9007af44b26b3064af86d94a2fdccf2c2 Mon Sep 17 00:00:00 2001
From: "Paul E. McKenney" <paulmck@kernel.org>
Date: Tue, 23 Nov 2021 13:51:11 -0800
Subject: [PATCH] rcutorture: Combine n_max_cbs from all kthreads in a callback
 flood

References: bnc#1189998 (PREEMPT_RT prerequisite backports)
Patch-mainline: v5.17-rc0
Git-commit: 53b541fbdb9c498db112216a0cc9fe4804f54742

With the addition of multiple callback-flood kthreads, the maximum number
of callbacks from any one of those kthreads is reported in the rcutorture
run summary.  This commit changes this to report the sum of each kthread's
maximum number of callbacks in a given callback-flooding episode.

Cc: Neeraj Upadhyay <neeraj.iitr10@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
 kernel/rcu/rcutorture.c                                   | 9 +++++++++
 tools/testing/selftests/rcutorture/bin/kvm-recheck-rcu.sh | 2 +-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 1e8360d15920..33ea446101b3 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -2170,6 +2170,7 @@ struct rcu_fwd {
 static DEFINE_MUTEX(rcu_fwd_mutex);
 static struct rcu_fwd *rcu_fwds;
 static unsigned long rcu_fwd_seq;
+static atomic_long_t rcu_fwd_max_cbs;
 static bool rcu_fwd_emergency_stop;
 
 static void rcu_torture_fwd_cb_hist(struct rcu_fwd *rfp)
@@ -2428,6 +2429,7 @@ static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp)
 			 n_launders + n_max_cbs - n_launders_cb_snap,
 			 n_launders, n_launders_sa,
 			 n_max_gps, n_max_cbs, cver, gps);
+		atomic_long_add(n_max_cbs, &rcu_fwd_max_cbs);
 		rcu_torture_fwd_cb_hist(rfp);
 	}
 	schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */
@@ -2489,6 +2491,8 @@ static struct notifier_block rcutorture_oom_nb = {
 /* Carry out grace-period forward-progress testing. */
 static int rcu_torture_fwd_prog(void *args)
 {
+	bool firsttime = true;
+	long max_cbs;
 	int oldnice = task_nice(current);
 	unsigned long oldseq = READ_ONCE(rcu_fwd_seq);
 	struct rcu_fwd *rfp = args;
@@ -2503,6 +2507,11 @@ static int rcu_torture_fwd_prog(void *args)
 		if (!rfp->rcu_fwd_id) {
 			schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
 			WRITE_ONCE(rcu_fwd_emergency_stop, false);
+			if (!firsttime) {
+				max_cbs = atomic_long_xchg(&rcu_fwd_max_cbs, 0);
+				pr_alert("%s n_max_cbs: %ld\n", __func__, max_cbs);
+			}
+			firsttime = false;
 			WRITE_ONCE(rcu_fwd_seq, rcu_fwd_seq + 1);
 		} else {
 			while (READ_ONCE(rcu_fwd_seq) == oldseq)
diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcu.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcu.sh
index fbdf162b6acd..1c4c2c727dad 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcu.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck-rcu.sh
@@ -25,7 +25,7 @@ stopstate="`grep 'End-test grace-period state: g' $i/console.log 2> /dev/null |
 	    tail -1 | sed -e 's/^\[[ 0-9.]*] //' |
 	    awk '{ print \"[\" $1 \" \" $5 \" \" $6 \" \" $7 \"]\"; }' |
 	    tr -d '\012\015'`"
-fwdprog="`grep 'rcu_torture_fwd_prog_cr Duration' $i/console.log 2> /dev/null | sed -e 's/^\[[^]]*] //' | sort -k15nr | head -1 | awk '{ print $14 " " $15 }'`"
+fwdprog="`grep 'rcu_torture_fwd_prog n_max_cbs: ' $i/console.log 2> /dev/null | sed -e 's/^\[[^]]*] //' | sort -k3nr | head -1 | awk '{ print $2 " " $3 }'`"
 if test -z "$ngps"
 then
 	echo "$configfile ------- " $stopstate