linux-kernel - [PATCH rcu 03/12] rcutorture: Simplify rcu_torture_read_exit

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Date:   Mon, 20 Jun 2022 15:58:08 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel-team@...com,
        rostedt@...dmis.org, "Paul E. McKenney" <paulmck@...nel.org>
Subject: [PATCH rcu 03/12] rcutorture: Simplify rcu_torture_read_exit_child() loop

The existing loop has an implicit manual loop that obscures the flow
and requires an extra control variable.  This commit makes this implicit
loop explicit, thus saving several lines of code.

Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 kernel/rcu/rcutorture.c | 47 ++++++++++++++++++-----------------------
 1 file changed, 20 insertions(+), 27 deletions(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 3032dd7c7ad35..9273264772b88 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -2874,7 +2874,6 @@ static int rcu_torture_read_exit_child(void *trsp_in)
 // Parent kthread which creates and destroys read-exit child kthreads.
 static int rcu_torture_read_exit(void *unused)
 {
-	int count = 0;
 	bool errexit = false;
 	int i;
 	struct task_struct *tsp;
@@ -2886,34 +2885,28 @@ static int rcu_torture_read_exit(void *unused)
 
 	// Each pass through this loop does one read-exit episode.
 	do {
-		if (++count > read_exit_burst) {
-			VERBOSE_TOROUT_STRING("rcu_torture_read_exit: End of episode");
-			rcu_barrier(); // Wait for task_struct free, avoid OOM.
-			for (i = 0; i < read_exit_delay; i++) {
-				schedule_timeout_uninterruptible(HZ);
-				if (READ_ONCE(read_exit_child_stop))
-					break;
+		VERBOSE_TOROUT_STRING("rcu_torture_read_exit: Start of episode");
+		for (i = 0; i < read_exit_burst; i++) {
+			if (READ_ONCE(read_exit_child_stop))
+				break;
+			stutter_wait("rcu_torture_read_exit");
+			// Spawn child.
+			tsp = kthread_run(rcu_torture_read_exit_child,
+					  &trs, "%s", "rcu_torture_read_exit_child");
+			if (IS_ERR(tsp)) {
+				TOROUT_ERRSTRING("out of memory");
+				errexit = true;
+				break;
 			}
-			if (!READ_ONCE(read_exit_child_stop))
-				VERBOSE_TOROUT_STRING("rcu_torture_read_exit: Start of episode");
-			count = 0;
-		}
-		if (READ_ONCE(read_exit_child_stop))
-			break;
-		// Spawn child.
-		tsp = kthread_run(rcu_torture_read_exit_child,
-				     &trs, "%s",
-				     "rcu_torture_read_exit_child");
-		if (IS_ERR(tsp)) {
-			TOROUT_ERRSTRING("out of memory");
-			errexit = true;
-			tsp = NULL;
-			break;
+			cond_resched();
+			kthread_stop(tsp);
+			n_read_exits ++;
 		}
-		cond_resched();
-		kthread_stop(tsp);
-		n_read_exits ++;
-		stutter_wait("rcu_torture_read_exit");
+		VERBOSE_TOROUT_STRING("rcu_torture_read_exit: End of episode");
+		rcu_barrier(); // Wait for task_struct free, avoid OOM.
+		i = 0;
+		for (; !errexit && !READ_ONCE(read_exit_child_stop) && i < read_exit_delay; i++)
+			schedule_timeout_uninterruptible(HZ);
 	} while (!errexit && !READ_ONCE(read_exit_child_stop));
 
 	// Clean up and exit.
-- 
2.31.1.189.g2e36527f23