rcutorture: Abstract torture_stop_kthread()

Stopping of kthreads is not RCU-specific, so this commit abstracts
out torture_stop_kthread(), saving a few lines of code in the process.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>

include/linux/torture.h

@@ -91,9 +91,12 @@ bool torture_must_stop_irq(void);
 void torture_kthread_stopping(char *title);
 int _torture_create_kthread(int (*fn)(void *arg), void *arg, char *s, char *m,
 			     char *f, struct task_struct **tp);
+void _torture_stop_kthread(char *m, struct task_struct **tp);
 
 #define torture_create_kthread(n, arg, tp) \
 	_torture_create_kthread(n, (arg), #n, "Creating " #n " task", \
 				"Failed to create " #n, &(tp))
+#define torture_stop_kthread(n, tp) \
+	_torture_stop_kthread("Stopping " #n " task", &(tp))
 
 #endif /* __LINUX_TORTURE_H */

kernel/rcu/rcutorture.c

@@ -1033,14 +1033,12 @@ static void rcutorture_booster_cleanup(int cpu)
 	if (boost_tasks[cpu] == NULL)
 		return;
 	mutex_lock(&boost_mutex);
-	VERBOSE_TOROUT_STRING("Stopping rcu_torture_boost task");
 	t = boost_tasks[cpu];
 	boost_tasks[cpu] = NULL;
 	mutex_unlock(&boost_mutex);
 
 	/* This must be outside of the mutex, otherwise deadlock! */
-	kthread_stop(t);
-	boost_tasks[cpu] = NULL;
+	torture_stop_kthread(rcu_torture_boost, t);
 }
 
 static int rcutorture_booster_init(int cpu)
@@ -1110,16 +1108,6 @@ static int __init rcu_torture_stall_init(void)
 	return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
 }
 
-/* Clean up after the CPU-stall kthread, if one was spawned. */
-static void rcu_torture_stall_cleanup(void)
-{
-	if (stall_task == NULL)
-		return;
-	VERBOSE_TOROUT_STRING("Stopping rcu_torture_stall_task.");
-	kthread_stop(stall_task);
-	stall_task = NULL;
-}
-
 /* Callback function for RCU barrier testing. */
 void rcu_torture_barrier_cbf(struct rcu_head *rcu)
 {
@@ -1230,19 +1218,11 @@ static void rcu_torture_barrier_cleanup(void)
 {
 	int i;
 
-	if (barrier_task != NULL) {
-		VERBOSE_TOROUT_STRING("Stopping rcu_torture_barrier task");
-		kthread_stop(barrier_task);
-		barrier_task = NULL;
-	}
+	torture_stop_kthread(rcu_torture_barrier, barrier_task);
 	if (barrier_cbs_tasks != NULL) {
-		for (i = 0; i < n_barrier_cbs; i++) {
-			if (barrier_cbs_tasks[i] != NULL) {
-				VERBOSE_TOROUT_STRING("Stopping rcu_torture_barrier_cbs task");
-				kthread_stop(barrier_cbs_tasks[i]);
-				barrier_cbs_tasks[i] = NULL;
-			}
-		}
+		for (i = 0; i < n_barrier_cbs; i++)
+			torture_stop_kthread(rcu_torture_barrier_cbs,
+					     barrier_cbs_tasks[i]);
 		kfree(barrier_cbs_tasks);
 		barrier_cbs_tasks = NULL;
 	}
@@ -1288,53 +1268,29 @@ rcu_torture_cleanup(void)
 	}
 
 	rcu_torture_barrier_cleanup();
-	rcu_torture_stall_cleanup();
+	torture_stop_kthread(rcu_torture_stall, stall_task);
 	torture_stutter_cleanup();
-
-	if (writer_task) {
-		VERBOSE_TOROUT_STRING("Stopping rcu_torture_writer task");
-		kthread_stop(writer_task);
-	}
-	writer_task = NULL;
+	torture_stop_kthread(rcu_torture_writer, writer_task);
 
 	if (reader_tasks) {
-		for (i = 0; i < nrealreaders; i++) {
-			if (reader_tasks[i]) {
-				VERBOSE_TOROUT_STRING(
-					"Stopping rcu_torture_reader task");
-				kthread_stop(reader_tasks[i]);
-			}
-			reader_tasks[i] = NULL;
-		}
+		for (i = 0; i < nrealreaders; i++)
+			torture_stop_kthread(rcu_torture_reader,
+					     reader_tasks[i]);
 		kfree(reader_tasks);
-		reader_tasks = NULL;
 	}
 	rcu_torture_current = NULL;
 
 	if (fakewriter_tasks) {
 		for (i = 0; i < nfakewriters; i++) {
-			if (fakewriter_tasks[i]) {
-				VERBOSE_TOROUT_STRING(
-					"Stopping rcu_torture_fakewriter task");
-				kthread_stop(fakewriter_tasks[i]);
-			}
-			fakewriter_tasks[i] = NULL;
+			torture_stop_kthread(rcu_torture_fakewriter,
+					     fakewriter_tasks[i]);
 		}
 		kfree(fakewriter_tasks);
 		fakewriter_tasks = NULL;
 	}
 
-	if (stats_task) {
-		VERBOSE_TOROUT_STRING("Stopping rcu_torture_stats task");
-		kthread_stop(stats_task);
-	}
-	stats_task = NULL;
-
-	if (fqs_task) {
-		VERBOSE_TOROUT_STRING("Stopping rcu_torture_fqs task");
-		kthread_stop(fqs_task);
-	}
-	fqs_task = NULL;
+	torture_stop_kthread(rcu_torture_stats, stats_task);
+	torture_stop_kthread(rcu_torture_fqs, fqs_task);
 	if ((test_boost == 1 && cur_ops->can_boost) ||
 	    test_boost == 2) {
 		unregister_cpu_notifier(&rcutorture_cpu_nb);

kernel/torture.c

@@ -700,3 +700,16 @@ int _torture_create_kthread(int (*fn)(void *arg), void *arg, char *s, char *m,
 	return ret;
 }
 EXPORT_SYMBOL_GPL(_torture_create_kthread);
+
+/*
+ * Stop a generic kthread, emitting a message.
+ */
+void _torture_stop_kthread(char *m, struct task_struct **tp)
+{
+	if (*tp == NULL)
+		return;
+	VERBOSE_TOROUT_STRING(m);
+	kthread_stop(*tp);
+	*tp = NULL;
+}
+EXPORT_SYMBOL_GPL(_torture_stop_kthread);