torture: Add dowarn argument to torture_sched_setaffinity()

Current use cases of torture_sched_setaffinity() are well served by its
unconditional warning on error.  However, an upcoming use case for a
preemption kthread needs to avoid warnings that might otherwise arise
when that kthread attempted to bind itself to a CPU on its way offline.
This commit therefore adds a dowarn argument that, when false, suppresses
the warning.

Signed-off-by: Paul E. McKenney <[email protected]>
Signed-off-by: Uladzislau Rezki (Sony) <[email protected]>

Author: paulmckrcu

include/linux/torture.h

@@ -130,7 +130,7 @@ void _torture_stop_kthread(char *m, struct task_struct **tp);
 #endif
 
 #if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST) || IS_ENABLED(CONFIG_LOCK_TORTURE_TEST) || IS_MODULE(CONFIG_LOCK_TORTURE_TEST)
-long torture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask);
+long torture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask, bool dowarn);
 #endif
 
 #endif /* __LINUX_TORTURE_H */

kernel/locking/locktorture.c

@@ -106,7 +106,7 @@ static const struct kernel_param_ops lt_bind_ops = {
 module_param_cb(bind_readers, &lt_bind_ops, &bind_readers, 0644);
 module_param_cb(bind_writers, &lt_bind_ops, &bind_writers, 0644);
 
-long torture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask);
+long torture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask, bool dowarn);
 
 static struct task_struct *stats_task;
 static struct task_struct **writer_tasks;
@@ -1358,7 +1358,7 @@ static int __init lock_torture_init(void)
 		if (torture_init_error(firsterr))
 			goto unwind;
 		if (cpumask_nonempty(bind_writers))
-			torture_sched_setaffinity(writer_tasks[i]->pid, bind_writers);
+			torture_sched_setaffinity(writer_tasks[i]->pid, bind_writers, true);
 
 	create_reader:
 		if (cxt.cur_ops->readlock == NULL || (j >= cxt.nrealreaders_stress))
@@ -1369,7 +1369,7 @@ static int __init lock_torture_init(void)
 		if (torture_init_error(firsterr))
 			goto unwind;
 		if (cpumask_nonempty(bind_readers))
-			torture_sched_setaffinity(reader_tasks[j]->pid, bind_readers);
+			torture_sched_setaffinity(reader_tasks[j]->pid, bind_readers, true);
 	}
 	if (stat_interval > 0) {
 		firsterr = torture_create_kthread(lock_torture_stats, NULL,

kernel/rcu/rcutorture.c

@@ -857,7 +857,7 @@ static void synchronize_rcu_trivial(void)
 	int cpu;
 
 	for_each_online_cpu(cpu) {
-		torture_sched_setaffinity(current->pid, cpumask_of(cpu));
+		torture_sched_setaffinity(current->pid, cpumask_of(cpu), true);
 		WARN_ON_ONCE(raw_smp_processor_id() != cpu);
 	}
 }

kernel/rcu/update.c

@@ -527,12 +527,12 @@ EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read);
 
 #if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST) || IS_ENABLED(CONFIG_LOCK_TORTURE_TEST) || IS_MODULE(CONFIG_LOCK_TORTURE_TEST)
 /* Get rcutorture access to sched_setaffinity(). */
-long torture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
+long torture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask, bool dowarn)
 {
 	int ret;
 
 	ret = sched_setaffinity(pid, in_mask);
-	WARN_ONCE(ret, "%s: sched_setaffinity(%d) returned %d\n", __func__, pid, ret);
+	WARN_ONCE(dowarn && ret, "%s: sched_setaffinity(%d) returned %d\n", __func__, pid, ret);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(torture_sched_setaffinity);