// SPDX-License-Identifier: GPL-2.0#include <linux/init.h>#include <linux/kthread.h>#include <linux/hrtimer.h>#include <linux/fs.h>#include <linux/debugfs.h>#include <linux/export.h>#include <linux/spinlock.h>#include <asm/debug.h> static int ss_get(void *data, u64 *val){	ktime_t start, finish;	int loops;	int cont;	DEFINE_RAW_SPINLOCK(ss_spin); 	loops = 1000000;	cont = 1; 	start = ktime_get(); 	while (cont) {		raw_spin_lock(&ss_spin);		loops--;		if (loops == 0)			cont = 0;		raw_spin_unlock(&ss_spin);	} 	finish = ktime_get(); 	*val = ktime_us_delta(finish, start); 	return 0;} DEFINE_DEBUGFS_ATTRIBUTE(fops_ss, ss_get, NULL, "%llu\n");   struct spin_multi_state {	raw_spinlock_t lock;	atomic_t start_wait;	atomic_t enter_wait;	atomic_t exit_wait;	int loops;}; struct spin_multi_per_thread {	struct spin_multi_state *state;	ktime_t start;}; static int multi_other(void *data){	int loops;	int cont;	struct spin_multi_per_thread *pt = data;	struct spin_multi_state *s = pt->state; 	loops = s->loops;	cont = 1; 	atomic_dec(&s->enter_wait); 	while (atomic_read(&s->enter_wait))		; /* spin */ 	pt->start = ktime_get(); 	atomic_dec(&s->start_wait); 	while (atomic_read(&s->start_wait))		; /* spin */ 	while (cont) {		raw_spin_lock(&s->lock);		loops--;		if (loops == 0)			cont = 0;		raw_spin_unlock(&s->lock);	} 	atomic_dec(&s->exit_wait);	while (atomic_read(&s->exit_wait))		; /* spin */	return 0;} static int multi_get(void *data, u64 *val){	ktime_t finish;	struct spin_multi_state ms;	struct spin_multi_per_thread t1, t2; 	ms.lock = __RAW_SPIN_LOCK_UNLOCKED("multi_get");	ms.loops = 1000000; 	atomic_set(&ms.start_wait, 2);	atomic_set(&ms.enter_wait, 2);	atomic_set(&ms.exit_wait, 2);	t1.state = &ms;	t2.state = &ms; 	kthread_run(multi_other, &t2, "multi_get"); 	multi_other(&t1); 	finish = ktime_get(); 	*val = ktime_us_delta(finish, t1.start); 	return 0;} DEFINE_DEBUGFS_ATTRIBUTE(fops_multi, multi_get, NULL, "%llu\n"); static int __init spinlock_test(void){	debugfs_create_file_unsafe("spin_single", S_IRUGO, mips_debugfs_dir, NULL,			    &fops_ss);	debugfs_create_file_unsafe("spin_multi", S_IRUGO, mips_debugfs_dir, NULL,			    &fops_multi);	return 0;}device_initcall(spinlock_test);