1// SPDX-License-Identifier: GPL-2.0-or-later
2/******************************************************************************
3 *
4 *   Copyright �� International Business Machines  Corp., 2006-2008
5 *
6 * DESCRIPTION
7 *      This test exercises the futex_wait_requeue_pi() signal handling both
8 *      before and after the requeue. The first should be restarted by the
9 *      kernel. The latter should return EWOULDBLOCK to the waiter.
10 *
11 * AUTHORS
12 *      Darren Hart <dvhart@linux.intel.com>
13 *
14 * HISTORY
15 *      2008-May-5: Initial version by Darren Hart <dvhart@linux.intel.com>
16 *
17 *****************************************************************************/
18
19#include <errno.h>
20#include <getopt.h>
21#include <limits.h>
22#include <pthread.h>
23#include <signal.h>
24#include <stdio.h>
25#include <stdlib.h>
26#include <string.h>
27#include "atomic.h"
28#include "futextest.h"
29#include "logging.h"
30
31#define TEST_NAME "futex-requeue-pi-signal-restart"
32#define DELAY_US 100
33
34futex_t f1 = FUTEX_INITIALIZER;
35futex_t f2 = FUTEX_INITIALIZER;
36atomic_t requeued = ATOMIC_INITIALIZER;
37
38int waiter_ret = 0;
39
40void usage(char *prog)
41{
42	printf("Usage: %s\n", prog);
43	printf("  -c	Use color\n");
44	printf("  -h	Display this help message\n");
45	printf("  -v L	Verbosity level: %d=QUIET %d=CRITICAL %d=INFO\n",
46	       VQUIET, VCRITICAL, VINFO);
47}
48
49int create_rt_thread(pthread_t *pth, void*(*func)(void *), void *arg,
50		     int policy, int prio)
51{
52	struct sched_param schedp;
53	pthread_attr_t attr;
54	int ret;
55
56	pthread_attr_init(&attr);
57	memset(&schedp, 0, sizeof(schedp));
58
59	ret = pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED);
60	if (ret) {
61		error("pthread_attr_setinheritsched\n", ret);
62		return -1;
63	}
64
65	ret = pthread_attr_setschedpolicy(&attr, policy);
66	if (ret) {
67		error("pthread_attr_setschedpolicy\n", ret);
68		return -1;
69	}
70
71	schedp.sched_priority = prio;
72	ret = pthread_attr_setschedparam(&attr, &schedp);
73	if (ret) {
74		error("pthread_attr_setschedparam\n", ret);
75		return -1;
76	}
77
78	ret = pthread_create(pth, &attr, func, arg);
79	if (ret) {
80		error("pthread_create\n", ret);
81		return -1;
82	}
83	return 0;
84}
85
86void handle_signal(int signo)
87{
88	info("signal received %s requeue\n",
89	     requeued.val ? "after" : "prior to");
90}
91
92void *waiterfn(void *arg)
93{
94	unsigned int old_val;
95	int res;
96
97	waiter_ret = RET_PASS;
98
99	info("Waiter running\n");
100	info("Calling FUTEX_LOCK_PI on f2=%x @ %p\n", f2, &f2);
101	old_val = f1;
102	res = futex_wait_requeue_pi(&f1, old_val, &(f2), NULL,
103				    FUTEX_PRIVATE_FLAG);
104	if (!requeued.val || errno != EWOULDBLOCK) {
105		fail("unexpected return from futex_wait_requeue_pi: %d (%s)\n",
106		     res, strerror(errno));
107		info("w2:futex: %x\n", f2);
108		if (!res)
109			futex_unlock_pi(&f2, FUTEX_PRIVATE_FLAG);
110		waiter_ret = RET_FAIL;
111	}
112
113	info("Waiter exiting with %d\n", waiter_ret);
114	pthread_exit(NULL);
115}
116
117
118int main(int argc, char *argv[])
119{
120	unsigned int old_val;
121	struct sigaction sa;
122	pthread_t waiter;
123	int c, res, ret = RET_PASS;
124
125	while ((c = getopt(argc, argv, "chv:")) != -1) {
126		switch (c) {
127		case 'c':
128			log_color(1);
129			break;
130		case 'h':
131			usage(basename(argv[0]));
132			exit(0);
133		case 'v':
134			log_verbosity(atoi(optarg));
135			break;
136		default:
137			usage(basename(argv[0]));
138			exit(1);
139		}
140	}
141
142	ksft_print_header();
143	ksft_set_plan(1);
144	ksft_print_msg("%s: Test signal handling during requeue_pi\n",
145	       basename(argv[0]));
146	ksft_print_msg("\tArguments: <none>\n");
147
148	sa.sa_handler = handle_signal;
149	sigemptyset(&sa.sa_mask);
150	sa.sa_flags = 0;
151	if (sigaction(SIGUSR1, &sa, NULL)) {
152		error("sigaction\n", errno);
153		exit(1);
154	}
155
156	info("m1:f2: %x\n", f2);
157	info("Creating waiter\n");
158	res = create_rt_thread(&waiter, waiterfn, NULL, SCHED_FIFO, 1);
159	if (res) {
160		error("Creating waiting thread failed", res);
161		ret = RET_ERROR;
162		goto out;
163	}
164
165	info("Calling FUTEX_LOCK_PI on f2=%x @ %p\n", f2, &f2);
166	info("m2:f2: %x\n", f2);
167	futex_lock_pi(&f2, 0, 0, FUTEX_PRIVATE_FLAG);
168	info("m3:f2: %x\n", f2);
169
170	while (1) {
171		/*
172		 * signal the waiter before requeue, waiter should automatically
173		 * restart futex_wait_requeue_pi() in the kernel. Wait for the
174		 * waiter to block on f1 again.
175		 */
176		info("Issuing SIGUSR1 to waiter\n");
177		pthread_kill(waiter, SIGUSR1);
178		usleep(DELAY_US);
179
180		info("Requeueing waiter via FUTEX_CMP_REQUEUE_PI\n");
181		old_val = f1;
182		res = futex_cmp_requeue_pi(&f1, old_val, &(f2), 1, 0,
183					   FUTEX_PRIVATE_FLAG);
184		/*
185		 * If res is non-zero, we either requeued the waiter or hit an
186		 * error, break out and handle it. If it is zero, then the
187		 * signal may have hit before the waiter was blocked on f1.
188		 * Try again.
189		 */
190		if (res > 0) {
191			atomic_set(&requeued, 1);
192			break;
193		} else if (res < 0) {
194			error("FUTEX_CMP_REQUEUE_PI failed\n", errno);
195			ret = RET_ERROR;
196			break;
197		}
198	}
199	info("m4:f2: %x\n", f2);
200
201	/*
202	 * Signal the waiter after requeue, waiter should return from
203	 * futex_wait_requeue_pi() with EWOULDBLOCK. Join the thread here so the
204	 * futex_unlock_pi() can't happen before the signal wakeup is detected
205	 * in the kernel.
206	 */
207	info("Issuing SIGUSR1 to waiter\n");
208	pthread_kill(waiter, SIGUSR1);
209	info("Waiting for waiter to return\n");
210	pthread_join(waiter, NULL);
211
212	info("Calling FUTEX_UNLOCK_PI on mutex=%x @ %p\n", f2, &f2);
213	futex_unlock_pi(&f2, FUTEX_PRIVATE_FLAG);
214	info("m5:f2: %x\n", f2);
215
216 out:
217	if (ret == RET_PASS && waiter_ret)
218		ret = waiter_ret;
219
220	print_result(TEST_NAME, ret);
221	return ret;
222}
223