1/******************************************************************************
2 *
3 *   Copyright �� International Business Machines  Corp., 2006-2008
4 *
5 *   This program is free software;  you can redistribute it and/or modify
6 *   it under the terms of the GNU General Public License as published by
7 *   the Free Software Foundation; either version 2 of the License, or
8 *   (at your option) any later version.
9 *
10 * DESCRIPTION
11 *      This test exercises the futex_wait_requeue_pi() signal handling both
12 *      before and after the requeue. The first should be restarted by the
13 *      kernel. The latter should return EWOULDBLOCK to the waiter.
14 *
15 * AUTHORS
16 *      Darren Hart <dvhart@linux.intel.com>
17 *
18 * HISTORY
19 *      2008-May-5: Initial version by Darren Hart <dvhart@linux.intel.com>
20 *
21 *****************************************************************************/
22
23#include <errno.h>
24#include <getopt.h>
25#include <limits.h>
26#include <pthread.h>
27#include <signal.h>
28#include <stdio.h>
29#include <stdlib.h>
30#include <string.h>
31#include "atomic.h"
32#include "futextest.h"
33#include "logging.h"
34
35#define DELAY_US 100
36
37futex_t f1 = FUTEX_INITIALIZER;
38futex_t f2 = FUTEX_INITIALIZER;
39atomic_t requeued = ATOMIC_INITIALIZER;
40
41int waiter_ret = 0;
42
43void usage(char *prog)
44{
45	printf("Usage: %s\n", prog);
46	printf("  -c	Use color\n");
47	printf("  -h	Display this help message\n");
48	printf("  -v L	Verbosity level: %d=QUIET %d=CRITICAL %d=INFO\n",
49	       VQUIET, VCRITICAL, VINFO);
50}
51
52int create_rt_thread(pthread_t *pth, void*(*func)(void *), void *arg,
53		     int policy, int prio)
54{
55	struct sched_param schedp;
56	pthread_attr_t attr;
57	int ret;
58
59	pthread_attr_init(&attr);
60	memset(&schedp, 0, sizeof(schedp));
61
62	ret = pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED);
63	if (ret) {
64		error("pthread_attr_setinheritsched\n", ret);
65		return -1;
66	}
67
68	ret = pthread_attr_setschedpolicy(&attr, policy);
69	if (ret) {
70		error("pthread_attr_setschedpolicy\n", ret);
71		return -1;
72	}
73
74	schedp.sched_priority = prio;
75	ret = pthread_attr_setschedparam(&attr, &schedp);
76	if (ret) {
77		error("pthread_attr_setschedparam\n", ret);
78		return -1;
79	}
80
81	ret = pthread_create(pth, &attr, func, arg);
82	if (ret) {
83		error("pthread_create\n", ret);
84		return -1;
85	}
86	return 0;
87}
88
89void handle_signal(int signo)
90{
91	info("signal received %s requeue\n",
92	     requeued.val ? "after" : "prior to");
93}
94
95void *waiterfn(void *arg)
96{
97	unsigned int old_val;
98	int res;
99
100	waiter_ret = RET_PASS;
101
102	info("Waiter running\n");
103	info("Calling FUTEX_LOCK_PI on f2=%x @ %p\n", f2, &f2);
104	old_val = f1;
105	res = futex_wait_requeue_pi(&f1, old_val, &(f2), NULL,
106				    FUTEX_PRIVATE_FLAG);
107	if (!requeued.val || errno != EWOULDBLOCK) {
108		fail("unexpected return from futex_wait_requeue_pi: %d (%s)\n",
109		     res, strerror(errno));
110		info("w2:futex: %x\n", f2);
111		if (!res)
112			futex_unlock_pi(&f2, FUTEX_PRIVATE_FLAG);
113		waiter_ret = RET_FAIL;
114	}
115
116	info("Waiter exiting with %d\n", waiter_ret);
117	pthread_exit(NULL);
118}
119
120
121int main(int argc, char *argv[])
122{
123	unsigned int old_val;
124	struct sigaction sa;
125	pthread_t waiter;
126	int c, res, ret = RET_PASS;
127
128	while ((c = getopt(argc, argv, "chv:")) != -1) {
129		switch (c) {
130		case 'c':
131			log_color(1);
132			break;
133		case 'h':
134			usage(basename(argv[0]));
135			exit(0);
136		case 'v':
137			log_verbosity(atoi(optarg));
138			break;
139		default:
140			usage(basename(argv[0]));
141			exit(1);
142		}
143	}
144
145	printf("%s: Test signal handling during requeue_pi\n",
146	       basename(argv[0]));
147	printf("\tArguments: <none>\n");
148
149	sa.sa_handler = handle_signal;
150	sigemptyset(&sa.sa_mask);
151	sa.sa_flags = 0;
152	if (sigaction(SIGUSR1, &sa, NULL)) {
153		error("sigaction\n", errno);
154		exit(1);
155	}
156
157	info("m1:f2: %x\n", f2);
158	info("Creating waiter\n");
159	res = create_rt_thread(&waiter, waiterfn, NULL, SCHED_FIFO, 1);
160	if (res) {
161		error("Creating waiting thread failed", res);
162		ret = RET_ERROR;
163		goto out;
164	}
165
166	info("Calling FUTEX_LOCK_PI on f2=%x @ %p\n", f2, &f2);
167	info("m2:f2: %x\n", f2);
168	futex_lock_pi(&f2, 0, 0, FUTEX_PRIVATE_FLAG);
169	info("m3:f2: %x\n", f2);
170
171	while (1) {
172		/*
173		 * signal the waiter before requeue, waiter should automatically
174		 * restart futex_wait_requeue_pi() in the kernel. Wait for the
175		 * waiter to block on f1 again.
176		 */
177		info("Issuing SIGUSR1 to waiter\n");
178		pthread_kill(waiter, SIGUSR1);
179		usleep(DELAY_US);
180
181		info("Requeueing waiter via FUTEX_CMP_REQUEUE_PI\n");
182		old_val = f1;
183		res = futex_cmp_requeue_pi(&f1, old_val, &(f2), 1, 0,
184					   FUTEX_PRIVATE_FLAG);
185		/*
186		 * If res is non-zero, we either requeued the waiter or hit an
187		 * error, break out and handle it. If it is zero, then the
188		 * signal may have hit before the the waiter was blocked on f1.
189		 * Try again.
190		 */
191		if (res > 0) {
192			atomic_set(&requeued, 1);
193			break;
194		} else if (res < 0) {
195			error("FUTEX_CMP_REQUEUE_PI failed\n", errno);
196			ret = RET_ERROR;
197			break;
198		}
199	}
200	info("m4:f2: %x\n", f2);
201
202	/*
203	 * Signal the waiter after requeue, waiter should return from
204	 * futex_wait_requeue_pi() with EWOULDBLOCK. Join the thread here so the
205	 * futex_unlock_pi() can't happen before the signal wakeup is detected
206	 * in the kernel.
207	 */
208	info("Issuing SIGUSR1 to waiter\n");
209	pthread_kill(waiter, SIGUSR1);
210	info("Waiting for waiter to return\n");
211	pthread_join(waiter, NULL);
212
213	info("Calling FUTEX_UNLOCK_PI on mutex=%x @ %p\n", f2, &f2);
214	futex_unlock_pi(&f2, FUTEX_PRIVATE_FLAG);
215	info("m5:f2: %x\n", f2);
216
217 out:
218	if (ret == RET_PASS && waiter_ret)
219		ret = waiter_ret;
220
221	print_result(ret);
222	return ret;
223}
224