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Linux/tools/testing/selftests/futex/functional/futex_requeue_pi_signal_restart.c

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  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 TEST_NAME "futex-requeue-pi-signal-restart"
 36 #define DELAY_US 100
 37 
 38 futex_t f1 = FUTEX_INITIALIZER;
 39 futex_t f2 = FUTEX_INITIALIZER;
 40 atomic_t requeued = ATOMIC_INITIALIZER;
 41 
 42 int waiter_ret = 0;
 43 
 44 void usage(char *prog)
 45 {
 46         printf("Usage: %s\n", prog);
 47         printf("  -c    Use color\n");
 48         printf("  -h    Display this help message\n");
 49         printf("  -v L  Verbosity level: %d=QUIET %d=CRITICAL %d=INFO\n",
 50                VQUIET, VCRITICAL, VINFO);
 51 }
 52 
 53 int create_rt_thread(pthread_t *pth, void*(*func)(void *), void *arg,
 54                      int policy, int prio)
 55 {
 56         struct sched_param schedp;
 57         pthread_attr_t attr;
 58         int ret;
 59 
 60         pthread_attr_init(&attr);
 61         memset(&schedp, 0, sizeof(schedp));
 62 
 63         ret = pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED);
 64         if (ret) {
 65                 error("pthread_attr_setinheritsched\n", ret);
 66                 return -1;
 67         }
 68 
 69         ret = pthread_attr_setschedpolicy(&attr, policy);
 70         if (ret) {
 71                 error("pthread_attr_setschedpolicy\n", ret);
 72                 return -1;
 73         }
 74 
 75         schedp.sched_priority = prio;
 76         ret = pthread_attr_setschedparam(&attr, &schedp);
 77         if (ret) {
 78                 error("pthread_attr_setschedparam\n", ret);
 79                 return -1;
 80         }
 81 
 82         ret = pthread_create(pth, &attr, func, arg);
 83         if (ret) {
 84                 error("pthread_create\n", ret);
 85                 return -1;
 86         }
 87         return 0;
 88 }
 89 
 90 void handle_signal(int signo)
 91 {
 92         info("signal received %s requeue\n",
 93              requeued.val ? "after" : "prior to");
 94 }
 95 
 96 void *waiterfn(void *arg)
 97 {
 98         unsigned int old_val;
 99         int res;
100 
101         waiter_ret = RET_PASS;
102 
103         info("Waiter running\n");
104         info("Calling FUTEX_LOCK_PI on f2=%x @ %p\n", f2, &f2);
105         old_val = f1;
106         res = futex_wait_requeue_pi(&f1, old_val, &(f2), NULL,
107                                     FUTEX_PRIVATE_FLAG);
108         if (!requeued.val || errno != EWOULDBLOCK) {
109                 fail("unexpected return from futex_wait_requeue_pi: %d (%s)\n",
110                      res, strerror(errno));
111                 info("w2:futex: %x\n", f2);
112                 if (!res)
113                         futex_unlock_pi(&f2, FUTEX_PRIVATE_FLAG);
114                 waiter_ret = RET_FAIL;
115         }
116 
117         info("Waiter exiting with %d\n", waiter_ret);
118         pthread_exit(NULL);
119 }
120 
121 
122 int main(int argc, char *argv[])
123 {
124         unsigned int old_val;
125         struct sigaction sa;
126         pthread_t waiter;
127         int c, res, ret = RET_PASS;
128 
129         while ((c = getopt(argc, argv, "chv:")) != -1) {
130                 switch (c) {
131                 case 'c':
132                         log_color(1);
133                         break;
134                 case 'h':
135                         usage(basename(argv[0]));
136                         exit(0);
137                 case 'v':
138                         log_verbosity(atoi(optarg));
139                         break;
140                 default:
141                         usage(basename(argv[0]));
142                         exit(1);
143                 }
144         }
145 
146         ksft_print_header();
147         ksft_print_msg("%s: Test signal handling during requeue_pi\n",
148                basename(argv[0]));
149         ksft_print_msg("\tArguments: <none>\n");
150 
151         sa.sa_handler = handle_signal;
152         sigemptyset(&sa.sa_mask);
153         sa.sa_flags = 0;
154         if (sigaction(SIGUSR1, &sa, NULL)) {
155                 error("sigaction\n", errno);
156                 exit(1);
157         }
158 
159         info("m1:f2: %x\n", f2);
160         info("Creating waiter\n");
161         res = create_rt_thread(&waiter, waiterfn, NULL, SCHED_FIFO, 1);
162         if (res) {
163                 error("Creating waiting thread failed", res);
164                 ret = RET_ERROR;
165                 goto out;
166         }
167 
168         info("Calling FUTEX_LOCK_PI on f2=%x @ %p\n", f2, &f2);
169         info("m2:f2: %x\n", f2);
170         futex_lock_pi(&f2, 0, 0, FUTEX_PRIVATE_FLAG);
171         info("m3:f2: %x\n", f2);
172 
173         while (1) {
174                 /*
175                  * signal the waiter before requeue, waiter should automatically
176                  * restart futex_wait_requeue_pi() in the kernel. Wait for the
177                  * waiter to block on f1 again.
178                  */
179                 info("Issuing SIGUSR1 to waiter\n");
180                 pthread_kill(waiter, SIGUSR1);
181                 usleep(DELAY_US);
182 
183                 info("Requeueing waiter via FUTEX_CMP_REQUEUE_PI\n");
184                 old_val = f1;
185                 res = futex_cmp_requeue_pi(&f1, old_val, &(f2), 1, 0,
186                                            FUTEX_PRIVATE_FLAG);
187                 /*
188                  * If res is non-zero, we either requeued the waiter or hit an
189                  * error, break out and handle it. If it is zero, then the
190                  * signal may have hit before the the waiter was blocked on f1.
191                  * Try again.
192                  */
193                 if (res > 0) {
194                         atomic_set(&requeued, 1);
195                         break;
196                 } else if (res < 0) {
197                         error("FUTEX_CMP_REQUEUE_PI failed\n", errno);
198                         ret = RET_ERROR;
199                         break;
200                 }
201         }
202         info("m4:f2: %x\n", f2);
203 
204         /*
205          * Signal the waiter after requeue, waiter should return from
206          * futex_wait_requeue_pi() with EWOULDBLOCK. Join the thread here so the
207          * futex_unlock_pi() can't happen before the signal wakeup is detected
208          * in the kernel.
209          */
210         info("Issuing SIGUSR1 to waiter\n");
211         pthread_kill(waiter, SIGUSR1);
212         info("Waiting for waiter to return\n");
213         pthread_join(waiter, NULL);
214 
215         info("Calling FUTEX_UNLOCK_PI on mutex=%x @ %p\n", f2, &f2);
216         futex_unlock_pi(&f2, FUTEX_PRIVATE_FLAG);
217         info("m5:f2: %x\n", f2);
218 
219  out:
220         if (ret == RET_PASS && waiter_ret)
221                 ret = waiter_ret;
222 
223         print_result(TEST_NAME, ret);
224         return ret;
225 }
226 

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