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

   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 }