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 DELAY_US 100
  36
  37 futex_t f1 = FUTEX_INITIALIZER;
  38 futex_t f2 = FUTEX_INITIALIZER;
  39 atomic_t requeued = ATOMIC_INITIALIZER;
  40
  41 int waiter_ret = 0;
  42
  43 void 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
  52 int 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
  89 void handle_signal(int signo)
  90 {
  91         info("signal received %s requeue\n",
  92              requeued.val ? "after" : "prior to");
  93 }
  94
  95 void *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
 121 int 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 }