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

DEFINITIONS

1. usage
2. create_rt_thread
3. handle_signal
4. waiterfn
5. main

   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 
  34 futex_t f1 = FUTEX_INITIALIZER;
  35 futex_t f2 = FUTEX_INITIALIZER;
  36 atomic_t requeued = ATOMIC_INITIALIZER;
  37 
  38 int waiter_ret = 0;
  39 
  40 void 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 
  49 int 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 
  86 void handle_signal(int signo)
  87 {
  88         info("signal received %s requeue\n",
  89              requeued.val ? "after" : "prior to");
  90 }
  91 
  92 void *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 
 118 int 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 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 }