futex/functional/futex_requeue_pi.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /******************************************************************************
0003  *
0004  *   Copyright © International Business Machines  Corp., 2006-2008
0005  *
0006  * DESCRIPTION
0007  *      This test excercises the futex syscall op codes needed for requeuing
0008  *      priority inheritance aware POSIX condition variables and mutexes.
0009  *
0010  * AUTHORS
0011  *      Sripathi Kodi <sripathik@in.ibm.com>
0012  *      Darren Hart <dvhart@linux.intel.com>
0013  *
0014  * HISTORY
0015  *      2008-Jan-13: Initial version by Sripathi Kodi <sripathik@in.ibm.com>
0016  *      2009-Nov-6: futex test adaptation by Darren Hart <dvhart@linux.intel.com>
0017  *
0018  *****************************************************************************/
0019
0020 #include <errno.h>
0021 #include <limits.h>
0022 #include <pthread.h>
0023 #include <stdio.h>
0024 #include <stdlib.h>
0025 #include <signal.h>
0026 #include <string.h>
0027 #include "atomic.h"
0028 #include "futextest.h"
0029 #include "logging.h"
0030
0031 #define TEST_NAME "futex-requeue-pi"
0032 #define MAX_WAKE_ITERS 1000
0033 #define THREAD_MAX 10
0034 #define SIGNAL_PERIOD_US 100
0035
0036 atomic_t waiters_blocked = ATOMIC_INITIALIZER;
0037 atomic_t waiters_woken = ATOMIC_INITIALIZER;
0038
0039 futex_t f1 = FUTEX_INITIALIZER;
0040 futex_t f2 = FUTEX_INITIALIZER;
0041 futex_t wake_complete = FUTEX_INITIALIZER;
0042
0043 /* Test option defaults */
0044 static long timeout_ns;
0045 static int broadcast;
0046 static int owner;
0047 static int locked;
0048
0049 struct thread_arg {
0050     long id;
0051     struct timespec *timeout;
0052     int lock;
0053     int ret;
0054 };
0055 #define THREAD_ARG_INITIALIZER { 0, NULL, 0, 0 }
0056
0057 void usage(char *prog)
0058 {
0059     printf("Usage: %s\n", prog);
0060     printf("  -b    Broadcast wakeup (all waiters)\n");
0061     printf("  -c    Use color\n");
0062     printf("  -h    Display this help message\n");
0063     printf("  -l    Lock the pi futex across requeue\n");
0064     printf("  -o    Use a third party pi futex owner during requeue (cancels -l)\n");
0065     printf("  -t N  Timeout in nanoseconds (default: 0)\n");
0066     printf("  -v L  Verbosity level: %d=QUIET %d=CRITICAL %d=INFO\n",
0067            VQUIET, VCRITICAL, VINFO);
0068 }
0069
0070 int create_rt_thread(pthread_t *pth, void*(*func)(void *), void *arg,
0071              int policy, int prio)
0072 {
0073     int ret;
0074     struct sched_param schedp;
0075     pthread_attr_t attr;
0076
0077     pthread_attr_init(&attr);
0078     memset(&schedp, 0, sizeof(schedp));
0079
0080     ret = pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED);
0081     if (ret) {
0082         error("pthread_attr_setinheritsched\n", ret);
0083         return -1;
0084     }
0085
0086     ret = pthread_attr_setschedpolicy(&attr, policy);
0087     if (ret) {
0088         error("pthread_attr_setschedpolicy\n", ret);
0089         return -1;
0090     }
0091
0092     schedp.sched_priority = prio;
0093     ret = pthread_attr_setschedparam(&attr, &schedp);
0094     if (ret) {
0095         error("pthread_attr_setschedparam\n", ret);
0096         return -1;
0097     }
0098
0099     ret = pthread_create(pth, &attr, func, arg);
0100     if (ret) {
0101         error("pthread_create\n", ret);
0102         return -1;
0103     }
0104     return 0;
0105 }
0106
0107
0108 void *waiterfn(void *arg)
0109 {
0110     struct thread_arg *args = (struct thread_arg *)arg;
0111     futex_t old_val;
0112
0113     info("Waiter %ld: running\n", args->id);
0114     /* Each thread sleeps for a different amount of time
0115      * This is to avoid races, because we don't lock the
0116      * external mutex here */
0117     usleep(1000 * (long)args->id);
0118
0119     old_val = f1;
0120     atomic_inc(&waiters_blocked);
0121     info("Calling futex_wait_requeue_pi: %p (%u) -> %p\n",
0122          &f1, f1, &f2);
0123     args->ret = futex_wait_requeue_pi(&f1, old_val, &f2, args->timeout,
0124                       FUTEX_PRIVATE_FLAG);
0125
0126     info("waiter %ld woke with %d %s\n", args->id, args->ret,
0127          args->ret < 0 ? strerror(errno) : "");
0128     atomic_inc(&waiters_woken);
0129     if (args->ret < 0) {
0130         if (args->timeout && errno == ETIMEDOUT)
0131             args->ret = 0;
0132         else {
0133             args->ret = RET_ERROR;
0134             error("futex_wait_requeue_pi\n", errno);
0135         }
0136         futex_lock_pi(&f2, NULL, 0, FUTEX_PRIVATE_FLAG);
0137     }
0138     futex_unlock_pi(&f2, FUTEX_PRIVATE_FLAG);
0139
0140     info("Waiter %ld: exiting with %d\n", args->id, args->ret);
0141     pthread_exit((void *)&args->ret);
0142 }
0143
0144 void *broadcast_wakerfn(void *arg)
0145 {
0146     struct thread_arg *args = (struct thread_arg *)arg;
0147     int nr_requeue = INT_MAX;
0148     int task_count = 0;
0149     futex_t old_val;
0150     int nr_wake = 1;
0151     int i = 0;
0152
0153     info("Waker: waiting for waiters to block\n");
0154     while (waiters_blocked.val < THREAD_MAX)
0155         usleep(1000);
0156     usleep(1000);
0157
0158     info("Waker: Calling broadcast\n");
0159     if (args->lock) {
0160         info("Calling FUTEX_LOCK_PI on mutex=%x @ %p\n", f2, &f2);
0161         futex_lock_pi(&f2, NULL, 0, FUTEX_PRIVATE_FLAG);
0162     }
0163  continue_requeue:
0164     old_val = f1;
0165     args->ret = futex_cmp_requeue_pi(&f1, old_val, &f2, nr_wake, nr_requeue,
0166                    FUTEX_PRIVATE_FLAG);
0167     if (args->ret < 0) {
0168         args->ret = RET_ERROR;
0169         error("FUTEX_CMP_REQUEUE_PI failed\n", errno);
0170     } else if (++i < MAX_WAKE_ITERS) {
0171         task_count += args->ret;
0172         if (task_count < THREAD_MAX - waiters_woken.val)
0173             goto continue_requeue;
0174     } else {
0175         error("max broadcast iterations (%d) reached with %d/%d tasks woken or requeued\n",
0176                0, MAX_WAKE_ITERS, task_count, THREAD_MAX);
0177         args->ret = RET_ERROR;
0178     }
0179
0180     futex_wake(&wake_complete, 1, FUTEX_PRIVATE_FLAG);
0181
0182     if (args->lock)
0183         futex_unlock_pi(&f2, FUTEX_PRIVATE_FLAG);
0184
0185     if (args->ret > 0)
0186         args->ret = task_count;
0187
0188     info("Waker: exiting with %d\n", args->ret);
0189     pthread_exit((void *)&args->ret);
0190 }
0191
0192 void *signal_wakerfn(void *arg)
0193 {
0194     struct thread_arg *args = (struct thread_arg *)arg;
0195     unsigned int old_val;
0196     int nr_requeue = 0;
0197     int task_count = 0;
0198     int nr_wake = 1;
0199     int i = 0;
0200
0201     info("Waker: waiting for waiters to block\n");
0202     while (waiters_blocked.val < THREAD_MAX)
0203         usleep(1000);
0204     usleep(1000);
0205
0206     while (task_count < THREAD_MAX && waiters_woken.val < THREAD_MAX) {
0207         info("task_count: %d, waiters_woken: %d\n",
0208              task_count, waiters_woken.val);
0209         if (args->lock) {
0210             info("Calling FUTEX_LOCK_PI on mutex=%x @ %p\n",
0211                  f2, &f2);
0212             futex_lock_pi(&f2, NULL, 0, FUTEX_PRIVATE_FLAG);
0213         }
0214         info("Waker: Calling signal\n");
0215         /* cond_signal */
0216         old_val = f1;
0217         args->ret = futex_cmp_requeue_pi(&f1, old_val, &f2,
0218                          nr_wake, nr_requeue,
0219                          FUTEX_PRIVATE_FLAG);
0220         if (args->ret < 0)
0221             args->ret = -errno;
0222         info("futex: %x\n", f2);
0223         if (args->lock) {
0224             info("Calling FUTEX_UNLOCK_PI on mutex=%x @ %p\n",
0225                  f2, &f2);
0226             futex_unlock_pi(&f2, FUTEX_PRIVATE_FLAG);
0227         }
0228         info("futex: %x\n", f2);
0229         if (args->ret < 0) {
0230             error("FUTEX_CMP_REQUEUE_PI failed\n", errno);
0231             args->ret = RET_ERROR;
0232             break;
0233         }
0234
0235         task_count += args->ret;
0236         usleep(SIGNAL_PERIOD_US);
0237         i++;
0238         /* we have to loop at least THREAD_MAX times */
0239         if (i > MAX_WAKE_ITERS + THREAD_MAX) {
0240             error("max signaling iterations (%d) reached, giving up on pending waiters.\n",
0241                   0, MAX_WAKE_ITERS + THREAD_MAX);
0242             args->ret = RET_ERROR;
0243             break;
0244         }
0245     }
0246
0247     futex_wake(&wake_complete, 1, FUTEX_PRIVATE_FLAG);
0248
0249     if (args->ret >= 0)
0250         args->ret = task_count;
0251
0252     info("Waker: exiting with %d\n", args->ret);
0253     info("Waker: waiters_woken: %d\n", waiters_woken.val);
0254     pthread_exit((void *)&args->ret);
0255 }
0256
0257 void *third_party_blocker(void *arg)
0258 {
0259     struct thread_arg *args = (struct thread_arg *)arg;
0260     int ret2 = 0;
0261
0262     args->ret = futex_lock_pi(&f2, NULL, 0, FUTEX_PRIVATE_FLAG);
0263     if (args->ret)
0264         goto out;
0265     args->ret = futex_wait(&wake_complete, wake_complete, NULL,
0266                    FUTEX_PRIVATE_FLAG);
0267     ret2 = futex_unlock_pi(&f2, FUTEX_PRIVATE_FLAG);
0268
0269  out:
0270     if (args->ret || ret2) {
0271         error("third_party_blocker() futex error", 0);
0272         args->ret = RET_ERROR;
0273     }
0274
0275     pthread_exit((void *)&args->ret);
0276 }
0277
0278 int unit_test(int broadcast, long lock, int third_party_owner, long timeout_ns)
0279 {
0280     void *(*wakerfn)(void *) = signal_wakerfn;
0281     struct thread_arg blocker_arg = THREAD_ARG_INITIALIZER;
0282     struct thread_arg waker_arg = THREAD_ARG_INITIALIZER;
0283     pthread_t waiter[THREAD_MAX], waker, blocker;
0284     struct timespec ts, *tsp = NULL;
0285     struct thread_arg args[THREAD_MAX];
0286     int *waiter_ret;
0287     int i, ret = RET_PASS;
0288
0289     if (timeout_ns) {
0290         time_t secs;
0291
0292         info("timeout_ns = %ld\n", timeout_ns);
0293         ret = clock_gettime(CLOCK_MONOTONIC, &ts);
0294         secs = (ts.tv_nsec + timeout_ns) / 1000000000;
0295         ts.tv_nsec = ((int64_t)ts.tv_nsec + timeout_ns) % 1000000000;
0296         ts.tv_sec += secs;
0297         info("ts.tv_sec  = %ld\n", ts.tv_sec);
0298         info("ts.tv_nsec = %ld\n", ts.tv_nsec);
0299         tsp = &ts;
0300     }
0301
0302     if (broadcast)
0303         wakerfn = broadcast_wakerfn;
0304
0305     if (third_party_owner) {
0306         if (create_rt_thread(&blocker, third_party_blocker,
0307                      (void *)&blocker_arg, SCHED_FIFO, 1)) {
0308             error("Creating third party blocker thread failed\n",
0309                   errno);
0310             ret = RET_ERROR;
0311             goto out;
0312         }
0313     }
0314
0315     atomic_set(&waiters_woken, 0);
0316     for (i = 0; i < THREAD_MAX; i++) {
0317         args[i].id = i;
0318         args[i].timeout = tsp;
0319         info("Starting thread %d\n", i);
0320         if (create_rt_thread(&waiter[i], waiterfn, (void *)&args[i],
0321                      SCHED_FIFO, 1)) {
0322             error("Creating waiting thread failed\n", errno);
0323             ret = RET_ERROR;
0324             goto out;
0325         }
0326     }
0327     waker_arg.lock = lock;
0328     if (create_rt_thread(&waker, wakerfn, (void *)&waker_arg,
0329                  SCHED_FIFO, 1)) {
0330         error("Creating waker thread failed\n", errno);
0331         ret = RET_ERROR;
0332         goto out;
0333     }
0334
0335     /* Wait for threads to finish */
0336     /* Store the first error or failure encountered in waiter_ret */
0337     waiter_ret = &args[0].ret;
0338     for (i = 0; i < THREAD_MAX; i++)
0339         pthread_join(waiter[i],
0340                  *waiter_ret ? NULL : (void **)&waiter_ret);
0341
0342     if (third_party_owner)
0343         pthread_join(blocker, NULL);
0344     pthread_join(waker, NULL);
0345
0346 out:
0347     if (!ret) {
0348         if (*waiter_ret)
0349             ret = *waiter_ret;
0350         else if (waker_arg.ret < 0)
0351             ret = waker_arg.ret;
0352         else if (blocker_arg.ret)
0353             ret = blocker_arg.ret;
0354     }
0355
0356     return ret;
0357 }
0358
0359 int main(int argc, char *argv[])
0360 {
0361     int c, ret;
0362
0363     while ((c = getopt(argc, argv, "bchlot:v:")) != -1) {
0364         switch (c) {
0365         case 'b':
0366             broadcast = 1;
0367             break;
0368         case 'c':
0369             log_color(1);
0370             break;
0371         case 'h':
0372             usage(basename(argv[0]));
0373             exit(0);
0374         case 'l':
0375             locked = 1;
0376             break;
0377         case 'o':
0378             owner = 1;
0379             locked = 0;
0380             break;
0381         case 't':
0382             timeout_ns = atoi(optarg);
0383             break;
0384         case 'v':
0385             log_verbosity(atoi(optarg));
0386             break;
0387         default:
0388             usage(basename(argv[0]));
0389             exit(1);
0390         }
0391     }
0392
0393     ksft_print_header();
0394     ksft_set_plan(1);
0395     ksft_print_msg("%s: Test requeue functionality\n", basename(argv[0]));
0396     ksft_print_msg(
0397         "\tArguments: broadcast=%d locked=%d owner=%d timeout=%ldns\n",
0398         broadcast, locked, owner, timeout_ns);
0399
0400     /*
0401      * FIXME: unit_test is obsolete now that we parse options and the
0402      * various style of runs are done by run.sh - simplify the code and move
0403      * unit_test into main()
0404      */
0405     ret = unit_test(broadcast, locked, owner, timeout_ns);
0406
0407     print_result(TEST_NAME, ret);
0408     return ret;
0409 }