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Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
selftests: futex: Add futex wait test
There are three different strategies to uniquely identify a futex in the
kernel:
- Private futexes: uses the pointer to mm_struct and the page address
- Shared futexes: checks if the page containing the address is a PageAnon:
- If it is, uses the same data as a private futexes
- If it isn't, uses an inode sequence number from struct inode and
the page's index
Create a selftest to check those three paths and basic wait/wake
mechanism.
Signed-off-by: André Almeida <andrealmeid@collabora.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Link: https://lore.kernel.org/r/20210531165036.41468-2-andrealmeid@collabora.com
authored by
André Almeida
and committed by
Thomas Gleixner
c3d12858
149876d9
+177
-1
+1
tools/testing/selftests/futex/functional/.gitignore
+1
tools/testing/selftests/futex/functional/.gitignore
+2
-1
tools/testing/selftests/futex/functional/Makefile
+2
-1
tools/testing/selftests/futex/functional/Makefile
+171
tools/testing/selftests/futex/functional/futex_wait.c
+171
tools/testing/selftests/futex/functional/futex_wait.c
···
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright Collabora Ltd., 2021
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*
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* futex cmp requeue test by André Almeida <andrealmeid@collabora.com>
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*/
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#include <pthread.h>
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#include <sys/shm.h>
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#include <sys/mman.h>
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#include <fcntl.h>
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#include "logging.h"
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#include "futextest.h"
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#define TEST_NAME "futex-wait"
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#define timeout_ns 30000000
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#define WAKE_WAIT_US 10000
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#define SHM_PATH "futex_shm_file"
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void *futex;
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void usage(char *prog)
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{
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printf("Usage: %s\n", prog);
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printf(" -c Use color\n");
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printf(" -h Display this help message\n");
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printf(" -v L Verbosity level: %d=QUIET %d=CRITICAL %d=INFO\n",
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VQUIET, VCRITICAL, VINFO);
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}
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static void *waiterfn(void *arg)
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{
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struct timespec to;
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unsigned int flags = 0;
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if (arg)
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flags = *((unsigned int *) arg);
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to.tv_sec = 0;
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to.tv_nsec = timeout_ns;
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if (futex_wait(futex, 0, &to, flags))
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printf("waiter failed errno %d\n", errno);
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return NULL;
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}
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int main(int argc, char *argv[])
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{
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int res, ret = RET_PASS, fd, c, shm_id;
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u_int32_t f_private = 0, *shared_data;
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unsigned int flags = FUTEX_PRIVATE_FLAG;
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pthread_t waiter;
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void *shm;
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futex = &f_private;
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while ((c = getopt(argc, argv, "cht:v:")) != -1) {
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switch (c) {
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case 'c':
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log_color(1);
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break;
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case 'h':
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usage(basename(argv[0]));
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exit(0);
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case 'v':
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log_verbosity(atoi(optarg));
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break;
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default:
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usage(basename(argv[0]));
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exit(1);
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}
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}
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ksft_print_header();
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ksft_set_plan(3);
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ksft_print_msg("%s: Test futex_wait\n", basename(argv[0]));
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/* Testing a private futex */
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info("Calling private futex_wait on futex: %p\n", futex);
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if (pthread_create(&waiter, NULL, waiterfn, (void *) &flags))
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error("pthread_create failed\n", errno);
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usleep(WAKE_WAIT_US);
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info("Calling private futex_wake on futex: %p\n", futex);
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res = futex_wake(futex, 1, FUTEX_PRIVATE_FLAG);
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if (res != 1) {
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ksft_test_result_fail("futex_wake private returned: %d %s\n",
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errno, strerror(errno));
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ret = RET_FAIL;
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} else {
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ksft_test_result_pass("futex_wake private succeeds\n");
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}
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/* Testing an anon page shared memory */
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shm_id = shmget(IPC_PRIVATE, 4096, IPC_CREAT | 0666);
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if (shm_id < 0) {
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perror("shmget");
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exit(1);
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}
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shared_data = shmat(shm_id, NULL, 0);
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*shared_data = 0;
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futex = shared_data;
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info("Calling shared (page anon) futex_wait on futex: %p\n", futex);
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if (pthread_create(&waiter, NULL, waiterfn, NULL))
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error("pthread_create failed\n", errno);
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usleep(WAKE_WAIT_US);
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info("Calling shared (page anon) futex_wake on futex: %p\n", futex);
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res = futex_wake(futex, 1, 0);
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if (res != 1) {
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ksft_test_result_fail("futex_wake shared (page anon) returned: %d %s\n",
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errno, strerror(errno));
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ret = RET_FAIL;
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} else {
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ksft_test_result_pass("futex_wake shared (page anon) succeeds\n");
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}
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/* Testing a file backed shared memory */
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fd = open(SHM_PATH, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
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if (fd < 0) {
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perror("open");
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exit(1);
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}
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if (ftruncate(fd, sizeof(f_private))) {
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perror("ftruncate");
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exit(1);
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}
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shm = mmap(NULL, sizeof(f_private), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
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if (shm == MAP_FAILED) {
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perror("mmap");
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exit(1);
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}
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memcpy(shm, &f_private, sizeof(f_private));
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futex = shm;
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info("Calling shared (file backed) futex_wait on futex: %p\n", futex);
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if (pthread_create(&waiter, NULL, waiterfn, NULL))
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error("pthread_create failed\n", errno);
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usleep(WAKE_WAIT_US);
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info("Calling shared (file backed) futex_wake on futex: %p\n", futex);
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res = futex_wake(shm, 1, 0);
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if (res != 1) {
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ksft_test_result_fail("futex_wake shared (file backed) returned: %d %s\n",
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errno, strerror(errno));
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ret = RET_FAIL;
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} else {
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ksft_test_result_pass("futex_wake shared (file backed) succeeds\n");
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}
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/* Freeing resources */
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shmdt(shared_data);
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munmap(shm, sizeof(f_private));
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remove(SHM_PATH);
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close(fd);
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ksft_print_cnts();
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return ret;
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}