selftests: futex2: Add requeue test

Add testing for futex_requeue(). The first test just requeue from one
waiter to another one, and wake it. The second performs both wake and
requeue, and we check return values to see if the operation
woke/requeued the expected number of waiters.

Signed-off-by: André Almeida <andrealmeid@collabora.com>

tools/testing/selftests/futex/functional/.gitignore

@@ -8,3 +8,4 @@ futex_wait_uninitialized_heap
 futex_wait_wouldblock
 futex2_wait
 futex2_waitv
+futex2_requeue

tools/testing/selftests/futex/functional/Makefile

@@ -17,7 +17,8 @@ TEST_GEN_FILES := \
 	futex_wait_uninitialized_heap \
 	futex_wait_private_mapped_file \
 	futex2_wait \
-	futex2_waitv
+	futex2_waitv \
+	futex2_requeue
 
 TEST_PROGS := run.sh
 

tools/testing/selftests/futex/functional/futex2_requeue.c

@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/******************************************************************************
+ *
+ *   Copyright Collabora Ltd., 2021
+ *
+ * DESCRIPTION
+ *	Test requeue mechanism of futex2, using 32bit sized futexes.
+ *
+ * AUTHOR
+ *	André Almeida <andrealmeid@collabora.com>
+ *
+ * HISTORY
+ *      2021-Feb-5: Initial version by André <andrealmeid@collabora.com>
+ *
+ *****************************************************************************/
+
+#include <errno.h>
+#include <error.h>
+#include <getopt.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <pthread.h>
+#include <sys/shm.h>
+#include <limits.h>
+#include "futex2test.h"
+#include "logging.h"
+
+#define TEST_NAME "futex2-wait"
+#define timeout_ns  30000000
+#define WAKE_WAIT_US 10000
+volatile futex_t *f1;
+
+void usage(char *prog)
+{
+	printf("Usage: %s\n", prog);
+	printf("  -c	Use color\n");
+	printf("  -h	Display this help message\n");
+	printf("  -v L	Verbosity level: %d=QUIET %d=CRITICAL %d=INFO\n",
+	       VQUIET, VCRITICAL, VINFO);
+}
+
+void *waiterfn(void *arg)
+{
+	struct timespec64 to64;
+
+	/* setting absolute timeout for futex2 */
+	if (gettime64(CLOCK_MONOTONIC, &to64))
+		error("gettime64 failed\n", errno);
+
+	to64.tv_nsec += timeout_ns;
+
+	if (to64.tv_nsec >= 1000000000) {
+		to64.tv_sec++;
+		to64.tv_nsec -= 1000000000;
+	}
+
+	if (futex2_wait(f1, *f1, FUTEX_32, &to64))
+		printf("waiter failed errno %d\n", errno);
+
+	return NULL;
+}
+
+int main(int argc, char *argv[])
+{
+	pthread_t waiter[10];
+	int res, ret = RET_PASS;
+	int c, i;
+	volatile futex_t _f1 = 0;
+	volatile futex_t f2 = 0;
+	struct futex_requeue r1, r2;
+
+	f1 = &_f1;
+
+	r1.flags = FUTEX_32;
+	r2.flags = FUTEX_32;
+
+	r1.uaddr = f1;
+	r2.uaddr = &f2;
+
+	while ((c = getopt(argc, argv, "cht:v:")) != -1) {
+		switch (c) {
+		case 'c':
+			log_color(1);
+			break;
+		case 'h':
+			usage(basename(argv[0]));
+			exit(0);
+		case 'v':
+			log_verbosity(atoi(optarg));
+			break;
+		default:
+			usage(basename(argv[0]));
+			exit(1);
+		}
+	}
+
+	ksft_print_header();
+	ksft_set_plan(2);
+	ksft_print_msg("%s: Test FUTEX2_REQUEUE\n",
+		       basename(argv[0]));
+
+	/*
+	 * Requeue a waiter from f1 to f2, and wake f2.
+	 */
+	if (pthread_create(&waiter[0], NULL, waiterfn, NULL))
+		error("pthread_create failed\n", errno);
+
+	usleep(WAKE_WAIT_US);
+
+	res = futex2_requeue(&r1, &r2, 0, 1, 0, 0);
+	if (res != 1) {
+		ksft_test_result_fail("futex2_requeue private returned: %d %s\n",
+				      res ? errno : res,
+				      res ? strerror(errno) : "");
+		ret = RET_FAIL;
+	}
+
+
+	info("Calling private futex2_wake on f2: %u @ %p with val=%u\n", f2, &f2, f2);
+	res = futex2_wake(&f2, 1, FUTEX_32);
+	if (res != 1) {
+		ksft_test_result_fail("futex2_requeue private returned: %d %s\n",
+				      res ? errno : res,
+				      res ? strerror(errno) : "");
+		ret = RET_FAIL;
+	} else {
+		ksft_test_result_pass("futex2_requeue simple succeeds\n");
+	}
+
+
+	/*
+	 * Create 10 waiters at f1. At futex_requeue, wake 3 and requeue 7.
+	 * At futex_wake, wake INT_MAX (should be exaclty 7).
+	 */
+	for (i = 0; i < 10; i++) {
+		if (pthread_create(&waiter[i], NULL, waiterfn, NULL))
+			error("pthread_create failed\n", errno);
+	}
+
+	usleep(WAKE_WAIT_US);
+
+	res = futex2_requeue(&r1, &r2, 3, 7, 0, 0);
+	if (res != 10) {
+		ksft_test_result_fail("futex2_requeue private returned: %d %s\n",
+				      res ? errno : res,
+				      res ? strerror(errno) : "");
+		ret = RET_FAIL;
+	}
+
+	res = futex2_wake(&f2, INT_MAX, FUTEX_32);
+	if (res != 7) {
+		ksft_test_result_fail("futex2_requeue private returned: %d %s\n",
+				      res ? errno : res,
+				      res ? strerror(errno) : "");
+		ret = RET_FAIL;
+	} else {
+		ksft_test_result_pass("futex2_requeue succeeds\n");
+	}
+
+	ksft_print_cnts();
+	return ret;
+}

tools/testing/selftests/futex/include/futex2test.h

@@ -103,3 +103,19 @@ static inline int futex2_waitv(volatile struct futex_waitv *waiters, unsigned lo
 {
 	return syscall(__NR_futex_waitv, waiters, nr_waiters, flags, timo);
 }
+
+/**
+ * futex2_requeue - Wake futexes at uaddr1 and requeue from uaddr1 to uaddr2
+ * @uaddr1:     Original address to wake and requeue from
+ * @uaddr2:     Address to requeue to
+ * @nr_wake:    Number of futexes to wake at uaddr1 before requeuing
+ * @nr_requeue: Number of futexes to requeue from uaddr1 to uaddr2
+ * @cmpval:     If (uaddr1->uaddr != cmpval), return immediatally
+ * @flgas:      Operation flags
+ */
+static inline int futex2_requeue(struct futex_requeue *uaddr1, struct futex_requeue *uaddr2,
+				 unsigned int nr_wake, unsigned int nr_requeue,
+				 unsigned int cmpval, unsigned long flags)
+{
+	return syscall(__NR_futex_requeue, uaddr1, uaddr2, nr_wake, nr_requeue, cmpval, flags);
+}