[PATCH 0/2] selftests: futex: Improve timeout testing

[PATCH 0/2] selftests: futex: Improve timeout testing

[André Almeida]

This small series expands futex timeout selftests by checking if all
operations that allows timeouts works as expected. When some version of
Thomas' series "futex: Bugfixes and FUTEX_LOCK_PI2"[0] get merged, I'll
add the new rules to the timeout test. This test should be used to check
for regressions when modifying the timeout path or changing the
interface.

Additionally, fix a bug in the Makefile that can be found when compiling
selftests with new operations, like the one defined at [0] or from the
futex2 patchset.

[0] https://lore.kernel.org/lkml/20210422194417.866740847@linutronix.de/

André Almeida (2):
  selftests: futex: Correctly include headers dirs
  selftests: futex: Expand timeout test

 .../selftests/futex/functional/Makefile       |   3 +-
 .../futex/functional/futex_wait_timeout.c     | 126 +++++++++++++++---
 2 files changed, 112 insertions(+), 17 deletions(-)

-- 
2.31.1

[PATCH 1/2] selftests: futex: Correctly include headers dirs

[André Almeida]

When building selftests, the build system will install uapi linux
headers at usr/include in kernel source's root directory. When building
with a different output folder, the headers will be installed at
kselftests/usr/include. Add both paths so we can build the tests using
up-to-date headers. Currently, this is uncommon to happen since it's
rare to find a build system with an outdated futex header, but it
happens when testing new futex operations.

Signed-off-by: André Almeida <andrealmeid@collabora.com>
---
 tools/testing/selftests/futex/functional/Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/futex/functional/Makefile b/tools/testing/selftests/futex/functional/Makefile
index 23207829ec75..1d2b3b2a5b86 100644
--- a/tools/testing/selftests/futex/functional/Makefile
+++ b/tools/testing/selftests/futex/functional/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
-INCLUDES := -I../include -I../../
+INCLUDES := -I../include -I../../ -I../../../../../usr/include/ \
+	-I$(KBUILD_OUTPUT)/kselftest/usr/include
 CFLAGS := $(CFLAGS) -g -O2 -Wall -D_GNU_SOURCE -pthread $(INCLUDES)
 LDLIBS := -lpthread -lrt
 
-- 
2.31.1

[PATCH 2/2] selftests: futex: Expand timeout test

[André Almeida]

Improve futex timeout testing by checking all the operations that
supports timeout and their available modes.

Signed-off-by: André Almeida <andrealmeid@collabora.com>
---
 .../futex/functional/futex_wait_timeout.c     | 126 +++++++++++++++---
 1 file changed, 110 insertions(+), 16 deletions(-)

diff --git a/tools/testing/selftests/futex/functional/futex_wait_timeout.c b/tools/testing/selftests/futex/functional/futex_wait_timeout.c
index ee55e6d389a3..1f8f6daaf1e7 100644
--- a/tools/testing/selftests/futex/functional/futex_wait_timeout.c
+++ b/tools/testing/selftests/futex/functional/futex_wait_timeout.c
@@ -11,21 +11,18 @@
  *
  * HISTORY
  *      2009-Nov-6: Initial version by Darren Hart <dvhart@linux.intel.com>
+ *      2021-Apr-26: More test cases by André Almeida <andrealmeid@collabora.com>
  *
  *****************************************************************************/
 
-#include <errno.h>
-#include <getopt.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <time.h>
+#include <pthread.h>
 #include "futextest.h"
 #include "logging.h"
 
 #define TEST_NAME "futex-wait-timeout"
 
 static long timeout_ns = 100000;	/* 100us default timeout */
+static futex_t futex_pi;
 
 void usage(char *prog)
 {
@@ -37,11 +34,67 @@ void usage(char *prog)
 	       VQUIET, VCRITICAL, VINFO);
 }
 
+/*
+ * Get a PI lock and hold it forever, so the main thread lock_pi will block
+ * and we can test the timeout
+ */
+void *get_pi_lock(void *arg)
+{
+	int ret;
+	volatile futex_t lock = 0;
+
+	ret = futex_lock_pi(&futex_pi, NULL, 0, 0);
+	if (ret != 0)
+		error("futex_lock_pi failed\n", ret);
+
+	/* Blocks forever */
+	ret = futex_wait(&lock, 0, NULL, 0);
+	error("futex_wait failed\n", ret);
+
+	return NULL;
+}
+
+/*
+ * Check if the function returned the expected error
+ */
+static void test_timeout(int res, int *ret, char *test_name, int err)
+{
+	if (!res || errno != err) {
+		ksft_test_result_fail("%s returned %d\n", test_name,
+				      res < 0 ? errno : res);
+		*ret = RET_FAIL;
+	} else {
+		ksft_test_result_pass("%s succeeds\n", test_name);
+	}
+}
+
+/*
+ * Calculate absolute timeout and correct overflow
+ */
+static int futex_get_abs_timeout(clockid_t clockid, struct timespec *to,
+				 long timeout_ns)
+{
+	if (clock_gettime(clockid, to)) {
+		error("clock_gettime failed\n", errno);
+		return errno;
+	}
+
+	to->tv_nsec += timeout_ns;
+
+	if (to->tv_nsec >= 1000000000) {
+		to->tv_sec++;
+		to->tv_nsec -= 1000000000;
+	}
+
+	return 0;
+}
+
 int main(int argc, char *argv[])
 {
 	futex_t f1 = FUTEX_INITIALIZER;
-	struct timespec to;
 	int res, ret = RET_PASS;
+	struct timespec to;
+	pthread_t thread;
 	int c;
 
 	while ((c = getopt(argc, argv, "cht:v:")) != -1) {
@@ -65,22 +118,63 @@ int main(int argc, char *argv[])
 	}
 
 	ksft_print_header();
-	ksft_set_plan(1);
+	ksft_set_plan(7);
 	ksft_print_msg("%s: Block on a futex and wait for timeout\n",
 	       basename(argv[0]));
 	ksft_print_msg("\tArguments: timeout=%ldns\n", timeout_ns);
 
-	/* initialize timeout */
+	pthread_create(&thread, NULL, get_pi_lock, NULL);
+
+	/* initialize relative timeout */
 	to.tv_sec = 0;
 	to.tv_nsec = timeout_ns;
 
-	info("Calling futex_wait on f1: %u @ %p\n", f1, &f1);
-	res = futex_wait(&f1, f1, &to, FUTEX_PRIVATE_FLAG);
-	if (!res || errno != ETIMEDOUT) {
-		fail("futex_wait returned %d\n", ret < 0 ? errno : ret);
-		ret = RET_FAIL;
-	}
+	res = futex_wait(&f1, f1, &to, 0);
+	test_timeout(res, &ret, "futex_wait relative", ETIMEDOUT);
+
+	/* FUTEX_WAIT_BITSET with CLOCK_REALTIME */
+	if (futex_get_abs_timeout(CLOCK_REALTIME, &to, timeout_ns))
+		return RET_FAIL;
+	res = futex_wait_bitset(&f1, f1, &to, 1, FUTEX_CLOCK_REALTIME);
+	test_timeout(res, &ret, "futex_wait_bitset realtime", ETIMEDOUT);
+
+	/* FUTEX_WAIT_BITSET with CLOCK_MONOTONIC */
+	if (futex_get_abs_timeout(CLOCK_MONOTONIC, &to, timeout_ns))
+		return RET_FAIL;
+	res = futex_wait_bitset(&f1, f1, &to, 1, 0);
+	test_timeout(res, &ret, "futex_wait_bitset monotonic", ETIMEDOUT);
+
+	/* FUTEX_WAIT_REQUEUE_PI with CLOCK_REALTIME */
+	if (futex_get_abs_timeout(CLOCK_REALTIME, &to, timeout_ns))
+		return RET_FAIL;
+	res = futex_wait_requeue_pi(&f1, f1, &futex_pi, &to, FUTEX_CLOCK_REALTIME);
+	test_timeout(res, &ret, "futex_wait_requeue_pi realtime", ETIMEDOUT);
+
+	/* FUTEX_WAIT_REQUEUE_PI with CLOCK_MONOTONIC */
+	if (futex_get_abs_timeout(CLOCK_MONOTONIC, &to, timeout_ns))
+		return RET_FAIL;
+	res = futex_wait_requeue_pi(&f1, f1, &futex_pi, &to, 0);
+	test_timeout(res, &ret, "futex_wait_requeue_pi monotonic", ETIMEDOUT);
+
+	/*
+	 * FUTEX_LOCK_PI with CLOCK_REALTIME
+	 * Due to historical reasons, FUTEX_LOCK_PI supports only realtime
+	 * clock, but requires the caller to not set CLOCK_REALTIME flag.
+	 *
+	 * If you call FUTEX_LOCK_PI with a monotonic clock, it'll be
+	 * interpreted as a realtime clock, and (unless you mess your machine's
+	 * time or your time machine) the monotonic clock value is always
+	 * smaller than realtime and the syscall will timeout immediately.
+	 */
+	if (futex_get_abs_timeout(CLOCK_REALTIME, &to, timeout_ns))
+		return RET_FAIL;
+	res = futex_lock_pi(&futex_pi, &to, 0, 0);
+	test_timeout(res, &ret, "futex_lock_pi realtime", ETIMEDOUT);
+
+	/* Test operations that don't support FUTEX_CLOCK_REALTIME */
+	res = futex_lock_pi(&futex_pi, NULL, 0, FUTEX_CLOCK_REALTIME);
+	test_timeout(res, &ret, "futex_lock_pi invalid timeout flag", ENOSYS);
 
-	print_result(TEST_NAME, ret);
+	ksft_print_cnts();
 	return ret;
 }
-- 
2.31.1

[tip: locking/core] selftests: futex: Expand timeout test

[tip-bot2 for André Almeida]

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     f4addd54b1617067f735ad194a3580a2db7b8bf5
Gitweb:        https://git.kernel.org/tip/f4addd54b1617067f735ad194a3580a2db7b8bf5
Author:        André Almeida <andrealmeid@collabora.com>
AuthorDate:    Tue, 27 Apr 2021 10:53:28 -03:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Wed, 12 May 2021 20:44:59 +02:00

selftests: futex: Expand timeout test

Improve futex timeout testing by checking all the operations that
supports timeout and their available modes.

Signed-off-by: André Almeida <andrealmeid@collabora.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210427135328.11013-3-andrealmeid@collabora.com
---
 tools/testing/selftests/futex/functional/futex_wait_timeout.c | 126 ++++++-
 1 file changed, 110 insertions(+), 16 deletions(-)

diff --git a/tools/testing/selftests/futex/functional/futex_wait_timeout.c b/tools/testing/selftests/futex/functional/futex_wait_timeout.c
index ee55e6d..1f8f6da 100644
--- a/tools/testing/selftests/futex/functional/futex_wait_timeout.c
+++ b/tools/testing/selftests/futex/functional/futex_wait_timeout.c
@@ -11,21 +11,18 @@
  *
  * HISTORY
  *      2009-Nov-6: Initial version by Darren Hart <dvhart@linux.intel.com>
+ *      2021-Apr-26: More test cases by André Almeida <andrealmeid@collabora.com>
  *
  *****************************************************************************/
 
-#include <errno.h>
-#include <getopt.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <time.h>
+#include <pthread.h>
 #include "futextest.h"
 #include "logging.h"
 
 #define TEST_NAME "futex-wait-timeout"
 
 static long timeout_ns = 100000;	/* 100us default timeout */
+static futex_t futex_pi;
 
 void usage(char *prog)
 {
@@ -37,11 +34,67 @@ void usage(char *prog)
 	       VQUIET, VCRITICAL, VINFO);
 }
 
+/*
+ * Get a PI lock and hold it forever, so the main thread lock_pi will block
+ * and we can test the timeout
+ */
+void *get_pi_lock(void *arg)
+{
+	int ret;
+	volatile futex_t lock = 0;
+
+	ret = futex_lock_pi(&futex_pi, NULL, 0, 0);
+	if (ret != 0)
+		error("futex_lock_pi failed\n", ret);
+
+	/* Blocks forever */
+	ret = futex_wait(&lock, 0, NULL, 0);
+	error("futex_wait failed\n", ret);
+
+	return NULL;
+}
+
+/*
+ * Check if the function returned the expected error
+ */
+static void test_timeout(int res, int *ret, char *test_name, int err)
+{
+	if (!res || errno != err) {
+		ksft_test_result_fail("%s returned %d\n", test_name,
+				      res < 0 ? errno : res);
+		*ret = RET_FAIL;
+	} else {
+		ksft_test_result_pass("%s succeeds\n", test_name);
+	}
+}
+
+/*
+ * Calculate absolute timeout and correct overflow
+ */
+static int futex_get_abs_timeout(clockid_t clockid, struct timespec *to,
+				 long timeout_ns)
+{
+	if (clock_gettime(clockid, to)) {
+		error("clock_gettime failed\n", errno);
+		return errno;
+	}
+
+	to->tv_nsec += timeout_ns;
+
+	if (to->tv_nsec >= 1000000000) {
+		to->tv_sec++;
+		to->tv_nsec -= 1000000000;
+	}
+
+	return 0;
+}
+
 int main(int argc, char *argv[])
 {
 	futex_t f1 = FUTEX_INITIALIZER;
-	struct timespec to;
 	int res, ret = RET_PASS;
+	struct timespec to;
+	pthread_t thread;
 	int c;
 
 	while ((c = getopt(argc, argv, "cht:v:")) != -1) {
@@ -65,22 +118,63 @@ int main(int argc, char *argv[])
 	}
 
 	ksft_print_header();
-	ksft_set_plan(1);
+	ksft_set_plan(7);
 	ksft_print_msg("%s: Block on a futex and wait for timeout\n",
 	       basename(argv[0]));
 	ksft_print_msg("\tArguments: timeout=%ldns\n", timeout_ns);
 
-	/* initialize timeout */
+	pthread_create(&thread, NULL, get_pi_lock, NULL);
+
+	/* initialize relative timeout */
 	to.tv_sec = 0;
 	to.tv_nsec = timeout_ns;
 
-	info("Calling futex_wait on f1: %u @ %p\n", f1, &f1);
-	res = futex_wait(&f1, f1, &to, FUTEX_PRIVATE_FLAG);
-	if (!res || errno != ETIMEDOUT) {
-		fail("futex_wait returned %d\n", ret < 0 ? errno : ret);
-		ret = RET_FAIL;
-	}
+	res = futex_wait(&f1, f1, &to, 0);
+	test_timeout(res, &ret, "futex_wait relative", ETIMEDOUT);
+
+	/* FUTEX_WAIT_BITSET with CLOCK_REALTIME */
+	if (futex_get_abs_timeout(CLOCK_REALTIME, &to, timeout_ns))
+		return RET_FAIL;
+	res = futex_wait_bitset(&f1, f1, &to, 1, FUTEX_CLOCK_REALTIME);
+	test_timeout(res, &ret, "futex_wait_bitset realtime", ETIMEDOUT);
+
+	/* FUTEX_WAIT_BITSET with CLOCK_MONOTONIC */
+	if (futex_get_abs_timeout(CLOCK_MONOTONIC, &to, timeout_ns))
+		return RET_FAIL;
+	res = futex_wait_bitset(&f1, f1, &to, 1, 0);
+	test_timeout(res, &ret, "futex_wait_bitset monotonic", ETIMEDOUT);
+
+	/* FUTEX_WAIT_REQUEUE_PI with CLOCK_REALTIME */
+	if (futex_get_abs_timeout(CLOCK_REALTIME, &to, timeout_ns))
+		return RET_FAIL;
+	res = futex_wait_requeue_pi(&f1, f1, &futex_pi, &to, FUTEX_CLOCK_REALTIME);
+	test_timeout(res, &ret, "futex_wait_requeue_pi realtime", ETIMEDOUT);
+
+	/* FUTEX_WAIT_REQUEUE_PI with CLOCK_MONOTONIC */
+	if (futex_get_abs_timeout(CLOCK_MONOTONIC, &to, timeout_ns))
+		return RET_FAIL;
+	res = futex_wait_requeue_pi(&f1, f1, &futex_pi, &to, 0);
+	test_timeout(res, &ret, "futex_wait_requeue_pi monotonic", ETIMEDOUT);
+
+	/*
+	 * FUTEX_LOCK_PI with CLOCK_REALTIME
+	 * Due to historical reasons, FUTEX_LOCK_PI supports only realtime
+	 * clock, but requires the caller to not set CLOCK_REALTIME flag.
+	 *
+	 * If you call FUTEX_LOCK_PI with a monotonic clock, it'll be
+	 * interpreted as a realtime clock, and (unless you mess your machine's
+	 * time or your time machine) the monotonic clock value is always
+	 * smaller than realtime and the syscall will timeout immediately.
+	 */
+	if (futex_get_abs_timeout(CLOCK_REALTIME, &to, timeout_ns))
+		return RET_FAIL;
+	res = futex_lock_pi(&futex_pi, &to, 0, 0);
+	test_timeout(res, &ret, "futex_lock_pi realtime", ETIMEDOUT);
+
+	/* Test operations that don't support FUTEX_CLOCK_REALTIME */
+	res = futex_lock_pi(&futex_pi, NULL, 0, FUTEX_CLOCK_REALTIME);
+	test_timeout(res, &ret, "futex_lock_pi invalid timeout flag", ENOSYS);
 
-	print_result(TEST_NAME, ret);
+	ksft_print_cnts();
 	return ret;
 }

[tip: locking/core] selftests: futex: Correctly include headers dirs

[tip-bot2 for André Almeida]

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     c7d84e7ff5a651d186a6ec41361c4f07acc2fb9c
Gitweb:        https://git.kernel.org/tip/c7d84e7ff5a651d186a6ec41361c4f07acc2fb9c
Author:        André Almeida <andrealmeid@collabora.com>
AuthorDate:    Tue, 27 Apr 2021 10:53:27 -03:00
Committer:     Ingo Molnar <mingo@kernel.org>
CommitterDate: Wed, 12 May 2021 20:44:58 +02:00

selftests: futex: Correctly include headers dirs

When building selftests, the build system will install uapi linux
headers at usr/include in kernel source's root directory. When building
with a different output folder, the headers will be installed at
kselftests/usr/include.

Add both paths so we can build the tests using up-to-date headers.

Currently, this is uncommon to happen since it's rare to find a
build system with an outdated futex header, but it happens
when testing new futex operations.

Signed-off-by: André Almeida <andrealmeid@collabora.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210427135328.11013-2-andrealmeid@collabora.com
---
 tools/testing/selftests/futex/functional/Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/futex/functional/Makefile b/tools/testing/selftests/futex/functional/Makefile
index 2320782..1d2b3b2 100644
--- a/tools/testing/selftests/futex/functional/Makefile
+++ b/tools/testing/selftests/futex/functional/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
-INCLUDES := -I../include -I../../
+INCLUDES := -I../include -I../../ -I../../../../../usr/include/ \
+	-I$(KBUILD_OUTPUT)/kselftest/usr/include
 CFLAGS := $(CFLAGS) -g -O2 -Wall -D_GNU_SOURCE -pthread $(INCLUDES)
 LDLIBS := -lpthread -lrt