[PATCH 0/2] ntsync: docs uAPI fixup and timens selftest

[PATCH 0/2] ntsync: docs uAPI fixup and timens selftest

[Iván Ezequiel Rodriguez]

Short series for ntsync:

1/2 docs: align ioctl macro names and struct field order in
   Documentation/userspace-api/ntsync.rst with include/uapi/linux/ntsync.h,
   and note that absolute MONOTONIC timeouts use the caller's time namespace.

2/2 selftests: add wait_any_monotonic_timens to lock in the timens
   conversion in ntsync_schedule() (negative CLOCK_MONOTONIC offset must
   not make a 100 ms absolute wait return immediately).

No driver code changes.


Iván Ezequiel Rodriguez (2):
  docs: ntsync: align ioctl names and struct layouts with uapi
  selftests: ntsync: test absolute MONOTONIC waits under time namespaces

 Documentation/userspace-api/ntsync.rst        | 33 +++----
 .../testing/selftests/drivers/ntsync/ntsync.c | 87 +++++++++++++++++++
 2 files changed, 104 insertions(+), 16 deletions(-)

-- 
2.43.0

[PATCH 1/2] docs: ntsync: align ioctl names and struct layouts with uapi

[Iván Ezequiel Rodriguez]

The uAPI documentation used outdated or conceptual ioctl macro names
and listed ntsync_event_args / ntsync_wait_args fields in the wrong
order. Match include/uapi/linux/ntsync.h and note that absolute
MONOTONIC timeouts are interpreted in the caller's time namespace.

Signed-off-by: Iván Ezequiel Rodriguez <ivanrwcm25@gmail.com>
---
 Documentation/userspace-api/ntsync.rst | 33 +++++++++++++-------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/Documentation/userspace-api/ntsync.rst b/Documentation/userspace-api/ntsync.rst
index 25e7c4aef968..a778016feb87 100644
--- a/Documentation/userspace-api/ntsync.rst
+++ b/Documentation/userspace-api/ntsync.rst
@@ -83,18 +83,18 @@ structures used in ioctl calls::
    };
 
    struct ntsync_event_args {
-   	__u32 signaled;
    	__u32 manual;
+   	__u32 signaled;
    };
 
    struct ntsync_wait_args {
    	__u64 timeout;
    	__u64 objs;
    	__u32 count;
-   	__u32 owner;
    	__u32 index;
-   	__u32 alert;
    	__u32 flags;
+   	__u32 owner;
+   	__u32 alert;
    	__u32 pad;
    };
 
@@ -152,7 +152,7 @@ The ioctls on the device file are as follows:
 
 The ioctls on the individual objects are as follows:
 
-.. c:macro:: NTSYNC_IOC_SEM_POST
+.. c:macro:: NTSYNC_IOC_SEM_RELEASE
 
   Post to a semaphore object. Takes a pointer to a 32-bit integer,
   which on input holds the count to be added to the semaphore, and on
@@ -186,7 +186,7 @@ The ioctls on the individual objects are as follows:
   unowned and signaled, and eligible threads waiting on it will be
   woken as appropriate.
 
-.. c:macro:: NTSYNC_IOC_SET_EVENT
+.. c:macro:: NTSYNC_IOC_EVENT_SET
 
   Signal an event object. Takes a pointer to a 32-bit integer, which on
   output contains the previous state of the event.
@@ -194,12 +194,12 @@ The ioctls on the individual objects are as follows:
   Eligible threads will be woken, and auto-reset events will be
   designaled appropriately.
 
-.. c:macro:: NTSYNC_IOC_RESET_EVENT
+.. c:macro:: NTSYNC_IOC_EVENT_RESET
 
   Designal an event object. Takes a pointer to a 32-bit integer, which
   on output contains the previous state of the event.
 
-.. c:macro:: NTSYNC_IOC_PULSE_EVENT
+.. c:macro:: NTSYNC_IOC_EVENT_PULSE
 
   Wake threads waiting on an event object while leaving it in an
   unsignaled state. Takes a pointer to a 32-bit integer, which on
@@ -213,7 +213,7 @@ The ioctls on the individual objects are as follows:
   afterwards, and a simultaneous read operation will always report the
   event as unsignaled.
 
-.. c:macro:: NTSYNC_IOC_READ_SEM
+.. c:macro:: NTSYNC_IOC_SEM_READ
 
   Read the current state of a semaphore object. Takes a pointer to
   struct :c:type:`ntsync_sem_args`, which is used as follows:
@@ -225,7 +225,7 @@ The ioctls on the individual objects are as follows:
      * - ``max``
        - On output, contains the maximum count of the semaphore.
 
-.. c:macro:: NTSYNC_IOC_READ_MUTEX
+.. c:macro:: NTSYNC_IOC_MUTEX_READ
 
   Read the current state of a mutex object. Takes a pointer to struct
   :c:type:`ntsync_mutex_args`, which is used as follows:
@@ -242,7 +242,7 @@ The ioctls on the individual objects are as follows:
   ``EOWNERDEAD``. In this case, ``count`` and ``owner`` are set to
   zero.
 
-.. c:macro:: NTSYNC_IOC_READ_EVENT
+.. c:macro:: NTSYNC_IOC_EVENT_READ
 
   Read the current state of an event object. Takes a pointer to struct
   :c:type:`ntsync_event_args`, which is used as follows:
@@ -255,7 +255,7 @@ The ioctls on the individual objects are as follows:
        - On output, contains 1 if the event is a manual-reset event,
          and 0 otherwise.
 
-.. c:macro:: NTSYNC_IOC_KILL_OWNER
+.. c:macro:: NTSYNC_IOC_MUTEX_KILL
 
   Mark a mutex as unowned and abandoned if it is owned by the given
   owner. Takes an input-only pointer to a 32-bit integer denoting the
@@ -276,11 +276,12 @@ The ioctls on the individual objects are as follows:
      * - ``timeout``
        - Absolute timeout in nanoseconds. If ``NTSYNC_WAIT_REALTIME``
          is set, the timeout is measured against the REALTIME clock;
-         otherwise it is measured against the MONOTONIC clock. If the
-         timeout is equal to or earlier than the current time, the
-         function returns immediately without sleeping. If ``timeout``
-         is U64_MAX, the function will sleep until an object is
-         signaled, and will not fail with ``ETIMEDOUT``.
+         otherwise it is measured against the MONOTONIC clock in the
+         caller's time namespace. If the timeout is equal to or earlier
+         than the current time, the function returns immediately
+         without sleeping. If ``timeout`` is U64_MAX, the function will
+         sleep until an object is signaled, and will not fail with
+         ``ETIMEDOUT``.
      * - ``objs``
        - Pointer to an array of ``count`` file descriptors
          (specified as an integer so that the structure has the same
-- 
2.43.0

[PATCH 2/2] selftests: ntsync: test absolute MONOTONIC waits under time namespaces

[Iván Ezequiel Rodriguez]

Cover the timens conversion in ntsync_schedule(): with a negative
CLOCK_MONOTONIC offset, a 100 ms absolute wait must not return
immediately against the host clock.

Suggested-by: Maoyi Xie <maoyixie.tju@gmail.com>
Signed-off-by: Iván Ezequiel Rodriguez <ivanrwcm25@gmail.com>
---
 .../testing/selftests/drivers/ntsync/ntsync.c | 87 +++++++++++++++++++
 1 file changed, 87 insertions(+)

diff --git a/tools/testing/selftests/drivers/ntsync/ntsync.c b/tools/testing/selftests/drivers/ntsync/ntsync.c
index e6a37214aa46..ce000ff41535 100644
--- a/tools/testing/selftests/drivers/ntsync/ntsync.c
+++ b/tools/testing/selftests/drivers/ntsync/ntsync.c
@@ -8,12 +8,18 @@
 #define _GNU_SOURCE
 #include <sys/ioctl.h>
 #include <sys/stat.h>
+#include <sys/wait.h>
 #include <fcntl.h>
+#include <sched.h>
 #include <time.h>
 #include <pthread.h>
 #include <linux/ntsync.h>
 #include "kselftest_harness.h"
 
+#ifndef CLONE_NEWTIME
+#define CLONE_NEWTIME 0x00000080
+#endif
+
 static int read_sem_state(int sem, __u32 *count, __u32 *max)
 {
 	struct ntsync_sem_args args;
@@ -1340,4 +1346,85 @@ TEST(stress_wait)
 	close(stress_device);
 }
 
+/*
+ * Absolute MONOTONIC timeouts must honour the caller's time namespace.
+ * With a negative monotonic offset, a 100 ms wait must still take ~100 ms
+ * of namespace time (not return immediately against the host clock).
+ */
+TEST(wait_any_monotonic_timens)
+{
+	struct ntsync_sem_args sem_args = {0};
+	struct ntsync_wait_args wait_args = {0};
+	struct timespec start, end;
+	char buf[64];
+	__u64 elapsed_ns;
+	int fd, offset_fd, sem, ret, status, len;
+	pid_t pid;
+
+	if (access("/proc/self/ns/time", F_OK))
+		SKIP(return, "Time namespaces are not supported");
+
+	fd = open("/dev/ntsync", O_CLOEXEC | O_RDONLY);
+	if (fd < 0)
+		SKIP(return, "/dev/ntsync is not available");
+
+	ret = unshare(CLONE_NEWTIME);
+	if (ret) {
+		close(fd);
+		if (errno == EPERM)
+			SKIP(return, "need CAP_SYS_ADMIN for CLONE_NEWTIME");
+		ASSERT_EQ(0, ret);
+	}
+
+	len = snprintf(buf, sizeof(buf), "%d %d 0", CLOCK_MONOTONIC, -10);
+	offset_fd = open("/proc/self/timens_offsets", O_WRONLY);
+	ASSERT_LE(0, offset_fd);
+	ASSERT_EQ(len, write(offset_fd, buf, len));
+	close(offset_fd);
+
+	pid = fork();
+	ASSERT_LE(0, pid);
+	if (!pid) {
+		int obj;
+
+		sem_args.count = 0;
+		sem_args.max = 1;
+		sem = ioctl(fd, NTSYNC_IOC_CREATE_SEM, &sem_args);
+		if (sem < 0)
+			_exit(1);
+
+		obj = sem;
+		wait_args.timeout = get_abs_timeout(100);
+		wait_args.objs = (uintptr_t)&obj;
+		wait_args.count = 1;
+		wait_args.owner = 123;
+		wait_args.index = 0xdeadbeef;
+
+		if (clock_gettime(CLOCK_MONOTONIC, &start))
+			_exit(2);
+		ret = ioctl(fd, NTSYNC_IOC_WAIT_ANY, &wait_args);
+		if (clock_gettime(CLOCK_MONOTONIC, &end))
+			_exit(2);
+
+		if (ret != -1 || errno != ETIMEDOUT)
+			_exit(3);
+
+		elapsed_ns = (end.tv_sec - start.tv_sec) * 1000000000ULL +
+			     (end.tv_nsec - start.tv_nsec);
+		/* Without timens conversion this returns in ~0 ms. */
+		if (elapsed_ns < 50 * 1000000ULL)
+			_exit(4);
+		if (elapsed_ns > 1000 * 1000000ULL)
+			_exit(5);
+
+		_exit(0);
+	}
+
+	ASSERT_EQ(pid, waitpid(pid, &status, 0));
+	EXPECT_TRUE(WIFEXITED(status));
+	EXPECT_EQ(0, WEXITSTATUS(status));
+
+	close(fd);
+}
+
 TEST_HARNESS_MAIN
-- 
2.43.0