* [PATCH v5 27/28] docs: ntsync: Add documentation for the ntsync uAPI.
From: Elizabeth Figura @ 2024-05-19 20:24 UTC (permalink / raw)
To: Arnd Bergmann, Greg Kroah-Hartman, Jonathan Corbet, Shuah Khan
Cc: linux-kernel, linux-api, wine-devel, André Almeida,
Wolfram Sang, Arkadiusz Hiler, Peter Zijlstra, Andy Lutomirski,
linux-doc, linux-kselftest, Randy Dunlap, Ingo Molnar,
Will Deacon, Waiman Long, Boqun Feng, Elizabeth Figura
In-Reply-To: <20240519202454.1192826-1-zfigura@codeweavers.com>
Add an overall explanation of the driver architecture, and complete and precise
specification for its intended behaviour.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
---
Documentation/userspace-api/index.rst | 1 +
Documentation/userspace-api/ntsync.rst | 398 +++++++++++++++++++++++++
2 files changed, 399 insertions(+)
create mode 100644 Documentation/userspace-api/ntsync.rst
diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst
index afecfe3cc4a8..d5745a500fa7 100644
--- a/Documentation/userspace-api/index.rst
+++ b/Documentation/userspace-api/index.rst
@@ -62,6 +62,7 @@ Everything else
vduse
futex2
perf_ring_buffer
+ ntsync
.. only:: subproject and html
diff --git a/Documentation/userspace-api/ntsync.rst b/Documentation/userspace-api/ntsync.rst
new file mode 100644
index 000000000000..767844637a7d
--- /dev/null
+++ b/Documentation/userspace-api/ntsync.rst
@@ -0,0 +1,398 @@
+===================================
+NT synchronization primitive driver
+===================================
+
+This page documents the user-space API for the ntsync driver.
+
+ntsync is a support driver for emulation of NT synchronization
+primitives by user-space NT emulators. It exists because implementation
+in user-space, using existing tools, cannot match Windows performance
+while offering accurate semantics. It is implemented entirely in
+software, and does not drive any hardware device.
+
+This interface is meant as a compatibility tool only, and should not
+be used for general synchronization. Instead use generic, versatile
+interfaces such as futex(2) and poll(2).
+
+Synchronization primitives
+==========================
+
+The ntsync driver exposes three types of synchronization primitives:
+semaphores, mutexes, and events.
+
+A semaphore holds a single volatile 32-bit counter, and a static 32-bit
+integer denoting the maximum value. It is considered signaled (that is,
+can be acquired without contention, or will wake up a waiting thread)
+when the counter is nonzero. The counter is decremented by one when a
+wait is satisfied. Both the initial and maximum count are established
+when the semaphore is created.
+
+A mutex holds a volatile 32-bit recursion count, and a volatile 32-bit
+identifier denoting its owner. A mutex is considered signaled when its
+owner is zero (indicating that it is not owned). The recursion count is
+incremented when a wait is satisfied, and ownership is set to the given
+identifier.
+
+A mutex also holds an internal flag denoting whether its previous owner
+has died; such a mutex is said to be abandoned. Owner death is not
+tracked automatically based on thread death, but rather must be
+communicated using ``NTSYNC_IOC_MUTEX_KILL``. An abandoned mutex is
+inherently considered unowned.
+
+Except for the "unowned" semantics of zero, the actual value of the
+owner identifier is not interpreted by the ntsync driver at all. The
+intended use is to store a thread identifier; however, the ntsync
+driver does not actually validate that a calling thread provides
+consistent or unique identifiers.
+
+An event is similar to a semaphore with a maximum count of one. It holds
+a volatile boolean state denoting whether it is signaled or not. There
+are two types of events, auto-reset and manual-reset. An auto-reset
+event is designaled when a wait is satisfied; a manual-reset event is
+not. The event type is specified when the event is created.
+
+Unless specified otherwise, all operations on an object are atomic and
+totally ordered with respect to other operations on the same object.
+
+Objects are represented by files. When all file descriptors to an
+object are closed, that object is deleted.
+
+Char device
+===========
+
+The ntsync driver creates a single char device /dev/ntsync. Each file
+description opened on the device represents a unique instance intended
+to back an individual NT virtual machine. Objects created by one ntsync
+instance may only be used with other objects created by the same
+instance.
+
+ioctl reference
+===============
+
+All operations on the device are done through ioctls. There are four
+structures used in ioctl calls::
+
+ struct ntsync_sem_args {
+ __u32 sem;
+ __u32 count;
+ __u32 max;
+ };
+
+ struct ntsync_mutex_args {
+ __u32 mutex;
+ __u32 owner;
+ __u32 count;
+ };
+
+ struct ntsync_event_args {
+ __u32 event;
+ __u32 signaled;
+ __u32 manual;
+ };
+
+ struct ntsync_wait_args {
+ __u64 timeout;
+ __u64 objs;
+ __u32 count;
+ __u32 owner;
+ __u32 index;
+ __u32 alert;
+ __u32 flags;
+ __u32 pad;
+ };
+
+Depending on the ioctl, members of the structure may be used as input,
+output, or not at all. All ioctls return 0 on success.
+
+The ioctls on the device file are as follows:
+
+.. c:macro:: NTSYNC_IOC_CREATE_SEM
+
+ Create a semaphore object. Takes a pointer to struct
+ :c:type:`ntsync_sem_args`, which is used as follows:
+
+ .. list-table::
+
+ * - ``sem``
+ - On output, contains a file descriptor to the created semaphore.
+ * - ``count``
+ - Initial count of the semaphore.
+ * - ``max``
+ - Maximum count of the semaphore.
+
+ Fails with ``EINVAL`` if ``count`` is greater than ``max``.
+
+.. c:macro:: NTSYNC_IOC_CREATE_MUTEX
+
+ Create a mutex object. Takes a pointer to struct
+ :c:type:`ntsync_mutex_args`, which is used as follows:
+
+ .. list-table::
+
+ * - ``mutex``
+ - On output, contains a file descriptor to the created mutex.
+ * - ``count``
+ - Initial recursion count of the mutex.
+ * - ``owner``
+ - Initial owner of the mutex.
+
+ If ``owner`` is nonzero and ``count`` is zero, or if ``owner`` is
+ zero and ``count`` is nonzero, the function fails with ``EINVAL``.
+
+.. c:macro:: NTSYNC_IOC_CREATE_EVENT
+
+ Create an event object. Takes a pointer to struct
+ :c:type:`ntsync_event_args`, which is used as follows:
+
+ .. list-table::
+
+ * - ``event``
+ - On output, contains a file descriptor to the created event.
+ * - ``signaled``
+ - If nonzero, the event is initially signaled, otherwise
+ nonsignaled.
+ * - ``manual``
+ - If nonzero, the event is a manual-reset event, otherwise
+ auto-reset.
+
+The ioctls on the individual objects are as follows:
+
+.. c:macro:: NTSYNC_IOC_SEM_POST
+
+ 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
+ output contains its previous count.
+
+ If adding to the semaphore's current count would raise the latter
+ past the semaphore's maximum count, the ioctl fails with
+ ``EOVERFLOW`` and the semaphore is not affected. If raising the
+ semaphore's count causes it to become signaled, eligible threads
+ waiting on this semaphore will be woken and the semaphore's count
+ decremented appropriately.
+
+.. c:macro:: NTSYNC_IOC_MUTEX_UNLOCK
+
+ Release a mutex object. Takes a pointer to struct
+ :c:type:`ntsync_mutex_args`, which is used as follows:
+
+ .. list-table::
+
+ * - ``mutex``
+ - Ignored.
+ * - ``owner``
+ - Specifies the owner trying to release this mutex.
+ * - ``count``
+ - On output, contains the previous recursion count.
+
+ If ``owner`` is zero, the ioctl fails with ``EINVAL``. If ``owner``
+ is not the current owner of the mutex, the ioctl fails with
+ ``EPERM``.
+
+ The mutex's count will be decremented by one. If decrementing the
+ mutex's count causes it to become zero, the mutex is marked as
+ unowned and signaled, and eligible threads waiting on it will be
+ woken as appropriate.
+
+.. c:macro:: NTSYNC_IOC_SET_EVENT
+
+ Signal an event object. Takes a pointer to a 32-bit integer, which on
+ output contains the previous state of the event.
+
+ Eligible threads will be woken, and auto-reset events will be
+ designaled appropriately.
+
+.. c:macro:: NTSYNC_IOC_RESET_EVENT
+
+ 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
+
+ Wake threads waiting on an event object while leaving it in an
+ unsignaled state. Takes a pointer to a 32-bit integer, which on
+ output contains the previous state of the event.
+
+ A pulse operation can be thought of as a set followed by a reset,
+ performed as a single atomic operation. If two threads are waiting on
+ an auto-reset event which is pulsed, only one will be woken. If two
+ threads are waiting a manual-reset event which is pulsed, both will
+ be woken. However, in both cases, the event will be unsignaled
+ afterwards, and a simultaneous read operation will always report the
+ event as unsignaled.
+
+.. c:macro:: NTSYNC_IOC_READ_SEM
+
+ Read the current state of a semaphore object. Takes a pointer to
+ struct :c:type:`ntsync_sem_args`, which is used as follows:
+
+ .. list-table::
+
+ * - ``sem``
+ - Ignored.
+ * - ``count``
+ - On output, contains the current count of the semaphore.
+ * - ``max``
+ - On output, contains the maximum count of the semaphore.
+
+.. c:macro:: NTSYNC_IOC_READ_MUTEX
+
+ Read the current state of a mutex object. Takes a pointer to struct
+ :c:type:`ntsync_mutex_args`, which is used as follows:
+
+ .. list-table::
+
+ * - ``mutex``
+ - Ignored.
+ * - ``owner``
+ - On output, contains the current owner of the mutex, or zero
+ if the mutex is not currently owned.
+ * - ``count``
+ - On output, contains the current recursion count of the mutex.
+
+ If the mutex is marked as abandoned, the function fails with
+ ``EOWNERDEAD``. In this case, ``count`` and ``owner`` are set to
+ zero.
+
+.. c:macro:: NTSYNC_IOC_READ_EVENT
+
+ Read the current state of an event object. Takes a pointer to struct
+ :c:type:`ntsync_event_args`, which is used as follows:
+
+ .. list-table::
+
+ * - ``event``
+ - Ignored.
+ * - ``signaled``
+ - On output, contains the current state of the event.
+ * - ``manual``
+ - On output, contains 1 if the event is a manual-reset event,
+ and 0 otherwise.
+
+.. c:macro:: NTSYNC_IOC_KILL_OWNER
+
+ 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
+ owner. If the owner is zero, the ioctl fails with ``EINVAL``. If the
+ owner does not own the mutex, the function fails with ``EPERM``.
+
+ Eligible threads waiting on the mutex will be woken as appropriate
+ (and such waits will fail with ``EOWNERDEAD``, as described below).
+
+.. c:macro:: NTSYNC_IOC_WAIT_ANY
+
+ Poll on any of a list of objects, atomically acquiring at most one.
+ Takes a pointer to struct :c:type:`ntsync_wait_args`, which is
+ used as follows:
+
+ .. list-table::
+
+ * - ``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``.
+ * - ``objs``
+ - Pointer to an array of ``count`` file descriptors
+ (specified as an integer so that the structure has the same
+ size regardless of architecture). If any object is
+ invalid, the function fails with ``EINVAL``.
+ * - ``count``
+ - Number of objects specified in the ``objs`` array.
+ If greater than ``NTSYNC_MAX_WAIT_COUNT``, the function fails
+ with ``EINVAL``.
+ * - ``owner``
+ - Mutex owner identifier. If any object in ``objs`` is a mutex,
+ the ioctl will attempt to acquire that mutex on behalf of
+ ``owner``. If ``owner`` is zero, the ioctl fails with
+ ``EINVAL``.
+ * - ``index``
+ - On success, contains the index (into ``objs``) of the object
+ which was signaled. If ``alert`` was signaled instead,
+ this contains ``count``.
+ * - ``alert``
+ - Optional event object file descriptor. If nonzero, this
+ specifies an "alert" event object which, if signaled, will
+ terminate the wait. If nonzero, the identifier must point to a
+ valid event.
+ * - ``flags``
+ - Zero or more flags. Currently the only flag is
+ ``NTSYNC_WAIT_REALTIME``, which causes the timeout to be
+ measured against the REALTIME clock instead of MONOTONIC.
+ * - ``pad``
+ - Unused, must be set to zero.
+
+ This function attempts to acquire one of the given objects. If unable
+ to do so, it sleeps until an object becomes signaled, subsequently
+ acquiring it, or the timeout expires. In the latter case the ioctl
+ fails with ``ETIMEDOUT``. The function only acquires one object, even
+ if multiple objects are signaled.
+
+ A semaphore is considered to be signaled if its count is nonzero, and
+ is acquired by decrementing its count by one. A mutex is considered
+ to be signaled if it is unowned or if its owner matches the ``owner``
+ argument, and is acquired by incrementing its recursion count by one
+ and setting its owner to the ``owner`` argument. An auto-reset event
+ is acquired by designaling it; a manual-reset event is not affected
+ by acquisition.
+
+ Acquisition is atomic and totally ordered with respect to other
+ operations on the same object. If two wait operations (with different
+ ``owner`` identifiers) are queued on the same mutex, only one is
+ signaled. If two wait operations are queued on the same semaphore,
+ and a value of one is posted to it, only one is signaled.
+
+ If an abandoned mutex is acquired, the ioctl fails with
+ ``EOWNERDEAD``. Although this is a failure return, the function may
+ otherwise be considered successful. The mutex is marked as owned by
+ the given owner (with a recursion count of 1) and as no longer
+ abandoned, and ``index`` is still set to the index of the mutex.
+
+ The ``alert`` argument is an "extra" event which can terminate the
+ wait, independently of all other objects.
+
+ It is valid to pass the same object more than once, including by
+ passing the same event in the ``objs`` array and in ``alert``. If a
+ wakeup occurs due to that object being signaled, ``index`` is set to
+ the lowest index corresponding to that object.
+
+ The function may fail with ``EINTR`` if a signal is received.
+
+.. c:macro:: NTSYNC_IOC_WAIT_ALL
+
+ Poll on a list of objects, atomically acquiring all of them. Takes a
+ pointer to struct :c:type:`ntsync_wait_args`, which is used
+ identically to ``NTSYNC_IOC_WAIT_ANY``, except that ``index`` is
+ always filled with zero on success if not woken via alert.
+
+ This function attempts to simultaneously acquire all of the given
+ objects. If unable to do so, it sleeps until all objects become
+ simultaneously signaled, subsequently acquiring them, or the timeout
+ expires. In the latter case the ioctl fails with ``ETIMEDOUT`` and no
+ objects are modified.
+
+ Objects may become signaled and subsequently designaled (through
+ acquisition by other threads) while this thread is sleeping. Only
+ once all objects are simultaneously signaled does the ioctl acquire
+ them and return. The entire acquisition is atomic and totally ordered
+ with respect to other operations on any of the given objects.
+
+ If an abandoned mutex is acquired, the ioctl fails with
+ ``EOWNERDEAD``. Similarly to ``NTSYNC_IOC_WAIT_ANY``, all objects are
+ nevertheless marked as acquired. Note that if multiple mutex objects
+ are specified, there is no way to know which were marked as
+ abandoned.
+
+ As with "any" waits, the ``alert`` argument is an "extra" event which
+ can terminate the wait. Critically, however, an "all" wait will
+ succeed if all members in ``objs`` are signaled, *or* if ``alert`` is
+ signaled. In the latter case ``index`` will be set to ``count``. As
+ with "any" waits, if both conditions are filled, the former takes
+ priority, and objects in ``objs`` will be acquired.
+
+ Unlike ``NTSYNC_IOC_WAIT_ANY``, it is not valid to pass the same
+ object more than once, nor is it valid to pass the same object in
+ ``objs`` and in ``alert``. If this is attempted, the function fails
+ with ``EINVAL``.
--
2.43.0
^ permalink raw reply related
* [PATCH v5 17/28] selftests: ntsync: Add some tests for NTSYNC_IOC_WAIT_ALL.
From: Elizabeth Figura @ 2024-05-19 20:24 UTC (permalink / raw)
To: Arnd Bergmann, Greg Kroah-Hartman, Jonathan Corbet, Shuah Khan
Cc: linux-kernel, linux-api, wine-devel, André Almeida,
Wolfram Sang, Arkadiusz Hiler, Peter Zijlstra, Andy Lutomirski,
linux-doc, linux-kselftest, Randy Dunlap, Ingo Molnar,
Will Deacon, Waiman Long, Boqun Feng, Elizabeth Figura
In-Reply-To: <20240519202454.1192826-1-zfigura@codeweavers.com>
Test basic synchronous functionality of NTSYNC_IOC_WAIT_ALL, and when objects
are considered simultaneously signaled.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
---
.../testing/selftests/drivers/ntsync/ntsync.c | 99 ++++++++++++++++++-
1 file changed, 97 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/drivers/ntsync/ntsync.c b/tools/testing/selftests/drivers/ntsync/ntsync.c
index 40ad8cbd3138..c0f372167557 100644
--- a/tools/testing/selftests/drivers/ntsync/ntsync.c
+++ b/tools/testing/selftests/drivers/ntsync/ntsync.c
@@ -73,7 +73,8 @@ static int unlock_mutex(int mutex, __u32 owner, __u32 *count)
return ret;
}
-static int wait_any(int fd, __u32 count, const int *objs, __u32 owner, __u32 *index)
+static int wait_objs(int fd, unsigned long request, __u32 count,
+ const int *objs, __u32 owner, __u32 *index)
{
struct ntsync_wait_args args = {0};
struct timespec timeout;
@@ -86,11 +87,21 @@ static int wait_any(int fd, __u32 count, const int *objs, __u32 owner, __u32 *in
args.objs = (uintptr_t)objs;
args.owner = owner;
args.index = 0xdeadbeef;
- ret = ioctl(fd, NTSYNC_IOC_WAIT_ANY, &args);
+ ret = ioctl(fd, request, &args);
*index = args.index;
return ret;
}
+static int wait_any(int fd, __u32 count, const int *objs, __u32 owner, __u32 *index)
+{
+ return wait_objs(fd, NTSYNC_IOC_WAIT_ANY, count, objs, owner, index);
+}
+
+static int wait_all(int fd, __u32 count, const int *objs, __u32 owner, __u32 *index)
+{
+ return wait_objs(fd, NTSYNC_IOC_WAIT_ALL, count, objs, owner, index);
+}
+
TEST(semaphore_state)
{
struct ntsync_sem_args sem_args;
@@ -461,4 +472,88 @@ TEST(test_wait_any)
close(fd);
}
+TEST(test_wait_all)
+{
+ struct ntsync_mutex_args mutex_args = {0};
+ struct ntsync_sem_args sem_args = {0};
+ __u32 owner, index, count;
+ int objs[2], fd, ret;
+
+ fd = open("/dev/ntsync", O_CLOEXEC | O_RDONLY);
+ ASSERT_LE(0, fd);
+
+ sem_args.count = 2;
+ sem_args.max = 3;
+ sem_args.sem = 0xdeadbeef;
+ ret = ioctl(fd, NTSYNC_IOC_CREATE_SEM, &sem_args);
+ EXPECT_EQ(0, ret);
+ EXPECT_NE(0xdeadbeef, sem_args.sem);
+
+ mutex_args.owner = 0;
+ mutex_args.count = 0;
+ mutex_args.mutex = 0xdeadbeef;
+ ret = ioctl(fd, NTSYNC_IOC_CREATE_MUTEX, &mutex_args);
+ EXPECT_EQ(0, ret);
+ EXPECT_NE(0xdeadbeef, mutex_args.mutex);
+
+ objs[0] = sem_args.sem;
+ objs[1] = mutex_args.mutex;
+
+ ret = wait_all(fd, 2, objs, 123, &index);
+ EXPECT_EQ(0, ret);
+ EXPECT_EQ(0, index);
+ check_sem_state(sem_args.sem, 1, 3);
+ check_mutex_state(mutex_args.mutex, 1, 123);
+
+ ret = wait_all(fd, 2, objs, 456, &index);
+ EXPECT_EQ(-1, ret);
+ EXPECT_EQ(ETIMEDOUT, errno);
+ check_sem_state(sem_args.sem, 1, 3);
+ check_mutex_state(mutex_args.mutex, 1, 123);
+
+ ret = wait_all(fd, 2, objs, 123, &index);
+ EXPECT_EQ(0, ret);
+ EXPECT_EQ(0, index);
+ check_sem_state(sem_args.sem, 0, 3);
+ check_mutex_state(mutex_args.mutex, 2, 123);
+
+ ret = wait_all(fd, 2, objs, 123, &index);
+ EXPECT_EQ(-1, ret);
+ EXPECT_EQ(ETIMEDOUT, errno);
+ check_sem_state(sem_args.sem, 0, 3);
+ check_mutex_state(mutex_args.mutex, 2, 123);
+
+ count = 3;
+ ret = post_sem(sem_args.sem, &count);
+ EXPECT_EQ(0, ret);
+ EXPECT_EQ(0, count);
+
+ ret = wait_all(fd, 2, objs, 123, &index);
+ EXPECT_EQ(0, ret);
+ EXPECT_EQ(0, index);
+ check_sem_state(sem_args.sem, 2, 3);
+ check_mutex_state(mutex_args.mutex, 3, 123);
+
+ owner = 123;
+ ret = ioctl(mutex_args.mutex, NTSYNC_IOC_MUTEX_KILL, &owner);
+ EXPECT_EQ(0, ret);
+
+ ret = wait_all(fd, 2, objs, 123, &index);
+ EXPECT_EQ(-1, ret);
+ EXPECT_EQ(EOWNERDEAD, errno);
+ check_sem_state(sem_args.sem, 1, 3);
+ check_mutex_state(mutex_args.mutex, 1, 123);
+
+ /* test waiting on the same object twice */
+ objs[0] = objs[1] = sem_args.sem;
+ ret = wait_all(fd, 2, objs, 123, &index);
+ EXPECT_EQ(-1, ret);
+ EXPECT_EQ(EINVAL, errno);
+
+ close(sem_args.sem);
+ close(mutex_args.mutex);
+
+ close(fd);
+}
+
TEST_HARNESS_MAIN
--
2.43.0
^ permalink raw reply related
* [PATCH v5 26/28] maintainers: Add an entry for ntsync.
From: Elizabeth Figura @ 2024-05-19 20:24 UTC (permalink / raw)
To: Arnd Bergmann, Greg Kroah-Hartman, Jonathan Corbet, Shuah Khan
Cc: linux-kernel, linux-api, wine-devel, André Almeida,
Wolfram Sang, Arkadiusz Hiler, Peter Zijlstra, Andy Lutomirski,
linux-doc, linux-kselftest, Randy Dunlap, Ingo Molnar,
Will Deacon, Waiman Long, Boqun Feng, Elizabeth Figura
In-Reply-To: <20240519202454.1192826-1-zfigura@codeweavers.com>
Add myself as maintainer, supported by CodeWeavers.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
---
MAINTAINERS | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index c6dbde10bfc1..c9c9f1d98dd6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15748,6 +15748,15 @@ T: git https://github.com/Paragon-Software-Group/linux-ntfs3.git
F: Documentation/filesystems/ntfs3.rst
F: fs/ntfs3/
+NTSYNC SYNCHRONIZATION PRIMITIVE DRIVER
+M: Elizabeth Figura <zfigura@codeweavers.com>
+L: wine-devel@winehq.org
+S: Supported
+F: Documentation/userspace-api/ntsync.rst
+F: drivers/misc/ntsync.c
+F: include/uapi/linux/ntsync.h
+F: tools/testing/selftests/drivers/ntsync/
+
NUBUS SUBSYSTEM
M: Finn Thain <fthain@linux-m68k.org>
L: linux-m68k@lists.linux-m68k.org
--
2.43.0
^ permalink raw reply related
* [PATCH v5 04/28] ntsync: Introduce NTSYNC_IOC_MUTEX_UNLOCK.
From: Elizabeth Figura @ 2024-05-19 20:24 UTC (permalink / raw)
To: Arnd Bergmann, Greg Kroah-Hartman, Jonathan Corbet, Shuah Khan
Cc: linux-kernel, linux-api, wine-devel, André Almeida,
Wolfram Sang, Arkadiusz Hiler, Peter Zijlstra, Andy Lutomirski,
linux-doc, linux-kselftest, Randy Dunlap, Ingo Molnar,
Will Deacon, Waiman Long, Boqun Feng, Elizabeth Figura
In-Reply-To: <20240519202454.1192826-1-zfigura@codeweavers.com>
This corresponds to the NT syscall NtReleaseMutant().
This syscall decrements the mutex's recursion count by one, and returns the
previous value. If the mutex is not owned by the current task, the function
instead fails and returns -EPERM.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
---
drivers/misc/ntsync.c | 53 +++++++++++++++++++++++++++++++++++++
include/uapi/linux/ntsync.h | 1 +
2 files changed, 54 insertions(+)
diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c
index cfe802c79d7d..f00af9b15164 100644
--- a/drivers/misc/ntsync.c
+++ b/drivers/misc/ntsync.c
@@ -396,6 +396,57 @@ static int ntsync_sem_post(struct ntsync_obj *sem, void __user *argp)
return ret;
}
+/*
+ * Actually change the mutex state, returning -EPERM if not the owner.
+ */
+static int unlock_mutex_state(struct ntsync_obj *mutex,
+ const struct ntsync_mutex_args *args)
+{
+ ntsync_assert_held(mutex);
+
+ if (mutex->u.mutex.owner != args->owner)
+ return -EPERM;
+
+ if (!--mutex->u.mutex.count)
+ mutex->u.mutex.owner = 0;
+ return 0;
+}
+
+static int ntsync_mutex_unlock(struct ntsync_obj *mutex, void __user *argp)
+{
+ struct ntsync_mutex_args __user *user_args = argp;
+ struct ntsync_device *dev = mutex->dev;
+ struct ntsync_mutex_args args;
+ __u32 prev_count;
+ bool all;
+ int ret;
+
+ if (copy_from_user(&args, argp, sizeof(args)))
+ return -EFAULT;
+ if (!args.owner)
+ return -EINVAL;
+
+ if (mutex->type != NTSYNC_TYPE_MUTEX)
+ return -EINVAL;
+
+ all = ntsync_lock_obj(dev, mutex);
+
+ prev_count = mutex->u.mutex.count;
+ ret = unlock_mutex_state(mutex, &args);
+ if (!ret) {
+ if (all)
+ try_wake_all_obj(dev, mutex);
+ try_wake_any_mutex(mutex);
+ }
+
+ ntsync_unlock_obj(dev, mutex, all);
+
+ if (!ret && put_user(prev_count, &user_args->count))
+ ret = -EFAULT;
+
+ return ret;
+}
+
static int ntsync_obj_release(struct inode *inode, struct file *file)
{
struct ntsync_obj *obj = file->private_data;
@@ -415,6 +466,8 @@ static long ntsync_obj_ioctl(struct file *file, unsigned int cmd,
switch (cmd) {
case NTSYNC_IOC_SEM_POST:
return ntsync_sem_post(obj, argp);
+ case NTSYNC_IOC_MUTEX_UNLOCK:
+ return ntsync_mutex_unlock(obj, argp);
default:
return -ENOIOCTLCMD;
}
diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h
index d5e5a2fbcb4d..a633db34f284 100644
--- a/include/uapi/linux/ntsync.h
+++ b/include/uapi/linux/ntsync.h
@@ -42,5 +42,6 @@ struct ntsync_wait_args {
#define NTSYNC_IOC_CREATE_MUTEX _IOWR('N', 0x84, struct ntsync_sem_args)
#define NTSYNC_IOC_SEM_POST _IOWR('N', 0x81, __u32)
+#define NTSYNC_IOC_MUTEX_UNLOCK _IOWR('N', 0x85, struct ntsync_mutex_args)
#endif
--
2.43.0
^ permalink raw reply related
* [PATCH v5 06/28] ntsync: Introduce NTSYNC_IOC_CREATE_EVENT.
From: Elizabeth Figura @ 2024-05-19 20:24 UTC (permalink / raw)
To: Arnd Bergmann, Greg Kroah-Hartman, Jonathan Corbet, Shuah Khan
Cc: linux-kernel, linux-api, wine-devel, André Almeida,
Wolfram Sang, Arkadiusz Hiler, Peter Zijlstra, Andy Lutomirski,
linux-doc, linux-kselftest, Randy Dunlap, Ingo Molnar,
Will Deacon, Waiman Long, Boqun Feng, Elizabeth Figura
In-Reply-To: <20240519202454.1192826-1-zfigura@codeweavers.com>
This correspond to the NT syscall NtCreateEvent().
An NT event holds a single bit of state denoting whether it is signaled or
unsignaled.
There are two types of events: manual-reset and automatic-reset. When an
automatic-reset event is acquired via a wait function, its state is reset to
unsignaled. Manual-reset events are not affected by wait functions.
Whether the event is manual-reset, and its initial state, are specified at
creation time.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
---
drivers/misc/ntsync.c | 62 +++++++++++++++++++++++++++++++++++++
include/uapi/linux/ntsync.h | 7 +++++
2 files changed, 69 insertions(+)
diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c
index 5aaf9dad76b6..2bce03187c17 100644
--- a/drivers/misc/ntsync.c
+++ b/drivers/misc/ntsync.c
@@ -26,6 +26,7 @@
enum ntsync_type {
NTSYNC_TYPE_SEM,
NTSYNC_TYPE_MUTEX,
+ NTSYNC_TYPE_EVENT,
};
/*
@@ -61,6 +62,10 @@ struct ntsync_obj {
pid_t owner;
bool ownerdead;
} mutex;
+ struct {
+ bool manual;
+ bool signaled;
+ } event;
} u;
/*
@@ -233,6 +238,8 @@ static bool is_signaled(struct ntsync_obj *obj, __u32 owner)
if (obj->u.mutex.owner && obj->u.mutex.owner != owner)
return false;
return obj->u.mutex.count < UINT_MAX;
+ case NTSYNC_TYPE_EVENT:
+ return obj->u.event.signaled;
}
WARN(1, "bad object type %#x\n", obj->type);
@@ -283,6 +290,10 @@ static void try_wake_all(struct ntsync_device *dev, struct ntsync_q *q,
obj->u.mutex.count++;
obj->u.mutex.owner = q->owner;
break;
+ case NTSYNC_TYPE_EVENT:
+ if (!obj->u.event.manual)
+ obj->u.event.signaled = false;
+ break;
}
}
wake_up_process(q->task);
@@ -353,6 +364,28 @@ static void try_wake_any_mutex(struct ntsync_obj *mutex)
}
}
+static void try_wake_any_event(struct ntsync_obj *event)
+{
+ struct ntsync_q_entry *entry;
+
+ ntsync_assert_held(event);
+ lockdep_assert(event->type == NTSYNC_TYPE_EVENT);
+
+ list_for_each_entry(entry, &event->any_waiters, node) {
+ struct ntsync_q *q = entry->q;
+ int signaled = -1;
+
+ if (!event->u.event.signaled)
+ break;
+
+ if (atomic_try_cmpxchg(&q->signaled, &signaled, entry->index)) {
+ if (!event->u.event.manual)
+ event->u.event.signaled = false;
+ wake_up_process(q->task);
+ }
+ }
+}
+
/*
* Actually change the semaphore state, returning -EOVERFLOW if it is made
* invalid.
@@ -629,6 +662,30 @@ static int ntsync_create_mutex(struct ntsync_device *dev, void __user *argp)
return put_user(fd, &user_args->mutex);
}
+static int ntsync_create_event(struct ntsync_device *dev, void __user *argp)
+{
+ struct ntsync_event_args __user *user_args = argp;
+ struct ntsync_event_args args;
+ struct ntsync_obj *event;
+ int fd;
+
+ if (copy_from_user(&args, argp, sizeof(args)))
+ return -EFAULT;
+
+ event = ntsync_alloc_obj(dev, NTSYNC_TYPE_EVENT);
+ if (!event)
+ return -ENOMEM;
+ event->u.event.manual = args.manual;
+ event->u.event.signaled = args.signaled;
+ fd = ntsync_obj_get_fd(event);
+ if (fd < 0) {
+ kfree(event);
+ return fd;
+ }
+
+ return put_user(fd, &user_args->event);
+}
+
static struct ntsync_obj *get_obj(struct ntsync_device *dev, int fd)
{
struct file *file = fget(fd);
@@ -759,6 +816,9 @@ static void try_wake_any_obj(struct ntsync_obj *obj)
case NTSYNC_TYPE_MUTEX:
try_wake_any_mutex(obj);
break;
+ case NTSYNC_TYPE_EVENT:
+ try_wake_any_event(obj);
+ break;
}
}
@@ -948,6 +1008,8 @@ static long ntsync_char_ioctl(struct file *file, unsigned int cmd,
void __user *argp = (void __user *)parm;
switch (cmd) {
+ case NTSYNC_IOC_CREATE_EVENT:
+ return ntsync_create_event(dev, argp);
case NTSYNC_IOC_CREATE_MUTEX:
return ntsync_create_mutex(dev, argp);
case NTSYNC_IOC_CREATE_SEM:
diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h
index d7996180c1d2..4c0c4271c7de 100644
--- a/include/uapi/linux/ntsync.h
+++ b/include/uapi/linux/ntsync.h
@@ -22,6 +22,12 @@ struct ntsync_mutex_args {
__u32 count;
};
+struct ntsync_event_args {
+ __u32 event;
+ __u32 manual;
+ __u32 signaled;
+};
+
#define NTSYNC_WAIT_REALTIME 0x1
struct ntsync_wait_args {
@@ -40,6 +46,7 @@ struct ntsync_wait_args {
#define NTSYNC_IOC_WAIT_ANY _IOWR('N', 0x82, struct ntsync_wait_args)
#define NTSYNC_IOC_WAIT_ALL _IOWR('N', 0x83, struct ntsync_wait_args)
#define NTSYNC_IOC_CREATE_MUTEX _IOWR('N', 0x84, struct ntsync_sem_args)
+#define NTSYNC_IOC_CREATE_EVENT _IOWR('N', 0x87, struct ntsync_event_args)
#define NTSYNC_IOC_SEM_POST _IOWR('N', 0x81, __u32)
#define NTSYNC_IOC_MUTEX_UNLOCK _IOWR('N', 0x85, struct ntsync_mutex_args)
--
2.43.0
^ permalink raw reply related
* [PATCH v5 01/28] ntsync: Introduce NTSYNC_IOC_WAIT_ANY.
From: Elizabeth Figura @ 2024-05-19 20:24 UTC (permalink / raw)
To: Arnd Bergmann, Greg Kroah-Hartman, Jonathan Corbet, Shuah Khan
Cc: linux-kernel, linux-api, wine-devel, André Almeida,
Wolfram Sang, Arkadiusz Hiler, Peter Zijlstra, Andy Lutomirski,
linux-doc, linux-kselftest, Randy Dunlap, Ingo Molnar,
Will Deacon, Waiman Long, Boqun Feng, Elizabeth Figura
In-Reply-To: <20240519202454.1192826-1-zfigura@codeweavers.com>
This corresponds to part of the functionality of the NT syscall
NtWaitForMultipleObjects(). Specifically, it implements the behaviour where
the third argument (wait_any) is TRUE, and it does not handle alertable waits.
Those features have been split out into separate patches to ease review.
This patch therefore implements the wait/wake infrastructure which comprises the
core of ntsync's functionality.
NTSYNC_IOC_WAIT_ANY is a vectored wait function similar to poll(). Unlike
poll(), it "consumes" objects when they are signaled. For semaphores, this means
decreasing one from the internal counter. At most one object can be consumed by
this function.
This wait/wake model is fundamentally different from that used anywhere else in
the kernel, and for that reason ntsync does not use any existing infrastructure,
such as futexes, kernel mutexes or semaphores, or wait_event().
Up to 64 objects can be waited on at once. As soon as one is signaled, the
object with the lowest index is consumed, and that index is returned via the
"index" field.
A timeout is supported. The timeout is passed as a u64 nanosecond value, which
represents absolute time measured against either the MONOTONIC or REALTIME clock
(controlled by the flags argument). If U64_MAX is passed, the ioctl waits
indefinitely.
This ioctl validates that all objects belong to the relevant device. This is not
necessary for any technical reason related to NTSYNC_IOC_WAIT_ANY, but will be
necessary for NTSYNC_IOC_WAIT_ALL introduced in the following patch.
Some padding fields are added for alignment and for fields which will be added
in future patches (split out to ease review).
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
---
drivers/misc/ntsync.c | 245 ++++++++++++++++++++++++++++++++++++
include/uapi/linux/ntsync.h | 14 +++
2 files changed, 259 insertions(+)
diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c
index 3c2f743c58b0..d5864891caf0 100644
--- a/drivers/misc/ntsync.c
+++ b/drivers/misc/ntsync.c
@@ -6,11 +6,16 @@
*/
#include <linux/anon_inodes.h>
+#include <linux/atomic.h>
#include <linux/file.h>
#include <linux/fs.h>
+#include <linux/hrtimer.h>
+#include <linux/ktime.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/overflow.h>
+#include <linux/sched.h>
+#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <uapi/linux/ntsync.h>
@@ -30,6 +35,8 @@ enum ntsync_type {
*
* Both rely on struct file for reference counting. Individual
* ntsync_obj objects take a reference to the device when created.
+ * Wait operations take a reference to each object being waited on for
+ * the duration of the wait.
*/
struct ntsync_obj {
@@ -47,12 +54,55 @@ struct ntsync_obj {
__u32 max;
} sem;
} u;
+
+ struct list_head any_waiters;
+};
+
+struct ntsync_q_entry {
+ struct list_head node;
+ struct ntsync_q *q;
+ struct ntsync_obj *obj;
+ __u32 index;
+};
+
+struct ntsync_q {
+ struct task_struct *task;
+
+ /*
+ * Protected via atomic_try_cmpxchg(). Only the thread that wins the
+ * compare-and-swap may actually change object states and wake this
+ * task.
+ */
+ atomic_t signaled;
+
+ __u32 count;
+ struct ntsync_q_entry entries[];
};
struct ntsync_device {
struct file *file;
};
+static void try_wake_any_sem(struct ntsync_obj *sem)
+{
+ struct ntsync_q_entry *entry;
+
+ lockdep_assert_held(&sem->lock);
+
+ list_for_each_entry(entry, &sem->any_waiters, node) {
+ struct ntsync_q *q = entry->q;
+ int signaled = -1;
+
+ if (!sem->u.sem.count)
+ break;
+
+ if (atomic_try_cmpxchg(&q->signaled, &signaled, entry->index)) {
+ sem->u.sem.count--;
+ wake_up_process(q->task);
+ }
+ }
+}
+
/*
* Actually change the semaphore state, returning -EOVERFLOW if it is made
* invalid.
@@ -88,6 +138,8 @@ static int ntsync_sem_post(struct ntsync_obj *sem, void __user *argp)
prev_count = sem->u.sem.count;
ret = post_sem_state(sem, args);
+ if (!ret)
+ try_wake_any_sem(sem);
spin_unlock(&sem->lock);
@@ -141,6 +193,7 @@ static struct ntsync_obj *ntsync_alloc_obj(struct ntsync_device *dev,
obj->dev = dev;
get_file(dev->file);
spin_lock_init(&obj->lock);
+ INIT_LIST_HEAD(&obj->any_waiters);
return obj;
}
@@ -191,6 +244,196 @@ static int ntsync_create_sem(struct ntsync_device *dev, void __user *argp)
return put_user(fd, &user_args->sem);
}
+static struct ntsync_obj *get_obj(struct ntsync_device *dev, int fd)
+{
+ struct file *file = fget(fd);
+ struct ntsync_obj *obj;
+
+ if (!file)
+ return NULL;
+
+ if (file->f_op != &ntsync_obj_fops) {
+ fput(file);
+ return NULL;
+ }
+
+ obj = file->private_data;
+ if (obj->dev != dev) {
+ fput(file);
+ return NULL;
+ }
+
+ return obj;
+}
+
+static void put_obj(struct ntsync_obj *obj)
+{
+ fput(obj->file);
+}
+
+static int ntsync_schedule(const struct ntsync_q *q, const struct ntsync_wait_args *args)
+{
+ ktime_t timeout = ns_to_ktime(args->timeout);
+ clockid_t clock = CLOCK_MONOTONIC;
+ ktime_t *timeout_ptr;
+ int ret = 0;
+
+ timeout_ptr = (args->timeout == U64_MAX ? NULL : &timeout);
+
+ if (args->flags & NTSYNC_WAIT_REALTIME)
+ clock = CLOCK_REALTIME;
+
+ do {
+ if (signal_pending(current)) {
+ ret = -ERESTARTSYS;
+ break;
+ }
+
+ set_current_state(TASK_INTERRUPTIBLE);
+ if (atomic_read(&q->signaled) != -1) {
+ ret = 0;
+ break;
+ }
+ ret = schedule_hrtimeout_range_clock(timeout_ptr, 0, HRTIMER_MODE_ABS, clock);
+ } while (ret < 0);
+ __set_current_state(TASK_RUNNING);
+
+ return ret;
+}
+
+/*
+ * Allocate and initialize the ntsync_q structure, but do not queue us yet.
+ */
+static int setup_wait(struct ntsync_device *dev,
+ const struct ntsync_wait_args *args,
+ struct ntsync_q **ret_q)
+{
+ const __u32 count = args->count;
+ int fds[NTSYNC_MAX_WAIT_COUNT];
+ struct ntsync_q *q;
+ __u32 i, j;
+
+ if (args->pad[0] || args->pad[1] || args->pad[2] || (args->flags & ~NTSYNC_WAIT_REALTIME))
+ return -EINVAL;
+
+ if (args->count > NTSYNC_MAX_WAIT_COUNT)
+ return -EINVAL;
+
+ if (copy_from_user(fds, u64_to_user_ptr(args->objs),
+ array_size(count, sizeof(*fds))))
+ return -EFAULT;
+
+ q = kmalloc(struct_size(q, entries, count), GFP_KERNEL);
+ if (!q)
+ return -ENOMEM;
+ q->task = current;
+ atomic_set(&q->signaled, -1);
+ q->count = count;
+
+ for (i = 0; i < count; i++) {
+ struct ntsync_q_entry *entry = &q->entries[i];
+ struct ntsync_obj *obj = get_obj(dev, fds[i]);
+
+ if (!obj)
+ goto err;
+
+ entry->obj = obj;
+ entry->q = q;
+ entry->index = i;
+ }
+
+ *ret_q = q;
+ return 0;
+
+err:
+ for (j = 0; j < i; j++)
+ put_obj(q->entries[j].obj);
+ kfree(q);
+ return -EINVAL;
+}
+
+static void try_wake_any_obj(struct ntsync_obj *obj)
+{
+ switch (obj->type) {
+ case NTSYNC_TYPE_SEM:
+ try_wake_any_sem(obj);
+ break;
+ }
+}
+
+static int ntsync_wait_any(struct ntsync_device *dev, void __user *argp)
+{
+ struct ntsync_wait_args args;
+ struct ntsync_q *q;
+ int signaled;
+ __u32 i;
+ int ret;
+
+ if (copy_from_user(&args, argp, sizeof(args)))
+ return -EFAULT;
+
+ ret = setup_wait(dev, &args, &q);
+ if (ret < 0)
+ return ret;
+
+ /* queue ourselves */
+
+ for (i = 0; i < args.count; i++) {
+ struct ntsync_q_entry *entry = &q->entries[i];
+ struct ntsync_obj *obj = entry->obj;
+
+ spin_lock(&obj->lock);
+ list_add_tail(&entry->node, &obj->any_waiters);
+ spin_unlock(&obj->lock);
+ }
+
+ /* check if we are already signaled */
+
+ for (i = 0; i < args.count; i++) {
+ struct ntsync_obj *obj = q->entries[i].obj;
+
+ if (atomic_read(&q->signaled) != -1)
+ break;
+
+ spin_lock(&obj->lock);
+ try_wake_any_obj(obj);
+ spin_unlock(&obj->lock);
+ }
+
+ /* sleep */
+
+ ret = ntsync_schedule(q, &args);
+
+ /* and finally, unqueue */
+
+ for (i = 0; i < args.count; i++) {
+ struct ntsync_q_entry *entry = &q->entries[i];
+ struct ntsync_obj *obj = entry->obj;
+
+ spin_lock(&obj->lock);
+ list_del(&entry->node);
+ spin_unlock(&obj->lock);
+
+ put_obj(obj);
+ }
+
+ signaled = atomic_read(&q->signaled);
+ if (signaled != -1) {
+ struct ntsync_wait_args __user *user_args = argp;
+
+ /* even if we caught a signal, we need to communicate success */
+ ret = 0;
+
+ if (put_user(signaled, &user_args->index))
+ ret = -EFAULT;
+ } else if (!ret) {
+ ret = -ETIMEDOUT;
+ }
+
+ kfree(q);
+ return ret;
+}
+
static int ntsync_char_open(struct inode *inode, struct file *file)
{
struct ntsync_device *dev;
@@ -222,6 +465,8 @@ static long ntsync_char_ioctl(struct file *file, unsigned int cmd,
switch (cmd) {
case NTSYNC_IOC_CREATE_SEM:
return ntsync_create_sem(dev, argp);
+ case NTSYNC_IOC_WAIT_ANY:
+ return ntsync_wait_any(dev, argp);
default:
return -ENOIOCTLCMD;
}
diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h
index dcfa38fdc93c..edc12c7a10dc 100644
--- a/include/uapi/linux/ntsync.h
+++ b/include/uapi/linux/ntsync.h
@@ -16,7 +16,21 @@ struct ntsync_sem_args {
__u32 max;
};
+#define NTSYNC_WAIT_REALTIME 0x1
+
+struct ntsync_wait_args {
+ __u64 timeout;
+ __u64 objs;
+ __u32 count;
+ __u32 index;
+ __u32 flags;
+ __u32 pad[3];
+};
+
+#define NTSYNC_MAX_WAIT_COUNT 64
+
#define NTSYNC_IOC_CREATE_SEM _IOWR('N', 0x80, struct ntsync_sem_args)
+#define NTSYNC_IOC_WAIT_ANY _IOWR('N', 0x82, struct ntsync_wait_args)
#define NTSYNC_IOC_SEM_POST _IOWR('N', 0x81, __u32)
--
2.43.0
^ permalink raw reply related
* [PATCH v5 07/28] ntsync: Introduce NTSYNC_IOC_EVENT_SET.
From: Elizabeth Figura @ 2024-05-19 20:24 UTC (permalink / raw)
To: Arnd Bergmann, Greg Kroah-Hartman, Jonathan Corbet, Shuah Khan
Cc: linux-kernel, linux-api, wine-devel, André Almeida,
Wolfram Sang, Arkadiusz Hiler, Peter Zijlstra, Andy Lutomirski,
linux-doc, linux-kselftest, Randy Dunlap, Ingo Molnar,
Will Deacon, Waiman Long, Boqun Feng, Elizabeth Figura
In-Reply-To: <20240519202454.1192826-1-zfigura@codeweavers.com>
This corresponds to the NT syscall NtSetEvent().
This sets the event to the signaled state, and returns its previous state.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
---
drivers/misc/ntsync.c | 27 +++++++++++++++++++++++++++
include/uapi/linux/ntsync.h | 1 +
2 files changed, 28 insertions(+)
diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c
index 2bce03187c17..97d9b6047fbe 100644
--- a/drivers/misc/ntsync.c
+++ b/drivers/misc/ntsync.c
@@ -534,6 +534,31 @@ static int ntsync_mutex_kill(struct ntsync_obj *mutex, void __user *argp)
return ret;
}
+static int ntsync_event_set(struct ntsync_obj *event, void __user *argp)
+{
+ struct ntsync_device *dev = event->dev;
+ __u32 prev_state;
+ bool all;
+
+ if (event->type != NTSYNC_TYPE_EVENT)
+ return -EINVAL;
+
+ all = ntsync_lock_obj(dev, event);
+
+ prev_state = event->u.event.signaled;
+ event->u.event.signaled = true;
+ if (all)
+ try_wake_all_obj(dev, event);
+ try_wake_any_event(event);
+
+ ntsync_unlock_obj(dev, event, all);
+
+ if (put_user(prev_state, (__u32 __user *)argp))
+ return -EFAULT;
+
+ return 0;
+}
+
static int ntsync_obj_release(struct inode *inode, struct file *file)
{
struct ntsync_obj *obj = file->private_data;
@@ -557,6 +582,8 @@ static long ntsync_obj_ioctl(struct file *file, unsigned int cmd,
return ntsync_mutex_unlock(obj, argp);
case NTSYNC_IOC_MUTEX_KILL:
return ntsync_mutex_kill(obj, argp);
+ case NTSYNC_IOC_EVENT_SET:
+ return ntsync_event_set(obj, argp);
default:
return -ENOIOCTLCMD;
}
diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h
index 4c0c4271c7de..36d903521bbe 100644
--- a/include/uapi/linux/ntsync.h
+++ b/include/uapi/linux/ntsync.h
@@ -51,5 +51,6 @@ struct ntsync_wait_args {
#define NTSYNC_IOC_SEM_POST _IOWR('N', 0x81, __u32)
#define NTSYNC_IOC_MUTEX_UNLOCK _IOWR('N', 0x85, struct ntsync_mutex_args)
#define NTSYNC_IOC_MUTEX_KILL _IOW ('N', 0x86, __u32)
+#define NTSYNC_IOC_EVENT_SET _IOR ('N', 0x88, __u32)
#endif
--
2.43.0
^ permalink raw reply related
* [PATCH v5 02/28] ntsync: Introduce NTSYNC_IOC_WAIT_ALL.
From: Elizabeth Figura @ 2024-05-19 20:24 UTC (permalink / raw)
To: Arnd Bergmann, Greg Kroah-Hartman, Jonathan Corbet, Shuah Khan
Cc: linux-kernel, linux-api, wine-devel, André Almeida,
Wolfram Sang, Arkadiusz Hiler, Peter Zijlstra, Andy Lutomirski,
linux-doc, linux-kselftest, Randy Dunlap, Ingo Molnar,
Will Deacon, Waiman Long, Boqun Feng, Elizabeth Figura
In-Reply-To: <20240519202454.1192826-1-zfigura@codeweavers.com>
This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are
simultaneously signaled, and then acquires all of them as a single atomic
operation.
Because acquisition of multiple objects is atomic, some complex locking is
required. We cannot simply spin-lock multiple objects simultaneously, as that
may disable preëmption for a problematically long time.
Instead, modifying any object which may be involved in a wait-all operation takes
a device-wide sleeping mutex, "wait_all_lock", instead of the normal object
spinlock.
Because wait-for-all is a rare operation, in order to optimize wait-for-any,
this lock is only taken when necessary. "all_hint" is used to mark objects which
are involved in a wait-for-all operation, and if an object is not, only its
spinlock is taken.
The locking scheme used here was written by Peter Zijlstra.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
---
drivers/misc/ntsync.c | 334 ++++++++++++++++++++++++++++++++++--
include/uapi/linux/ntsync.h | 1 +
2 files changed, 322 insertions(+), 13 deletions(-)
diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c
index d5864891caf0..a2f2dfadc3ee 100644
--- a/drivers/misc/ntsync.c
+++ b/drivers/misc/ntsync.c
@@ -13,6 +13,7 @@
#include <linux/ktime.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
+#include <linux/mutex.h>
#include <linux/overflow.h>
#include <linux/sched.h>
#include <linux/sched/signal.h>
@@ -41,6 +42,7 @@ enum ntsync_type {
struct ntsync_obj {
spinlock_t lock;
+ int dev_locked;
enum ntsync_type type;
@@ -55,7 +57,30 @@ struct ntsync_obj {
} sem;
} u;
+ /*
+ * any_waiters is protected by the object lock, but all_waiters is
+ * protected by the device wait_all_lock.
+ */
struct list_head any_waiters;
+ struct list_head all_waiters;
+
+ /*
+ * Hint describing how many tasks are queued on this object in a
+ * wait-all operation.
+ *
+ * Any time we do a wake, we may need to wake "all" waiters as well as
+ * "any" waiters. In order to atomically wake "all" waiters, we must
+ * lock all of the objects, and that means grabbing the wait_all_lock
+ * below (and, due to lock ordering rules, before locking this object).
+ * However, wait-all is a rare operation, and grabbing the wait-all
+ * lock for every wake would create unnecessary contention.
+ * Therefore we first check whether all_hint is zero, and, if it is,
+ * we skip trying to wake "all" waiters.
+ *
+ * Since wait requests must originate from user-space threads, we're
+ * limited here by PID_MAX_LIMIT, so there's no risk of overflow.
+ */
+ atomic_t all_hint;
};
struct ntsync_q_entry {
@@ -75,19 +100,198 @@ struct ntsync_q {
*/
atomic_t signaled;
+ bool all;
__u32 count;
struct ntsync_q_entry entries[];
};
struct ntsync_device {
+ /*
+ * Wait-all operations must atomically grab all objects, and be totally
+ * ordered with respect to each other and wait-any operations.
+ * If one thread is trying to acquire several objects, another thread
+ * cannot touch the object at the same time.
+ *
+ * This device-wide lock is used to serialize wait-for-all
+ * operations, and operations on an object that is involved in a
+ * wait-for-all.
+ */
+ struct mutex wait_all_lock;
+
struct file *file;
};
+/*
+ * Single objects are locked using obj->lock.
+ *
+ * Multiple objects are 'locked' while holding dev->wait_all_lock.
+ * In this case however, individual objects are not locked by holding
+ * obj->lock, but by setting obj->dev_locked.
+ *
+ * This means that in order to lock a single object, the sequence is slightly
+ * more complicated than usual. Specifically it needs to check obj->dev_locked
+ * after acquiring obj->lock, if set, it needs to drop the lock and acquire
+ * dev->wait_all_lock in order to serialize against the multi-object operation.
+ */
+
+static void dev_lock_obj(struct ntsync_device *dev, struct ntsync_obj *obj)
+{
+ lockdep_assert_held(&dev->wait_all_lock);
+ lockdep_assert(obj->dev == dev);
+ spin_lock(&obj->lock);
+ /*
+ * By setting obj->dev_locked inside obj->lock, it is ensured that
+ * anyone holding obj->lock must see the value.
+ */
+ obj->dev_locked = 1;
+ spin_unlock(&obj->lock);
+}
+
+static void dev_unlock_obj(struct ntsync_device *dev, struct ntsync_obj *obj)
+{
+ lockdep_assert_held(&dev->wait_all_lock);
+ lockdep_assert(obj->dev == dev);
+ spin_lock(&obj->lock);
+ obj->dev_locked = 0;
+ spin_unlock(&obj->lock);
+}
+
+static void obj_lock(struct ntsync_obj *obj)
+{
+ struct ntsync_device *dev = obj->dev;
+
+ for (;;) {
+ spin_lock(&obj->lock);
+ if (likely(!obj->dev_locked))
+ break;
+
+ spin_unlock(&obj->lock);
+ mutex_lock(&dev->wait_all_lock);
+ spin_lock(&obj->lock);
+ /*
+ * obj->dev_locked should be set and released under the same
+ * wait_all_lock section, since we now own this lock, it should
+ * be clear.
+ */
+ lockdep_assert(!obj->dev_locked);
+ spin_unlock(&obj->lock);
+ mutex_unlock(&dev->wait_all_lock);
+ }
+}
+
+static void obj_unlock(struct ntsync_obj *obj)
+{
+ spin_unlock(&obj->lock);
+}
+
+static bool ntsync_lock_obj(struct ntsync_device *dev, struct ntsync_obj *obj)
+{
+ bool all;
+
+ obj_lock(obj);
+ all = atomic_read(&obj->all_hint);
+ if (unlikely(all)) {
+ obj_unlock(obj);
+ mutex_lock(&dev->wait_all_lock);
+ dev_lock_obj(dev, obj);
+ }
+
+ return all;
+}
+
+static void ntsync_unlock_obj(struct ntsync_device *dev, struct ntsync_obj *obj, bool all)
+{
+ if (all) {
+ dev_unlock_obj(dev, obj);
+ mutex_unlock(&dev->wait_all_lock);
+ } else {
+ obj_unlock(obj);
+ }
+}
+
+#define ntsync_assert_held(obj) \
+ lockdep_assert((lockdep_is_held(&(obj)->lock) != LOCK_STATE_NOT_HELD) || \
+ ((lockdep_is_held(&(obj)->dev->wait_all_lock) != LOCK_STATE_NOT_HELD) && \
+ (obj)->dev_locked))
+
+static bool is_signaled(struct ntsync_obj *obj)
+{
+ ntsync_assert_held(obj);
+
+ switch (obj->type) {
+ case NTSYNC_TYPE_SEM:
+ return !!obj->u.sem.count;
+ }
+
+ WARN(1, "bad object type %#x\n", obj->type);
+ return false;
+}
+
+/*
+ * "locked_obj" is an optional pointer to an object which is already locked and
+ * should not be locked again. This is necessary so that changing an object's
+ * state and waking it can be a single atomic operation.
+ */
+static void try_wake_all(struct ntsync_device *dev, struct ntsync_q *q,
+ struct ntsync_obj *locked_obj)
+{
+ __u32 count = q->count;
+ bool can_wake = true;
+ int signaled = -1;
+ __u32 i;
+
+ lockdep_assert_held(&dev->wait_all_lock);
+ if (locked_obj)
+ lockdep_assert(locked_obj->dev_locked);
+
+ for (i = 0; i < count; i++) {
+ if (q->entries[i].obj != locked_obj)
+ dev_lock_obj(dev, q->entries[i].obj);
+ }
+
+ for (i = 0; i < count; i++) {
+ if (!is_signaled(q->entries[i].obj)) {
+ can_wake = false;
+ break;
+ }
+ }
+
+ if (can_wake && atomic_try_cmpxchg(&q->signaled, &signaled, 0)) {
+ for (i = 0; i < count; i++) {
+ struct ntsync_obj *obj = q->entries[i].obj;
+
+ switch (obj->type) {
+ case NTSYNC_TYPE_SEM:
+ obj->u.sem.count--;
+ break;
+ }
+ }
+ wake_up_process(q->task);
+ }
+
+ for (i = 0; i < count; i++) {
+ if (q->entries[i].obj != locked_obj)
+ dev_unlock_obj(dev, q->entries[i].obj);
+ }
+}
+
+static void try_wake_all_obj(struct ntsync_device *dev, struct ntsync_obj *obj)
+{
+ struct ntsync_q_entry *entry;
+
+ lockdep_assert_held(&dev->wait_all_lock);
+ lockdep_assert(obj->dev_locked);
+
+ list_for_each_entry(entry, &obj->all_waiters, node)
+ try_wake_all(dev, entry->q, obj);
+}
+
static void try_wake_any_sem(struct ntsync_obj *sem)
{
struct ntsync_q_entry *entry;
- lockdep_assert_held(&sem->lock);
+ ntsync_assert_held(sem);
+ lockdep_assert(sem->type == NTSYNC_TYPE_SEM);
list_for_each_entry(entry, &sem->any_waiters, node) {
struct ntsync_q *q = entry->q;
@@ -111,7 +315,7 @@ static int post_sem_state(struct ntsync_obj *sem, __u32 count)
{
__u32 sum;
- lockdep_assert_held(&sem->lock);
+ ntsync_assert_held(sem);
if (check_add_overflow(sem->u.sem.count, count, &sum) ||
sum > sem->u.sem.max)
@@ -123,9 +327,11 @@ static int post_sem_state(struct ntsync_obj *sem, __u32 count)
static int ntsync_sem_post(struct ntsync_obj *sem, void __user *argp)
{
+ struct ntsync_device *dev = sem->dev;
__u32 __user *user_args = argp;
__u32 prev_count;
__u32 args;
+ bool all;
int ret;
if (copy_from_user(&args, argp, sizeof(args)))
@@ -134,14 +340,17 @@ static int ntsync_sem_post(struct ntsync_obj *sem, void __user *argp)
if (sem->type != NTSYNC_TYPE_SEM)
return -EINVAL;
- spin_lock(&sem->lock);
+ all = ntsync_lock_obj(dev, sem);
prev_count = sem->u.sem.count;
ret = post_sem_state(sem, args);
- if (!ret)
+ if (!ret) {
+ if (all)
+ try_wake_all_obj(dev, sem);
try_wake_any_sem(sem);
+ }
- spin_unlock(&sem->lock);
+ ntsync_unlock_obj(dev, sem, all);
if (!ret && put_user(prev_count, user_args))
ret = -EFAULT;
@@ -194,6 +403,8 @@ static struct ntsync_obj *ntsync_alloc_obj(struct ntsync_device *dev,
get_file(dev->file);
spin_lock_init(&obj->lock);
INIT_LIST_HEAD(&obj->any_waiters);
+ INIT_LIST_HEAD(&obj->all_waiters);
+ atomic_set(&obj->all_hint, 0);
return obj;
}
@@ -305,7 +516,7 @@ static int ntsync_schedule(const struct ntsync_q *q, const struct ntsync_wait_ar
* Allocate and initialize the ntsync_q structure, but do not queue us yet.
*/
static int setup_wait(struct ntsync_device *dev,
- const struct ntsync_wait_args *args,
+ const struct ntsync_wait_args *args, bool all,
struct ntsync_q **ret_q)
{
const __u32 count = args->count;
@@ -328,6 +539,7 @@ static int setup_wait(struct ntsync_device *dev,
return -ENOMEM;
q->task = current;
atomic_set(&q->signaled, -1);
+ q->all = all;
q->count = count;
for (i = 0; i < count; i++) {
@@ -337,6 +549,16 @@ static int setup_wait(struct ntsync_device *dev,
if (!obj)
goto err;
+ if (all) {
+ /* Check that the objects are all distinct. */
+ for (j = 0; j < i; j++) {
+ if (obj == q->entries[j].obj) {
+ put_obj(obj);
+ goto err;
+ }
+ }
+ }
+
entry->obj = obj;
entry->q = q;
entry->index = i;
@@ -366,13 +588,14 @@ static int ntsync_wait_any(struct ntsync_device *dev, void __user *argp)
struct ntsync_wait_args args;
struct ntsync_q *q;
int signaled;
+ bool all;
__u32 i;
int ret;
if (copy_from_user(&args, argp, sizeof(args)))
return -EFAULT;
- ret = setup_wait(dev, &args, &q);
+ ret = setup_wait(dev, &args, false, &q);
if (ret < 0)
return ret;
@@ -382,9 +605,9 @@ static int ntsync_wait_any(struct ntsync_device *dev, void __user *argp)
struct ntsync_q_entry *entry = &q->entries[i];
struct ntsync_obj *obj = entry->obj;
- spin_lock(&obj->lock);
+ all = ntsync_lock_obj(dev, obj);
list_add_tail(&entry->node, &obj->any_waiters);
- spin_unlock(&obj->lock);
+ ntsync_unlock_obj(dev, obj, all);
}
/* check if we are already signaled */
@@ -395,9 +618,9 @@ static int ntsync_wait_any(struct ntsync_device *dev, void __user *argp)
if (atomic_read(&q->signaled) != -1)
break;
- spin_lock(&obj->lock);
+ all = ntsync_lock_obj(dev, obj);
try_wake_any_obj(obj);
- spin_unlock(&obj->lock);
+ ntsync_unlock_obj(dev, obj, all);
}
/* sleep */
@@ -410,9 +633,9 @@ static int ntsync_wait_any(struct ntsync_device *dev, void __user *argp)
struct ntsync_q_entry *entry = &q->entries[i];
struct ntsync_obj *obj = entry->obj;
- spin_lock(&obj->lock);
+ all = ntsync_lock_obj(dev, obj);
list_del(&entry->node);
- spin_unlock(&obj->lock);
+ ntsync_unlock_obj(dev, obj, all);
put_obj(obj);
}
@@ -434,6 +657,87 @@ static int ntsync_wait_any(struct ntsync_device *dev, void __user *argp)
return ret;
}
+static int ntsync_wait_all(struct ntsync_device *dev, void __user *argp)
+{
+ struct ntsync_wait_args args;
+ struct ntsync_q *q;
+ int signaled;
+ __u32 i;
+ int ret;
+
+ if (copy_from_user(&args, argp, sizeof(args)))
+ return -EFAULT;
+
+ ret = setup_wait(dev, &args, true, &q);
+ if (ret < 0)
+ return ret;
+
+ /* queue ourselves */
+
+ mutex_lock(&dev->wait_all_lock);
+
+ for (i = 0; i < args.count; i++) {
+ struct ntsync_q_entry *entry = &q->entries[i];
+ struct ntsync_obj *obj = entry->obj;
+
+ atomic_inc(&obj->all_hint);
+
+ /*
+ * obj->all_waiters is protected by dev->wait_all_lock rather
+ * than obj->lock, so there is no need to acquire obj->lock
+ * here.
+ */
+ list_add_tail(&entry->node, &obj->all_waiters);
+ }
+
+ /* check if we are already signaled */
+
+ try_wake_all(dev, q, NULL);
+
+ mutex_unlock(&dev->wait_all_lock);
+
+ /* sleep */
+
+ ret = ntsync_schedule(q, &args);
+
+ /* and finally, unqueue */
+
+ mutex_lock(&dev->wait_all_lock);
+
+ for (i = 0; i < args.count; i++) {
+ struct ntsync_q_entry *entry = &q->entries[i];
+ struct ntsync_obj *obj = entry->obj;
+
+ /*
+ * obj->all_waiters is protected by dev->wait_all_lock rather
+ * than obj->lock, so there is no need to acquire it here.
+ */
+ list_del(&entry->node);
+
+ atomic_dec(&obj->all_hint);
+
+ put_obj(obj);
+ }
+
+ mutex_unlock(&dev->wait_all_lock);
+
+ signaled = atomic_read(&q->signaled);
+ if (signaled != -1) {
+ struct ntsync_wait_args __user *user_args = argp;
+
+ /* even if we caught a signal, we need to communicate success */
+ ret = 0;
+
+ if (put_user(signaled, &user_args->index))
+ ret = -EFAULT;
+ } else if (!ret) {
+ ret = -ETIMEDOUT;
+ }
+
+ kfree(q);
+ return ret;
+}
+
static int ntsync_char_open(struct inode *inode, struct file *file)
{
struct ntsync_device *dev;
@@ -442,6 +746,8 @@ static int ntsync_char_open(struct inode *inode, struct file *file)
if (!dev)
return -ENOMEM;
+ mutex_init(&dev->wait_all_lock);
+
file->private_data = dev;
dev->file = file;
return nonseekable_open(inode, file);
@@ -465,6 +771,8 @@ static long ntsync_char_ioctl(struct file *file, unsigned int cmd,
switch (cmd) {
case NTSYNC_IOC_CREATE_SEM:
return ntsync_create_sem(dev, argp);
+ case NTSYNC_IOC_WAIT_ALL:
+ return ntsync_wait_all(dev, argp);
case NTSYNC_IOC_WAIT_ANY:
return ntsync_wait_any(dev, argp);
default:
diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h
index edc12c7a10dc..addf187b1573 100644
--- a/include/uapi/linux/ntsync.h
+++ b/include/uapi/linux/ntsync.h
@@ -31,6 +31,7 @@ struct ntsync_wait_args {
#define NTSYNC_IOC_CREATE_SEM _IOWR('N', 0x80, struct ntsync_sem_args)
#define NTSYNC_IOC_WAIT_ANY _IOWR('N', 0x82, struct ntsync_wait_args)
+#define NTSYNC_IOC_WAIT_ALL _IOWR('N', 0x83, struct ntsync_wait_args)
#define NTSYNC_IOC_SEM_POST _IOWR('N', 0x81, __u32)
--
2.43.0
^ permalink raw reply related
* [PATCH v5 19/28] selftests: ntsync: Add some tests for wakeup signaling with WINESYNC_IOC_WAIT_ALL.
From: Elizabeth Figura @ 2024-05-19 20:24 UTC (permalink / raw)
To: Arnd Bergmann, Greg Kroah-Hartman, Jonathan Corbet, Shuah Khan
Cc: linux-kernel, linux-api, wine-devel, André Almeida,
Wolfram Sang, Arkadiusz Hiler, Peter Zijlstra, Andy Lutomirski,
linux-doc, linux-kselftest, Randy Dunlap, Ingo Molnar,
Will Deacon, Waiman Long, Boqun Feng, Elizabeth Figura
In-Reply-To: <20240519202454.1192826-1-zfigura@codeweavers.com>
Test contended "wait-for-all" waits, to make sure that scheduling and wakeup
logic works correctly, and that the wait only exits once objects are all
simultaneously signaled.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
---
.../testing/selftests/drivers/ntsync/ntsync.c | 98 +++++++++++++++++++
1 file changed, 98 insertions(+)
diff --git a/tools/testing/selftests/drivers/ntsync/ntsync.c b/tools/testing/selftests/drivers/ntsync/ntsync.c
index 993f5db23768..b77fb0b2c4b1 100644
--- a/tools/testing/selftests/drivers/ntsync/ntsync.c
+++ b/tools/testing/selftests/drivers/ntsync/ntsync.c
@@ -706,4 +706,102 @@ TEST(wake_any)
close(fd);
}
+TEST(wake_all)
+{
+ struct ntsync_mutex_args mutex_args = {0};
+ struct ntsync_wait_args wait_args = {0};
+ struct ntsync_sem_args sem_args = {0};
+ struct wait_args thread_args;
+ int objs[2], fd, ret;
+ __u32 count, index;
+ pthread_t thread;
+
+ fd = open("/dev/ntsync", O_CLOEXEC | O_RDONLY);
+ ASSERT_LE(0, fd);
+
+ sem_args.count = 0;
+ sem_args.max = 3;
+ sem_args.sem = 0xdeadbeef;
+ ret = ioctl(fd, NTSYNC_IOC_CREATE_SEM, &sem_args);
+ EXPECT_EQ(0, ret);
+ EXPECT_NE(0xdeadbeef, sem_args.sem);
+
+ mutex_args.owner = 123;
+ mutex_args.count = 1;
+ mutex_args.mutex = 0xdeadbeef;
+ ret = ioctl(fd, NTSYNC_IOC_CREATE_MUTEX, &mutex_args);
+ EXPECT_EQ(0, ret);
+ EXPECT_NE(0xdeadbeef, mutex_args.mutex);
+
+ objs[0] = sem_args.sem;
+ objs[1] = mutex_args.mutex;
+
+ wait_args.timeout = get_abs_timeout(1000);
+ wait_args.objs = (uintptr_t)objs;
+ wait_args.count = 2;
+ wait_args.owner = 456;
+ thread_args.fd = fd;
+ thread_args.args = &wait_args;
+ thread_args.request = NTSYNC_IOC_WAIT_ALL;
+ ret = pthread_create(&thread, NULL, wait_thread, &thread_args);
+ EXPECT_EQ(0, ret);
+
+ ret = wait_for_thread(thread, 100);
+ EXPECT_EQ(ETIMEDOUT, ret);
+
+ count = 1;
+ ret = post_sem(sem_args.sem, &count);
+ EXPECT_EQ(0, ret);
+ EXPECT_EQ(0, count);
+
+ ret = pthread_tryjoin_np(thread, NULL);
+ EXPECT_EQ(EBUSY, ret);
+
+ check_sem_state(sem_args.sem, 1, 3);
+
+ ret = wait_any(fd, 1, &sem_args.sem, 123, &index);
+ EXPECT_EQ(0, ret);
+ EXPECT_EQ(0, index);
+
+ ret = unlock_mutex(mutex_args.mutex, 123, &count);
+ EXPECT_EQ(0, ret);
+ EXPECT_EQ(1, count);
+
+ ret = pthread_tryjoin_np(thread, NULL);
+ EXPECT_EQ(EBUSY, ret);
+
+ check_mutex_state(mutex_args.mutex, 0, 0);
+
+ count = 2;
+ ret = post_sem(sem_args.sem, &count);
+ EXPECT_EQ(0, ret);
+ EXPECT_EQ(0, count);
+ check_sem_state(sem_args.sem, 1, 3);
+ check_mutex_state(mutex_args.mutex, 1, 456);
+
+ ret = wait_for_thread(thread, 100);
+ EXPECT_EQ(0, ret);
+ EXPECT_EQ(0, thread_args.ret);
+
+ /* delete an object while it's being waited on */
+
+ wait_args.timeout = get_abs_timeout(200);
+ wait_args.owner = 123;
+ ret = pthread_create(&thread, NULL, wait_thread, &thread_args);
+ EXPECT_EQ(0, ret);
+
+ ret = wait_for_thread(thread, 100);
+ EXPECT_EQ(ETIMEDOUT, ret);
+
+ close(sem_args.sem);
+ close(mutex_args.mutex);
+
+ ret = wait_for_thread(thread, 200);
+ EXPECT_EQ(0, ret);
+ EXPECT_EQ(-1, thread_args.ret);
+ EXPECT_EQ(ETIMEDOUT, thread_args.err);
+
+ close(fd);
+}
+
TEST_HARNESS_MAIN
--
2.43.0
^ permalink raw reply related
* [PATCH v5 14/28] selftests: ntsync: Add some tests for semaphore state.
From: Elizabeth Figura @ 2024-05-19 20:24 UTC (permalink / raw)
To: Arnd Bergmann, Greg Kroah-Hartman, Jonathan Corbet, Shuah Khan
Cc: linux-kernel, linux-api, wine-devel, André Almeida,
Wolfram Sang, Arkadiusz Hiler, Peter Zijlstra, Andy Lutomirski,
linux-doc, linux-kselftest, Randy Dunlap, Ingo Molnar,
Will Deacon, Waiman Long, Boqun Feng, Elizabeth Figura
In-Reply-To: <20240519202454.1192826-1-zfigura@codeweavers.com>
Wine has tests for its synchronization primitives, but these are more accessible
to kernel developers, and also allow us to test some edge cases that Wine does
not care about.
This patch adds tests for semaphore-specific ioctls NTSYNC_IOC_SEM_POST and
NTSYNC_IOC_SEM_READ, and waiting on semaphores.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
---
tools/testing/selftests/Makefile | 1 +
.../selftests/drivers/ntsync/.gitignore | 1 +
.../testing/selftests/drivers/ntsync/Makefile | 7 +
tools/testing/selftests/drivers/ntsync/config | 1 +
.../testing/selftests/drivers/ntsync/ntsync.c | 149 ++++++++++++++++++
5 files changed, 159 insertions(+)
create mode 100644 tools/testing/selftests/drivers/ntsync/.gitignore
create mode 100644 tools/testing/selftests/drivers/ntsync/Makefile
create mode 100644 tools/testing/selftests/drivers/ntsync/config
create mode 100644 tools/testing/selftests/drivers/ntsync/ntsync.c
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index e1504833654d..6f95206325e1 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -16,6 +16,7 @@ TARGETS += damon
TARGETS += devices
TARGETS += dmabuf-heaps
TARGETS += drivers/dma-buf
+TARGETS += drivers/ntsync
TARGETS += drivers/s390x/uvdevice
TARGETS += drivers/net/bonding
TARGETS += drivers/net/team
diff --git a/tools/testing/selftests/drivers/ntsync/.gitignore b/tools/testing/selftests/drivers/ntsync/.gitignore
new file mode 100644
index 000000000000..848573a3d3ea
--- /dev/null
+++ b/tools/testing/selftests/drivers/ntsync/.gitignore
@@ -0,0 +1 @@
+ntsync
diff --git a/tools/testing/selftests/drivers/ntsync/Makefile b/tools/testing/selftests/drivers/ntsync/Makefile
new file mode 100644
index 000000000000..dbf2b055c0b2
--- /dev/null
+++ b/tools/testing/selftests/drivers/ntsync/Makefile
@@ -0,0 +1,7 @@
+# SPDX-LICENSE-IDENTIFIER: GPL-2.0-only
+TEST_GEN_PROGS := ntsync
+
+CFLAGS += $(KHDR_INCLUDES)
+LDLIBS += -lpthread
+
+include ../../lib.mk
diff --git a/tools/testing/selftests/drivers/ntsync/config b/tools/testing/selftests/drivers/ntsync/config
new file mode 100644
index 000000000000..60539c826d06
--- /dev/null
+++ b/tools/testing/selftests/drivers/ntsync/config
@@ -0,0 +1 @@
+CONFIG_WINESYNC=y
diff --git a/tools/testing/selftests/drivers/ntsync/ntsync.c b/tools/testing/selftests/drivers/ntsync/ntsync.c
new file mode 100644
index 000000000000..1e145c6dfded
--- /dev/null
+++ b/tools/testing/selftests/drivers/ntsync/ntsync.c
@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Various unit tests for the "ntsync" synchronization primitive driver.
+ *
+ * Copyright (C) 2021-2022 Elizabeth Figura <zfigura@codeweavers.com>
+ */
+
+#define _GNU_SOURCE
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <time.h>
+#include <pthread.h>
+#include <linux/ntsync.h>
+#include "../../kselftest_harness.h"
+
+static int read_sem_state(int sem, __u32 *count, __u32 *max)
+{
+ struct ntsync_sem_args args;
+ int ret;
+
+ memset(&args, 0xcc, sizeof(args));
+ ret = ioctl(sem, NTSYNC_IOC_SEM_READ, &args);
+ *count = args.count;
+ *max = args.max;
+ return ret;
+}
+
+#define check_sem_state(sem, count, max) \
+ ({ \
+ __u32 __count, __max; \
+ int ret = read_sem_state((sem), &__count, &__max); \
+ EXPECT_EQ(0, ret); \
+ EXPECT_EQ((count), __count); \
+ EXPECT_EQ((max), __max); \
+ })
+
+static int post_sem(int sem, __u32 *count)
+{
+ return ioctl(sem, NTSYNC_IOC_SEM_POST, count);
+}
+
+static int wait_any(int fd, __u32 count, const int *objs, __u32 owner, __u32 *index)
+{
+ struct ntsync_wait_args args = {0};
+ struct timespec timeout;
+ int ret;
+
+ clock_gettime(CLOCK_MONOTONIC, &timeout);
+
+ args.timeout = timeout.tv_sec * 1000000000 + timeout.tv_nsec;
+ args.count = count;
+ args.objs = (uintptr_t)objs;
+ args.owner = owner;
+ args.index = 0xdeadbeef;
+ ret = ioctl(fd, NTSYNC_IOC_WAIT_ANY, &args);
+ *index = args.index;
+ return ret;
+}
+
+TEST(semaphore_state)
+{
+ struct ntsync_sem_args sem_args;
+ struct timespec timeout;
+ __u32 count, index;
+ int fd, ret, sem;
+
+ clock_gettime(CLOCK_MONOTONIC, &timeout);
+
+ fd = open("/dev/ntsync", O_CLOEXEC | O_RDONLY);
+ ASSERT_LE(0, fd);
+
+ sem_args.count = 3;
+ sem_args.max = 2;
+ sem_args.sem = 0xdeadbeef;
+ ret = ioctl(fd, NTSYNC_IOC_CREATE_SEM, &sem_args);
+ EXPECT_EQ(-1, ret);
+ EXPECT_EQ(EINVAL, errno);
+
+ sem_args.count = 2;
+ sem_args.max = 2;
+ sem_args.sem = 0xdeadbeef;
+ ret = ioctl(fd, NTSYNC_IOC_CREATE_SEM, &sem_args);
+ EXPECT_EQ(0, ret);
+ EXPECT_NE(0xdeadbeef, sem_args.sem);
+ sem = sem_args.sem;
+ check_sem_state(sem, 2, 2);
+
+ count = 0;
+ ret = post_sem(sem, &count);
+ EXPECT_EQ(0, ret);
+ EXPECT_EQ(2, count);
+ check_sem_state(sem, 2, 2);
+
+ count = 1;
+ ret = post_sem(sem, &count);
+ EXPECT_EQ(-1, ret);
+ EXPECT_EQ(EOVERFLOW, errno);
+ check_sem_state(sem, 2, 2);
+
+ ret = wait_any(fd, 1, &sem, 123, &index);
+ EXPECT_EQ(0, ret);
+ EXPECT_EQ(0, index);
+ check_sem_state(sem, 1, 2);
+
+ ret = wait_any(fd, 1, &sem, 123, &index);
+ EXPECT_EQ(0, ret);
+ EXPECT_EQ(0, index);
+ check_sem_state(sem, 0, 2);
+
+ ret = wait_any(fd, 1, &sem, 123, &index);
+ EXPECT_EQ(-1, ret);
+ EXPECT_EQ(ETIMEDOUT, errno);
+
+ count = 3;
+ ret = post_sem(sem, &count);
+ EXPECT_EQ(-1, ret);
+ EXPECT_EQ(EOVERFLOW, errno);
+ check_sem_state(sem, 0, 2);
+
+ count = 2;
+ ret = post_sem(sem, &count);
+ EXPECT_EQ(0, ret);
+ EXPECT_EQ(0, count);
+ check_sem_state(sem, 2, 2);
+
+ ret = wait_any(fd, 1, &sem, 123, &index);
+ EXPECT_EQ(0, ret);
+ ret = wait_any(fd, 1, &sem, 123, &index);
+ EXPECT_EQ(0, ret);
+
+ count = 1;
+ ret = post_sem(sem, &count);
+ EXPECT_EQ(0, ret);
+ EXPECT_EQ(0, count);
+ check_sem_state(sem, 1, 2);
+
+ count = ~0u;
+ ret = post_sem(sem, &count);
+ EXPECT_EQ(-1, ret);
+ EXPECT_EQ(EOVERFLOW, errno);
+ check_sem_state(sem, 1, 2);
+
+ close(sem);
+
+ close(fd);
+}
+
+TEST_HARNESS_MAIN
--
2.43.0
^ permalink raw reply related
* [PATCH v5 00/28] NT synchronization primitive driver
From: Elizabeth Figura @ 2024-05-19 20:24 UTC (permalink / raw)
To: Arnd Bergmann, Greg Kroah-Hartman, Jonathan Corbet, Shuah Khan
Cc: linux-kernel, linux-api, wine-devel, André Almeida,
Wolfram Sang, Arkadiusz Hiler, Peter Zijlstra, Andy Lutomirski,
linux-doc, linux-kselftest, Randy Dunlap, Ingo Molnar,
Will Deacon, Waiman Long, Boqun Feng, Elizabeth Figura
This patch series implements a new char misc driver, /dev/ntsync, which is used
to implement Windows NT synchronization primitives.
NT synchronization primitives are unique in that the wait functions both are
vectored, operate on multiple types of object with different behaviour (mutex,
semaphore, event), and affect the state of the objects they wait on. This model
is not compatible with existing kernel synchronization objects or interfaces,
and therefore the ntsync driver implements its own wait queues and locking.
This patch series is rebased against the "char-misc-next" branch of
gregkh/char-misc.git.
== Background ==
The Wine project emulates the Windows API in user space. One particular part of
that API, namely the NT synchronization primitives, have historically been
implemented via RPC to a dedicated "kernel" process. However, more recent
applications use these APIs more strenuously, and the overhead of RPC has become
a bottleneck.
The NT synchronization APIs are too complex to implement on top of existing
primitives without sacrificing correctness. Certain operations, such as
NtPulseEvent() or the "wait-for-all" mode of NtWaitForMultipleObjects(), require
direct control over the underlying wait queue, and implementing a wait queue
sufficiently robust for Wine in user space is not possible. This proposed
driver, therefore, implements the problematic interfaces directly in the Linux
kernel.
This driver was presented at Linux Plumbers Conference 2023. For those further
interested in the history of synchronization in Wine and past attempts to solve
this problem in user space, a recording of the presentation can be viewed here:
https://www.youtube.com/watch?v=NjU4nyWyhU8
== Performance ==
The performance measurements described below are copied from earlier versions of
the patch set. While some of the code has changed, I do not currently anticipate
that it has changed drastically enough to affect those measurements.
The gain in performance varies wildly depending on the application in question
and the user's hardware. For some games NT synchronization is not a bottleneck
and no change can be observed, but for others frame rate improvements of 50 to
150 percent are not atypical. The following table lists frame rate measurements
from a variety of games on a variety of hardware, taken by users Dmitry
Skvortsov, FuzzyQuils, OnMars, and myself:
Game Upstream ntsync improvement
===========================================================================
Anger Foot 69 99 43%
Call of Juarez 99.8 224.1 125%
Dirt 3 110.6 860.7 678%
Forza Horizon 5 108 160 48%
Lara Croft: Temple of Osiris 141 326 131%
Metro 2033 164.4 199.2 21%
Resident Evil 2 26 77 196%
The Crew 26 51 96%
Tiny Tina's Wonderlands 130 360 177%
Total War Saga: Troy 109 146 34%
===========================================================================
== Patches ==
The intended semantics of the patches are broadly intended to match those of the
corresponding Windows functions. For those not already familiar with the Windows
functions (or their undocumented behaviour), patch 27/28 provides a detailed
specification, and individual patches also include a brief description of the
API they are implementing.
The patches making use of this driver in Wine can be retrieved or browsed here:
https://repo.or.cz/wine/zf.git/shortlog/refs/heads/ntsync5
== Previous versions ==
Changes from v4:
* Rework wait-all locking code to avoid taking more than one spinlock at a time,
and also to fix a race where the wait-all lock would not be not correctly
taken. The new locking mechanism involves taking a simple spinlock for normal
"any" waits, and taking a device-wide mutex for "all" waits or when locking
any object that is involved in an "all" wait. The mechanism was written by
Peter Zijlstra.
* Try to reword or clarify various parts of the documentation (patch 27), per
Peter Zijlstra.
* I did not rename NTSYNC_IOC_SEM_POST to RELEASE (like NT) although this was
suggested by Peter Zijlstra, mostly because it's not clear to me that renaming
an already committed ioctl would be fine. The API committed isn't actually
usable yet, though, so if altering it would be fine on those grounds, I can
revise this series to rename the function accordingly.
* Similarly, I did not change the create ioctls to return the fd directly,
although this was suggested and would be a bit simpler and cleaner, because
NTSYNC_IOC_CREATE_SEM already exists upstream and returns the fd through a
struct. I can make this change in the next revision if that'd be preferable. I
also still would appreciate a clarification on the advice in [1].
[1] https://docs.kernel.org/driver-api/ioctl.html#return-code
* Link to v4: https://lore.kernel.org/lkml/20240416010837.333694-1-zfigura@codeweavers.com/
* Link to v3: https://lore.kernel.org/lkml/20240329000621.148791-1-zfigura@codeweavers.com/
* Link to v2: https://lore.kernel.org/lkml/20240219223833.95710-1-zfigura@codeweavers.com/
* Link to v1: https://lore.kernel.org/lkml/20240214233645.9273-1-zfigura@codeweavers.com/
* Link to RFC v2: https://lore.kernel.org/lkml/20240131021356.10322-1-zfigura@codeweavers.com/
* Link to RFC v1: https://lore.kernel.org/lkml/20240124004028.16826-1-zfigura@codeweavers.com/
Elizabeth Figura (28):
ntsync: Introduce NTSYNC_IOC_WAIT_ANY.
ntsync: Introduce NTSYNC_IOC_WAIT_ALL.
ntsync: Introduce NTSYNC_IOC_CREATE_MUTEX.
ntsync: Introduce NTSYNC_IOC_MUTEX_UNLOCK.
ntsync: Introduce NTSYNC_IOC_MUTEX_KILL.
ntsync: Introduce NTSYNC_IOC_CREATE_EVENT.
ntsync: Introduce NTSYNC_IOC_EVENT_SET.
ntsync: Introduce NTSYNC_IOC_EVENT_RESET.
ntsync: Introduce NTSYNC_IOC_EVENT_PULSE.
ntsync: Introduce NTSYNC_IOC_SEM_READ.
ntsync: Introduce NTSYNC_IOC_MUTEX_READ.
ntsync: Introduce NTSYNC_IOC_EVENT_READ.
ntsync: Introduce alertable waits.
selftests: ntsync: Add some tests for semaphore state.
selftests: ntsync: Add some tests for mutex state.
selftests: ntsync: Add some tests for NTSYNC_IOC_WAIT_ANY.
selftests: ntsync: Add some tests for NTSYNC_IOC_WAIT_ALL.
selftests: ntsync: Add some tests for wakeup signaling with
WINESYNC_IOC_WAIT_ANY.
selftests: ntsync: Add some tests for wakeup signaling with
WINESYNC_IOC_WAIT_ALL.
selftests: ntsync: Add some tests for manual-reset event state.
selftests: ntsync: Add some tests for auto-reset event state.
selftests: ntsync: Add some tests for wakeup signaling with events.
selftests: ntsync: Add tests for alertable waits.
selftests: ntsync: Add some tests for wakeup signaling via alerts.
selftests: ntsync: Add a stress test for contended waits.
maintainers: Add an entry for ntsync.
docs: ntsync: Add documentation for the ntsync uAPI.
ntsync: No longer depend on BROKEN.
Documentation/userspace-api/index.rst | 1 +
Documentation/userspace-api/ntsync.rst | 398 +++++
MAINTAINERS | 9 +
drivers/misc/Kconfig | 1 -
drivers/misc/ntsync.c | 989 +++++++++++-
include/uapi/linux/ntsync.h | 39 +
tools/testing/selftests/Makefile | 1 +
.../selftests/drivers/ntsync/.gitignore | 1 +
.../testing/selftests/drivers/ntsync/Makefile | 7 +
tools/testing/selftests/drivers/ntsync/config | 1 +
.../testing/selftests/drivers/ntsync/ntsync.c | 1407 +++++++++++++++++
11 files changed, 2850 insertions(+), 4 deletions(-)
create mode 100644 Documentation/userspace-api/ntsync.rst
create mode 100644 tools/testing/selftests/drivers/ntsync/.gitignore
create mode 100644 tools/testing/selftests/drivers/ntsync/Makefile
create mode 100644 tools/testing/selftests/drivers/ntsync/config
create mode 100644 tools/testing/selftests/drivers/ntsync/ntsync.c
base-commit: f5b335dc025cfee90957efa90dc72fada0d5abb4
--
2.43.0
^ permalink raw reply
* [PATCH v5 09/28] ntsync: Introduce NTSYNC_IOC_EVENT_PULSE.
From: Elizabeth Figura @ 2024-05-19 20:24 UTC (permalink / raw)
To: Arnd Bergmann, Greg Kroah-Hartman, Jonathan Corbet, Shuah Khan
Cc: linux-kernel, linux-api, wine-devel, André Almeida,
Wolfram Sang, Arkadiusz Hiler, Peter Zijlstra, Andy Lutomirski,
linux-doc, linux-kselftest, Randy Dunlap, Ingo Molnar,
Will Deacon, Waiman Long, Boqun Feng, Elizabeth Figura
In-Reply-To: <20240519202454.1192826-1-zfigura@codeweavers.com>
This corresponds to the NT syscall NtPulseEvent().
This wakes up any waiters as if the event had been set, but does not set the
event, instead resetting it if it had been signalled. Thus, for a manual-reset
event, all waiters are woken, whereas for an auto-reset event, at most one
waiter is woken.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
---
drivers/misc/ntsync.c | 8 ++++++--
include/uapi/linux/ntsync.h | 1 +
2 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c
index b070ceccc3af..b0c1d644f0af 100644
--- a/drivers/misc/ntsync.c
+++ b/drivers/misc/ntsync.c
@@ -534,7 +534,7 @@ static int ntsync_mutex_kill(struct ntsync_obj *mutex, void __user *argp)
return ret;
}
-static int ntsync_event_set(struct ntsync_obj *event, void __user *argp)
+static int ntsync_event_set(struct ntsync_obj *event, void __user *argp, bool pulse)
{
struct ntsync_device *dev = event->dev;
__u32 prev_state;
@@ -550,6 +550,8 @@ static int ntsync_event_set(struct ntsync_obj *event, void __user *argp)
if (all)
try_wake_all_obj(dev, event);
try_wake_any_event(event);
+ if (pulse)
+ event->u.event.signaled = false;
ntsync_unlock_obj(dev, event, all);
@@ -605,9 +607,11 @@ static long ntsync_obj_ioctl(struct file *file, unsigned int cmd,
case NTSYNC_IOC_MUTEX_KILL:
return ntsync_mutex_kill(obj, argp);
case NTSYNC_IOC_EVENT_SET:
- return ntsync_event_set(obj, argp);
+ return ntsync_event_set(obj, argp, false);
case NTSYNC_IOC_EVENT_RESET:
return ntsync_event_reset(obj, argp);
+ case NTSYNC_IOC_EVENT_PULSE:
+ return ntsync_event_set(obj, argp, true);
default:
return -ENOIOCTLCMD;
}
diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h
index 7fdf79729b20..5586fadd9bdd 100644
--- a/include/uapi/linux/ntsync.h
+++ b/include/uapi/linux/ntsync.h
@@ -53,5 +53,6 @@ struct ntsync_wait_args {
#define NTSYNC_IOC_MUTEX_KILL _IOW ('N', 0x86, __u32)
#define NTSYNC_IOC_EVENT_SET _IOR ('N', 0x88, __u32)
#define NTSYNC_IOC_EVENT_RESET _IOR ('N', 0x89, __u32)
+#define NTSYNC_IOC_EVENT_PULSE _IOR ('N', 0x8a, __u32)
#endif
--
2.43.0
^ permalink raw reply related
* [PATCH v5 12/28] ntsync: Introduce NTSYNC_IOC_EVENT_READ.
From: Elizabeth Figura @ 2024-05-19 20:24 UTC (permalink / raw)
To: Arnd Bergmann, Greg Kroah-Hartman, Jonathan Corbet, Shuah Khan
Cc: linux-kernel, linux-api, wine-devel, André Almeida,
Wolfram Sang, Arkadiusz Hiler, Peter Zijlstra, Andy Lutomirski,
linux-doc, linux-kselftest, Randy Dunlap, Ingo Molnar,
Will Deacon, Waiman Long, Boqun Feng, Elizabeth Figura
In-Reply-To: <20240519202454.1192826-1-zfigura@codeweavers.com>
This corresponds to the NT syscall NtQueryEvent().
This returns the signaled state of the event and whether it is manual-reset.
Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
---
drivers/misc/ntsync.c | 26 ++++++++++++++++++++++++++
include/uapi/linux/ntsync.h | 1 +
2 files changed, 27 insertions(+)
diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c
index 622be0075ba4..a11fe2469841 100644
--- a/drivers/misc/ntsync.c
+++ b/drivers/misc/ntsync.c
@@ -633,6 +633,30 @@ static int ntsync_mutex_read(struct ntsync_obj *mutex, void __user *argp)
return ret;
}
+static int ntsync_event_read(struct ntsync_obj *event, void __user *argp)
+{
+ struct ntsync_event_args __user *user_args = argp;
+ struct ntsync_device *dev = event->dev;
+ struct ntsync_event_args args;
+ bool all;
+
+ if (event->type != NTSYNC_TYPE_EVENT)
+ return -EINVAL;
+
+ args.event = 0;
+
+ all = ntsync_lock_obj(dev, event);
+
+ args.manual = event->u.event.manual;
+ args.signaled = event->u.event.signaled;
+
+ ntsync_unlock_obj(dev, event, all);
+
+ if (copy_to_user(user_args, &args, sizeof(args)))
+ return -EFAULT;
+ return 0;
+}
+
static int ntsync_obj_release(struct inode *inode, struct file *file)
{
struct ntsync_obj *obj = file->private_data;
@@ -666,6 +690,8 @@ static long ntsync_obj_ioctl(struct file *file, unsigned int cmd,
return ntsync_event_reset(obj, argp);
case NTSYNC_IOC_EVENT_PULSE:
return ntsync_event_set(obj, argp, true);
+ case NTSYNC_IOC_EVENT_READ:
+ return ntsync_event_read(obj, argp);
default:
return -ENOIOCTLCMD;
}
diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h
index eced73d08783..74abeba832f7 100644
--- a/include/uapi/linux/ntsync.h
+++ b/include/uapi/linux/ntsync.h
@@ -56,5 +56,6 @@ struct ntsync_wait_args {
#define NTSYNC_IOC_EVENT_PULSE _IOR ('N', 0x8a, __u32)
#define NTSYNC_IOC_SEM_READ _IOR ('N', 0x8b, struct ntsync_sem_args)
#define NTSYNC_IOC_MUTEX_READ _IOR ('N', 0x8c, struct ntsync_mutex_args)
+#define NTSYNC_IOC_EVENT_READ _IOR ('N', 0x8d, struct ntsync_event_args)
#endif
--
2.43.0
^ permalink raw reply related
* Re: [PATCH v4 00/30] NT synchronization primitive driver
From: Elizabeth Figura @ 2024-05-15 23:32 UTC (permalink / raw)
To: Peter Zijlstra, wine-devel
Cc: Arnd Bergmann, Greg Kroah-Hartman, Jonathan Corbet, Shuah Khan,
linux-kernel, linux-api, wine-devel, André Almeida,
Wolfram Sang, Andy Lutomirski, linux-doc, linux-kselftest,
Randy Dunlap, Ingo Molnar, Will Deacon, Waiman Long, Boqun Feng,
Elizabeth Figura
In-Reply-To: <1790266.VLH7GnMWUR@camazotz>
On Wednesday, April 17, 2024 3:02:13 PM CDT Elizabeth Figura wrote:
> > > Except for the "unowned" semantics of zero, the actual value of the
> > > owner identifier is not interpreted by the ntsync driver at all. The
> > > intended use is to store a thread identifier; however, the ntsync
> > > driver does not actually validate that a calling thread provides
> > > consistent or unique identifiers.
> >
> > Why not verify it? Seems simple enough to put in a TID check, esp. if NT
> > mandates the same.
>
> I mostly figured it'd be simplest to leave the driver completely
> agnostic, but I don't think there's any reason we can't use the real
> TID for most calls.
While trying to implement this I did realize a reason: if a Linux thread dies
and a new Wine thread is created which happens to have the same Linux TID
*before* Wine notices the thread death, that thread's TID will be conflated
with the thread that died. I don't think we can guarantee that we notice
thread death before we notice a request to create a new Wine thread.
Using Wine-managed TIDs avoids this by virtue of ensuring that a Wine TID is
not reused until the associated Wine thread has been cleaned up.
^ permalink raw reply
* Re: [PATCHv5 bpf-next 6/8] x86/shstk: Add return uprobe support
From: Oleg Nesterov @ 2024-05-15 15:42 UTC (permalink / raw)
To: Edgecombe, Rick P
Cc: olsajiri@gmail.com, songliubraving@fb.com, luto@kernel.org,
mhiramat@kernel.org, andrii@kernel.org, debug@rivosinc.com,
john.fastabend@gmail.com, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org, mingo@redhat.com,
rostedt@goodmis.org, ast@kernel.org, tglx@linutronix.de,
linux-man@vger.kernel.org, yhs@fb.com, daniel@iogearbox.net,
peterz@infradead.org, linux-trace-kernel@vger.kernel.org,
bp@alien8.de, bpf@vger.kernel.org, x86@kernel.org
In-Reply-To: <0fa9634e9ac0d30d513eefe6099f5d8d354d93c1.camel@intel.com>
On 05/15, Edgecombe, Rick P wrote:
>
> On Wed, 2024-05-15 at 13:35 +0200, Oleg Nesterov wrote:
> >
> > > I'm ok with not using optimized uretprobe when shadow stack is detected
> > > as enabled and we go with current uretprobe in that case
> >
> > But how can we detect it? Again, suppose userspace does
>
> the rdssp instruction returns the value of the shadow stack pointer. On non-
> shadow stack it is a nop. So you could check if the SSP is non-zero to find if
> shadow stack is enabled.
But again, the ret-probed function can enable it before it returns? And we
need to check if it is enabled on the function entry if we want to avoid
sys_uretprobe() in this case. Although I don't understand why we want to
avoid it.
> This would catch most cases, but I guess there is the
> possibility of it getting enabled in a signal that hit between checking and the
> rest of operation.
Or from signal handler.
> Is this uretprobe stuff signal safe in general?
In what sense?
I forgot everything about this code but I can't recall any problem with signals.
Except it doesn't support sigaltstack() + siglongjmp().
Oleg.
^ permalink raw reply
* Re: [PATCHv5 bpf-next 6/8] x86/shstk: Add return uprobe support
From: Edgecombe, Rick P @ 2024-05-15 15:31 UTC (permalink / raw)
To: olsajiri@gmail.com, oleg@redhat.com
Cc: songliubraving@fb.com, luto@kernel.org, mhiramat@kernel.org,
andrii@kernel.org, debug@rivosinc.com, john.fastabend@gmail.com,
linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
mingo@redhat.com, rostedt@goodmis.org, ast@kernel.org,
tglx@linutronix.de, linux-man@vger.kernel.org, yhs@fb.com,
daniel@iogearbox.net, peterz@infradead.org,
linux-trace-kernel@vger.kernel.org, bp@alien8.de,
bpf@vger.kernel.org, x86@kernel.org
In-Reply-To: <20240515152609.GD6821@redhat.com>
On Wed, 2024-05-15 at 17:26 +0200, Oleg Nesterov wrote:
> > I think it will crash, there's explanation in the comment in
> > tools/testing/selftests/x86/test_shadow_stack.c test
>
> OK, thanks...
>
> But test_shadow_stack.c doesn't do ARCH_PRCTL(ARCH_SHSTK_DISABLE) if
> all the tests succeed ? Confused but nevermind.
The last test disables shadow stack as part of the test. So if it succeeds it
doesn't need to disable the shadow stack to prevent underflow.
^ permalink raw reply
* Re: [PATCHv5 bpf-next 6/8] x86/shstk: Add return uprobe support
From: Oleg Nesterov @ 2024-05-15 15:26 UTC (permalink / raw)
To: Jiri Olsa
Cc: Deepak Gupta, Edgecombe, Rick P, songliubraving@fb.com,
luto@kernel.org, mhiramat@kernel.org, andrii@kernel.org,
john.fastabend@gmail.com, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org, mingo@redhat.com,
rostedt@goodmis.org, ast@kernel.org, tglx@linutronix.de,
linux-man@vger.kernel.org, yhs@fb.com, daniel@iogearbox.net,
peterz@infradead.org, linux-trace-kernel@vger.kernel.org,
bp@alien8.de, bpf@vger.kernel.org, x86@kernel.org
In-Reply-To: <ZkTIU1QUAJF0f0KK@krava>
On 05/15, Jiri Olsa wrote:
>
> On Wed, May 15, 2024 at 01:19:20PM +0200, Oleg Nesterov wrote:
> > Let me ask a couple of really stupid questions. What if the shadow stack
> > is "shorter" than the normal stack? I mean,
> >
> > enable_shstk()
> > {
> > prctl(ARCH_SHSTK_SHSTK);
I meant ARCH_SHSTK_ENABLE, of course
> > }
> >
> > what happens when enable_shstk() returns?
>
> I think it will crash, there's explanation in the comment in
> tools/testing/selftests/x86/test_shadow_stack.c test
OK, thanks...
But test_shadow_stack.c doesn't do ARCH_PRCTL(ARCH_SHSTK_DISABLE) if
all the tests succeed ? Confused but nevermind.
> > And what is the purpose of fpregs_lock_and_load() ? Why do we need to
> > fpregs_restore_userregs() in shstk_setup() and other places?
> >
> > Oleg.
> >
>
^ permalink raw reply
* Re: [PATCHv5 bpf-next 6/8] x86/shstk: Add return uprobe support
From: Edgecombe, Rick P @ 2024-05-15 15:18 UTC (permalink / raw)
To: olsajiri@gmail.com, oleg@redhat.com
Cc: songliubraving@fb.com, luto@kernel.org, mhiramat@kernel.org,
andrii@kernel.org, debug@rivosinc.com, john.fastabend@gmail.com,
linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
mingo@redhat.com, rostedt@goodmis.org, ast@kernel.org,
tglx@linutronix.de, linux-man@vger.kernel.org, yhs@fb.com,
daniel@iogearbox.net, peterz@infradead.org,
linux-trace-kernel@vger.kernel.org, bp@alien8.de,
bpf@vger.kernel.org, x86@kernel.org
In-Reply-To: <ZkTIU1QUAJF0f0KK@krava>
On Wed, 2024-05-15 at 08:36 -0600, Jiri Olsa wrote:
> >
> > Let me ask a couple of really stupid questions. What if the shadow stack
> > is "shorter" than the normal stack? I mean,
The shadow stack could overflow if it is not big enough. However since the
normal stack has return addresses and data, and shadow stack has the smaller
amount data of only return addresses, we can mostly avoid this by picking a
large size for the shadow stack.
For underflow, you can't return from the point where you enable shadow stack.
Almost all uses will enable it very early. Glibc loader does it before main is
reached, for example. The shadow stack selftest is not a typical usage in this
respect.
^ permalink raw reply
* Re: [PATCHv5 bpf-next 6/8] x86/shstk: Add return uprobe support
From: Edgecombe, Rick P @ 2024-05-15 15:13 UTC (permalink / raw)
To: olsajiri@gmail.com, oleg@redhat.com
Cc: songliubraving@fb.com, luto@kernel.org, mhiramat@kernel.org,
andrii@kernel.org, debug@rivosinc.com, john.fastabend@gmail.com,
linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
mingo@redhat.com, rostedt@goodmis.org, ast@kernel.org,
tglx@linutronix.de, linux-man@vger.kernel.org, yhs@fb.com,
daniel@iogearbox.net, peterz@infradead.org,
linux-trace-kernel@vger.kernel.org, bp@alien8.de,
bpf@vger.kernel.org, x86@kernel.org
In-Reply-To: <20240515113525.GB6821@redhat.com>
On Wed, 2024-05-15 at 13:35 +0200, Oleg Nesterov wrote:
> Let me repeat I know nothing about shadow stacks, only tried to
> read Documentation/arch/x86/shstk.rst few minutes ago ;)
>
> On 05/13, Jiri Olsa wrote:
> >
> > 1) current uretprobe which are not working at the moment and we change
> > the top value of shadow stack with shstk_push_frame
> > 2) optimized uretprobe which needs to push new frame on shadow stack
> > with shstk_update_last_frame
> >
> > I think we should do 1) and have current uretprobe working with shadow
> > stack, which is broken at the moment
>
> Agreed,
>
> > I'm ok with not using optimized uretprobe when shadow stack is detected
> > as enabled and we go with current uretprobe in that case
>
> But how can we detect it? Again, suppose userspace does
the rdssp instruction returns the value of the shadow stack pointer. On non-
shadow stack it is a nop. So you could check if the SSP is non-zero to find if
shadow stack is enabled. This would catch most cases, but I guess there is the
possibility of it getting enabled in a signal that hit between checking and the
rest of operation. Is this uretprobe stuff signal safe in general?
^ permalink raw reply
* Re: [PATCHv5 bpf-next 6/8] x86/shstk: Add return uprobe support
From: Jiri Olsa @ 2024-05-15 14:36 UTC (permalink / raw)
To: Oleg Nesterov
Cc: Deepak Gupta, Edgecombe, Rick P, olsajiri@gmail.com,
songliubraving@fb.com, luto@kernel.org, mhiramat@kernel.org,
andrii@kernel.org, john.fastabend@gmail.com,
linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
mingo@redhat.com, rostedt@goodmis.org, ast@kernel.org,
tglx@linutronix.de, linux-man@vger.kernel.org, yhs@fb.com,
daniel@iogearbox.net, peterz@infradead.org,
linux-trace-kernel@vger.kernel.org, bp@alien8.de,
bpf@vger.kernel.org, x86@kernel.org
In-Reply-To: <20240515111919.GA6821@redhat.com>
On Wed, May 15, 2024 at 01:19:20PM +0200, Oleg Nesterov wrote:
> Sorry for the late reply, I was on PTO.
>
> On 05/14, Deepak Gupta wrote:
> >
> > Question,
> >
> > Is it kernel who is maintaining all return probes, meaning original return addresses
> > are saved in kernel data structures on per task basis.
>
> Yes. task_struct->utask->return_instances
>
> See prepare_uretprobe() which inserts the new return_instance with
> ->orig_ret_vaddr = original return addresses
> when the tracee enters the ret-probed function.
>
> > Once uretprobe did its job then
> > its kernel who is ensuring return to original return address ?
>
> Yes. See instruction_pointer_set(regs, ri->orig_ret_vaddr) in
> handle_trampoline().
>
>
>
> I know absolutely nothing about the shadow stacks, trying to read
> Documentation/arch/x86/shstk.rst but it doesn't tell me too much...
> Where can I find more documentation? I didn't try to google yet.
>
> Upon function return, the processor pops the shadow stack copy
> and compares it to the normal stack copy. If the two differ, the
> processor raises a control-protection fault.
>
> grep-grep-grep... exc_control_protection I guess.
>
> Let me ask a couple of really stupid questions. What if the shadow stack
> is "shorter" than the normal stack? I mean,
>
> enable_shstk()
> {
> prctl(ARCH_SHSTK_SHSTK);
> }
>
> what happens when enable_shstk() returns?
I think it will crash, there's explanation in the comment in
tools/testing/selftests/x86/test_shadow_stack.c test
that's why ARCH_PRCTL is using syscall instruction directly and
not calling syscall function
jirka
> And what is the purpose of fpregs_lock_and_load() ? Why do we need to
> fpregs_restore_userregs() in shstk_setup() and other places?
>
> Oleg.
>
^ permalink raw reply
* Re: [PATCHv5 bpf-next 6/8] x86/shstk: Add return uprobe support
From: Oleg Nesterov @ 2024-05-15 11:35 UTC (permalink / raw)
To: Jiri Olsa
Cc: Edgecombe, Rick P, mhiramat@kernel.org, songliubraving@fb.com,
luto@kernel.org, andrii@kernel.org, debug@rivosinc.com,
john.fastabend@gmail.com, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org, mingo@redhat.com,
rostedt@goodmis.org, ast@kernel.org, tglx@linutronix.de,
yhs@fb.com, linux-man@vger.kernel.org, daniel@iogearbox.net,
peterz@infradead.org, linux-trace-kernel@vger.kernel.org,
bp@alien8.de, bpf@vger.kernel.org, x86@kernel.org
In-Reply-To: <ZkKE3qT1X_Jirb92@krava>
Let me repeat I know nothing about shadow stacks, only tried to
read Documentation/arch/x86/shstk.rst few minutes ago ;)
On 05/13, Jiri Olsa wrote:
>
> 1) current uretprobe which are not working at the moment and we change
> the top value of shadow stack with shstk_push_frame
> 2) optimized uretprobe which needs to push new frame on shadow stack
> with shstk_update_last_frame
>
> I think we should do 1) and have current uretprobe working with shadow
> stack, which is broken at the moment
Agreed,
> I'm ok with not using optimized uretprobe when shadow stack is detected
> as enabled and we go with current uretprobe in that case
But how can we detect it? Again, suppose userspace does
enable_shstk()
{
prctl(ARCH_SHSTK_SHSTK);
}
what if enable_shstk() is ret-probed ?
Oleg.
^ permalink raw reply
* Re: [PATCHv5 bpf-next 6/8] x86/shstk: Add return uprobe support
From: Oleg Nesterov @ 2024-05-15 11:19 UTC (permalink / raw)
To: Deepak Gupta
Cc: Edgecombe, Rick P, olsajiri@gmail.com, songliubraving@fb.com,
luto@kernel.org, mhiramat@kernel.org, andrii@kernel.org,
john.fastabend@gmail.com, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org, mingo@redhat.com,
rostedt@goodmis.org, ast@kernel.org, tglx@linutronix.de,
linux-man@vger.kernel.org, yhs@fb.com, daniel@iogearbox.net,
peterz@infradead.org, linux-trace-kernel@vger.kernel.org,
bp@alien8.de, bpf@vger.kernel.org, x86@kernel.org
In-Reply-To: <ZkQTgQ3aKU4MAjPu@debug.ba.rivosinc.com>
Sorry for the late reply, I was on PTO.
On 05/14, Deepak Gupta wrote:
>
> Question,
>
> Is it kernel who is maintaining all return probes, meaning original return addresses
> are saved in kernel data structures on per task basis.
Yes. task_struct->utask->return_instances
See prepare_uretprobe() which inserts the new return_instance with
->orig_ret_vaddr = original return addresses
when the tracee enters the ret-probed function.
> Once uretprobe did its job then
> its kernel who is ensuring return to original return address ?
Yes. See instruction_pointer_set(regs, ri->orig_ret_vaddr) in
handle_trampoline().
I know absolutely nothing about the shadow stacks, trying to read
Documentation/arch/x86/shstk.rst but it doesn't tell me too much...
Where can I find more documentation? I didn't try to google yet.
Upon function return, the processor pops the shadow stack copy
and compares it to the normal stack copy. If the two differ, the
processor raises a control-protection fault.
grep-grep-grep... exc_control_protection I guess.
Let me ask a couple of really stupid questions. What if the shadow stack
is "shorter" than the normal stack? I mean,
enable_shstk()
{
prctl(ARCH_SHSTK_SHSTK);
}
what happens when enable_shstk() returns?
And what is the purpose of fpregs_lock_and_load() ? Why do we need to
fpregs_restore_userregs() in shstk_setup() and other places?
Oleg.
^ permalink raw reply
* Re: [PATCHv5 bpf-next 6/8] x86/shstk: Add return uprobe support
From: Deepak Gupta @ 2024-05-15 1:44 UTC (permalink / raw)
To: Edgecombe, Rick P
Cc: olsajiri@gmail.com, songliubraving@fb.com, luto@kernel.org,
mhiramat@kernel.org, andrii@kernel.org, john.fastabend@gmail.com,
linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
mingo@redhat.com, rostedt@goodmis.org, ast@kernel.org,
tglx@linutronix.de, linux-man@vger.kernel.org, oleg@redhat.com,
yhs@fb.com, daniel@iogearbox.net, peterz@infradead.org,
linux-trace-kernel@vger.kernel.org, bp@alien8.de,
bpf@vger.kernel.org, x86@kernel.org
In-Reply-To: <3e15152888d543d2ee4e5a1d75298c80aa946659.camel@intel.com>
On Wed, May 15, 2024 at 01:10:03AM +0000, Edgecombe, Rick P wrote:
>On Mon, 2024-05-13 at 15:23 -0600, Jiri Olsa wrote:
>> so at the moment the patch 6 changes shadow stack for
>>
>> 1) current uretprobe which are not working at the moment and we change
>> the top value of shadow stack with shstk_push_frame
>> 2) optimized uretprobe which needs to push new frame on shadow stack
>> with shstk_update_last_frame
>>
>> I think we should do 1) and have current uretprobe working with shadow
>> stack, which is broken at the moment
>>
>> I'm ok with not using optimized uretprobe when shadow stack is detected
>> as enabled and we go with current uretprobe in that case
>>
>> would this work for you?
>
>Sorry for the delay. It seems reasonable to me due to 1 being at a fixed address
>where 2 was arbitrary address. But Peterz might have felt the opposite earlier.
>Not sure.
>
>I'd also love to get some second opinions from broonie (arm shadow stack) and
>Deepak (riscv shadow stack).
>
>Deepak, even if riscv has a special instruction that pushes to the shadow stack,
>will it be ok if there is a callable operation that does the same thing? Like,
>aren't you relying on endbranches or the compiler or something such that
>arbitrary data can't be pushed via that instruction?
Instruction is `sspush x1/ra`. It pushes contents of register return address (ra
also called x1) onto shadow stack. `ra` is like arm's equivalent of link register.
Prologue of function is supposed to have `sspush x1` to save it away.
ISA doesn't allow encodings with register in risc-v GPRs (except register x5
because some embedded riscv space toolchains have used x5 as ra too).
On question of callable operation, I think still need to fully understand who manages
the probe and forward progress.
Question,
Is it kernel who is maintaining all return probes, meaning original return addresses
are saved in kernel data structures on per task basis. Once uretprobe did its job then
its kernel who is ensuring return to original return address ?
>
>BTW Jiri, thanks for considering shadow stack in your work.
^ permalink raw reply
* Re: [PATCHv5 bpf-next 6/8] x86/shstk: Add return uprobe support
From: Edgecombe, Rick P @ 2024-05-15 1:10 UTC (permalink / raw)
To: olsajiri@gmail.com
Cc: songliubraving@fb.com, luto@kernel.org, mhiramat@kernel.org,
andrii@kernel.org, debug@rivosinc.com, john.fastabend@gmail.com,
linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
mingo@redhat.com, rostedt@goodmis.org, ast@kernel.org,
tglx@linutronix.de, linux-man@vger.kernel.org, oleg@redhat.com,
yhs@fb.com, daniel@iogearbox.net, peterz@infradead.org,
linux-trace-kernel@vger.kernel.org, bp@alien8.de,
bpf@vger.kernel.org, x86@kernel.org
In-Reply-To: <ZkKE3qT1X_Jirb92@krava>
On Mon, 2024-05-13 at 15:23 -0600, Jiri Olsa wrote:
> so at the moment the patch 6 changes shadow stack for
>
> 1) current uretprobe which are not working at the moment and we change
> the top value of shadow stack with shstk_push_frame
> 2) optimized uretprobe which needs to push new frame on shadow stack
> with shstk_update_last_frame
>
> I think we should do 1) and have current uretprobe working with shadow
> stack, which is broken at the moment
>
> I'm ok with not using optimized uretprobe when shadow stack is detected
> as enabled and we go with current uretprobe in that case
>
> would this work for you?
Sorry for the delay. It seems reasonable to me due to 1 being at a fixed address
where 2 was arbitrary address. But Peterz might have felt the opposite earlier.
Not sure.
I'd also love to get some second opinions from broonie (arm shadow stack) and
Deepak (riscv shadow stack).
Deepak, even if riscv has a special instruction that pushes to the shadow stack,
will it be ok if there is a callable operation that does the same thing? Like,
aren't you relying on endbranches or the compiler or something such that
arbitrary data can't be pushed via that instruction?
BTW Jiri, thanks for considering shadow stack in your work.
^ permalink raw reply
* Re: [PATCH v4 02/27] ntsync: Introduce NTSYNC_IOC_WAIT_ALL.
From: Elizabeth Figura @ 2024-05-14 4:15 UTC (permalink / raw)
To: Peter Zijlstra
Cc: Arnd Bergmann, Greg Kroah-Hartman, Jonathan Corbet, Shuah Khan,
linux-kernel, linux-api, wine-devel, André Almeida,
Wolfram Sang, Arkadiusz Hiler, Andy Lutomirski, linux-doc,
linux-kselftest, Randy Dunlap, Ingo Molnar, Will Deacon,
Waiman Long, Boqun Feng
In-Reply-To: <20240419162814.GA39162@noisy.programming.kicks-ass.net>
On Friday, April 19, 2024 11:28:14 AM CDT Peter Zijlstra wrote:
> On Thu, Apr 18, 2024 at 11:35:11AM +0200, Peter Zijlstra wrote:
> > On Wed, Apr 17, 2024 at 03:03:05PM -0500, Elizabeth Figura wrote:
> > > Ach. I wrote this with the idea that the race isn't meaningful, but
> > > looking at it again you're right—there is a harmful race here.
> > >
> > > I think it should be fixable by moving the atomic_read inside the lock,
> > > though.
> >
> > Right, I've ended up with the (as yet untested) below. I'll see if I can
> > find time later to actually test things.
>
> Latest hackery... I tried testing this but I'm not having luck using the
> patched wine as per the other email.
>
I converted the rest of the direct uses of spin_lock() using the below patch
and tested it myself, and it passes Wine tests. As far as I can tell the logic
is correct, too; I couldn't find any races.
I'll incorporate these changes into the next revision, unless there's a good
reason not to.
---
--- a/drivers/misc/ntsync.c
+++ b/drivers/misc/ntsync.c
@@ -569,17 +569,19 @@ static int ntsync_event_set(struct ntsync_obj *event,
void __user *argp, bool pu
static int ntsync_event_reset(struct ntsync_obj *event, void __user *argp)
{
+ struct ntsync_device *dev = event->dev;
__u32 prev_state;
+ bool all;
if (event->type != NTSYNC_TYPE_EVENT)
return -EINVAL;
- spin_lock(&event->lock);
+ all = ntsync_lock_obj(dev, event);
prev_state = event->u.event.signaled;
event->u.event.signaled = false;
- spin_unlock(&event->lock);
+ ntsync_unlock_obj(dev, event, all);
if (put_user(prev_state, (__u32 __user *)argp))
return -EFAULT;
@@ -590,16 +592,21 @@ static int ntsync_event_reset(struct ntsync_obj *event,
void __user *argp)
static int ntsync_sem_read(struct ntsync_obj *sem, void __user *argp)
{
struct ntsync_sem_args __user *user_args = argp;
+ struct ntsync_device *dev = sem->dev;
struct ntsync_sem_args args;
+ bool all;
if (sem->type != NTSYNC_TYPE_SEM)
return -EINVAL;
args.sem = 0;
- spin_lock(&sem->lock);
+
+ all = ntsync_lock_obj(dev, sem);
+
args.count = sem->u.sem.count;
args.max = sem->u.sem.max;
- spin_unlock(&sem->lock);
+
+ ntsync_unlock_obj(dev, sem, all);
if (copy_to_user(user_args, &args, sizeof(args)))
return -EFAULT;
@@ -609,18 +616,23 @@ static int ntsync_sem_read(struct ntsync_obj *sem, void
__user *argp)
static int ntsync_mutex_read(struct ntsync_obj *mutex, void __user *argp)
{
struct ntsync_mutex_args __user *user_args = argp;
+ struct ntsync_device *dev = mutex->dev;
struct ntsync_mutex_args args;
+ bool all;
int ret;
if (mutex->type != NTSYNC_TYPE_MUTEX)
return -EINVAL;
args.mutex = 0;
- spin_lock(&mutex->lock);
+
+ all = ntsync_lock_obj(dev, mutex);
+
args.count = mutex->u.mutex.count;
args.owner = mutex->u.mutex.owner;
ret = mutex->u.mutex.ownerdead ? -EOWNERDEAD : 0;
- spin_unlock(&mutex->lock);
+
+ ntsync_unlock_obj(dev, mutex, all);
if (copy_to_user(user_args, &args, sizeof(args)))
return -EFAULT;
@@ -630,16 +642,21 @@ static int ntsync_mutex_read(struct ntsync_obj *mutex,
void __user *argp)
static int ntsync_event_read(struct ntsync_obj *event, void __user *argp)
{
struct ntsync_event_args __user *user_args = argp;
+ struct ntsync_device *dev = event->dev;
struct ntsync_event_args args;
+ bool all;
if (event->type != NTSYNC_TYPE_EVENT)
return -EINVAL;
args.event = 0;
- spin_lock(&event->lock);
+
+ all = ntsync_lock_obj(dev, event);
+
args.manual = event->u.event.manual;
args.signaled = event->u.event.signaled;
- spin_unlock(&event->lock);
+
+ ntsync_unlock_obj(dev, event, all);
if (copy_to_user(user_args, &args, sizeof(args)))
return -EFAULT;
@@ -962,6 +979,7 @@ static int ntsync_wait_any(struct ntsync_device *dev, void
__user *argp)
__u32 i, total_count;
struct ntsync_q *q;
int signaled;
+ bool all;
int ret;
if (copy_from_user(&args, argp, sizeof(args)))
@@ -981,9 +999,9 @@ static int ntsync_wait_any(struct ntsync_device *dev, void
__user *argp)
struct ntsync_q_entry *entry = &q->entries[i];
struct ntsync_obj *obj = entry->obj;
- spin_lock(&obj->lock);
+ all = ntsync_lock_obj(dev, obj);
list_add_tail(&entry->node, &obj->any_waiters);
- spin_unlock(&obj->lock);
+ ntsync_unlock_obj(dev, obj, all);
}
/*
@@ -1000,9 +1018,9 @@ static int ntsync_wait_any(struct ntsync_device *dev,
void __user *argp)
if (atomic_read(&q->signaled) != -1)
break;
- spin_lock(&obj->lock);
+ all = ntsync_lock_obj(dev, obj);
try_wake_any_obj(obj);
- spin_unlock(&obj->lock);
+ ntsync_unlock_obj(dev, obj, all);
}
/* sleep */
@@ -1015,9 +1033,9 @@ static int ntsync_wait_any(struct ntsync_device *dev,
void __user *argp)
struct ntsync_q_entry *entry = &q->entries[i];
struct ntsync_obj *obj = entry->obj;
- spin_lock(&obj->lock);
+ all = ntsync_lock_obj(dev, obj);
list_del(&entry->node);
- spin_unlock(&obj->lock);
+ ntsync_unlock_obj(dev, obj, all);
put_obj(obj);
}
@@ -1075,9 +1093,9 @@ static int ntsync_wait_all(struct ntsync_device *dev,
void __user *argp)
struct ntsync_q_entry *entry = &q->entries[args.count];
struct ntsync_obj *obj = entry->obj;
- spin_lock_nest_lock(&obj->lock, &dev->wait_all_lock);
+ dev_lock_obj(dev, obj);
list_add_tail(&entry->node, &obj->any_waiters);
- spin_unlock(&obj->lock);
+ dev_unlock_obj(dev, obj);
}
/* check if we are already signaled */
@@ -1095,9 +1113,9 @@ static int ntsync_wait_all(struct ntsync_device *dev,
void __user *argp)
struct ntsync_obj *obj = q->entries[args.count].obj;
if (atomic_read(&q->signaled) == -1) {
- spin_lock(&obj->lock);
+ dev_lock_obj(dev, obj);
try_wake_any_obj(obj);
- spin_unlock(&obj->lock);
+ dev_unlock_obj(dev, obj);
}
}
@@ -1127,9 +1145,9 @@ static int ntsync_wait_all(struct ntsync_device *dev,
void __user *argp)
struct ntsync_q_entry *entry = &q->entries[args.count];
struct ntsync_obj *obj = entry->obj;
- spin_lock_nest_lock(&obj->lock, &dev->wait_all_lock);
+ dev_lock_obj(dev, obj);
list_del(&entry->node);
- spin_unlock(&obj->lock);
+ dev_unlock_obj(dev, obj);
put_obj(obj);
}
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