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ntsync: Introduce NTSYNC_IOC_CREATE_EVENT.

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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>
Link: https://lore.kernel.org/r/20241213193511.457338-9-zfigura@codeweavers.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Elizabeth Figura 2024-12-13 13:34:49 -06:00 • committed by Greg Kroah-Hartman
parent ecc2ee3614
commit 4c7404b9c2
2 changed files with 65 additions and 0 deletions
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59
drivers/misc/ntsync.c
View file

@ -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.
@ -622,6 +655,27 @@ static int ntsync_create_mutex(struct ntsync_device *dev, void __user *argp)
return fd;
}
static int ntsync_create_event(struct ntsync_device *dev, void __user *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;
}
static struct ntsync_obj *get_obj(struct ntsync_device *dev, int fd)
{
struct file *file = fget(fd);
@ -752,6 +806,9 @@ 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;
}
}
@ -941,6 +998,8 @@ 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:

6
include/uapi/linux/ntsync.h
View file

@ -20,6 +20,11 @@ struct ntsync_mutex_args {
__u32 count;
};
struct ntsync_event_args {
__u32 manual;
__u32 signaled;
};
#define NTSYNC_WAIT_REALTIME 0x1
struct ntsync_wait_args {
@ -38,6 +43,7 @@ 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 _IOW ('N', 0x84, struct ntsync_mutex_args)
#define NTSYNC_IOC_CREATE_EVENT _IOW ('N', 0x87, struct ntsync_event_args)
#define NTSYNC_IOC_SEM_RELEASE _IOWR('N', 0x81, __u32)
#define NTSYNC_IOC_MUTEX_UNLOCK _IOWR('N', 0x85, struct ntsync_mutex_args)