[RFC PATCH v2 12/29] ntsync: Introduce NTSYNC_IOC_EVENT_PULSE.

[Elizabeth Figura]

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@xxxxxxxxxxxxxxx>
---
 drivers/misc/ntsync.c       | 10 ++++++++--
 include/uapi/linux/ntsync.h |  1 +
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c
index 009d927739b8..240ae858fa96 100644
--- a/drivers/misc/ntsync.c
+++ b/drivers/misc/ntsync.c
@@ -447,7 +447,7 @@ 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;
@@ -463,6 +463,8 @@ static int ntsync_event_set(struct ntsync_obj *event, void __user *argp)
 		event->u.event.signaled = true;
 		try_wake_all_obj(dev, event);
 		try_wake_any_event(event);
+		if (pulse)
+			event->u.event.signaled = false;
 
 		spin_unlock(&event->lock);
 		spin_unlock(&dev->wait_all_lock);
@@ -472,6 +474,8 @@ static int ntsync_event_set(struct ntsync_obj *event, void __user *argp)
 		prev_state = event->u.event.signaled;
 		event->u.event.signaled = true;
 		try_wake_any_event(event);
+		if (pulse)
+			event->u.event.signaled = false;
 
 		spin_unlock(&event->lock);
 	}
@@ -526,9 +530,11 @@ 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 f2d7507d8438..598f894f868d 100644
--- a/include/uapi/linux/ntsync.h
+++ b/include/uapi/linux/ntsync.h
@@ -50,5 +50,6 @@ 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