[RFC PATCH v2 11/29] ntsync: Introduce NTSYNC_IOC_EVENT_RESET.

[Elizabeth Figura]

This corresponds to the NT syscall NtResetEvent().

This sets the event to the unsignaled state, and returns its previous state.

Signed-off-by: Elizabeth Figura <zfigura@xxxxxxxxxxxxxxx>
---
 drivers/misc/ntsync.c       | 22 ++++++++++++++++++++++
 include/uapi/linux/ntsync.h |  1 +
 2 files changed, 23 insertions(+)

diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c
index b2da50989953..009d927739b8 100644
--- a/drivers/misc/ntsync.c
+++ b/drivers/misc/ntsync.c
@@ -482,6 +482,26 @@ static int ntsync_event_set(struct ntsync_obj *event, void __user *argp)
 	return 0;
 }
 
+static int ntsync_event_reset(struct ntsync_obj *event, void __user *argp)
+{
+	__u32 prev_state;
+
+	if (event->type != NTSYNC_TYPE_EVENT)
+		return -EINVAL;
+
+	spin_lock(&event->lock);
+
+	prev_state = event->u.event.signaled;
+	event->u.event.signaled = false;
+
+	spin_unlock(&event->lock);
+
+	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;
@@ -507,6 +527,8 @@ static long ntsync_obj_ioctl(struct file *file, unsigned int cmd,
 		return ntsync_mutex_kill(obj, argp);
 	case NTSYNC_IOC_EVENT_SET:
 		return ntsync_event_set(obj, argp);
+	case NTSYNC_IOC_EVENT_RESET:
+		return ntsync_event_reset(obj, argp);
 	default:
 		return -ENOIOCTLCMD;
 	}
diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h
index 782057552483..f2d7507d8438 100644
--- a/include/uapi/linux/ntsync.h
+++ b/include/uapi/linux/ntsync.h
@@ -49,5 +49,6 @@ struct ntsync_wait_args {
 #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)
+#define NTSYNC_IOC_EVENT_RESET		_IOR ('N', 0x89, __u32)
 
 #endif
-- 
2.43.0