linux-kernel - [PATCH v4 09/27] ntsync: Introduce NTSYNC_IOC_EVENT

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Message-ID: <20240416010837.333694-10-zfigura@codeweavers.com>
Date: Mon, 15 Apr 2024 20:08:19 -0500
From: Elizabeth Figura <zfigura@...eweavers.com>
To: Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jonathan Corbet <corbet@....net>,
	Shuah Khan <shuah@...nel.org>
Cc: linux-kernel@...r.kernel.org,
	linux-api@...r.kernel.org,
	wine-devel@...ehq.org,
	André Almeida <andrealmeid@...lia.com>,
	Wolfram Sang <wsa@...nel.org>,
	Arkadiusz Hiler <ahiler@...eweavers.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Andy Lutomirski <luto@...nel.org>,
	linux-doc@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	Randy Dunlap <rdunlap@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Will Deacon <will@...nel.org>,
	Waiman Long <longman@...hat.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Elizabeth Figura <zfigura@...eweavers.com>
Subject: [PATCH v4 09/27] ntsync: Introduce NTSYNC_IOC_EVENT_PULSE.

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@...eweavers.com>
---
 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 ae78425c87d1..adba4657bf26 100644
--- a/drivers/misc/ntsync.c
+++ b/drivers/misc/ntsync.c
@@ -473,7 +473,7 @@ 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;
@@ -489,6 +489,8 @@ 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);
@@ -498,6 +500,8 @@ 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);
 	}
@@ -552,9 +556,11 @@ 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 657542107328..57721f5d31ba 100644
--- a/include/uapi/linux/ntsync.h
+++ b/include/uapi/linux/ntsync.h
@@ -54,5 +54,6 @@ 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