HID: hid-steam: Move hidraw input (un)registering to work

Due to an interplay between locking in the input and hid transport subsystems,
attempting to register or deregister the relevant input devices during the
hidraw open/close events can lead to a lock ordering issue. Though this
shouldn't cause a deadlock, this commit moves the input device manipulation to
deferred work to sidestep the issue.

Fixes: 385a488 ("HID: steam: remove input device when a hid client is running.")
Signed-off-by: Vicki Pfau <[email protected]>
Signed-off-by: Jiri Kosina <[email protected]>

Author: endrift

drivers/hid/hid-steam.c

@@ -313,6 +313,7 @@ struct steam_device {
 	u16 rumble_left;
 	u16 rumble_right;
 	unsigned int sensor_timestamp_us;
+	struct work_struct unregister_work;
 };
 
 static int steam_recv_report(struct steam_device *steam,
@@ -1072,6 +1073,31 @@ static void steam_mode_switch_cb(struct work_struct *work)
 	}
 }
 
+static void steam_work_unregister_cb(struct work_struct *work)
+{
+	struct steam_device *steam = container_of(work, struct steam_device,
+							unregister_work);
+	unsigned long flags;
+	bool connected;
+	bool opened;
+
+	spin_lock_irqsave(&steam->lock, flags);
+	opened = steam->client_opened;
+	connected = steam->connected;
+	spin_unlock_irqrestore(&steam->lock, flags);
+
+	if (connected) {
+		if (opened) {
+			steam_sensors_unregister(steam);
+			steam_input_unregister(steam);
+		} else {
+			steam_set_lizard_mode(steam, lizard_mode);
+			steam_input_register(steam);
+			steam_sensors_register(steam);
+		}
+	}
+}
+
 static bool steam_is_valve_interface(struct hid_device *hdev)
 {
 	struct hid_report_enum *rep_enum;
@@ -1117,8 +1143,7 @@ static int steam_client_ll_open(struct hid_device *hdev)
 	steam->client_opened++;
 	spin_unlock_irqrestore(&steam->lock, flags);
 
-	steam_sensors_unregister(steam);
-	steam_input_unregister(steam);
+	schedule_work(&steam->unregister_work);
 
 	return 0;
 }
@@ -1135,11 +1160,7 @@ static void steam_client_ll_close(struct hid_device *hdev)
 	connected = steam->connected && !steam->client_opened;
 	spin_unlock_irqrestore(&steam->lock, flags);
 
-	if (connected) {
-		steam_set_lizard_mode(steam, lizard_mode);
-		steam_input_register(steam);
-		steam_sensors_register(steam);
-	}
+	schedule_work(&steam->unregister_work);
 }
 
 static int steam_client_ll_raw_request(struct hid_device *hdev,
@@ -1231,6 +1252,7 @@ static int steam_probe(struct hid_device *hdev,
 	INIT_LIST_HEAD(&steam->list);
 	INIT_WORK(&steam->rumble_work, steam_haptic_rumble_cb);
 	steam->sensor_timestamp_us = 0;
+	INIT_WORK(&steam->unregister_work, steam_work_unregister_cb);
 
 	/*
 	 * With the real steam controller interface, do not connect hidraw.
@@ -1291,6 +1313,7 @@ static int steam_probe(struct hid_device *hdev,
 	cancel_work_sync(&steam->work_connect);
 	cancel_delayed_work_sync(&steam->mode_switch);
 	cancel_work_sync(&steam->rumble_work);
+	cancel_work_sync(&steam->unregister_work);
 
 	return ret;
 }
@@ -1307,6 +1330,7 @@ static void steam_remove(struct hid_device *hdev)
 	cancel_delayed_work_sync(&steam->mode_switch);
 	cancel_work_sync(&steam->work_connect);
 	cancel_work_sync(&steam->rumble_work);
+	cancel_work_sync(&steam->unregister_work);
 	hid_destroy_device(steam->client_hdev);
 	steam->client_hdev = NULL;
 	steam->client_opened = 0;