[PATCH 17/21] HID: mayflash: move FF initialization to .input_configured()

[Dmitry Torokhov]

The driver currently initializes force-feedback in its probe() function
after calling hid_hw_start(). This is racy as the input device is
already registered and visible to userspace at that point.

Move the FF initialization to the .input_configured() callback to ensure
the device is fully prepared before registration.

Assisted-by: Gemini:gemini-3.1-pro
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
---
 drivers/hid/hid-mf.c | 77 ++++++++++++++++++----------------------------------
 1 file changed, 27 insertions(+), 50 deletions(-)

diff --git a/drivers/hid/hid-mf.c b/drivers/hid/hid-mf.c
index 6ff54a1ec697..136e8b41d5f4 100644
--- a/drivers/hid/hid-mf.c
+++ b/drivers/hid/hid-mf.c
@@ -54,61 +54,45 @@ static int mf_play(struct input_dev *dev, void *data, struct ff_effect *effect)
 	return 0;
 }
 
-static int mf_init(struct hid_device *hid)
+static int mf_input_configured(struct hid_device *hid, struct hid_input *hidinput)
 {
 	struct mf_device *mf;
-
 	struct list_head *report_list =
 			&hid->report_enum[HID_OUTPUT_REPORT].report_list;
-
-	struct list_head *report_ptr;
 	struct hid_report *report;
-
-	struct list_head *input_ptr = &hid->inputs;
-	struct hid_input *input;
-
-	struct input_dev *dev;
-
+	struct input_dev *dev = hidinput->input;
 	int error;
 
-	/* Setup each of the four inputs */
-	list_for_each(report_ptr, report_list) {
-		report = list_entry(report_ptr, struct hid_report, list);
+	if (!list_is_first(&hidinput->list, &hid->inputs))
+		return 0;
 
-		if (report->maxfield < 1 || report->field[0]->report_count < 2) {
-			hid_err(hid, "Invalid report, this should never happen!\n");
-			return -ENODEV;
-		}
-
-		if (list_is_last(input_ptr, &hid->inputs)) {
-			hid_err(hid, "Missing input, this should never happen!\n");
-			return -ENODEV;
-		}
-
-		input_ptr = input_ptr->next;
-		input = list_entry(input_ptr, struct hid_input, list);
+	report = list_first_entry_or_null(report_list, struct hid_report, list);
+	if (!report) {
+		hid_err(hid, "no output reports found\n");
+		return -ENODEV;
+	}
 
-		mf = kzalloc_obj(struct mf_device);
-		if (!mf)
-			return -ENOMEM;
+	if (report->maxfield < 1 || report->field[0]->report_count < 2) {
+		hid_err(hid, "Invalid report, this should never happen!\n");
+		return -ENODEV;
+	}
 
-		dev = input->input;
-		set_bit(FF_RUMBLE, dev->ffbit);
+	mf = kzalloc_obj(struct mf_device);
+	if (!mf)
+		return -ENOMEM;
 
-		error = input_ff_create_memless(dev, mf, mf_play);
-		if (error) {
-			kfree(mf);
-			return error;
-		}
+	mf->report = report;
+	set_bit(FF_RUMBLE, dev->ffbit);
 
-		mf->report = report;
-		mf->report->field[0]->value[0] = 0x00;
-		mf->report->field[0]->value[1] = 0x00;
-		hid_hw_request(hid, mf->report, HID_REQ_SET_REPORT);
+	error = input_ff_create_memless(dev, mf, mf_play);
+	if (error) {
+		kfree(mf);
+		return error;
 	}
 
-	hid_info(hid, "Force feedback for HJZ Mayflash game controller "
-		      "adapters by Marcel Hasler <mahasler@xxxxxxxxx>\n");
+	mf->report->field[0]->value[0] = 0x00;
+	mf->report->field[0]->value[1] = 0x00;
+	hid_hw_request(hid, mf->report, HID_REQ_SET_REPORT);
 
 	return 0;
 }
@@ -128,22 +112,14 @@ static int mf_probe(struct hid_device *hid, const struct hid_device_id *id)
 		return error;
 	}
 
-	error = hid_hw_start(hid, HID_CONNECT_DEFAULT & ~HID_CONNECT_FF);
+	error = hid_hw_start(hid, HID_CONNECT_DEFAULT);
 	if (error) {
 		hid_err(hid, "HID hw start failed\n");
 		return error;
 	}
 
-	error = mf_init(hid);
-	if (error) {
-		hid_err(hid, "Force feedback init failed.\n");
-		hid_hw_stop(hid);
-		return error;
-	}
-
 	return 0;
 }
-
 static const struct hid_device_id mf_devices[] = {
 	{ HID_USB_DEVICE(USB_VENDOR_ID_DRAGONRISE, USB_DEVICE_ID_DRAGONRISE_PS3),
 		.driver_data = HID_QUIRK_MULTI_INPUT },
@@ -163,6 +139,7 @@ static struct hid_driver mf_driver = {
 	.name = "hid_mf",
 	.id_table = mf_devices,
 	.probe = mf_probe,
+	.input_configured = mf_input_configured,
 };
 module_hid_driver(mf_driver);
 

-- 
2.55.0.629.g250fe7f194-goog