[PATCH 03/21] HID: axff: move FF initialization to .input_configured()

[Dmitry Torokhov]

The driver currently initializes force-feedback in its probe() function
after calling hid_hw_start() with HID_CONNECT_DEFAULT. 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-axff.c | 40 ++++++++++++----------------------------
 1 file changed, 12 insertions(+), 28 deletions(-)

diff --git a/drivers/hid/hid-axff.c b/drivers/hid/hid-axff.c
index 3c5c2bf02425..2f46447086df 100644
--- a/drivers/hid/hid-axff.c
+++ b/drivers/hid/hid-axff.c
@@ -59,30 +59,24 @@ static int axff_play(struct input_dev *dev, void *data, struct ff_effect *effect
 	return 0;
 }
 
-static int axff_init(struct hid_device *hid)
+static int ax_input_configured(struct hid_device *hid, struct hid_input *hidinput)
 {
 	struct axff_device *axff;
 	struct hid_report *report;
-	struct hid_input *hidinput;
-	struct list_head *report_list =&hid->report_enum[HID_OUTPUT_REPORT].report_list;
-	struct input_dev *dev;
+	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
+	struct input_dev *dev = hidinput->input;
 	int field_count = 0;
 	int i, j;
 	int error;
 
-	if (list_empty(&hid->inputs)) {
-		hid_err(hid, "no inputs found\n");
-		return -ENODEV;
-	}
-	hidinput = list_first_entry(&hid->inputs, struct hid_input, list);
-	dev = hidinput->input;
+	if (!list_is_first(&hidinput->list, &hid->inputs))
+		return 0;
 
-	if (list_empty(report_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;
 	}
-
-	report = list_first_entry(report_list, struct hid_report, list);
 	for (i = 0; i < report->maxfield; i++) {
 		for (j = 0; j < report->field[i]->report_count; j++) {
 			report->field[i]->value[j] = 0x00;
@@ -100,13 +94,13 @@ static int axff_init(struct hid_device *hid)
 	if (!axff)
 		return -ENOMEM;
 
+	axff->report = report;
 	set_bit(FF_RUMBLE, dev->ffbit);
 
 	error = input_ff_create_memless(dev, axff, axff_play);
 	if (error)
 		goto err_free_mem;
 
-	axff->report = report;
 	hid_hw_request(hid, axff->report, HID_REQ_SET_REPORT);
 
 	hid_info(hid, "Force Feedback for ACRUX game controllers by Sergei Kolzun <x0r@xxxxxxxxxx>\n");
@@ -118,7 +112,8 @@ static int axff_init(struct hid_device *hid)
 	return error;
 }
 #else
-static inline int axff_init(struct hid_device *hid)
+static inline int ax_input_configured(struct hid_device *hid,
+				      struct hid_input *hidinput)
 {
 	return 0;
 }
@@ -136,23 +131,11 @@ static int ax_probe(struct hid_device *hdev, const struct hid_device_id *id)
 		return error;
 	}
 
-	error = hid_hw_start(hdev, HID_CONNECT_DEFAULT & ~HID_CONNECT_FF);
+	error = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
 	if (error) {
 		hid_err(hdev, "hw start failed\n");
 		return error;
 	}
-
-	error = axff_init(hdev);
-	if (error) {
-		/*
-		 * Do not fail device initialization completely as device
-		 * may still be partially operable, just warn.
-		 */
-		hid_warn(hdev,
-			 "Failed to enable force feedback support, error: %d\n",
-			 error);
-	}
-
 	/*
 	 * We need to start polling device right away, otherwise
 	 * it will go into a coma.
@@ -185,6 +168,7 @@ static struct hid_driver ax_driver = {
 	.id_table	= ax_devices,
 	.probe		= ax_probe,
 	.remove		= ax_remove,
+	.input_configured = ax_input_configured,
 };
 module_hid_driver(ax_driver);
 

-- 
2.55.0.629.g250fe7f194-goog