[PATCH] HID: sony: fix sleeping in atomic context in RB3 Pro raw event handler

[Sanjay Govind <sanjay.govind9@gmail.com>]

Rock Band 3 Pro instruments only send navigation reports until they
receive a magic SET_REPORT feature request. When such a report is seen,
rb3_pro_instrument_raw_event() sends that request directly through
rb3_pro_instrument_enable_full_report(), which does a GFP_KERNEL
allocation and a synchronous hid_hw_raw_request().

The raw event handler is called from the URB completion handler in
softirq context, and on USB hid_hw_raw_request() ends up in
usb_control_msg(), which sleeps. Plugging in an RB3 Pro instrument
therefore triggers:

  BUG: scheduling while atomic
  ...
  softirq: huh, entered softirq 0 HI ... preempt_count 101, exited with 0

This was reported on a Mustang guitar (12ba:2430).

Move the request to process context by registering
rb3_pro_instrument_enable_full_report() as the send_output_report
callback of the existing state worker. The raw event handler now only
schedules the work, keeping the 8 second rate limit. The state worker
is already cancelled by sony_cleanup() on remove and on probe failure,
and sony_schedule_work() is a no-op once cancellation has started, so
no new teardown is needed.

Fixes: 7245b0017d12 ("HID: sony: add support for more instruments")
Cc: stable@vger.kernel.org
Signed-off-by: Sanjay Govind <sanjay.govind9@gmail.com>
---

Notes:
    Reproduced and tested with a Santroller device emulating a 12ba:2430
    guitar: without the fix, 'BUG: scheduling while atomic' is logged every
    8 seconds; with the fix no more warnings are logged.
    
    The fix and changelog were written with the help of an AI coding
    assistant (Claude Opus 5.5).

 drivers/hid/hid-sony.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/hid/hid-sony.c b/drivers/hid/hid-sony.c
index 50f5ad6bbeb4..9ee175f9e58d 100644
--- a/drivers/hid/hid-sony.c
+++ b/drivers/hid/hid-sony.c
@@ -630,7 +630,7 @@ static int ghl_init_urb(struct sony_sc *sc, struct usb_device *usbdev,
  * Sending HID_REQ_SET_REPORT enables the full report. Without this
  * Rock Band 3 Pro instruments only report navigation events
  */
-static int rb3_pro_instrument_enable_full_report(struct sony_sc *sc)
+static void rb3_pro_instrument_enable_full_report(struct sony_sc *sc)
 {
 	struct hid_device *hdev = sc->hdev;
 	static const u8 report[] = { 0x00, 0xE9, 0x00, 0x89, 0x1B,
@@ -647,14 +647,14 @@ static int rb3_pro_instrument_enable_full_report(struct sony_sc *sc)
 
 	buf = kmemdup(report, sizeof(report), GFP_KERNEL);
 	if (!buf)
-		return -ENOMEM;
+		return;
 
 	ret = hid_hw_raw_request(hdev, buf[0], buf, sizeof(report),
 				  HID_FEATURE_REPORT, HID_REQ_SET_REPORT);
+	if (ret < 0)
+		hid_dbg(hdev, "failed to enable full report: %d\n", ret);
 
 	kfree(buf);
-
-	return ret;
 }
 
 static int djh_turntable_mapping(struct hid_device *hdev, struct hid_input *hi,
@@ -1098,10 +1098,10 @@ static int rb3_pro_instrument_raw_event(struct sony_sc *sc, u8 *rd, int size)
 	if (size < 25 || rd[24] != 0x02)
 		return 0;
 
-	/* Only attempt to enable full report every 8 seconds */
+	/* Only attempt to enable full report every 8 seconds, from the worker */
 	if (time_after(jiffies, sc->rb3_pro_poke_jiffies)) {
 		sc->rb3_pro_poke_jiffies = jiffies + secs_to_jiffies(8);
-		rb3_pro_instrument_enable_full_report(sc);
+		sony_schedule_work(sc);
 	}
 
 	return 0;
@@ -2217,6 +2217,7 @@ static int sony_input_configured(struct hid_device *hdev,
 		hdev->quirks |= HID_QUIRK_SKIP_OUTPUT_REPORT_ID;
 
 		sony_init_raw_event_handler(sc, rb3_pro_instrument_raw_event);
+		sony_init_output_report(sc, rb3_pro_instrument_enable_full_report);
 	} else if (sc->quirks & SIXAXIS_CONTROLLER_USB) {
 		/*
 		 * The Sony Sixaxis does not handle HID Output Reports on the
-- 
2.56.0