6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Douglas Anderson <dianders@xxxxxxxxxxxx>
[ Upstream commit e9087e828827e5a5c85e124ce77503f2b81c3491 ]
The documentation for usb_driver_claim_interface() says that "the
device lock" is needed when the function is called from places other
than probe(). This appears to be the lock for the USB interface
device. The Mediatek btusb code gets called via this path:
Workqueue: hci0 hci_power_on [bluetooth]
Call trace:
usb_driver_claim_interface
btusb_mtk_claim_iso_intf
btusb_mtk_setup
hci_dev_open_sync
hci_power_on
process_scheduled_works
worker_thread
kthread
With the above call trace the device lock hasn't been claimed. Claim
it.
Without this fix, we'd sometimes see the error "Failed to claim iso
interface". Sometimes we'd even see worse errors, like a NULL pointer
dereference (where `intf->dev.driver` was NULL) with a trace like:
Call trace:
usb_suspend_both
usb_runtime_suspend
__rpm_callback
rpm_suspend
pm_runtime_work
process_scheduled_works
Both errors appear to be fixed with the proper locking.
Fixes: ceac1cb0259d ("Bluetooth: btusb: mediatek: add ISO data transmission functions")
Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/bluetooth/btusb.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 0c85c981a8334..258a5cb6f27af 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -2632,8 +2632,15 @@ static void btusb_mtk_claim_iso_intf(struct btusb_data *data)
struct btmtk_data *btmtk_data = hci_get_priv(data->hdev);
int err;
+ /*
+ * The function usb_driver_claim_interface() is documented to need
+ * locks held if it's not called from a probe routine. The code here
+ * is called from the hci_power_on workqueue, so grab the lock.
+ */
+ device_lock(&btmtk_data->isopkt_intf->dev);
err = usb_driver_claim_interface(&btusb_driver,
btmtk_data->isopkt_intf, data);
+ device_unlock(&btmtk_data->isopkt_intf->dev);
if (err < 0) {
btmtk_data->isopkt_intf = NULL;
bt_dev_err(data->hdev, "Failed to claim iso interface");
--
2.39.5
