Bluetooth: hci_qca: Remove hdev dereference in qca_close().

When flag KASAN is set, we are seeing an following crash while removing
hci_uart module.

[   50.589909] Unable to handle kernel paging request at virtual address 6b6b6b6b6b6b73
[   50.597902] Mem abort info:
[   50.600846]   Exception class = DABT (current EL), IL = 32 bits
[   50.606959]   SET = 0, FnV = 0
[   50.610142]   EA = 0, S1PTW = 0
[   50.613396] Data abort info:
[   50.616401]   ISV = 0, ISS = 0x00000004
[   50.620373]   CM = 0, WnR = 0
[   50.623466] [006b6b6b6b6b6b73] address between user and kernel address ranges
[   50.630818] Internal error: Oops: 96000004 [#1] PREEMPT SMP

[   50.671670] PC is at qca_power_shutdown+0x28/0x100 [hci_uart]
[   50.677593] LR is at qca_close+0x74/0xb0 [hci_uart]
[   50.775689] Process rmmod (pid: 2144, stack limit = 0xffffff801ba90000)
[   50.782493] Call trace:

[   50.872150] [<ffffff8000c3c81c>] qca_power_shutdown+0x28/0x100 [hci_uart]
[   50.879138] [<ffffff8000c3c968>] qca_close+0x74/0xb0 [hci_uart]
[   50.885238] [<ffffff8000c3a71c>] hci_uart_unregister_device+0x44/0x50 [hci_uart]
[   50.892846] [<ffffff8000c3c9f4>] qca_serdev_remove+0x50/0x5c [hci_uart]
[   50.899654] [<ffffff800844f630>] serdev_drv_remove+0x28/0x38
[   50.905489] [<ffffff800850fc44>] device_release_driver_internal+0x140/0x1e4
[   50.912653] [<ffffff800850fd94>] driver_detach+0x78/0x84
[   50.918121] [<ffffff800850edac>] bus_remove_driver+0x80/0xa8
[   50.923942] [<ffffff80085107dc>] driver_unregister+0x4c/0x58
[   50.929768] [<ffffff8000c3ca8c>] qca_deinit+0x24/0x598 [hci_uart]
[   50.936045] [<ffffff8000c3ca10>] hci_uart_exit+0x10/0x48 [hci_uart]
[   50.942495] [<ffffff8008136630>] SyS_delete_module+0x17c/0x224

This crash is due to dereference of hdev, after freeing it.

Signed-off-by: Balakrishna Godavarthi <bgodavar@codeaurora.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/hci_qca.c

@@ -167,7 +167,7 @@ struct qca_serdev {
 };
 
 static int qca_power_setup(struct hci_uart *hu, bool on);
-static void qca_power_shutdown(struct hci_dev *hdev);
+static void qca_power_shutdown(struct hci_uart *hu);
 
 static void __serial_clock_on(struct tty_struct *tty)
 {
@@ -608,7 +608,7 @@ static int qca_close(struct hci_uart *hu)
 	if (hu->serdev) {
 		qcadev = serdev_device_get_drvdata(hu->serdev);
 		if (qcadev->btsoc_type == QCA_WCN3990)
-			qca_power_shutdown(hu->hdev);
+			qca_power_shutdown(hu);
 		else
 			gpiod_set_value_cansleep(qcadev->bt_en, 0);
 
@@ -1230,12 +1230,15 @@ static const struct qca_vreg_data qca_soc_data = {
 	.num_vregs = 4,
 };
 
-static void qca_power_shutdown(struct hci_dev *hdev)
+static void qca_power_shutdown(struct hci_uart *hu)
 {
-	struct hci_uart *hu = hci_get_drvdata(hdev);
+	struct serdev_device *serdev = hu->serdev;
+	unsigned char cmd = QCA_WCN3990_POWEROFF_PULSE;
 
 	host_set_baudrate(hu, 2400);
-	qca_send_power_pulse(hdev, QCA_WCN3990_POWEROFF_PULSE);
+	hci_uart_set_flow_control(hu, true);
+	serdev_device_write_buf(serdev, &cmd, sizeof(cmd));
+	hci_uart_set_flow_control(hu, false);
 	qca_power_setup(hu, false);
 }
 
@@ -1411,7 +1414,7 @@ static void qca_serdev_remove(struct serdev_device *serdev)
 	struct qca_serdev *qcadev = serdev_device_get_drvdata(serdev);
 
 	if (qcadev->btsoc_type == QCA_WCN3990)
-		qca_power_shutdown(qcadev->serdev_hu.hdev);
+		qca_power_shutdown(&qcadev->serdev_hu);
 	else
 		clk_disable_unprepare(qcadev->susclk);