[PATCH v1 02/16] serial: max3100: Update uart_driver_registered on driver removal

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

The removal of the last MAX3100 device triggers the removal of
the driver. However, code doesn't update the respective global
variable and after insmod — rmmod — insmod cycle the kernel
oopses:

  max3100 spi-PRP0001:01: max3100_probe: adding port 0
  BUG: kernel NULL pointer dereference, address: 0000000000000408
  ...
  RIP: 0010:serial_core_register_port+0xa0/0x840
  ...
   max3100_probe+0x1b6/0x280 [max3100]
   spi_probe+0x8d/0xb0

Update the actual state so next time UART driver will be registered
again.

Fixes: 7831d56b0a35 ("tty: MAX3100")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/tty/serial/max3100.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/tty/serial/max3100.c b/drivers/tty/serial/max3100.c
index 45022f2909f0..efe26f6d5ebf 100644
--- a/drivers/tty/serial/max3100.c
+++ b/drivers/tty/serial/max3100.c
@@ -841,6 +841,7 @@ static void max3100_remove(struct spi_device *spi)
 		}
 	pr_debug("removing max3100 driver\n");
 	uart_unregister_driver(&max3100_uart_driver);
+	uart_driver_registered = 0;
 
 	mutex_unlock(&max3100s_lock);
 }
-- 
2.43.0.rc1.1.gbec44491f096