From: Michal Simek <[email protected]>

commit 5e9bd2d70ae7c00a95a22994abf1eef728649e64 upstream.

There are two parts which should be fixed. The first one is to assigned
uartps_major at the end of probe() to avoid complicated logic when
something fails.
The second part is initialized uartps_major number to 0 when last device is
removed. This will ensure that on next probe driver will ask for new
dynamic major number.

Fixes: ab262666018d ("serial: uartps: Use the same dynamic major number for all 
ports")
Reported-by: Paul Thomas <[email protected]>
Cc: stable <[email protected]>
Signed-off-by: Michal Simek <[email protected]>
Link: 
https://lore.kernel.org/r/d2652cda992833315c4f96f06953eb547f928918.1570194248.git.michal.si...@xilinx.com
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 drivers/tty/serial/xilinx_uartps.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -1550,7 +1550,6 @@ static int cdns_uart_probe(struct platfo
                goto err_out_id;
        }
 
-       uartps_major = cdns_uart_uart_driver->tty_driver->major;
        cdns_uart_data->cdns_uart_driver = cdns_uart_uart_driver;
 
        /*
@@ -1680,6 +1679,7 @@ static int cdns_uart_probe(struct platfo
                console_port = NULL;
 #endif
 
+       uartps_major = cdns_uart_uart_driver->tty_driver->major;
        cdns_uart_data->cts_override = of_property_read_bool(pdev->dev.of_node,
                                                             "cts-override");
        return 0;
@@ -1741,6 +1741,12 @@ static int cdns_uart_remove(struct platf
                console_port = NULL;
 #endif
 
+       /* If this is last instance major number should be initialized */
+       mutex_lock(&bitmap_lock);
+       if (bitmap_empty(bitmap, MAX_UART_INSTANCES))
+               uartps_major = 0;
+       mutex_unlock(&bitmap_lock);
+
        uart_unregister_driver(cdns_uart_data->cdns_uart_driver);
        return rc;
 }


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