serial: amba-pl011: fix regression, causing an Oops on rmmod

A recent commit ef2889f7ffee67f0aed49e854c72be63f1466759 "serial: pl011:
Move uart_register_driver call to device probe" introduced a regression,
causing the pl011 driver to Oops if more than 1 port have been probed. Fix
the Oops by only calling uart_unregister_driver() once after the last port
has been removed.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index ca0ec600fab6..dacf0a09ab24 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2176,6 +2176,7 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
 static int pl011_remove(struct amba_device *dev)
 {
         struct uart_amba_port *uap = amba_get_drvdata(dev);
+        bool busy = false;
         int i;
 
         uart_remove_one_port(&amba_reg, &uap->port);
@@ -2183,9 +2184,12 @@ static int pl011_remove(struct amba_device *dev)
         for (i = 0; i < ARRAY_SIZE(amba_ports); i++)
                 if (amba_ports[i] == uap)
                         amba_ports[i] = NULL;
+                else if (amba_ports[i])
+                        busy = true;
 
         pl011_dma_remove(uap);
-        uart_unregister_driver(&amba_reg);
+        if (!busy)
+                uart_unregister_driver(&amba_reg);
         return 0;
 }