serial: core: mark port as initialized after successful IRQ change

Sebastian Andrzej Siewior · gregkh · commit 44117a1d1732 · 2018-01-22T14:20:56.000+01:00
setserial changes the IRQ via uart_set_info(). It invokes
uart_shutdown() which free the current used IRQ and clear
TTY_PORT_INITIALIZED. It will then update the IRQ number and invoke
uart_startup() before returning to the caller leaving
TTY_PORT_INITIALIZED cleared.

The next open will crash with
|  list_add double add: new=ffffffff839fcc98, prev=ffffffff839fcc98, next=ffffffff839fcc98.
since the close from the IOCTL won't free the IRQ (and clean the list)
due to the TTY_PORT_INITIALIZED check in uart_shutdown().

There is same pattern in uart_do_autoconfig() and I *think* it also
needs to set TTY_PORT_INITIALIZED there.
Is there a reason why uart_startup() does not set the flag by itself
after the IRQ has been acquired (since it is cleared in uart_shutdown)?

Signed-off-by: Sebastian Andrzej Siewior &lt;bigeasy@linutronix.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
@@ -974,6 +974,8 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
 		}
 	} else {
 		retval = uart_startup(tty, state, 1);
+		if (retval == 0)
+			tty_port_set_initialized(port, true);
 		if (retval > 0)
 			retval = 0;
 	}

Original file line number	Diff line number	Diff line change
`@@ -974,6 +974,8 @@ static int uart_set_info(struct tty_struct tty, struct tty_port port,`
`974`	`974`	`}`
`975`	`975`	`} else {`
`976`	`976`	`retval = uart_startup(tty, state, 1);`
	`977`	`+ if (retval == 0)`
	`978`	`+ tty_port_set_initialized(port, true);`
`977`	`979`	`if (retval > 0)`
`978`	`980`	`retval = 0;`
`979`	`981`	`}`