Upstream commit 44117a1d1732c513875d5a163f10d9adbe866c08
I wanted to wait initially to see if it breaks something so I omitted the
stable tag. Johan suggested to speed up things here after user report
against a v4.14 kernel.
Fixes: b3b576461864 ("tty: serial_core: convert uart_open to use tty_port_open")
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 <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/serial_core.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 2148883db66d..c8dde56b532b 100644
--- 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;
}
--
2.15.1