mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 19:29:37 +00:00
tty: serial_core: Set port active bit in uart_port_activate
A bug was introduced by commitb3b5764618
("tty: serial_core: convert uart_open to use tty_port_open"). It caused a constant warning printed into the system log regarding the tty and port counter mismatch: [ 21.644197] ttyS ttySx: tty_port_close_start: tty->count = 1 port count = 2 in case if session hangup was detected so the warning is printed starting from the second open-close iteration. Particularly the problem was discovered in situation when there is a serial tty device without hardware back-end being setup. It is considered by the tty-serial subsystems as a hardware problem with session hang up. In this case uart_startup() will return a positive value with TTY_IO_ERROR flag set in corresponding tty_struct instance. The same value will get passed to be returned from the activate() callback and then being returned from tty_port_open(). But since in this case tty_port_block_til_ready() isn't called the TTY_PORT_ACTIVE flag isn't set (while the method had been called before tty_port_open conversion was introduced and the rest of the subsystem code expected the bit being set in this case), which prevents the uart_hangup() method to perform any cleanups including the tty port counter setting to zero. So the next attempt to open/close the tty device will discover the counters mismatch. In order to fix the problem we need to manually set the TTY_PORT_ACTIVE flag in case if uart_startup() returned a positive value. In this case the hang up procedure will perform a full set of cleanup actions including the port ref-counter resetting. Fixes:b3b5764618
"tty: serial_core: convert uart_open to use tty_port_open" Signed-off-by: Serge Semin <fancer.lancer@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
4291208148
commit
13b18d3590
1 changed files with 6 additions and 1 deletions
|
@ -1777,6 +1777,7 @@ static int uart_port_activate(struct tty_port *port, struct tty_struct *tty)
|
|||
{
|
||||
struct uart_state *state = container_of(port, struct uart_state, port);
|
||||
struct uart_port *uport;
|
||||
int ret;
|
||||
|
||||
uport = uart_port_check(state);
|
||||
if (!uport || uport->flags & UPF_DEAD)
|
||||
|
@ -1787,7 +1788,11 @@ static int uart_port_activate(struct tty_port *port, struct tty_struct *tty)
|
|||
/*
|
||||
* Start up the serial port.
|
||||
*/
|
||||
return uart_startup(tty, state, 0);
|
||||
ret = uart_startup(tty, state, 0);
|
||||
if (ret > 0)
|
||||
tty_port_set_active(port, 1);
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
static const char *uart_type(struct uart_port *port)
|
||||
|
|
Loading…
Reference in a new issue