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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>
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@ -1777,6 +1777,7 @@ static int uart_port_activate(struct tty_port *port, struct tty_struct *tty)
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{
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struct uart_state *state = container_of(port, struct uart_state, port);
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struct uart_port *uport;
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int ret;
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uport = uart_port_check(state);
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if (!uport || uport->flags & UPF_DEAD)
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@ -1787,7 +1788,11 @@ static int uart_port_activate(struct tty_port *port, struct tty_struct *tty)
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/*
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* Start up the serial port.
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*/
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return uart_startup(tty, state, 0);
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ret = uart_startup(tty, state, 0);
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if (ret > 0)
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tty_port_set_active(port, 1);
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return ret;
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}
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static const char *uart_type(struct uart_port *port)
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