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    Subject[PATCH tty v1 13/74] serial: 8250_pci1xxxx: Use port lock wrappers
    Date
    From: Thomas Gleixner <tglx@linutronix.de>

    When a serial port is used for kernel console output, then all
    modifications to the UART registers which are done from other contexts,
    e.g. getty, termios, are interference points for the kernel console.

    So far this has been ignored and the printk output is based on the
    principle of hope. The rework of the console infrastructure which aims to
    support threaded and atomic consoles, requires to mark sections which
    modify the UART registers as unsafe. This allows the atomic write function
    to make informed decisions and eventually to restore operational state. It
    also allows to prevent the regular UART code from modifying UART registers
    while printk output is in progress.

    All modifications of UART registers are guarded by the UART port lock,
    which provides an obvious synchronization point with the console
    infrastructure.

    To avoid adding this functionality to all UART drivers, wrap the
    spin_[un]lock*() invocations for uart_port::lock into helper functions
    which just contain the spin_[un]lock*() invocations for now. In a
    subsequent step these helpers will gain the console synchronization
    mechanisms.

    Converted with coccinelle. No functional change.

    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    ---
    drivers/tty/serial/8250/8250_pci1xxxx.c | 8 ++++----
    1 file changed, 4 insertions(+), 4 deletions(-)

    diff --git a/drivers/tty/serial/8250/8250_pci1xxxx.c b/drivers/tty/serial/8250/8250_pci1xxxx.c
    index a3b25779d921..53e238c8cc89 100644
    --- a/drivers/tty/serial/8250/8250_pci1xxxx.c
    +++ b/drivers/tty/serial/8250/8250_pci1xxxx.c
    @@ -225,10 +225,10 @@ static bool pci1xxxx_port_suspend(int line)
    if (port->suspended == 0 && port->dev) {
    wakeup_mask = readb(up->port.membase + UART_WAKE_MASK_REG);

    - spin_lock_irqsave(&port->lock, flags);
    + uart_port_lock_irqsave(port, &flags);
    port->mctrl &= ~TIOCM_OUT2;
    port->ops->set_mctrl(port, port->mctrl);
    - spin_unlock_irqrestore(&port->lock, flags);
    + uart_port_unlock_irqrestore(port, flags);

    ret = (wakeup_mask & UART_WAKE_SRCS) != UART_WAKE_SRCS;
    }
    @@ -251,10 +251,10 @@ static void pci1xxxx_port_resume(int line)
    writeb(UART_WAKE_SRCS, port->membase + UART_WAKE_REG);

    if (port->suspended == 0) {
    - spin_lock_irqsave(&port->lock, flags);
    + uart_port_lock_irqsave(port, &flags);
    port->mctrl |= TIOCM_OUT2;
    port->ops->set_mctrl(port, port->mctrl);
    - spin_unlock_irqrestore(&port->lock, flags);
    + uart_port_unlock_irqrestore(port, flags);
    }
    mutex_unlock(&tport->mutex);
    }
    --
    2.39.2
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