Hi John,
On Thu, Sep 14 2023, John Ogness wrote:
> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxxx>
Acked-by: Baruch Siach <baruch@xxxxxxxxxx>
Thanks,
baruch
> ---
> drivers/tty/serial/digicolor-usart.c | 18 +++++++++---------
> 1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/tty/serial/digicolor-usart.c b/drivers/tty/serial/digicolor-usart.c
> index 128b5479e813..5004125f3045 100644
> --- a/drivers/tty/serial/digicolor-usart.c
> +++ b/drivers/tty/serial/digicolor-usart.c
> @@ -133,7 +133,7 @@ static void digicolor_uart_rx(struct uart_port *port)
> {
> unsigned long flags;
>
> - spin_lock_irqsave(&port->lock, flags);
> + uart_port_lock_irqsave(port, &flags);
>
> while (1) {
> u8 status, ch, ch_flag;
> @@ -172,7 +172,7 @@ static void digicolor_uart_rx(struct uart_port *port)
> ch_flag);
> }
>
> - spin_unlock_irqrestore(&port->lock, flags);
> + uart_port_unlock_irqrestore(port, flags);
>
> tty_flip_buffer_push(&port->state->port);
> }
> @@ -185,7 +185,7 @@ static void digicolor_uart_tx(struct uart_port *port)
> if (digicolor_uart_tx_full(port))
> return;
>
> - spin_lock_irqsave(&port->lock, flags);
> + uart_port_lock_irqsave(port, &flags);
>
> if (port->x_char) {
> writeb_relaxed(port->x_char, port->membase + UA_EMI_REC);
> @@ -211,7 +211,7 @@ static void digicolor_uart_tx(struct uart_port *port)
> uart_write_wakeup(port);
>
> out:
> - spin_unlock_irqrestore(&port->lock, flags);
> + uart_port_unlock_irqrestore(port, flags);
> }
>
> static irqreturn_t digicolor_uart_int(int irq, void *dev_id)
> @@ -333,7 +333,7 @@ static void digicolor_uart_set_termios(struct uart_port *port,
> port->ignore_status_mask |= UA_STATUS_OVERRUN_ERR
> | UA_STATUS_PARITY_ERR | UA_STATUS_FRAME_ERR;
>
> - spin_lock_irqsave(&port->lock, flags);
> + uart_port_lock_irqsave(port, &flags);
>
> uart_update_timeout(port, termios->c_cflag, baud);
>
> @@ -341,7 +341,7 @@ static void digicolor_uart_set_termios(struct uart_port *port,
> writeb_relaxed(divisor & 0xff, port->membase + UA_HBAUD_LO);
> writeb_relaxed(divisor >> 8, port->membase + UA_HBAUD_HI);
>
> - spin_unlock_irqrestore(&port->lock, flags);
> + uart_port_unlock_irqrestore(port, flags);
> }
>
> static const char *digicolor_uart_type(struct uart_port *port)
> @@ -398,14 +398,14 @@ static void digicolor_uart_console_write(struct console *co, const char *c,
> int locked = 1;
>
> if (oops_in_progress)
> - locked = spin_trylock_irqsave(&port->lock, flags);
> + locked = uart_port_trylock_irqsave(port, &flags);
> else
> - spin_lock_irqsave(&port->lock, flags);
> + uart_port_lock_irqsave(port, &flags);
>
> uart_console_write(port, c, n, digicolor_uart_console_putchar);
>
> if (locked)
> - spin_unlock_irqrestore(&port->lock, flags);
> + uart_port_unlock_irqrestore(port, flags);
>
> /* Wait for transmitter to become empty */
> do {
--
~. .~ Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
- baruch@xxxxxxxxxx - tel: +972.52.368.4656, http://www.tkos.co.il -
