diff options
Diffstat (limited to 'debian/patches-rt/0070-serial-timbuart-Use-port-lock-wrappers.patch')
| -rw-r--r-- | debian/patches-rt/0070-serial-timbuart-Use-port-lock-wrappers.patch | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/debian/patches-rt/0070-serial-timbuart-Use-port-lock-wrappers.patch b/debian/patches-rt/0070-serial-timbuart-Use-port-lock-wrappers.patch new file mode 100644 index 000000000..2d5a3d95e --- /dev/null +++ b/debian/patches-rt/0070-serial-timbuart-Use-port-lock-wrappers.patch @@ -0,0 +1,71 @@ +From: Thomas Gleixner <tglx@linutronix.de> +Date: Thu, 14 Sep 2023 20:44:27 +0206 +Subject: [PATCH 070/134] serial: timbuart: Use port lock wrappers +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz + +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> +Signed-off-by: John Ogness <john.ogness@linutronix.de> +Link: https://lore.kernel.org/r/20230914183831.587273-71-john.ogness@linutronix.de +Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + drivers/tty/serial/timbuart.c | 8 ++++---- + 1 file changed, 4 insertions(+), 4 deletions(-) + +--- a/drivers/tty/serial/timbuart.c ++++ b/drivers/tty/serial/timbuart.c +@@ -174,7 +174,7 @@ static void timbuart_tasklet(struct task + struct timbuart_port *uart = from_tasklet(uart, t, tasklet); + u32 isr, ier = 0; + +- spin_lock(&uart->port.lock); ++ uart_port_lock(&uart->port); + + isr = ioread32(uart->port.membase + TIMBUART_ISR); + dev_dbg(uart->port.dev, "%s ISR: %x\n", __func__, isr); +@@ -189,7 +189,7 @@ static void timbuart_tasklet(struct task + + iowrite32(ier, uart->port.membase + TIMBUART_IER); + +- spin_unlock(&uart->port.lock); ++ uart_port_unlock(&uart->port); + dev_dbg(uart->port.dev, "%s leaving\n", __func__); + } + +@@ -295,10 +295,10 @@ static void timbuart_set_termios(struct + tty_termios_copy_hw(termios, old); + tty_termios_encode_baud_rate(termios, baud, baud); + +- spin_lock_irqsave(&port->lock, flags); ++ uart_port_lock_irqsave(port, &flags); + iowrite8((u8)bindex, port->membase + TIMBUART_BAUDRATE); + uart_update_timeout(port, termios->c_cflag, baud); +- spin_unlock_irqrestore(&port->lock, flags); ++ uart_port_unlock_irqrestore(port, flags); + } + + static const char *timbuart_type(struct uart_port *port) |