diff options
Diffstat (limited to 'debian/patches-rt/0045-serial-pch-Use-port-lock-wrappers.patch')
| -rw-r--r-- | debian/patches-rt/0045-serial-pch-Use-port-lock-wrappers.patch | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/debian/patches-rt/0045-serial-pch-Use-port-lock-wrappers.patch b/debian/patches-rt/0045-serial-pch-Use-port-lock-wrappers.patch new file mode 100644 index 000000000..6c4781cd0 --- /dev/null +++ b/debian/patches-rt/0045-serial-pch-Use-port-lock-wrappers.patch @@ -0,0 +1,80 @@ +From: Thomas Gleixner <tglx@linutronix.de> +Date: Thu, 14 Sep 2023 20:44:02 +0206 +Subject: [PATCH 045/134] serial: pch: 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/20230914183831.587273-46-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/pch_uart.c | 10 +++++----- + 1 file changed, 5 insertions(+), 5 deletions(-) + +--- a/drivers/tty/serial/pch_uart.c ++++ b/drivers/tty/serial/pch_uart.c +@@ -1347,7 +1347,7 @@ static void pch_uart_set_termios(struct + baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16); + + spin_lock_irqsave(&priv->lock, flags); +- spin_lock(&port->lock); ++ uart_port_lock(port); + + uart_update_timeout(port, termios->c_cflag, baud); + rtn = pch_uart_hal_set_line(priv, baud, parity, bits, stb); +@@ -1360,7 +1360,7 @@ static void pch_uart_set_termios(struct + tty_termios_encode_baud_rate(termios, baud, baud); + + out: +- spin_unlock(&port->lock); ++ uart_port_unlock(port); + spin_unlock_irqrestore(&priv->lock, flags); + } + +@@ -1581,10 +1581,10 @@ pch_console_write(struct console *co, co + port_locked = 0; + } else if (oops_in_progress) { + priv_locked = spin_trylock(&priv->lock); +- port_locked = spin_trylock(&priv->port.lock); ++ port_locked = uart_port_trylock(&priv->port); + } else { + spin_lock(&priv->lock); +- spin_lock(&priv->port.lock); ++ uart_port_lock(&priv->port); + } + + /* +@@ -1604,7 +1604,7 @@ pch_console_write(struct console *co, co + iowrite8(ier, priv->membase + UART_IER); + + if (port_locked) +- spin_unlock(&priv->port.lock); ++ uart_port_unlock(&priv->port); + if (priv_locked) + spin_unlock(&priv->lock); + local_irq_restore(flags); |