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Diffstat (limited to '')
| -rw-r--r-- | debian/patches-rt/0008-serial-8250_dw-Use-port-lock-wrappers.patch | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/debian/patches-rt/0008-serial-8250_dw-Use-port-lock-wrappers.patch b/debian/patches-rt/0008-serial-8250_dw-Use-port-lock-wrappers.patch new file mode 100644 index 000000000..d5394fc7a --- /dev/null +++ b/debian/patches-rt/0008-serial-8250_dw-Use-port-lock-wrappers.patch @@ -0,0 +1,69 @@ +From: Thomas Gleixner <tglx@linutronix.de> +Date: Thu, 14 Sep 2023 20:43:25 +0206 +Subject: [PATCH 008/134] serial: 8250_dw: Use port lock wrappers +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit +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> +Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> +Signed-off-by: John Ogness <john.ogness@linutronix.de> +Link: https://lore.kernel.org/r/20230914183831.587273-9-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/8250/8250_dw.c | 8 ++++---- + 1 file changed, 4 insertions(+), 4 deletions(-) + +--- a/drivers/tty/serial/8250/8250_dw.c ++++ b/drivers/tty/serial/8250/8250_dw.c +@@ -263,20 +263,20 @@ static int dw8250_handle_irq(struct uart + * so we limit the workaround only to non-DMA mode. + */ + if (!up->dma && rx_timeout) { +- spin_lock_irqsave(&p->lock, flags); ++ uart_port_lock_irqsave(p, &flags); + status = serial_lsr_in(up); + + if (!(status & (UART_LSR_DR | UART_LSR_BI))) + (void) p->serial_in(p, UART_RX); + +- spin_unlock_irqrestore(&p->lock, flags); ++ uart_port_unlock_irqrestore(p, flags); + } + + /* Manually stop the Rx DMA transfer when acting as flow controller */ + if (quirks & DW_UART_QUIRK_IS_DMA_FC && up->dma && up->dma->rx_running && rx_timeout) { +- spin_lock_irqsave(&p->lock, flags); ++ uart_port_lock_irqsave(p, &flags); + status = serial_lsr_in(up); +- spin_unlock_irqrestore(&p->lock, flags); ++ uart_port_unlock_irqrestore(p, flags); + + if (status & (UART_LSR_DR | UART_LSR_BI)) { + dw8250_writel_ext(p, RZN1_UART_RDMACR, 0); |