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Diffstat (limited to '')
| -rw-r--r-- | debian/patches-rt/0002-serial-core-Use-lock-wrappers.patch | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/debian/patches-rt/0002-serial-core-Use-lock-wrappers.patch b/debian/patches-rt/0002-serial-core-Use-lock-wrappers.patch new file mode 100644 index 000000000..ad41a3dc7 --- /dev/null +++ b/debian/patches-rt/0002-serial-core-Use-lock-wrappers.patch @@ -0,0 +1,93 @@ +From: Thomas Gleixner <tglx@linutronix.de> +Date: Thu, 14 Sep 2023 20:43:19 +0206 +Subject: [PATCH 002/134] serial: core: Use 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/20230914183831.587273-3-john.ogness@linutronix.de +Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + include/linux/serial_core.h | 12 ++++++------ + 1 file changed, 6 insertions(+), 6 deletions(-) + +--- a/include/linux/serial_core.h ++++ b/include/linux/serial_core.h +@@ -1035,14 +1035,14 @@ static inline void uart_unlock_and_check + u8 sysrq_ch; + + if (!port->has_sysrq) { +- spin_unlock(&port->lock); ++ uart_port_unlock(port); + return; + } + + sysrq_ch = port->sysrq_ch; + port->sysrq_ch = 0; + +- spin_unlock(&port->lock); ++ uart_port_unlock(port); + + if (sysrq_ch) + handle_sysrq(sysrq_ch); +@@ -1054,14 +1054,14 @@ static inline void uart_unlock_and_check + u8 sysrq_ch; + + if (!port->has_sysrq) { +- spin_unlock_irqrestore(&port->lock, flags); ++ uart_port_unlock_irqrestore(port, flags); + return; + } + + sysrq_ch = port->sysrq_ch; + port->sysrq_ch = 0; + +- spin_unlock_irqrestore(&port->lock, flags); ++ uart_port_unlock_irqrestore(port, flags); + + if (sysrq_ch) + handle_sysrq(sysrq_ch); +@@ -1077,12 +1077,12 @@ static inline int uart_prepare_sysrq_cha + } + static inline void uart_unlock_and_check_sysrq(struct uart_port *port) + { +- spin_unlock(&port->lock); ++ uart_port_unlock(port); + } + static inline void uart_unlock_and_check_sysrq_irqrestore(struct uart_port *port, + unsigned long flags) + { +- spin_unlock_irqrestore(&port->lock, flags); ++ uart_port_unlock_irqrestore(port, flags); + } + #endif /* CONFIG_MAGIC_SYSRQ_SERIAL */ + |