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-rw-r--r--debian/patches-rt/0009-serial-8250_exar-Use-port-lock-wrappers.patch52
1 files changed, 52 insertions, 0 deletions
diff --git a/debian/patches-rt/0009-serial-8250_exar-Use-port-lock-wrappers.patch b/debian/patches-rt/0009-serial-8250_exar-Use-port-lock-wrappers.patch
new file mode 100644
index 0000000000..80c37fba6c
--- /dev/null
+++ b/debian/patches-rt/0009-serial-8250_exar-Use-port-lock-wrappers.patch
@@ -0,0 +1,52 @@
+From: Thomas Gleixner <tglx@linutronix.de>
+Date: Thu, 14 Sep 2023 20:43:26 +0206
+Subject: [PATCH 009/134] serial: 8250_exar: 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/20230914183831.587273-10-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_exar.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+--- a/drivers/tty/serial/8250/8250_exar.c
++++ b/drivers/tty/serial/8250/8250_exar.c
+@@ -201,9 +201,9 @@ static int xr17v35x_startup(struct uart_
+ *
+ * Synchronize UART_IER access against the console.
+ */
+- spin_lock_irq(&port->lock);
++ uart_port_lock_irq(port);
+ serial_port_out(port, UART_IER, 0);
+- spin_unlock_irq(&port->lock);
++ uart_port_unlock_irq(port);
+
+ return serial8250_do_startup(port);
+ }