diff options
Diffstat (limited to 'debian/patches-rt/0018-serial-pch-Use-uart_prepare_sysrq_char.patch')
| -rw-r--r-- | debian/patches-rt/0018-serial-pch-Use-uart_prepare_sysrq_char.patch | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/debian/patches-rt/0018-serial-pch-Use-uart_prepare_sysrq_char.patch b/debian/patches-rt/0018-serial-pch-Use-uart_prepare_sysrq_char.patch new file mode 100644 index 000000000..55e6615c9 --- /dev/null +++ b/debian/patches-rt/0018-serial-pch-Use-uart_prepare_sysrq_char.patch @@ -0,0 +1,79 @@ +From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +Date: Fri, 1 Mar 2024 22:45:31 +0100 +Subject: [PATCH 18/18] serial: pch: Use uart_prepare_sysrq_char(). +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.8/older/patches-6.8.2-rt11.tar.xz + +The port lock is a spinlock_t which is becomes a sleeping lock on PREEMPT_RT. +The driver splits the locking function into two parts: local_irq_save() and +uart_port_lock() and this breaks PREEMPT_RT. + +Delay handling sysrq until port lock is dropped. +Remove the special case in the console write routine an always use the +complete locking function. + +Link: https://lore.kernel.org/r/20240301215246.891055-19-bigeasy@linutronix.de +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + drivers/tty/serial/pch_uart.c | 24 +++++++++--------------- + 1 file changed, 9 insertions(+), 15 deletions(-) + +--- a/drivers/tty/serial/pch_uart.c ++++ b/drivers/tty/serial/pch_uart.c +@@ -564,7 +564,7 @@ static int pch_uart_hal_read(struct eg20 + if (uart_handle_break(port)) + continue; + } +- if (uart_handle_sysrq_char(port, rbr)) ++ if (uart_prepare_sysrq_char(port, rbr)) + continue; + + buf[i++] = rbr; +@@ -1070,7 +1070,7 @@ static irqreturn_t pch_uart_interrupt(in + handled |= (unsigned int)ret; + } + +- uart_port_unlock(&priv->port); ++ uart_unlock_and_check_sysrq(&priv->port); + return IRQ_RETVAL(handled); + } + +@@ -1550,22 +1550,17 @@ pch_console_write(struct console *co, co + { + struct eg20t_port *priv; + unsigned long flags; +- int port_locked = 1; ++ int locked = 1; + u8 ier; + + priv = pch_uart_ports[co->index]; + + touch_nmi_watchdog(); + +- local_irq_save(flags); +- if (priv->port.sysrq) { +- /* serial8250_handle_port() already took the port lock */ +- port_locked = 0; +- } else if (oops_in_progress) { +- port_locked = uart_port_trylock(&priv->port); +- } else { +- uart_port_lock(&priv->port); +- } ++ if (oops_in_progress) ++ locked = uart_port_trylock_irqsave(&priv->port, &flags); ++ else ++ uart_port_lock_irqsave(&priv->port, &flags); + + /* + * First save the IER then disable the interrupts +@@ -1583,9 +1578,8 @@ pch_console_write(struct console *co, co + wait_for_xmitr(priv, UART_LSR_BOTH_EMPTY); + iowrite8(ier, priv->membase + UART_IER); + +- if (port_locked) +- uart_port_unlock(&priv->port); +- local_irq_restore(flags); ++ if (locked) ++ uart_port_unlock_irqrestore(&priv->port, flags); + } + + static int __init pch_console_setup(struct console *co, char *options) |