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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-serial@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jirislaby@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Vladimir Zapolskiy <vz@mleia.com>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 09/18] serial: lpc32xx_hs: Use uart_prepare_sysrq_char() to handle sysrq.
Date: Fri,  1 Mar 2024 22:45:22 +0100	[thread overview]
Message-ID: <20240301215246.891055-10-bigeasy@linutronix.de> (raw)
In-Reply-To: <20240301215246.891055-1-bigeasy@linutronix.de>

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.

Handle sysrq requests sysrq once the port lock is dropped.
Remove the special case in the console write routine an always use the
complete locking function.

Cc: Vladimir Zapolskiy <vz@mleia.com>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/tty/serial/lpc32xx_hs.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/lpc32xx_hs.c b/drivers/tty/serial/lpc32xx_hs.c
index ec20329f06036..e70fa59dbcc3b 100644
--- a/drivers/tty/serial/lpc32xx_hs.c
+++ b/drivers/tty/serial/lpc32xx_hs.c
@@ -136,20 +136,16 @@ static void lpc32xx_hsuart_console_write(struct console *co, const char *s,
 	int locked = 1;
 
 	touch_nmi_watchdog();
-	local_irq_save(flags);
-	if (up->port.sysrq)
-		locked = 0;
-	else if (oops_in_progress)
-		locked = uart_port_trylock(&up->port);
+	if (oops_in_progress)
+		locked = uart_port_trylock_irqsave(&up->port, &flags);
 	else
-		uart_port_lock(&up->port);
+		uart_port_lock_irqsave(&up->port, &flags);
 
 	uart_console_write(&up->port, s, count, lpc32xx_hsuart_console_putchar);
 	wait_for_xmit_empty(&up->port);
 
 	if (locked)
-		uart_port_unlock(&up->port);
-	local_irq_restore(flags);
+		uart_port_unlock_irqrestore(&up->port, flags);
 }
 
 static int __init lpc32xx_hsuart_console_setup(struct console *co,
@@ -268,7 +264,8 @@ static void __serial_lpc32xx_rx(struct uart_port *port)
 			tty_insert_flip_char(tport, 0, TTY_FRAME);
 		}
 
-		tty_insert_flip_char(tport, (tmp & 0xFF), flag);
+		if (!uart_prepare_sysrq_char(port, tmp & 0xff))
+			tty_insert_flip_char(tport, (tmp & 0xFF), flag);
 
 		tmp = readl(LPC32XX_HSUART_FIFO(port->membase));
 	}
@@ -333,7 +330,7 @@ static irqreturn_t serial_lpc32xx_interrupt(int irq, void *dev_id)
 		__serial_lpc32xx_tx(port);
 	}
 
-	uart_port_unlock(port);
+	uart_unlock_and_check_sysrq(port);
 
 	return IRQ_HANDLED;
 }
-- 
2.43.0


WARNING: multiple messages have this Message-ID (diff)
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-serial@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jirislaby@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Vladimir Zapolskiy <vz@mleia.com>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 09/18] serial: lpc32xx_hs: Use uart_prepare_sysrq_char() to handle sysrq.
Date: Fri,  1 Mar 2024 22:45:22 +0100	[thread overview]
Message-ID: <20240301215246.891055-10-bigeasy@linutronix.de> (raw)
In-Reply-To: <20240301215246.891055-1-bigeasy@linutronix.de>

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.

Handle sysrq requests sysrq once the port lock is dropped.
Remove the special case in the console write routine an always use the
complete locking function.

Cc: Vladimir Zapolskiy <vz@mleia.com>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/tty/serial/lpc32xx_hs.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/lpc32xx_hs.c b/drivers/tty/serial/lpc32xx_hs.c
index ec20329f06036..e70fa59dbcc3b 100644
--- a/drivers/tty/serial/lpc32xx_hs.c
+++ b/drivers/tty/serial/lpc32xx_hs.c
@@ -136,20 +136,16 @@ static void lpc32xx_hsuart_console_write(struct console *co, const char *s,
 	int locked = 1;
 
 	touch_nmi_watchdog();
-	local_irq_save(flags);
-	if (up->port.sysrq)
-		locked = 0;
-	else if (oops_in_progress)
-		locked = uart_port_trylock(&up->port);
+	if (oops_in_progress)
+		locked = uart_port_trylock_irqsave(&up->port, &flags);
 	else
-		uart_port_lock(&up->port);
+		uart_port_lock_irqsave(&up->port, &flags);
 
 	uart_console_write(&up->port, s, count, lpc32xx_hsuart_console_putchar);
 	wait_for_xmit_empty(&up->port);
 
 	if (locked)
-		uart_port_unlock(&up->port);
-	local_irq_restore(flags);
+		uart_port_unlock_irqrestore(&up->port, flags);
 }
 
 static int __init lpc32xx_hsuart_console_setup(struct console *co,
@@ -268,7 +264,8 @@ static void __serial_lpc32xx_rx(struct uart_port *port)
 			tty_insert_flip_char(tport, 0, TTY_FRAME);
 		}
 
-		tty_insert_flip_char(tport, (tmp & 0xFF), flag);
+		if (!uart_prepare_sysrq_char(port, tmp & 0xff))
+			tty_insert_flip_char(tport, (tmp & 0xFF), flag);
 
 		tmp = readl(LPC32XX_HSUART_FIFO(port->membase));
 	}
@@ -333,7 +330,7 @@ static irqreturn_t serial_lpc32xx_interrupt(int irq, void *dev_id)
 		__serial_lpc32xx_tx(port);
 	}
 
-	uart_port_unlock(port);
+	uart_unlock_and_check_sysrq(port);
 
 	return IRQ_HANDLED;
 }
-- 
2.43.0


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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2024-03-01 21:52 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-01 21:45 [PATCH 00/18] serial: Use uart_prepare_sysrq_char() Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 01/18] serial: amba-pl011: " Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 02/18] serial: ar933x: " Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 03/18] serial: bcm63xx: " Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 04/18] serial: meson: " Sebastian Andrzej Siewior
2024-03-01 21:45   ` Sebastian Andrzej Siewior
2024-03-01 21:45   ` Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 05/18] serial: msm: " Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 06/18] serial: omap: " Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 07/18] serial: pxa: " Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 08/18] serial: sunplus: " Sebastian Andrzej Siewior
2024-03-01 21:45 ` Sebastian Andrzej Siewior [this message]
2024-03-01 21:45   ` [PATCH 09/18] serial: lpc32xx_hs: Use uart_prepare_sysrq_char() to handle sysrq Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 10/18] serial: owl: " Sebastian Andrzej Siewior
2024-03-01 21:45   ` Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 11/18] serial: rda: " Sebastian Andrzej Siewior
2024-03-01 21:45   ` Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 12/18] serial: sifive: " Sebastian Andrzej Siewior
2024-03-01 21:45   ` Sebastian Andrzej Siewior
2024-03-07  1:39   ` Samuel Holland
2024-03-07  1:39     ` Samuel Holland
2024-03-01 21:45 ` [PATCH 13/18] serial: pch: Invoke handle_rx_to() directly Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 14/18] serial: pch: Make push_rx() return void Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 15/18] serial: pch: Don't disable interrupts while acquiring lock in ISR Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 16/18] serial: pch: Don't initialize uart_port's spin_lock Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 17/18] serial: pch: Remove eg20t_port::lock Sebastian Andrzej Siewior
2024-03-01 21:45 ` [PATCH 18/18] serial: pch: Use uart_prepare_sysrq_char() Sebastian Andrzej Siewior

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