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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>
Subject: [PATCH 06/18] serial: omap: Use uart_prepare_sysrq_char().
Date: Fri,  1 Mar 2024 22:45:19 +0100	[thread overview]
Message-ID: <20240301215246.891055-7-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.

Delay handling sysrq until port lock is dropped.
Remove the special case in the console write routine an always use the
complete locking function.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/tty/serial/omap-serial.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index f5a0b401af63b..9be1c871cf116 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -508,7 +508,7 @@ static void serial_omap_rdi(struct uart_omap_port *up, unsigned int lsr)
 
 	up->port.icount.rx++;
 
-	if (uart_handle_sysrq_char(&up->port, ch))
+	if (uart_prepare_sysrq_char(&up->port, ch))
 		return;
 
 	uart_insert_char(&up->port, lsr, UART_LSR_OE, ch, TTY_NORMAL);
@@ -563,7 +563,7 @@ static irqreturn_t serial_omap_irq(int irq, void *dev_id)
 		}
 	} while (max_count--);
 
-	uart_port_unlock(&up->port);
+	uart_unlock_and_check_sysrq(&up->port);
 
 	tty_flip_buffer_push(&up->port.state->port);
 
@@ -1212,13 +1212,10 @@ serial_omap_console_write(struct console *co, const char *s,
 	unsigned int ier;
 	int locked = 1;
 
-	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);
 
 	/*
 	 * First save the IER then disable the interrupts
@@ -1245,8 +1242,7 @@ serial_omap_console_write(struct console *co, const char *s,
 		check_modem_status(up);
 
 	if (locked)
-		uart_port_unlock(&up->port);
-	local_irq_restore(flags);
+		uart_port_unlock_irqrestore(&up->port, flags);
 }
 
 static int __init
-- 
2.43.0


  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 ` Sebastian Andrzej Siewior [this message]
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 ` [PATCH 09/18] serial: lpc32xx_hs: Use uart_prepare_sysrq_char() to handle sysrq Sebastian Andrzej Siewior
2024-03-01 21:45   ` 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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