65 lines
2.6 KiB
Diff
65 lines
2.6 KiB
Diff
From d303da34308c0d86ec48943f96a9f66d8e039e68 Mon Sep 17 00:00:00 2001
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Thu, 14 Sep 2023 20:44:12 +0206
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Subject: [PATCH 081/198] serial: sc16is7xx: Use port lock wrappers
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When a serial port is used for kernel console output, then all
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modifications to the UART registers which are done from other contexts,
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e.g. getty, termios, are interference points for the kernel console.
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So far this has been ignored and the printk output is based on the
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principle of hope. The rework of the console infrastructure which aims to
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support threaded and atomic consoles, requires to mark sections which
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modify the UART registers as unsafe. This allows the atomic write function
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to make informed decisions and eventually to restore operational state. It
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also allows to prevent the regular UART code from modifying UART registers
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while printk output is in progress.
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All modifications of UART registers are guarded by the UART port lock,
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which provides an obvious synchronization point with the console
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infrastructure.
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To avoid adding this functionality to all UART drivers, wrap the
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spin_[un]lock*() invocations for uart_port::lock into helper functions
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which just contain the spin_[un]lock*() invocations for now. In a
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subsequent step these helpers will gain the console synchronization
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mechanisms.
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Converted with coccinelle. No functional change.
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Signed-off-by: John Ogness <john.ogness@linutronix.de>
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Link: https://lore.kernel.org/r/20230914183831.587273-56-john.ogness@linutronix.de
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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drivers/tty/serial/sc16is7xx.c | 5 +++++
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1 file changed, 5 insertions(+)
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diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
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index f75b8bceb8ca..2d7470457af4 100644
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--- a/drivers/tty/serial/sc16is7xx.c
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+++ b/drivers/tty/serial/sc16is7xx.c
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@@ -804,6 +804,7 @@ static void sc16is7xx_tx_proc(struct kthread_work *ws)
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{
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struct uart_port *port = &(to_sc16is7xx_one(ws, tx_work)->port);
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struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
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+ unsigned long flags;
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if ((port->rs485.flags & SER_RS485_ENABLED) &&
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(port->rs485.delay_rts_before_send > 0))
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@@ -812,6 +813,10 @@ static void sc16is7xx_tx_proc(struct kthread_work *ws)
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mutex_lock(&one->efr_lock);
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sc16is7xx_handle_tx(port);
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mutex_unlock(&one->efr_lock);
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+
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+ uart_port_lock_irqsave(port, &flags);
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+ sc16is7xx_ier_set(port, SC16IS7XX_IER_THRI_BIT);
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+ uart_port_unlock_irqrestore(port, flags);
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}
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static void sc16is7xx_reconf_rs485(struct uart_port *port)
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--
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2.44.0
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