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From: John Ogness <john.ogness@linutronix.de>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>,
	linux-serial@vger.kernel.org, Petr Mladek <pmladek@suse.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel@vger.kernel.org
Subject: [PATCH tty v1 01/74] serial: core: Provide port lock wrappers
Date: Thu, 14 Sep 2023 20:43:18 +0206	[thread overview]
Message-ID: <20230914183831.587273-2-john.ogness@linutronix.de> (raw)
In-Reply-To: <20230914183831.587273-1-john.ogness@linutronix.de>

From: Thomas Gleixner <tglx@linutronix.de>

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.

Provide wrapper functions for spin_[un]lock*(port->lock) invocations so
that the console mechanics can be applied later on at a single place and
does not require to copy the same logic all over the drivers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 include/linux/serial_core.h | 79 +++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)

diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index bb6f073bc159..f1d5c0d1568c 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -588,6 +588,85 @@ struct uart_port {
 	void			*private_data;		/* generic platform data pointer */
 };
 
+/**
+ * uart_port_lock - Lock the UART port
+ * @up:		Pointer to UART port structure
+ */
+static inline void uart_port_lock(struct uart_port *up)
+{
+	spin_lock(&up->lock);
+}
+
+/**
+ * uart_port_lock_irq - Lock the UART port and disable interrupts
+ * @up:		Pointer to UART port structure
+ */
+static inline void uart_port_lock_irq(struct uart_port *up)
+{
+	spin_lock_irq(&up->lock);
+}
+
+/**
+ * uart_port_lock_irqsave - Lock the UART port, save and disable interrupts
+ * @up:		Pointer to UART port structure
+ * @flags:	Pointer to interrupt flags storage
+ */
+static inline void uart_port_lock_irqsave(struct uart_port *up, unsigned long *flags)
+{
+	spin_lock_irqsave(&up->lock, *flags);
+}
+
+/**
+ * uart_port_trylock - Try to lock the UART port
+ * @up:		Pointer to UART port structure
+ *
+ * Returns: True if lock was acquired, false otherwise
+ */
+static inline bool uart_port_trylock(struct uart_port *up)
+{
+	return spin_trylock(&up->lock);
+}
+
+/**
+ * uart_port_trylock_irqsave - Try to lock the UART port, save and disable interrupts
+ * @up:		Pointer to UART port structure
+ * @flags:	Pointer to interrupt flags storage
+ *
+ * Returns: True if lock was acquired, false otherwise
+ */
+static inline bool uart_port_trylock_irqsave(struct uart_port *up, unsigned long *flags)
+{
+	return spin_trylock_irqsave(&up->lock, *flags);
+}
+
+/**
+ * uart_port_unlock - Unlock the UART port
+ * @up:		Pointer to UART port structure
+ */
+static inline void uart_port_unlock(struct uart_port *up)
+{
+	spin_unlock(&up->lock);
+}
+
+/**
+ * uart_port_unlock_irq - Unlock the UART port and re-enable interrupts
+ * @up:		Pointer to UART port structure
+ */
+static inline void uart_port_unlock_irq(struct uart_port *up)
+{
+	spin_unlock_irq(&up->lock);
+}
+
+/**
+ * uart_port_lock_irqrestore - Unlock the UART port, restore interrupts
+ * @up:		Pointer to UART port structure
+ * @flags:	The saved interrupt flags for restore
+ */
+static inline void uart_port_unlock_irqrestore(struct uart_port *up, unsigned long flags)
+{
+	spin_unlock_irqrestore(&up->lock, flags);
+}
+
 static inline int serial_port_in(struct uart_port *up, int offset)
 {
 	return up->serial_in(up, offset);
-- 
2.39.2


  reply	other threads:[~2023-09-14 18:38 UTC|newest]

Thread overview: 162+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-14 18:37 [PATCH tty v1 00/74] serial: wrappers for uart port lock John Ogness
2023-09-14 18:37 ` John Ogness
2023-09-14 18:37 ` John Ogness
2023-09-14 18:37 ` John Ogness
2023-09-14 18:37 ` John Ogness [this message]
2023-09-15  9:25   ` [PATCH tty v1 01/74] serial: core: Provide port lock wrappers Ilpo Järvinen
2023-09-19 14:24   ` Petr Mladek
2023-09-19 19:16     ` Greg Kroah-Hartman
2023-09-19 19:51     ` Thomas Gleixner
2023-09-20  7:58       ` Petr Mladek
2023-09-14 18:37 ` [PATCH tty v1 02/74] serial: core: Use " John Ogness
2023-09-15  9:26   ` Ilpo Järvinen
2023-09-14 18:37 ` [PATCH tty v1 03/74] serial: 21285: Use port " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 04/74] serial: 8250_aspeed_vuart: " John Ogness
2023-09-14 18:37   ` John Ogness
2023-09-14 18:37 ` [PATCH tty v1 05/74] serial: 8250_bcm7271: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 06/74] serial: 8250: " John Ogness
2023-09-15  9:24   ` Ilpo Järvinen
2023-09-15  9:35   ` Ilpo Järvinen
2023-09-15 11:21     ` John Ogness
2023-09-14 18:37 ` [PATCH tty v1 07/74] serial: 8250_dma: " John Ogness
2023-09-15  9:14   ` Ilpo Järvinen
2023-09-14 18:37 ` [PATCH tty v1 08/74] serial: 8250_dw: " John Ogness
2023-09-15  9:16   ` Ilpo Järvinen
2023-09-14 18:37 ` [PATCH tty v1 09/74] serial: 8250_exar: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 10/74] serial: 8250_fsl: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 11/74] serial: 8250_mtk: " John Ogness
2023-09-14 18:37   ` John Ogness
2023-09-15  4:07   ` Chen-Yu Tsai
2023-09-15  4:07     ` Chen-Yu Tsai
2023-09-14 18:37 ` [PATCH tty v1 12/74] serial: 8250_omap: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 13/74] serial: 8250_pci1xxxx: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 14/74] serial: altera_jtaguart: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 15/74] serial: altera_uart: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 16/74] serial: amba-pl010: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 17/74] serial: amba-pl011: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 18/74] serial: apb: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 19/74] serial: ar933x: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 20/74] serial: arc_uart: " John Ogness
2023-09-14 18:37   ` John Ogness
2023-09-14 18:37 ` [PATCH tty v1 21/74] serial: atmel: " John Ogness
2023-09-14 18:37   ` John Ogness
2023-09-14 18:37 ` [PATCH tty v1 22/74] serial: bcm63xx-uart: " John Ogness
2023-09-14 21:52   ` Florian Fainelli
2023-09-14 18:37 ` [PATCH tty v1 23/74] serial: cpm_uart: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 24/74] serial: digicolor: " John Ogness
2023-09-14 18:37   ` John Ogness
2023-09-18  6:13   ` Baruch Siach
2023-09-18  6:13     ` Baruch Siach
2023-09-14 18:37 ` [PATCH tty v1 25/74] serial: dz: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 26/74] serial: linflexuart: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 27/74] serial: fsl_lpuart: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 28/74] serial: icom: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 29/74] serial: imx: " John Ogness
2023-09-14 18:37   ` John Ogness
2023-09-15 20:21   ` Uwe Kleine-König
2023-09-15 20:21     ` Uwe Kleine-König
2023-09-16 19:45     ` John Ogness
2023-09-16 19:45       ` John Ogness
2023-09-17 12:11       ` Uwe Kleine-König
2023-09-17 12:11         ` Uwe Kleine-König
2023-09-14 18:37 ` [PATCH tty v1 30/74] serial: ip22zilog: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 31/74] serial: jsm: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 32/74] serial: liteuart: " John Ogness
2023-09-15 13:40   ` Gabriel L. Somlo
2023-09-14 18:37 ` [PATCH tty v1 33/74] serial: lpc32xx_hs: " John Ogness
2023-09-14 18:37   ` John Ogness
2023-09-14 18:37 ` [PATCH tty v1 34/74] serial: ma35d1: " John Ogness
2023-09-14 18:37   ` John Ogness
2023-09-14 18:37 ` [PATCH tty v1 35/74] serial: mcf: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 36/74] serial: men_z135_uart: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 37/74] serial: meson: " John Ogness
2023-09-14 18:37   ` John Ogness
2023-09-14 18:37   ` John Ogness
2023-09-15  6:56   ` Neil Armstrong
2023-09-15  6:56     ` Neil Armstrong
2023-09-15  6:56     ` Neil Armstrong
2023-09-14 18:37 ` [PATCH tty v1 38/74] serial: milbeaut_usio: " John Ogness
2023-09-14 18:37   ` John Ogness
2023-09-14 18:37 ` [PATCH tty v1 39/74] serial: mpc52xx: " John Ogness
2023-09-14 18:37 ` [PATCH tty v1 40/74] serial: mps2-uart: " John Ogness
2023-09-14 18:37   ` John Ogness
2023-09-14 18:37 ` [PATCH tty v1 41/74] serial: msm: " John Ogness
2023-09-14 19:13   ` Bjorn Andersson
2023-09-14 18:37 ` [PATCH tty v1 42/74] serial: mvebu-uart: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 43/74] serial: omap: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 44/74] serial: owl: " John Ogness
2023-09-14 18:38   ` John Ogness
2023-09-14 18:38 ` [PATCH tty v1 45/74] serial: pch: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 46/74] serial: pic32: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 47/74] serial: pmac_zilog: " John Ogness
2023-09-14 18:38   ` John Ogness
2023-09-14 18:38 ` [PATCH tty v1 48/74] serial: pxa: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 49/74] serial: qcom-geni: " John Ogness
2023-09-14 19:16   ` Bjorn Andersson
2023-09-14 18:38 ` [PATCH tty v1 50/74] serial: rda: " John Ogness
2023-09-14 18:38   ` John Ogness
2023-09-14 18:38 ` [PATCH tty v1 51/74] serial: rp2: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 52/74] serial: sa1100: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 53/74] serial: samsung_tty: " John Ogness
2023-09-14 18:38   ` John Ogness
2023-09-14 18:38 ` [PATCH tty v1 54/74] serial: sb1250-duart: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 55/74] serial: sc16is7xx: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 56/74] serial: tegra: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 57/74] serial: core: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 58/74] serial: mctrl_gpio: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 59/74] serial: txx9: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 60/74] serial: sh-sci: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 61/74] serial: sifive: " John Ogness
2023-09-14 18:38   ` John Ogness
2023-09-14 18:38 ` [PATCH tty v1 62/74] serial: sprd: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 63/74] serial: st-asc: " John Ogness
2023-09-14 18:38   ` John Ogness
2023-09-14 18:38 ` [PATCH tty v1 64/74] serial: stm32: " John Ogness
2023-09-14 18:38   ` John Ogness
2023-09-14 18:38 ` [PATCH tty v1 65/74] serial: sunhv: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 66/74] serial: sunplus-uart: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 67/74] serial: sunsab: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 68/74] serial: sunsu: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 69/74] serial: sunzilog: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 70/74] serial: timbuart: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 71/74] serial: uartlite: " John Ogness
2023-09-14 18:38 ` [PATCH tty v1 72/74] serial: ucc_uart: " John Ogness
2023-09-14 18:38   ` John Ogness
2023-09-15 15:06   ` Timur Tabi
2023-09-15 15:06     ` Timur Tabi
2023-09-14 18:38 ` [PATCH tty v1 73/74] serial: vt8500: " John Ogness
2023-09-14 18:38   ` John Ogness
2023-09-14 18:38 ` [PATCH tty v1 74/74] serial: xilinx_uartps: " John Ogness
2023-09-14 18:38   ` John Ogness
2023-09-14 19:01 ` [PATCH tty v1 00/74] serial: wrappers for uart port lock Maciej W. Rozycki
2023-09-14 19:01   ` Maciej W. Rozycki
2023-09-14 19:01   ` Maciej W. Rozycki
2023-09-14 19:01   ` Maciej W. Rozycki
2023-09-15 12:04   ` Thomas Gleixner
2023-09-15 12:04     ` Thomas Gleixner
2023-09-15 12:04     ` Thomas Gleixner
2023-09-15 12:04     ` Thomas Gleixner
2023-09-15 17:23     ` Maciej W. Rozycki
2023-09-15 17:23       ` Maciej W. Rozycki
2023-09-15 17:23       ` Maciej W. Rozycki
2023-09-15 17:23       ` Maciej W. Rozycki
2023-09-16 19:24       ` John Ogness
2023-09-16 19:24         ` John Ogness
2023-09-16 19:24         ` John Ogness
2023-09-16 19:24         ` John Ogness
2023-09-15  9:12 ` Ilpo Järvinen
2023-09-15  9:12   ` Ilpo Järvinen
2023-09-15  9:12   ` Ilpo Järvinen
2023-09-15  9:12   ` Ilpo Järvinen
2023-09-16 19:42   ` John Ogness
2023-09-16 19:42     ` John Ogness
2023-09-16 19:42     ` John Ogness
2023-09-16 19:42     ` John Ogness
2023-09-18  8:23 ` John Ogness
2023-09-18  8:23   ` John Ogness
2023-09-18  8:23   ` John Ogness
2023-09-18  8:23   ` John Ogness
2023-09-18  8:26   ` Greg Kroah-Hartman
2023-09-18  8:26     ` Greg Kroah-Hartman
2023-09-18  8:26     ` Greg Kroah-Hartman
2023-09-18  8:26     ` Greg Kroah-Hartman

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