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serial: mctrl_gpio: split disable_ms into sync and no_sync APIs

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The following splat has been observed on a SAMA5D27 platform using
atmel_serial:

BUG: sleeping function called from invalid context at kernel/irq/manage.c:738
in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 27, name: kworker/u5:0
preempt_count: 1, expected: 0
INFO: lockdep is turned off.
irq event stamp: 0
hardirqs last  enabled at (0): [<00000000>] 0x0
hardirqs last disabled at (0): [<c01588f0>] copy_process+0x1c4c/0x7bec
softirqs last  enabled at (0): [<c0158944>] copy_process+0x1ca0/0x7bec
softirqs last disabled at (0): [<00000000>] 0x0
CPU: 0 UID: 0 PID: 27 Comm: kworker/u5:0 Not tainted 6.13.0-rc7+ #74
Hardware name: Atmel SAMA5
Workqueue: hci0 hci_power_on [bluetooth]
Call trace:
  unwind_backtrace from show_stack+0x18/0x1c
  show_stack from dump_stack_lvl+0x44/0x70
  dump_stack_lvl from __might_resched+0x38c/0x598
  __might_resched from disable_irq+0x1c/0x48
  disable_irq from mctrl_gpio_disable_ms+0x74/0xc0
  mctrl_gpio_disable_ms from atmel_disable_ms.part.0+0x80/0x1f4
  atmel_disable_ms.part.0 from atmel_set_termios+0x764/0x11e8
  atmel_set_termios from uart_change_line_settings+0x15c/0x994
  uart_change_line_settings from uart_set_termios+0x2b0/0x668
  uart_set_termios from tty_set_termios+0x600/0x8ec
  tty_set_termios from ttyport_set_flow_control+0x188/0x1e0
  ttyport_set_flow_control from wilc_setup+0xd0/0x524 [hci_wilc]
  wilc_setup [hci_wilc] from hci_dev_open_sync+0x330/0x203c [bluetooth]
  hci_dev_open_sync [bluetooth] from hci_dev_do_open+0x40/0xb0 [bluetooth]
  hci_dev_do_open [bluetooth] from hci_power_on+0x12c/0x664 [bluetooth]
  hci_power_on [bluetooth] from process_one_work+0x998/0x1a38
  process_one_work from worker_thread+0x6e0/0xfb4
  worker_thread from kthread+0x3d4/0x484
  kthread from ret_from_fork+0x14/0x28

This warning is emitted when trying to toggle, at the highest level,
some flow control (with serdev_device_set_flow_control) in a device
driver. At the lowest level, the atmel_serial driver is using
serial_mctrl_gpio lib to enable/disable the corresponding IRQs
accordingly.  The warning emitted by CONFIG_DEBUG_ATOMIC_SLEEP is due to
disable_irq (called in mctrl_gpio_disable_ms) being possibly called in
some atomic context (some tty drivers perform modem lines configuration
in regions protected by port lock).

Split mctrl_gpio_disable_ms into two differents APIs, a non-blocking one
and a blocking one. Replace mctrl_gpio_disable_ms calls with the
relevant version depending on whether the call is protected by some port
lock.

Suggested-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Alexis Lothoré <alexis.lothore@bootlin.com>
Acked-by: Richard Genoud <richard.genoud@bootlin.com>
Link: https://lore.kernel.org/r/20250217-atomic_sleep_mctrl_serial_gpio-v3-1-59324b313eef@bootlin.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexis Lothoré 2025-02-17 07:21:53 +01:00 committed by Greg Kroah-Hartman
parent e749820252
commit 1bd2aad57d
8 changed files with 47 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/driver-api/serial/driver.rst
View File

@ -103,4 +103,4 @@ Some helpers are provided in order to set/get modem control lines via GPIO.
.. kernel-doc:: drivers/tty/serial/serial_mctrl_gpio.c
:identifiers: mctrl_gpio_init mctrl_gpio_to_gpiod
mctrl_gpio_set mctrl_gpio_get mctrl_gpio_enable_ms
mctrl_gpio_disable_ms
mctrl_gpio_disable_ms_sync mctrl_gpio_disable_ms_no_sync

2
drivers/tty/serial/8250/8250_port.c
View File

@ -1680,7 +1680,7 @@ static void serial8250_disable_ms(struct uart_port *port)
if (up->bugs & UART_BUG_NOMSR)
return;
mctrl_gpio_disable_ms(up->gpios);
mctrl_gpio_disable_ms_no_sync(up->gpios);
up->ier &= ~UART_IER_MSI;
serial_port_out(port, UART_IER, up->ier);

2
drivers/tty/serial/atmel_serial.c
View File

@ -700,7 +700,7 @@ static void atmel_disable_ms(struct uart_port *port)
atmel_port->ms_irq_enabled = false;
mctrl_gpio_disable_ms(atmel_port->gpios);
mctrl_gpio_disable_ms_no_sync(atmel_port->gpios);
if (!mctrl_gpio_to_gpiod(atmel_port->gpios, UART_GPIO_CTS))
idr |= ATMEL_US_CTSIC;

2
drivers/tty/serial/imx.c
View File

@ -1608,7 +1608,7 @@ static void imx_uart_shutdown(struct uart_port *port)
imx_uart_dma_exit(sport);
}
mctrl_gpio_disable_ms(sport->gpios);
mctrl_gpio_disable_ms_sync(sport->gpios);
uart_port_lock_irqsave(&sport->port, &flags);
ucr2 = imx_uart_readl(sport, UCR2);

34
drivers/tty/serial/serial_mctrl_gpio.c
View File

@ -296,11 +296,7 @@ void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios)
}
EXPORT_SYMBOL_GPL(mctrl_gpio_enable_ms);
/**
* mctrl_gpio_disable_ms - disable irqs and handling of changes to the ms lines
* @gpios: gpios to disable
*/
void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios)
static void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios, bool sync)
{
enum mctrl_gpio_idx i;
@ -316,10 +312,34 @@ void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios)
if (!gpios->irq[i])
continue;
disable_irq(gpios->irq[i]);
if (sync)
disable_irq(gpios->irq[i]);
else
disable_irq_nosync(gpios->irq[i]);
}
}
EXPORT_SYMBOL_GPL(mctrl_gpio_disable_ms);
/**
* mctrl_gpio_disable_ms_sync - disable irqs and handling of changes to the ms
* lines, and wait for any pending IRQ to be processed
* @gpios: gpios to disable
*/
void mctrl_gpio_disable_ms_sync(struct mctrl_gpios *gpios)
{
mctrl_gpio_disable_ms(gpios, true);
}
EXPORT_SYMBOL_GPL(mctrl_gpio_disable_ms_sync);
/**
* mctrl_gpio_disable_ms_no_sync - disable irqs and handling of changes to the
* ms lines, and return immediately
* @gpios: gpios to disable
*/
void mctrl_gpio_disable_ms_no_sync(struct mctrl_gpios *gpios)
{
mctrl_gpio_disable_ms(gpios, false);
}
EXPORT_SYMBOL_GPL(mctrl_gpio_disable_ms_no_sync);
void mctrl_gpio_enable_irq_wake(struct mctrl_gpios *gpios)
{

17
drivers/tty/serial/serial_mctrl_gpio.h
View File

@ -80,9 +80,16 @@ struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev,
void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios);
/*
* Disable gpio interrupts to report status line changes.
* Disable gpio interrupts to report status line changes, and block until
* any corresponding IRQ is processed
*/
void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios);
void mctrl_gpio_disable_ms_sync(struct mctrl_gpios *gpios);
/*
* Disable gpio interrupts to report status line changes, and return
* immediately
*/
void mctrl_gpio_disable_ms_no_sync(struct mctrl_gpios *gpios);
/*
* Enable gpio wakeup interrupts to enable wake up source.
@ -136,7 +143,11 @@ static inline void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios)
{
}
static inline void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios)
static inline void mctrl_gpio_disable_ms_sync(struct mctrl_gpios *gpios)
{
}
static inline void mctrl_gpio_disable_ms_no_sync(struct mctrl_gpios *gpios)
{
}

2
drivers/tty/serial/sh-sci.c
View File

@ -2310,7 +2310,7 @@ static void sci_shutdown(struct uart_port *port)
dev_dbg(port->dev, "%s(%d)\n", __func__, port->line);
s->autorts = false;
mctrl_gpio_disable_ms(to_sci_port(port)->gpios);
mctrl_gpio_disable_ms_sync(to_sci_port(port)->gpios);
uart_port_lock_irqsave(port, &flags);
sci_stop_rx(port);

2
drivers/tty/serial/stm32-usart.c
View File

@ -944,7 +944,7 @@ static void stm32_usart_enable_ms(struct uart_port *port)
static void stm32_usart_disable_ms(struct uart_port *port)
{
mctrl_gpio_disable_ms(to_stm32_port(port)->gpios);
mctrl_gpio_disable_ms_sync(to_stm32_port(port)->gpios);
}
/* Transmit stop */