kernel/linux.git/drivers/tty/serial/serial_core.c, branch v6.6.39

serial: core: Fix missing shutdown and startup for serial base port

2024-04-27T15:11:39+00:00

commit 1aa4ad4eb695bac1b0a7ba542a16d6833c9c8dd8 upstream. We are seeing start_tx being called after port shutdown as noted by Jiri. This happens because we are missing the startup and shutdown related functions for the serial base port. Let's fix the issue by adding startup and shutdown functions for the serial base port to block tx flushing for the serial base port when the port is not in use. Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM") Cc: stable Reported-by: Jiri Slaby Signed-off-by: Tony Lindgren Link: https://lore.kernel.org/r/20240411055848.38190-1-tony@atomide.com Signed-off-by: Greg Kroah-Hartman

serial: core: Clearing the circular buffer before NULLifying it

2024-04-27T15:11:39+00:00

commit 9cf7ea2eeb745213dc2a04103e426b960e807940 upstream. The circular buffer is NULLified in uart_tty_port_shutdown() under the spin lock. However, the PM or other timer based callbacks may still trigger after this event without knowning that buffer pointer is not valid. Since the serial code is a bit inconsistent in checking the buffer state (some rely on the head-tail positions, some on the buffer pointer), it's better to have both aligned, i.e. buffer pointer to be NULL and head-tail possitions to be the same, meaning it's empty. This will prevent asynchronous calls to dereference NULL pointer as reported recently in 8250 case: BUG: kernel NULL pointer dereference, address: 00000cf5 Workqueue: pm pm_runtime_work EIP: serial8250_tx_chars (drivers/tty/serial/8250/8250_port.c:1809) ... ? serial8250_tx_chars (drivers/tty/serial/8250/8250_port.c:1809) __start_tx (drivers/tty/serial/8250/8250_port.c:1551) serial8250_start_tx (drivers/tty/serial/8250/8250_port.c:1654) serial_port_runtime_suspend (include/linux/serial_core.h:667 drivers/tty/serial/serial_port.c:63) __rpm_callback (drivers/base/power/runtime.c:393) ? serial_port_remove (drivers/tty/serial/serial_port.c:50) rpm_suspend (drivers/base/power/runtime.c:447) The proposed change will prevent ->start_tx() to be called during suspend on shut down port. Fixes: 43066e32227e ("serial: port: Don't suspend if the port is still busy") Cc: stable Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202404031607.2e92eebe-lkp@intel.com Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20240404150034.41648-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman

serial: Lock console when calling into driver before registration

2024-04-03T13:28:26+00:00

[ Upstream commit 801410b26a0e8b8a16f7915b2b55c9528b69ca87 ] During the handoff from earlycon to the real console driver, we have two separate drivers operating on the same device concurrently. In the case of the 8250 driver these concurrent accesses cause problems due to the driver's use of banked registers, controlled by LCR.DLAB. It is possible for the setup(), config_port(), pm() and set_mctrl() callbacks to set DLAB, which can cause the earlycon code that intends to access TX to instead access DLL, leading to missed output and corruption on the serial line due to unintended modifications to the baud rate. In particular, for setup() we have: univ8250_console_setup() -> serial8250_console_setup() -> uart_set_options() -> serial8250_set_termios() -> serial8250_do_set_termios() -> serial8250_do_set_divisor() For config_port() we have: serial8250_config_port() -> autoconfig() For pm() we have: serial8250_pm() -> serial8250_do_pm() -> serial8250_set_sleep() For set_mctrl() we have (for some devices): serial8250_set_mctrl() -> omap8250_set_mctrl() -> __omap8250_set_mctrl() To avoid such problems, let's make it so that the console is locked during pre-registration calls to these callbacks, which will prevent the earlycon driver from running concurrently. Remove the partial solution to this problem in the 8250 driver that locked the console only during autoconfig_irq(), as this would result in a deadlock with the new approach. The console continues to be locked during autoconfig_irq() because it can only be called through uart_configure_port(). Although this patch introduces more locking than strictly necessary (and in particular it also locks during the call to rs485_config() which is not affected by this issue as far as I can tell), it follows the principle that it is the responsibility of the generic console code to manage the earlycon handoff by ensuring that earlycon and real console driver code cannot run concurrently, and not the individual drivers. Signed-off-by: Peter Collingbourne Reviewed-by: John Ogness Link: https://linux-review.googlesource.com/id/I7cf8124dcebf8618e6b2ee543fa5b25532de55d8 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240304214350.501253-1-pcc@google.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

serial: Do not hold the port lock when setting rx-during-tx GPIO

2024-02-01T00:18:58+00:00

commit 07c30ea5861fb26a77dade8cdc787252f6122fb1 upstream. Both the imx and stm32 driver set the rx-during-tx GPIO in rs485_config(). Since this function is called with the port lock held, this can be a problem in case that setting the GPIO line can sleep (e.g. if a GPIO expander is used which is connected via SPI or I2C). Avoid this issue by moving the GPIO setting outside of the port lock into the serial core and thus making it a generic feature. Also with commit c54d48543689 ("serial: stm32: Add support for rs485 RX_DURING_TX output GPIO") the SER_RS485_RX_DURING_TX flag is only set if a rx-during-tx GPIO is _not_ available, which is wrong. Fix this, too. Furthermore reset old GPIO settings in case that changing the RS485 configuration failed. Fixes: c54d48543689 ("serial: stm32: Add support for rs485 RX_DURING_TX output GPIO") Fixes: ca530cfa968c ("serial: imx: Add support for RS485 RX_DURING_TX output GPIO") Cc: Shawn Guo Cc: Sascha Hauer Cc: Signed-off-by: Lino Sanfilippo Link: https://lore.kernel.org/r/20240103061818.564-2-l.sanfilippo@kunbus.com Signed-off-by: Lino Sanfilippo Signed-off-by: Greg Kroah-Hartman

serial: core: set missing supported flag for RX during TX GPIO

2024-02-01T00:18:47+00:00

[ Upstream commit 1a33e33ca0e80d485458410f149265cdc0178cfa ] If the RS485 feature RX-during-TX is supported by means of a GPIO set the according supported flag. Otherwise setting this feature from userspace may not be possible, since in uart_sanitize_serial_rs485() the passed RS485 configuration is matched against the supported features and unsupported settings are thereby removed and thus take no effect. Cc: Fixes: 163f080eb717 ("serial: core: Add option to output RS485 RX_DURING_TX state via GPIO") Reviewed-by: Ilpo Järvinen Signed-off-by: Lino Sanfilippo Link: https://lore.kernel.org/r/20240103061818.564-3-l.sanfilippo@kunbus.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

serial: core: Simplify uart_get_rs485_mode()

2024-02-01T00:18:47+00:00

[ Upstream commit 7cda0b9eb6eb9e761f452e2ef4e81eca20b19938 ] Simplify uart_get_rs485_mode() by using temporary variable for the GPIO descriptor. With that, use proper type for the flags of the GPIO descriptor. Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20231003142346.3072929-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman Stable-dep-of: 1a33e33ca0e8 ("serial: core: set missing supported flag for RX during TX GPIO") Signed-off-by: Sasha Levin

serial: core, imx: do not set RS485 enabled if it is not supported

2024-01-25T23:35:43+00:00

commit 74eab89b26ac433ad857292f4707b43c1a8f0209 upstream. If the imx driver cannot support RS485 it nullifies the ports rs485_supported structure. But it still calls uart_get_rs485_mode() which may set the RS485_ENABLED flag nevertheless. This may lead to an attempt to configure RS485 even if it is not supported when the flag is evaluated in uart_configure_port() at port startup. Avoid this by bailing out of uart_get_rs485_mode() if the RS485_ENABLED flag is not supported by the caller. With this fix a check for RTS availability is now obsolete in the imx driver, since it can not evaluate to true any more. So remove this check. Furthermore the explicit nullifcation of rs485_supported is not needed, since the memory has already been set to zeros at allocation. So remove this, too. Fixes: 00d7a00e2a6f ("serial: imx: Fill in rs485_supported") Cc: Shawn Guo Cc: Sascha Hauer Cc: Suggested-by: Uwe Kleine-König Signed-off-by: Lino Sanfilippo Reviewed-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20240103061818.564-6-l.sanfilippo@kunbus.com Signed-off-by: Greg Kroah-Hartman

serial: core: make sure RS485 cannot be enabled when it is not supported

2024-01-25T23:35:43+00:00

commit c73986913fa47e71e0b1ad7f039f6444915e8810 upstream. Some uart drivers specify a rs485_config() function and then decide later to disable RS485 support for some reason (e.g. imx and ar933). In these cases userspace may be able to activate RS485 via TIOCSRS485 nevertheless, since in uart_set_rs485_config() an existing rs485_config() function indicates that RS485 is supported. Make sure that this is not longer possible by checking the uarts rs485_supported.flags instead and bailing out if SER_RS485_ENABLED is not set. Furthermore instead of returning an empty structure return -ENOTTY if the RS485 configuration is requested via TIOCGRS485 but RS485 is not supported. This has a small impact on userspace visibility but it is consistent with the -ENOTTY error for TIOCGRS485. Fixes: e849145e1fdd ("serial: ar933x: Fill in rs485_supported") Fixes: 55e18c6b6d42 ("serial: imx: Remove serial_rs485 sanitization") Cc: Shawn Guo Cc: Sascha Hauer Cc: Reviewed-by: Ilpo Järvinen Signed-off-by: Lino Sanfilippo Link: https://lore.kernel.org/r/20240103061818.564-5-l.sanfilippo@kunbus.com Signed-off-by: Greg Kroah-Hartman

serial: core: fix sanitizing check for RTS settings

2024-01-25T23:35:43+00:00

commit 4afeced55baa391490b61ed9164867e2927353ed upstream. Among other things uart_sanitize_serial_rs485() tests the sanity of the RTS settings in a RS485 configuration that has been passed by userspace. If RTS-on-send and RTS-after-send are both set or unset the configuration is adjusted and RTS-after-send is disabled and RTS-on-send enabled. This however makes only sense if both RTS modes are actually supported by the driver. With commit be2e2cb1d281 ("serial: Sanitize rs485_struct") the code does take the driver support into account but only checks if one of both RTS modes are supported. This may lead to the errorneous result of RTS-on-send being set even if only RTS-after-send is supported. Fix this by changing the implemented logic: First clear all unsupported flags in the RS485 configuration, then adjust an invalid RTS setting by taking into account which RTS mode is supported. Cc: Fixes: be2e2cb1d281 ("serial: Sanitize rs485_struct") Reviewed-by: Ilpo Järvinen Signed-off-by: Lino Sanfilippo Link: https://lore.kernel.org/r/20240103061818.564-4-l.sanfilippo@kunbus.com Signed-off-by: Greg Kroah-Hartman

serial: core: Fix runtime PM handling for pending tx

2023-11-08T10:56:24+00:00

commit 6f699743aebf07538e506a46c5965eb8bdd2c716 upstream. Richard reported that a serial port may end up sometimes with tx data pending in the buffer for long periods of time. Turns out we bail out early on any errors from pm_runtime_get(), including -EINPROGRESS. To fix the issue, we need to ignore -EINPROGRESS as we only care about the runtime PM usage count at this point. We check for an active runtime PM state later on for tx. Fixes: 84a9582fd203 ("serial: core: Start managing serial controllers to enable runtime PM") Cc: stable Reported-by: Richard Purdie Cc: Bruce Ashfield Cc: Mikko Rapeli Cc: Paul Gortmaker Cc: Randy MacLeod Signed-off-by: Tony Lindgren Tested-by: Richard Purdie Link: https://lore.kernel.org/r/20231023074856.61896-1-tony@atomide.com Signed-off-by: Greg Kroah-Hartman