kernel/drivers/tty/serial/pch_uart.c, branch linux-6.9.y

serial: pch: Use uart_prepare_sysrq_char().

2024-03-02T21:06:22Z

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 Link: https://lore.kernel.org/r/20240301215246.891055-19-bigeasy@linutronix.de Signed-off-by: Greg Kroah-Hartman

serial: pch: Remove eg20t_port::lock.

2024-03-02T21:06:22Z

The struct eg20t_port has a spinlock_t which is used for locking while access I/O of the device. Then there is the uart_portlock which is sometimes and nests within eg20t_port's lock. The uart_port lock is not used while using the struct in pch_uart_hal_read() which might be okay. Then both locks are used in pch_console_write() which looks odd especially the double try_lock part. All in all it looks like the uart_port's lock could replace eg20t_port's lock and simplify the code. Remove eg20t_port::lock and use uart_port's lock for the lock scope. Signed-off-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20240301215246.891055-18-bigeasy@linutronix.de Signed-off-by: Greg Kroah-Hartman

serial: pch: Don't initialize uart_port's spin_lock.

2024-03-02T21:06:22Z

There is no need to directly initialize the spinlock_t in struct uart_port. The structure is later passed to uart_add_one_port() which initialize the complete struct including the lock member. Remove spin_lock_init() on uart_port's internal lock. Signed-off-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20240301215246.891055-17-bigeasy@linutronix.de Signed-off-by: Greg Kroah-Hartman

serial: pch: Don't disable interrupts while acquiring lock in ISR.

2024-03-02T21:06:22Z

The interrupt service routine is always invoked with disabled interrupts. Remove the _irqsave() from the locking functions in the interrupts service routine/ pch_uart_interrupt(). Signed-off-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20240301215246.891055-16-bigeasy@linutronix.de Signed-off-by: Greg Kroah-Hartman

serial: pch: Make push_rx() return void.

2024-03-02T21:06:21Z

push_rx() returns always 0. Make push_rx() return void. Signed-off-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20240301215246.891055-15-bigeasy@linutronix.de Signed-off-by: Greg Kroah-Hartman

serial: pch: Invoke handle_rx_to() directly.

2024-03-02T21:06:21Z

handle_rx() is only a wrapper around handle_rx_to() without any additional functionality. Invoke handle_rx_to() directly and remove handle_rx(). Signed-off-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20240301215246.891055-14-bigeasy@linutronix.de Signed-off-by: Greg Kroah-Hartman

serial: pch: Use port lock wrappers

2023-09-18T09:18:13Z

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. To avoid adding this functionality to all UART drivers, wrap the spin_[un]lock*() invocations for uart_port::lock into helper functions which just contain the spin_[un]lock*() invocations for now. In a subsequent step these helpers will gain the console synchronization mechanisms. Converted with coccinelle. No functional change. Signed-off-by: Thomas Gleixner Signed-off-by: John Ogness Link: https://lore.kernel.org/r/20230914183831.587273-46-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman

tty: pcn_uart: fix memory leak with using debugfs_lookup()

2023-02-08T12:09:55Z

When calling debugfs_lookup() the result must have dput() called on it, otherwise the memory will leak over time. To make things simpler, just call debugfs_lookup_and_remove() instead which handles all of the logic at once. Cc: Jiri Slaby Link: https://lore.kernel.org/r/20230202141221.2293012-1-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman

serial: pch_uart: Pass correct sg to dma_unmap_sg()

2023-01-19T13:54:56Z

A local variable sg is used to store scatterlist pointer in pch_dma_tx_complete(). The for loop doing Tx byte accounting before dma_unmap_sg() alters sg in its increment statement. Therefore, the pointer passed into dma_unmap_sg() won't match to the one given to dma_map_sg(). To fix the problem, use priv->sg_tx_p directly in dma_unmap_sg() instead of the local variable. Fixes: da3564ee027e ("pch_uart: add multi-scatter processing") Cc: stable@vger.kernel.org Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20230103093435.4396-1-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman

serial: pch: Fix PCI device refcount leak in pch_request_dma()

2022-11-22T16:58:51Z

As comment of pci_get_slot() says, it returns a pci_device with its refcount increased. The caller must decrement the reference count by calling pci_dev_put(). Since 'dma_dev' is only used to filter the channel in filter(), we can call pci_dev_put() before exiting from pch_request_dma(). Add the missing pci_dev_put() for the normal and error path. Fixes: 3c6a483275f4 ("Serial: EG20T: add PCH_UART driver") Signed-off-by: Xiongfeng Wang Link: https://lore.kernel.org/r/20221122114559.27692-1-wangxiongfeng2@huawei.com Signed-off-by: Greg Kroah-Hartman