From: Thomas Gleixner Date: Thu, 14 Sep 2023 20:43:58 +0206 Subject: [PATCH 041/134] serial: msm: Use port lock wrappers Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz 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 Reviewed-by: Bjorn Andersson Signed-off-by: John Ogness Link: https://lore.kernel.org/r/20230914183831.587273-42-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sebastian Andrzej Siewior --- drivers/tty/serial/msm_serial.c | 38 +++++++++++++++++++------------------- 1 file changed, 19 insertions(+), 19 deletions(-) --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -444,7 +444,7 @@ static void msm_complete_tx_dma(void *ar unsigned int count; u32 val; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); /* Already stopped */ if (!dma->count) @@ -476,7 +476,7 @@ static void msm_complete_tx_dma(void *ar msm_handle_tx(port); done: - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } static int msm_handle_tx_dma(struct msm_port *msm_port, unsigned int count) @@ -549,7 +549,7 @@ static void msm_complete_rx_dma(void *ar unsigned long flags; u32 val; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); /* Already stopped */ if (!dma->count) @@ -587,16 +587,16 @@ static void msm_complete_rx_dma(void *ar if (!(port->read_status_mask & MSM_UART_SR_RX_BREAK)) flag = TTY_NORMAL; - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); sysrq = uart_handle_sysrq_char(port, dma->virt[i]); - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); if (!sysrq) tty_insert_flip_char(tport, dma->virt[i], flag); } msm_start_rx_dma(msm_port); done: - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); if (count) tty_flip_buffer_push(tport); @@ -762,9 +762,9 @@ static void msm_handle_rx_dm(struct uart if (!(port->read_status_mask & MSM_UART_SR_RX_BREAK)) flag = TTY_NORMAL; - spin_unlock(&port->lock); + uart_port_unlock(port); sysrq = uart_handle_sysrq_char(port, buf[i]); - spin_lock(&port->lock); + uart_port_lock(port); if (!sysrq) tty_insert_flip_char(tport, buf[i], flag); } @@ -824,9 +824,9 @@ static void msm_handle_rx(struct uart_po else if (sr & MSM_UART_SR_PAR_FRAME_ERR) flag = TTY_FRAME; - spin_unlock(&port->lock); + uart_port_unlock(port); sysrq = uart_handle_sysrq_char(port, c); - spin_lock(&port->lock); + uart_port_lock(port); if (!sysrq) tty_insert_flip_char(tport, c, flag); } @@ -951,7 +951,7 @@ static irqreturn_t msm_uart_irq(int irq, unsigned int misr; u32 val; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); misr = msm_read(port, MSM_UART_MISR); msm_write(port, 0, MSM_UART_IMR); /* disable interrupt */ @@ -983,7 +983,7 @@ static irqreturn_t msm_uart_irq(int irq, msm_handle_delta_cts(port); msm_write(port, msm_port->imr, MSM_UART_IMR); /* restore interrupt */ - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); return IRQ_HANDLED; } @@ -1128,13 +1128,13 @@ static int msm_set_baud_rate(struct uart unsigned long flags, rate; flags = *saved_flags; - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); entry = msm_find_best_baud(port, baud, &rate); clk_set_rate(msm_port->clk, rate); baud = rate / 16 / entry->divisor; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); *saved_flags = flags; port->uartclk = rate; @@ -1266,7 +1266,7 @@ static void msm_set_termios(struct uart_ unsigned long flags; unsigned int baud, mr; - spin_lock_irqsave(&port->lock, flags); + uart_port_lock_irqsave(port, &flags); if (dma->chan) /* Terminate if any */ msm_stop_dma(port, dma); @@ -1338,7 +1338,7 @@ static void msm_set_termios(struct uart_ /* Try to use DMA */ msm_start_rx_dma(msm_port); - spin_unlock_irqrestore(&port->lock, flags); + uart_port_unlock_irqrestore(port, flags); } static const char *msm_type(struct uart_port *port) @@ -1620,9 +1620,9 @@ static void __msm_console_write(struct u if (port->sysrq) locked = 0; else if (oops_in_progress) - locked = spin_trylock(&port->lock); + locked = uart_port_trylock(port); else - spin_lock(&port->lock); + uart_port_lock(port); if (is_uartdm) msm_reset_dm_count(port, count); @@ -1661,7 +1661,7 @@ static void __msm_console_write(struct u } if (locked) - spin_unlock(&port->lock); + uart_port_unlock(port); local_irq_restore(flags); }