From 6cbd979080c788db32b2b3960599dadf1d001368 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 14 Sep 2023 20:43:58 +0206 Subject: [PATCH] serial: msm: Use port lock wrappers 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 --- drivers/tty/serial/msm_serial.c | 38 ++++++++++++++++----------------- 1 file changed, 19 insertions(+), 19 deletions(-) diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index 90953e679e38..597264b546fd 100644 --- 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 *args) 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 *args) 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 *args) 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 *args) 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_port *port, unsigned int misr) 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_port *port) 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, void *dev_id) 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, void *dev_id) 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_port *port, unsigned int baud, 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_port *port, struct ktermios *termios, 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_port *port, struct ktermios *termios, /* 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 uart_port *port, const char *s, 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 uart_port *port, const char *s, } if (locked) - spin_unlock(&port->lock); + uart_port_unlock(port); local_irq_restore(flags); }