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. Cc: Bjorn Andersson <andersson@xxxxxxxxxx> Cc: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> Cc: linux-arm-msm@xxxxxxxxxxxxxxx Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> --- drivers/tty/serial/msm_serial.c | 33 ++++++++++----------------------- 1 file changed, 10 insertions(+), 23 deletions(-) diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c index e24204ad35def..d27c4c8c84e13 100644 --- a/drivers/tty/serial/msm_serial.c +++ b/drivers/tty/serial/msm_serial.c @@ -588,16 +588,14 @@ static void msm_complete_rx_dma(void *args) if (!(port->read_status_mask & MSM_UART_SR_RX_BREAK)) flag = TTY_NORMAL; - uart_port_unlock_irqrestore(port, flags); - sysrq = uart_handle_sysrq_char(port, dma->virt[i]); - uart_port_lock_irqsave(port, &flags); + sysrq = uart_prepare_sysrq_char(port, dma->virt[i]); if (!sysrq) tty_insert_flip_char(tport, dma->virt[i], flag); } msm_start_rx_dma(msm_port); done: - uart_port_unlock_irqrestore(port, flags); + uart_unlock_and_check_sysrq_irqrestore(port, flags); if (count) tty_flip_buffer_push(tport); @@ -763,9 +761,7 @@ 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; - uart_port_unlock(port); - sysrq = uart_handle_sysrq_char(port, buf[i]); - uart_port_lock(port); + sysrq = uart_prepare_sysrq_char(port, buf[i]); if (!sysrq) tty_insert_flip_char(tport, buf[i], flag); } @@ -825,9 +821,7 @@ static void msm_handle_rx(struct uart_port *port) else if (sr & MSM_UART_SR_PAR_FRAME_ERR) flag = TTY_FRAME; - uart_port_unlock(port); - sysrq = uart_handle_sysrq_char(port, c); - uart_port_lock(port); + sysrq = uart_prepare_sysrq_char(port, c); if (!sysrq) tty_insert_flip_char(tport, c, flag); } @@ -948,11 +942,10 @@ static irqreturn_t msm_uart_irq(int irq, void *dev_id) struct uart_port *port = dev_id; struct msm_port *msm_port = to_msm_port(port); struct msm_dma *dma = &msm_port->rx_dma; - unsigned long flags; unsigned int misr; u32 val; - uart_port_lock_irqsave(port, &flags); + uart_port_lock(port); misr = msm_read(port, MSM_UART_MISR); msm_write(port, 0, MSM_UART_IMR); /* disable interrupt */ @@ -984,7 +977,7 @@ 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 */ - uart_port_unlock_irqrestore(port, flags); + uart_unlock_and_check_sysrq(port); return IRQ_HANDLED; } @@ -1621,14 +1614,10 @@ static void __msm_console_write(struct uart_port *port, const char *s, num_newlines++; count += num_newlines; - local_irq_save(flags); - - if (port->sysrq) - locked = 0; - else if (oops_in_progress) - locked = uart_port_trylock(port); + if (oops_in_progress) + locked = uart_port_trylock_irqsave(port, &flags); else - uart_port_lock(port); + uart_port_lock_irqsave(port, &flags); if (is_uartdm) msm_reset_dm_count(port, count); @@ -1667,9 +1656,7 @@ static void __msm_console_write(struct uart_port *port, const char *s, } if (locked) - uart_port_unlock(port); - - local_irq_restore(flags); + uart_port_unlock_irqrestore(port, flags); } static void msm_console_write(struct console *co, const char *s, -- 2.43.0
