serial: stm32: Merge hard IRQ and threaded IRQ handling into single IRQ handler

Requesting an interrupt with IRQF_ONESHOT will run the primary handler
in the hard-IRQ context even in the force-threaded mode. The
force-threaded mode is used by PREEMPT_RT in order to avoid acquiring
sleeping locks (spinlock_t) in hard-IRQ context. This combination
makes it impossible and leads to "sleeping while atomic" warnings.

Use one interrupt handler for both handlers (primary and secondary)
and drop the IRQF_ONESHOT flag which is not needed.

Fixes: e359b4411c283 ("serial: stm32: fix threaded interrupt handling")
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Valentin Caron <valentin.caron@foss.st.com> # V3
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230120160332.57930-1-marex@denx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index a149003..409e91d 100644 (file)
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -797,25 +797,11 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
                spin_unlock(&port->lock);
        }
 
-       if (stm32_usart_rx_dma_enabled(port))
-               return IRQ_WAKE_THREAD;
-       else
-               return IRQ_HANDLED;
-}
-
-static irqreturn_t stm32_usart_threaded_interrupt(int irq, void *ptr)
-{
-       struct uart_port *port = ptr;
-       struct tty_port *tport = &port->state->port;
-       struct stm32_port *stm32_port = to_stm32_port(port);
-       unsigned int size;
-       unsigned long flags;
-
        /* Receiver timeout irq for DMA RX */
-       if (!stm32_port->throttled) {
-               spin_lock_irqsave(&port->lock, flags);
+       if (stm32_usart_rx_dma_enabled(port) && !stm32_port->throttled) {
+               spin_lock(&port->lock);
                size = stm32_usart_receive_chars(port, false);
-               uart_unlock_and_check_sysrq_irqrestore(port, flags);
+               uart_unlock_and_check_sysrq(port);
                if (size)
                        tty_flip_buffer_push(tport);
        }
@@ -1015,10 +1001,8 @@ static int stm32_usart_startup(struct uart_port *port)
        u32 val;
        int ret;
 
-       ret = request_threaded_irq(port->irq, stm32_usart_interrupt,
-                                  stm32_usart_threaded_interrupt,
-                                  IRQF_ONESHOT | IRQF_NO_SUSPEND,
-                                  name, port);
+       ret = request_irq(port->irq, stm32_usart_interrupt,
+                         IRQF_NO_SUSPEND, name, port);
        if (ret)
                return ret;
 
@@ -1601,13 +1585,6 @@ static int stm32_usart_of_dma_rx_probe(struct stm32_port *stm32port,
        struct dma_slave_config config;
        int ret;
 
-       /*
-        * Using DMA and threaded handler for the console could lead to
-        * deadlocks.
-        */
-       if (uart_console(port))
-               return -ENODEV;
-
        stm32port->rx_buf = dma_alloc_coherent(dev, RX_BUF_L,
                                               &stm32port->rx_dma_buf,
                                               GFP_KERNEL);