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 --- Cc: Alexandre Torgue alexandre.torgue@foss.st.com Cc: Erwan Le Ray erwan.leray@foss.st.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Jiri Slaby jirislaby@kernel.org Cc: Maxime Coquelin mcoquelin.stm32@gmail.com Cc: Sebastian Andrzej Siewior bigeasy@linutronix.de Cc: Thomas Gleixner tglx@linutronix.de Cc: Valentin Caron valentin.caron@foss.st.com Cc: linux-arm-kernel@lists.infradead.org Cc: linux-stm32@st-md-mailman.stormreply.com To: linux-serial@vger.kernel.org --- V2: - Update patch subject, was: serial: stm32: Move hard IRQ handling to threaded interrupt context - Use request_irq() instead, rename the IRQ handler function V3: - Update the commit message per suggestion from Sebastian - Add RB from Sebastian - Add Fixes tag V4: - Remove uart_console() deadlock check from stm32_usart_of_dma_rx_probe() - Use plain spin_lock()/spin_unlock() instead of the _irqsave/_irqrestore variants in IRQ handler - Add TB from Valentin V5: - Add CC stable@ - Do not move the sr variable, removes one useless hunk from the patch V6: - Replace uart_unlock_and_check_sysrq_irqrestore with uart_unlock_and_check_sysrq and drop last instance of flags --- drivers/tty/serial/stm32-usart.c | 33 +++++--------------------------- 1 file changed, 5 insertions(+), 28 deletions(-)

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index a1490033aa164..409e91d6829a5 100644 --- 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);