6.8-stable patches

[thirdparty/kernel/stable-queue.git] / queue-6.8 / serial-stm32-return-irq_none-in-the-isr-if-no-handling-happend.patch

diff --git a/queue-6.8/serial-stm32-return-irq_none-in-the-isr-if-no-handling-happend.patch b/queue-6.8/serial-stm32-return-irq_none-in-the-isr-if-no-handling-happend.patch
new file mode 100644 (file)
index 0000000..5ad9d78
--- /dev/null
+++ b/queue-6.8/serial-stm32-return-irq_none-in-the-isr-if-no-handling-happend.patch
@@ -0,0 +1,92 @@
+From 13c785323b36b845300b256d0e5963c3727667d7 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
+Date: Wed, 17 Apr 2024 11:03:27 +0200
+Subject: serial: stm32: Return IRQ_NONE in the ISR if no handling happend
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
+
+commit 13c785323b36b845300b256d0e5963c3727667d7 upstream.
+
+If there is a stuck irq that the handler doesn't address, returning
+IRQ_HANDLED unconditionally makes it impossible for the irq core to
+detect the problem and disable the irq. So only return IRQ_HANDLED if
+an event was handled.
+
+A stuck irq is still problematic, but with this change at least it only
+makes the UART nonfunctional instead of occupying the (usually only) CPU
+by 100% and so stall the whole machine.
+
+Fixes: 48a6092fb41f ("serial: stm32-usart: Add STM32 USART Driver")
+Cc: stable@vger.kernel.org
+Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
+Link: https://lore.kernel.org/r/5f92603d0dfd8a5b8014b2b10a902d91e0bb881f.1713344161.git.u.kleine-koenig@pengutronix.de
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/tty/serial/stm32-usart.c |   12 ++++++++++--
+ 1 file changed, 10 insertions(+), 2 deletions(-)
+
+--- a/drivers/tty/serial/stm32-usart.c
++++ b/drivers/tty/serial/stm32-usart.c
+@@ -857,6 +857,7 @@ static irqreturn_t stm32_usart_interrupt
+       const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
+       u32 sr;
+       unsigned int size;
++      irqreturn_t ret = IRQ_NONE;
+ 
+       sr = readl_relaxed(port->membase + ofs->isr);
+ 
+@@ -865,11 +866,14 @@ static irqreturn_t stm32_usart_interrupt
+           (sr & USART_SR_TC)) {
+               stm32_usart_tc_interrupt_disable(port);
+               stm32_usart_rs485_rts_disable(port);
++              ret = IRQ_HANDLED;
+       }
+ 
+-      if ((sr & USART_SR_RTOF) && ofs->icr != UNDEF_REG)
++      if ((sr & USART_SR_RTOF) && ofs->icr != UNDEF_REG) {
+               writel_relaxed(USART_ICR_RTOCF,
+                              port->membase + ofs->icr);
++              ret = IRQ_HANDLED;
++      }
+ 
+       if ((sr & USART_SR_WUF) && ofs->icr != UNDEF_REG) {
+               /* Clear wake up flag and disable wake up interrupt */
+@@ -878,6 +882,7 @@ static irqreturn_t stm32_usart_interrupt
+               stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_WUFIE);
+               if (irqd_is_wakeup_set(irq_get_irq_data(port->irq)))
+                       pm_wakeup_event(tport->tty->dev, 0);
++              ret = IRQ_HANDLED;
+       }
+ 
+       /*
+@@ -892,6 +897,7 @@ static irqreturn_t stm32_usart_interrupt
+                       uart_unlock_and_check_sysrq(port);
+                       if (size)
+                               tty_flip_buffer_push(tport);
++                      ret = IRQ_HANDLED;
+               }
+       }
+ 
+@@ -899,6 +905,7 @@ static irqreturn_t stm32_usart_interrupt
+               uart_port_lock(port);
+               stm32_usart_transmit_chars(port);
+               uart_port_unlock(port);
++              ret = IRQ_HANDLED;
+       }
+ 
+       /* Receiver timeout irq for DMA RX */
+@@ -908,9 +915,10 @@ static irqreturn_t stm32_usart_interrupt
+               uart_unlock_and_check_sysrq(port);
+               if (size)
+                       tty_flip_buffer_push(tport);
++              ret = IRQ_HANDLED;
+       }
+ 
+-      return IRQ_HANDLED;
++      return ret;
+ }
+ 
+ static void stm32_usart_set_mctrl(struct uart_port *port, unsigned int mctrl)