FAILED: patch "[PATCH] serial: stm32: Return IRQ_NONE in the ISR if no handling" failed to apply to 5.15-stable tree

FAILED: patch "[PATCH] serial: stm32: Return IRQ_NONE in the ISR if no handling" failed to apply to 5.15-stable tree

[gregkh]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 13c785323b36b845300b256d0e5963c3727667d7
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024042344-phonics-simile-0b3c@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

13c785323b36 ("serial: stm32: Return IRQ_NONE in the ISR if no handling happend")
c5d06662551c ("serial: stm32: Use port lock wrappers")
a01ae50d7eae ("serial: stm32: replace access to DMAR bit by dmaengine_pause/resume")
7f28bcea824e ("serial: stm32: group dma pause/resume error handling into single function")
00d1f9c6af0d ("serial: stm32: modify parameter and rename stm32_usart_rx_dma_enabled")
db89728abad5 ("serial: stm32: avoid clearing DMAT bit during transfer")
3f6c02fa712b ("serial: stm32: Merge hard IRQ and threaded IRQ handling into single IRQ handler")
d7c76716169d ("serial: stm32: Use TC interrupt to deassert GPIO RTS in RS485 mode")
3bcea529b295 ("serial: stm32: Factor out GPIO RTS toggling into separate function")
037b91ec7729 ("serial: stm32: fix software flow control transfer")
d3d079bde07e ("serial: stm32: prevent TDR register overwrite when sending x_char")
195437d14fb4 ("serial: stm32: correct loop for dma error handling")
2a3bcfe03725 ("serial: stm32: fix flow control transfer in DMA mode")
9a135f16d228 ("serial: stm32: rework TX DMA state condition")
56a23f9319e8 ("serial: stm32: move tx dma terminate DMA to shutdown")
6333a4850621 ("serial: stm32: push DMA RX data before suspending")
6eeb348c8482 ("serial: stm32: terminate / restart DMA transfer at suspend / resume")
e0abc903deea ("serial: stm32: rework RX dma initialization and release")
d1ec8a2eabe9 ("serial: stm32: update throttle and unthrottle ops for dma mode")
33bb2f6ac308 ("serial: stm32: rework RX over DMA")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

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: [PATCH] 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

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>

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 58d169e5c1db..d60cbac69194 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -861,6 +861,7 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
 	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);
 
@@ -869,11 +870,14 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
 	    (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 */
@@ -882,6 +886,7 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
 		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;
 	}
 
 	/*
@@ -896,6 +901,7 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
 			uart_unlock_and_check_sysrq(port);
 			if (size)
 				tty_flip_buffer_push(tport);
+			ret = IRQ_HANDLED;
 		}
 	}
 
@@ -903,6 +909,7 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
 		uart_port_lock(port);
 		stm32_usart_transmit_chars(port);
 		uart_port_unlock(port);
+		ret = IRQ_HANDLED;
 	}
 
 	/* Receiver timeout irq for DMA RX */
@@ -912,9 +919,10 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
 		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)

Re: FAILED: patch "[PATCH] serial: stm32: Return IRQ_NONE in the ISR if no handling" failed to apply to 5.15-stable tree

[Uwe Kleine-König]

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Hello,

On Tue, Apr 23, 2024 at 05:36:44AM -0700, gregkh@linuxfoundation.org wrote:
> The patch below does not apply to the 5.15-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
> 
> To reproduce the conflict and resubmit, you may use the following commands:
> 
> git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
> git checkout FETCH_HEAD
> git cherry-pick -x 13c785323b36b845300b256d0e5963c3727667d7
> # <resolve conflicts, build, test, etc.>
> git commit -s
> git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2024042344-phonics-simile-0b3c@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..
> 
> Possible dependencies:
> 
> 13c785323b36 ("serial: stm32: Return IRQ_NONE in the ISR if no handling happend")
> c5d06662551c ("serial: stm32: Use port lock wrappers")
> a01ae50d7eae ("serial: stm32: replace access to DMAR bit by dmaengine_pause/resume")
> 7f28bcea824e ("serial: stm32: group dma pause/resume error handling into single function")
> 00d1f9c6af0d ("serial: stm32: modify parameter and rename stm32_usart_rx_dma_enabled")
> db89728abad5 ("serial: stm32: avoid clearing DMAT bit during transfer")
> 3f6c02fa712b ("serial: stm32: Merge hard IRQ and threaded IRQ handling into single IRQ handler")
> d7c76716169d ("serial: stm32: Use TC interrupt to deassert GPIO RTS in RS485 mode")
> 3bcea529b295 ("serial: stm32: Factor out GPIO RTS toggling into separate function")
> 037b91ec7729 ("serial: stm32: fix software flow control transfer")
> d3d079bde07e ("serial: stm32: prevent TDR register overwrite when sending x_char")
> 195437d14fb4 ("serial: stm32: correct loop for dma error handling")
> 2a3bcfe03725 ("serial: stm32: fix flow control transfer in DMA mode")
> 9a135f16d228 ("serial: stm32: rework TX DMA state condition")
> 56a23f9319e8 ("serial: stm32: move tx dma terminate DMA to shutdown")
> 6333a4850621 ("serial: stm32: push DMA RX data before suspending")
> 6eeb348c8482 ("serial: stm32: terminate / restart DMA transfer at suspend / resume")
> e0abc903deea ("serial: stm32: rework RX dma initialization and release")
> d1ec8a2eabe9 ("serial: stm32: update throttle and unthrottle ops for dma mode")
> 33bb2f6ac308 ("serial: stm32: rework RX over DMA")

I think it's not that important to backport this patch further than 6.1.
It only improves the behaviour in the presence of another bug. If
someone wants to look anyhow, it would probably make sense to backport
13c785323b36 on top of a backport of 3f6c02fa712b.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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