This is a note to let you know that I've just added the patch titled
serial: stm32: Return IRQ_NONE in the ISR if no handling happend
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
serial-stm32-return-irq_none-in-the-isr-if-no-handling-happend.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 13c785323b36b845300b256d0e5963c3727667d7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@xxxxxxxxxxxxxx>
Date: Wed, 17 Apr 2024 11:03:27 +0200
Subject: serial: stm32: Return IRQ_NONE in the ISR if no handling happend
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From: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/5f92603d0dfd8a5b8014b2b10a902d91e0bb881f.1713344161.git.u.kleine-koenig@xxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -755,6 +755,7 @@ 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);
@@ -763,11 +764,14 @@ 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 */
@@ -776,6 +780,7 @@ 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;
}
/*
@@ -790,6 +795,7 @@ static irqreturn_t stm32_usart_interrupt
uart_unlock_and_check_sysrq(port);
if (size)
tty_flip_buffer_push(tport);
+ ret = IRQ_HANDLED;
}
}
@@ -797,6 +803,7 @@ static irqreturn_t stm32_usart_interrupt
spin_lock(&port->lock);
stm32_usart_transmit_chars(port);
spin_unlock(&port->lock);
+ ret = IRQ_HANDLED;
}
/* Receiver timeout irq for DMA RX */
@@ -806,9 +813,10 @@ 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)
Patches currently in stable-queue which might be from u.kleine-koenig@xxxxxxxxxxxxxx are
queue-6.1/serial-stm32-return-irq_none-in-the-isr-if-no-handling-happend.patch
queue-6.1/serial-stm32-reset-.throttled-state-in-.startup.patch
