The patch titled
Subject: kexec: prevent redundant IRQ masking by checking state before shutdown
has been added to the -mm mm-nonmm-unstable branch. Its filename is
kexec-prevent-redundant-irq-masking-by-checking-state-before-shutdown.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kexec-prevent-redundant-irq-masking-by-checking-state-before-shutdown.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Eliav Farber <farbere@xxxxxxxxxx>
Subject: kexec: prevent redundant IRQ masking by checking state before shutdown
Date: Wed, 4 Dec 2024 14:20:03 +0000
During machine kexec, the function machine_kexec_mask_interrupts() is
responsible for disabling or masking all interrupts. While the
irq_disable hook ensures that an already-disabled IRQ is not disabled
again, the current implementation unconditionally invokes the irq_mask()
function for every interrupt descriptor, even when the interrupt is
already masked.
A specific issue was observed in the crash kernel flow after unbinding a
device (prior to kexec) that used a GPIO as an IRQ source. The warning
was triggered by the gpiochip_disable_irq() function, which attempted to
clear the FLAG_IRQ_IS_ENABLED flag when FLAG_USED_AS_IRQ was not set:
```
void gpiochip_disable_irq(struct gpio_chip *gc, unsigned int offset)
{
struct gpio_desc *desc = gpiochip_get_desc(gc, offset);
if (!IS_ERR(desc) &&
!WARN_ON(!test_bit(FLAG_USED_AS_IRQ, &desc->flags)))
clear_bit(FLAG_IRQ_IS_ENABLED, &desc->flags);
}
```
This issue surfaced after commit a8173820f441 ("gpio: gpiolib: Allow GPIO
IRQs to lazy disable") introduced lazy disablement for GPIO IRQs. It
replaced disable/enable hooks with mask/unmask hooks. Unlike the disable
hook, the mask hook doesn't handle already-masked IRQs.
When a GPIO-IRQ driver is unbound, the IRQ is released, triggering
__irq_disable() and irq_state_set_masked(). A subsequent call to
machine_kexec_mask_interrupts() re-invokes chip->irq_mask(). This results
in a call chain, including gpiochip_irq_mask() and gpiochip_disable_irq().
Since FLAG_USED_AS_IRQ was cleared earlier, a warning occurs.
Replace calls to irq_mask() and irq_disable() hooks with a simplified call
to irq_shutdown(), and check if the interrupt is started (irqd_is_started)
before calling the shutdown.
Link: https://lkml.kernel.org/r/20241204142003.32859-3-farbere@xxxxxxxxxx
Signed-off-by: Eliav Farber <farbere@xxxxxxxxxx>
Cc: Aditya Gupta <adityag@xxxxxxxxxxxxx>
Cc: Albert Ou <aou@xxxxxxxxxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Hari Bathini <hbathini@xxxxxxxxxxxxx>
Cc: Jonathan Chocron <jonnyc@xxxxxxxxxx>
Cc: Madhavan Srinivasan <maddy@xxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Naveen N Rao <naveen@xxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Ryo Takakura <takakura@xxxxxxxxxxxxx>
Cc: Song Shuai <songshuaishuai@xxxxxxxxxxx>
Cc: Sourabh Jain <sourabhjain@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/irq/kexec.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
--- a/kernel/irq/kexec.c~kexec-prevent-redundant-irq-masking-by-checking-state-before-shutdown
+++ a/kernel/irq/kexec.c
@@ -17,7 +17,7 @@ void machine_kexec_mask_interrupts(void)
int check_eoi = 1;
chip = irq_desc_get_chip(desc);
- if (!chip)
+ if (!chip || !irqd_is_started(&desc->irq_data))
continue;
if (IS_ENABLED(CONFIG_GENERIC_IRQ_KEXEC_CLEAR_VM_FORWARD)) {
@@ -31,10 +31,6 @@ void machine_kexec_mask_interrupts(void)
if (check_eoi && chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data))
chip->irq_eoi(&desc->irq_data);
- if (chip->irq_mask)
- chip->irq_mask(&desc->irq_data);
-
- if (chip->irq_disable && !irqd_irq_disabled(&desc->irq_data))
- chip->irq_disable(&desc->irq_data);
+ irq_shutdown(desc);
}
}
_
Patches currently in -mm which might be from farbere@xxxxxxxxxx are
kexec-consolidate-machine_kexec_mask_interrupts-implementation.patch
kexec-prevent-redundant-irq-masking-by-checking-state-before-shutdown.patch
