This is a note to let you know that I've just added the patch titled
genirq: Remove WARN_ON_ONCE() in generic_handle_domain_irq()
to the 5.17-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:
genirq-remove-warn_on_once-in-generic_handle_domain_irq.patch
and it can be found in the queue-5.17 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 792ea6a074ae7ea5ab6f1b8b31f76bb0297de66c Mon Sep 17 00:00:00 2001
From: Lukas Wunner <lukas@xxxxxxxxx>
Date: Tue, 10 May 2022 09:56:05 +0200
Subject: genirq: Remove WARN_ON_ONCE() in generic_handle_domain_irq()
From: Lukas Wunner <lukas@xxxxxxxxx>
commit 792ea6a074ae7ea5ab6f1b8b31f76bb0297de66c upstream.
Since commit 0953fb263714 ("irq: remove handle_domain_{irq,nmi}()"),
generic_handle_domain_irq() warns if called outside hardirq context, even
though the function calls down to handle_irq_desc(), which warns about the
same, but conditionally on handle_enforce_irqctx().
The newly added warning is a false positive if the interrupt originates
from any other irqchip than x86 APIC or ARM GIC/GICv3. Those are the only
ones for which handle_enforce_irqctx() returns true. Per commit
c16816acd086 ("genirq: Add protection against unsafe usage of
generic_handle_irq()"):
"In general calling generic_handle_irq() with interrupts disabled from non
interrupt context is harmless. For some interrupt controllers like the
x86 trainwrecks this is outright dangerous as it might corrupt state if
an interrupt affinity change is pending."
Examples for interrupt chips where the warning is a false positive are
USB-attached GPIO controllers such as drivers/gpio/gpio-dln2.c:
USB gadgets are incapable of directly signaling an interrupt because they
cannot initiate a bus transaction by themselves. All communication on
the bus is initiated by the host controller, which polls a gadget's
Interrupt Endpoint in regular intervals. If an interrupt is pending,
that information is passed up the stack in softirq context, from which a
hardirq is synthesized via generic_handle_domain_irq().
Remove the warning to eliminate such false positives.
Fixes: 0953fb263714 ("irq: remove handle_domain_{irq,nmi}()")
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
CC: Linus Walleij <linus.walleij@xxxxxxxxxx>
Cc: Bartosz Golaszewski <brgl@xxxxxxxx>
Cc: Octavian Purdila <octavian.purdila@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20220505113207.487861b2@xxxxxxxxxx
Link: https://lore.kernel.org/r/20220506203242.GA1855@xxxxxxxxx
Link: https://lore.kernel.org/r/c3caf60bfa78e5fdbdf483096b7174da65d1813a.1652168866.git.lukas@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/irq/irqdesc.c | 1 -
1 file changed, 1 deletion(-)
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -678,7 +678,6 @@ EXPORT_SYMBOL_GPL(generic_handle_irq);
*/
int generic_handle_domain_irq(struct irq_domain *domain, unsigned int hwirq)
{
- WARN_ON_ONCE(!in_irq());
return handle_irq_desc(irq_resolve_mapping(domain, hwirq));
}
EXPORT_SYMBOL_GPL(generic_handle_domain_irq);
Patches currently in stable-queue which might be from lukas@xxxxxxxxx are
queue-5.17/genirq-remove-warn_on_once-in-generic_handle_domain_irq.patch
