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FROMGIT: genirq/cpuhotplug: Restore affinity even for suspended IRQ

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Commit 788019eb559f ("genirq: Retain disable depth for managed interrupts
across CPU hotplug") tried to make managed shutdown/startup properly
reference counted, but it missed the fact that the unplug and hotplug code
has an intentional imbalance by skipping IRQS_SUSPENDED interrupts on
the "restore" path.

This means that if a managed-affinity interrupt was both suspended and
managed-shutdown (such as may happen during system suspend / S3), resume
skips calling irq_startup_managed(), and would again have an unbalanced
depth this time, with a positive value (i.e., remaining unexpectedly
masked).

This IRQS_SUSPENDED check was introduced in commit a60dd06af674
("genirq/cpuhotplug: Skip suspended interrupts when restoring affinity")
for essentially the same reason as commit 788019eb559f, to prevent that
irq_startup() would unconditionally re-enable an interrupt too early.

Because irq_startup_managed() now respsects the disable-depth count, the
IRQS_SUSPENDED check is not longer needed, and instead, it causes harm.

Thus, drop the IRQS_SUSPENDED check, and restore balance.

This effectively reverts commit a60dd06af674 ("genirq/cpuhotplug: Skip
suspended interrupts when restoring affinity"), because it is replaced
by commit 788019eb559f ("genirq: Retain disable depth for managed
interrupts across CPU hotplug").

Bug: 422250901
Change-Id: I7551aebceb2a2289b987ce84165743161ffbf69b
Fixes: 788019eb559f ("genirq: Retain disable depth for managed interrupts across CPU hotplug")
Reported-by: Aleksandrs Vinarskis <alex.vinarskis@gmail.com>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Aleksandrs Vinarskis <alex.vinarskis@gmail.com>
Link: https://lore.kernel.org/all/20250612183303.3433234-3-briannorris@chromium.org
Closes: https://lore.kernel.org/lkml/24ec4adc-7c80-49e9-93ee-19908a97ab84@gmail.com/
(cherry picked from commit 72218d74c9c57b8ea36c2a58875dff406fc10462
 git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git irq/urgent)
This commit is contained in:
Brian Norris
2025-06-12 11:32:52 -07:00
committed by Brian Norris
parent fc6844d9d2
commit a74f052176
1 changed files with 0 additions and 7 deletions
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7
kernel/irq/cpuhotplug.c
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@@ -211,13 +211,6 @@ static void irq_restore_affinity_of_irq(struct irq_desc *desc, unsigned int cpu)
!irq_data_get_irq_chip(data) || !cpumask_test_cpu(cpu, affinity))
return;
/*
* Don't restore suspended interrupts here when a system comes back
* from S3. They are reenabled via resume_device_irqs().
*/
if (desc->istate & IRQS_SUSPENDED)
return;
if (irqd_is_managed_and_shutdown(data))
irq_startup_managed(desc);