genirq/cpuhotplug: Restore affinity even for suspended IRQ

Commit 788019e ("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 a60dd06
("genirq/cpuhotplug: Skip suspended interrupts when restoring affinity")
for essentially the same reason as commit 788019e, 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 a60dd06 ("genirq/cpuhotplug: Skip
suspended interrupts when restoring affinity"), because it is replaced
by commit 788019e ("genirq: Retain disable depth for managed
interrupts across CPU hotplug").

Fixes: 788019e ("genirq: Retain disable depth for managed interrupts across CPU hotplug")
Reported-by: Aleksandrs Vinarskis <[email protected]>
Signed-off-by: Brian Norris <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Aleksandrs Vinarskis <[email protected]>
Link: https://lore.kernel.org/all/[email protected]
Closes: https://lore.kernel.org/lkml/[email protected]/

Author: computersforpeace

kernel/irq/cpuhotplug.c

@@ -210,13 +210,6 @@ 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);