Merge tag 'irq-core-2025-07-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull irq updates from Thomas Gleixner:

 - Prevent a interrupt migration related live lock in handle_edge_irq()

   If the interrupt affinity is moved to a new target CPU and the
   interrupt is currently handled on the previous target CPU for edge
   type interrupts the handler might get stuck on the previous target
   for a long time, which causes both involved CPUs to waste cycles and
   eventually run into a soft-lockup situation.

   Solve this by checking whether the interrupt is redirected to a new
   target CPU and if the interrupt is handled on that new target CPU,
   busy wait for completion instead of masking it and sending the
   pending but which would cause the old CPU to re-run the handler and
   in the worst case repeating this excercise for a long time.

   This only works on architectures which use single CPU interrupt
   targets, but that's so far the only ones where this behaviour has
   been observed.

 - Add a kunit test for interrupt disable depth counts

   The nested interrupt disable depth has been an issue in the past
   especially vs. free_irq(), interrupt shutdown and CPU hotplug and
   their interactions. The test exercises the combinations of these
   scenarios and checks for correctness.

* tag 'irq-core-2025-07-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq: Prevent migration live lock in handle_edge_irq()
  genirq: Split up irq_pm_check_wakeup()
  genirq: Move irq_wait_for_poll() to call site
  genirq: Remove pointless local variable
  genirq: Add kunit tests for depth counts

1 files changed, 229 insertions, 0 deletions

diff --git a/kernel/irq/irq_test.c b/kernel/irq/irq_test.c
new file mode 100644
index 000000000000..5161b56a12f9
--- /dev/null
+++ b/kernel/irq/irq_test.c
@@ -0,0 +1,229 @@
+// SPDX-License-Identifier: LGPL-2.1+
+
+#include <linux/cpu.h>
+#include <linux/cpumask.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqdesc.h>
+#include <linux/irqdomain.h>
+#include <linux/nodemask.h>
+#include <kunit/test.h>
+
+#include "internals.h"
+
+static irqreturn_t noop_handler(int irq, void *data)
+{
+	return IRQ_HANDLED;
+}
+
+static void noop(struct irq_data *data) { }
+static unsigned int noop_ret(struct irq_data *data) { return 0; }
+
+static int noop_affinity(struct irq_data *data, const struct cpumask *dest,
+			 bool force)
+{
+	irq_data_update_effective_affinity(data, dest);
+
+	return 0;
+}
+
+static struct irq_chip fake_irq_chip = {
+	.name           = "fake",
+	.irq_startup    = noop_ret,
+	.irq_shutdown   = noop,
+	.irq_enable     = noop,
+	.irq_disable    = noop,
+	.irq_ack        = noop,
+	.irq_mask       = noop,
+	.irq_unmask     = noop,
+	.irq_set_affinity = noop_affinity,
+	.flags          = IRQCHIP_SKIP_SET_WAKE,
+};
+
+static void irq_disable_depth_test(struct kunit *test)
+{
+	struct irq_desc *desc;
+	int virq, ret;
+
+	virq = irq_domain_alloc_descs(-1, 1, 0, NUMA_NO_NODE, NULL);
+	KUNIT_ASSERT_GE(test, virq, 0);
+
+	irq_set_chip_and_handler(virq, &dummy_irq_chip, handle_simple_irq);
+
+	desc = irq_to_desc(virq);
+	KUNIT_ASSERT_PTR_NE(test, desc, NULL);
+
+	ret = request_irq(virq, noop_handler, 0, "test_irq", NULL);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+
+	KUNIT_EXPECT_EQ(test, desc->depth, 0);
+
+	disable_irq(virq);
+	KUNIT_EXPECT_EQ(test, desc->depth, 1);
+
+	enable_irq(virq);
+	KUNIT_EXPECT_EQ(test, desc->depth, 0);
+
+	free_irq(virq, NULL);
+}
+
+static void irq_free_disabled_test(struct kunit *test)
+{
+	struct irq_desc *desc;
+	int virq, ret;
+
+	virq = irq_domain_alloc_descs(-1, 1, 0, NUMA_NO_NODE, NULL);
+	KUNIT_ASSERT_GE(test, virq, 0);
+
+	irq_set_chip_and_handler(virq, &dummy_irq_chip, handle_simple_irq);
+
+	desc = irq_to_desc(virq);
+	KUNIT_ASSERT_PTR_NE(test, desc, NULL);
+
+	ret = request_irq(virq, noop_handler, 0, "test_irq", NULL);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+
+	KUNIT_EXPECT_EQ(test, desc->depth, 0);
+
+	disable_irq(virq);
+	KUNIT_EXPECT_EQ(test, desc->depth, 1);
+
+	free_irq(virq, NULL);
+	KUNIT_EXPECT_GE(test, desc->depth, 1);
+
+	ret = request_irq(virq, noop_handler, 0, "test_irq", NULL);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, desc->depth, 0);
+
+	free_irq(virq, NULL);
+}
+
+static void irq_shutdown_depth_test(struct kunit *test)
+{
+	struct irq_desc *desc;
+	struct irq_data *data;
+	int virq, ret;
+	struct irq_affinity_desc affinity = {
+		.is_managed = 1,
+		.mask = CPU_MASK_ALL,
+	};
+
+	if (!IS_ENABLED(CONFIG_SMP))
+		kunit_skip(test, "requires CONFIG_SMP for managed shutdown");
+
+	virq = irq_domain_alloc_descs(-1, 1, 0, NUMA_NO_NODE, &affinity);
+	KUNIT_ASSERT_GE(test, virq, 0);
+
+	irq_set_chip_and_handler(virq, &dummy_irq_chip, handle_simple_irq);
+
+	desc = irq_to_desc(virq);
+	KUNIT_ASSERT_PTR_NE(test, desc, NULL);
+
+	data = irq_desc_get_irq_data(desc);
+	KUNIT_ASSERT_PTR_NE(test, data, NULL);
+
+	ret = request_irq(virq, noop_handler, 0, "test_irq", NULL);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+
+	KUNIT_EXPECT_TRUE(test, irqd_is_activated(data));
+	KUNIT_EXPECT_TRUE(test, irqd_is_started(data));
+	KUNIT_EXPECT_TRUE(test, irqd_affinity_is_managed(data));
+
+	KUNIT_EXPECT_EQ(test, desc->depth, 0);
+
+	disable_irq(virq);
+	KUNIT_EXPECT_EQ(test, desc->depth, 1);
+
+	irq_shutdown_and_deactivate(desc);
+
+	KUNIT_EXPECT_FALSE(test, irqd_is_activated(data));
+	KUNIT_EXPECT_FALSE(test, irqd_is_started(data));
+
+	KUNIT_EXPECT_EQ(test, irq_activate(desc), 0);
+#ifdef CONFIG_SMP
+	irq_startup_managed(desc);
+#endif
+
+	KUNIT_EXPECT_EQ(test, desc->depth, 1);
+
+	enable_irq(virq);
+	KUNIT_EXPECT_EQ(test, desc->depth, 0);
+
+	free_irq(virq, NULL);
+}
+
+static void irq_cpuhotplug_test(struct kunit *test)
+{
+	struct irq_desc *desc;
+	struct irq_data *data;
+	int virq, ret;
+	struct irq_affinity_desc affinity = {
+		.is_managed = 1,
+	};
+
+	if (!IS_ENABLED(CONFIG_SMP))
+		kunit_skip(test, "requires CONFIG_SMP for CPU hotplug");
+	if (!get_cpu_device(1))
+		kunit_skip(test, "requires more than 1 CPU for CPU hotplug");
+	if (!cpu_is_hotpluggable(1))
+		kunit_skip(test, "CPU 1 must be hotpluggable");
+
+	cpumask_copy(&affinity.mask, cpumask_of(1));
+
+	virq = irq_domain_alloc_descs(-1, 1, 0, NUMA_NO_NODE, &affinity);
+	KUNIT_ASSERT_GE(test, virq, 0);
+
+	irq_set_chip_and_handler(virq, &fake_irq_chip, handle_simple_irq);
+
+	desc = irq_to_desc(virq);
+	KUNIT_ASSERT_PTR_NE(test, desc, NULL);
+
+	data = irq_desc_get_irq_data(desc);
+	KUNIT_ASSERT_PTR_NE(test, data, NULL);
+
+	ret = request_irq(virq, noop_handler, 0, "test_irq", NULL);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+
+	KUNIT_EXPECT_TRUE(test, irqd_is_activated(data));
+	KUNIT_EXPECT_TRUE(test, irqd_is_started(data));
+	KUNIT_EXPECT_TRUE(test, irqd_affinity_is_managed(data));
+
+	KUNIT_EXPECT_EQ(test, desc->depth, 0);
+
+	disable_irq(virq);
+	KUNIT_EXPECT_EQ(test, desc->depth, 1);
+
+	KUNIT_EXPECT_EQ(test, remove_cpu(1), 0);
+	KUNIT_EXPECT_FALSE(test, irqd_is_activated(data));
+	KUNIT_EXPECT_FALSE(test, irqd_is_started(data));
+	KUNIT_EXPECT_GE(test, desc->depth, 1);
+	KUNIT_EXPECT_EQ(test, add_cpu(1), 0);
+
+	KUNIT_EXPECT_FALSE(test, irqd_is_activated(data));
+	KUNIT_EXPECT_FALSE(test, irqd_is_started(data));
+	KUNIT_EXPECT_EQ(test, desc->depth, 1);
+
+	enable_irq(virq);
+	KUNIT_EXPECT_TRUE(test, irqd_is_activated(data));
+	KUNIT_EXPECT_TRUE(test, irqd_is_started(data));
+	KUNIT_EXPECT_EQ(test, desc->depth, 0);
+
+	free_irq(virq, NULL);
+}
+
+static struct kunit_case irq_test_cases[] = {
+	KUNIT_CASE(irq_disable_depth_test),
+	KUNIT_CASE(irq_free_disabled_test),
+	KUNIT_CASE(irq_shutdown_depth_test),
+	KUNIT_CASE(irq_cpuhotplug_test),
+	{}
+};
+
+static struct kunit_suite irq_test_suite = {
+	.name = "irq_test_cases",
+	.test_cases = irq_test_cases,
+};
+
+kunit_test_suite(irq_test_suite);
+MODULE_DESCRIPTION("IRQ unit test suite");
+MODULE_LICENSE("GPL");