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computersforpeaceKAGA-KOKO
computersforpeace
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genirq: Add kunit tests for depth counts
There have been a few bugs and/or misunderstandings about the reference counting, and startup/shutdown behaviors in the IRQ core and related CPU hotplug code. These 4 test cases try to capture a few interesting cases. * irq_disable_depth_test: basic request/disable/enable sequence * irq_free_disabled_test: request/disable/free/re-request sequence - this catches errors on previous revisions of my work * irq_cpuhotplug_test: exercises managed-affinity IRQ + CPU hotplug. This captures a problematic test case which was fixed recently. This test requires CONFIG_SMP and a hotpluggable CPU#1. * irq_shutdown_depth_test: exercises similar behavior from irq_cpuhotplug_test, but directly using irq_*() APIs instead of going through CPU hotplug. This still requires CONFIG_SMP, because managed-affinity is stubbed out (and not all APIs are even present) without it. Note the use of 'imply SMP': ARCH=um doesn't support SMP, and kunit is often exercised there. Thus, 'imply' will force SMP on where possible (such as ARCH=x86_64), but leave it off where it's not. Behavior on various SMP and ARCH configurations: $ tools/testing/kunit/kunit.py run 'irq_test_cases*' --arch x86_64 --qemu_args '-smp 2' [...] [11:12:24] Testing complete. Ran 4 tests: passed: 4 $ tools/testing/kunit/kunit.py run 'irq_test_cases*' --arch x86_64 [...] [11:13:27] [SKIPPED] irq_cpuhotplug_test [11:13:27] ================= [PASSED] irq_test_cases ================== [11:13:27] ============================================================ [11:13:27] Testing complete. Ran 4 tests: passed: 3, skipped: 1 # default: ARCH=um $ tools/testing/kunit/kunit.py run 'irq_test_cases*' [11:14:26] [SKIPPED] irq_shutdown_depth_test [11:14:26] [SKIPPED] irq_cpuhotplug_test [11:14:26] ================= [PASSED] irq_test_cases ================== [11:14:26] ============================================================ [11:14:26] Testing complete. Ran 4 tests: passed: 2, skipped: 2 Without commit 788019e ("genirq: Retain disable depth for managed interrupts across CPU hotplug"), this fails as follows: [11:18:55] =============== irq_test_cases (4 subtests) ================ [11:18:55] [PASSED] irq_disable_depth_test [11:18:55] [PASSED] irq_free_disabled_test [11:18:55] # irq_shutdown_depth_test: EXPECTATION FAILED at kernel/irq/irq_test.c:147 [11:18:55] Expected desc->depth == 1, but [11:18:55] desc->depth == 0 (0x0) [11:18:55] ------------[ cut here ]------------ [11:18:55] Unbalanced enable for IRQ 26 [11:18:55] WARNING: CPU: 1 PID: 36 at kernel/irq/manage.c:792 __enable_irq+0x36/0x60 ... [11:18:55] [FAILED] irq_shutdown_depth_test [11:18:55] #1 [11:18:55] # irq_cpuhotplug_test: EXPECTATION FAILED at kernel/irq/irq_test.c:202 [11:18:55] Expected irqd_is_activated(data) to be false, but is true [11:18:55] # irq_cpuhotplug_test: EXPECTATION FAILED at kernel/irq/irq_test.c:203 [11:18:55] Expected irqd_is_started(data) to be false, but is true [11:18:55] # irq_cpuhotplug_test: EXPECTATION FAILED at kernel/irq/irq_test.c:204 [11:18:55] Expected desc->depth == 1, but [11:18:55] desc->depth == 0 (0x0) [11:18:55] ------------[ cut here ]------------ [11:18:55] Unbalanced enable for IRQ 27 [11:18:55] WARNING: CPU: 0 PID: 38 at kernel/irq/manage.c:792 __enable_irq+0x36/0x60 ... [11:18:55] [FAILED] irq_cpuhotplug_test [11:18:55] # module: irq_test [11:18:55] # irq_test_cases: pass:2 fail:2 skip:0 total:4 [11:18:55] # Totals: pass:2 fail:2 skip:0 total:4 [11:18:55] ================= [FAILED] irq_test_cases ================== [11:18:55] ============================================================ [11:18:55] Testing complete. Ran 4 tests: passed: 2, failed: 2 Signed-off-by: Brian Norris <briannorris@chromium.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/all/20250522210837.4135244-1-briannorris@chromium.org
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‎kernel/irq/Kconfig‎

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@@ -144,6 +144,17 @@ config GENERIC_IRQ_DEBUGFS
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config GENERIC_IRQ_KEXEC_CLEAR_VM_FORWARD
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bool
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config IRQ_KUNIT_TEST
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bool "KUnit tests for IRQ management APIs" if !KUNIT_ALL_TESTS
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depends on KUNIT=y
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default KUNIT_ALL_TESTS
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imply SMP
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help
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This option enables KUnit tests for the IRQ subsystem API. These are
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only for development and testing, not for regular kernel use cases.
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If unsure, say N.
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endmenu
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config GENERIC_IRQ_MULTI_HANDLER

‎kernel/irq/Makefile‎

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@@ -19,3 +19,4 @@ obj-$(CONFIG_GENERIC_IRQ_IPI_MUX) += ipi-mux.o
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obj-$(CONFIG_SMP) += affinity.o
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obj-$(CONFIG_GENERIC_IRQ_DEBUGFS) += debugfs.o
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obj-$(CONFIG_GENERIC_IRQ_MATRIX_ALLOCATOR) += matrix.o
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obj-$(CONFIG_IRQ_KUNIT_TEST) += irq_test.o

‎kernel/irq/irq_test.c‎

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

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