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Message-ID: <20250513224402.864767-2-briannorris@chromium.org>
Date: Tue, 13 May 2025 15:42:37 -0700
From: Brian Norris <briannorris@...omium.org>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Douglas Anderson <dianders@...omium.org>,
Tsai Sung-Fu <danielsftsai@...gle.com>,
linux-kernel@...r.kernel.org,
Brian Norris <briannorris@...omium.org>
Subject: [PATCH 1/2] genirq: Add kunit tests for depth counts
These tests demonstrate bugs in the irq shutdown/startup code. See the
appended test report.
In summary, the latter two cases cover:
## shutdown depth:
disable_irq()
irq_shutdown_and_deactivate()
irq_activate_and_startup() <-- BUG: depth is 0 after this
enable_irq()
## cpu hotplug:
affine IRQ to CPU 1
disable_irq()
remove CPU 1
add CPU 1 <-- BUG: depth is 0 after this
enable_irq()
NB: since one of the tests intersects with CPU hotplug, these tests
requires SMP support. They can be easily run with:
$ tools/testing/kunit/kunit.py run 'irq_test_cases*' --arch x86_64 --qemu_args '-smp 2'
[13:24:21] =============== irq_test_cases (3 subtests) ================
[13:24:21] [PASSED] irq_disable_depth_test
[13:24:21] # irq_shutdown_depth_test: EXPECTATION FAILED at kernel/irq/irq_test.c:93
[13:24:21] Expected desc->depth == 1, but
[13:24:21] desc->depth == 0 (0x0)
[13:24:21] ------------[ cut here ]------------
[13:24:21] Unbalanced enable for IRQ 25
[13:24:21] WARNING: CPU: 1 PID: 34 at kernel/irq/manage.c:792 __enable_irq+0x36/0x60
...
[13:24:21] Call Trace:
[13:24:21] <TASK>
[13:24:21] enable_irq+0x4a/0x90
[13:24:21] irq_shutdown_depth_test+0x17b/0x3b0
[13:24:21] kunit_try_run_case+0x90/0x120
...
[13:24:21] </TASK>
[13:24:21] ---[ end trace 0000000000000000 ]---
[13:24:21] # irq_shutdown_depth_test.speed: slow
[13:24:21] [FAILED] irq_shutdown_depth_test
[13:24:21] #1
[13:24:21] # irq_cpuhotplug_test: EXPECTATION FAILED at kernel/irq/irq_test.c:140
[13:24:21] Expected desc->depth == 1, but
[13:24:21] desc->depth == 0 (0x0)
[13:24:21] ------------[ cut here ]------------
[13:24:21] Unbalanced enable for IRQ 26
[13:24:21] WARNING: CPU: 0 PID: 36 at kernel/irq/manage.c:792 __enable_irq+0x36/0x60
...
[13:24:21] Call Trace:
[13:24:21] <TASK>
[13:24:21] enable_irq+0x4a/0x90
[13:24:21] irq_cpuhotplug_test+0x28f/0x660
[13:24:21] kunit_try_run_case+0x90/0x120
...
[13:24:21] </TASK>
[13:24:21] ---[ end trace 0000000000000000 ]---
[13:24:21] # irq_cpuhotplug_test.speed: slow
[13:24:21] [FAILED] irq_cpuhotplug_test
[13:24:21] # module: irq_test
[13:24:21] # irq_test_cases: pass:1 fail:2 skip:0 total:3
[13:24:21] # Totals: pass:1 fail:2 skip:0 total:3
[13:24:21] ================= [FAILED] irq_test_cases ==================
[13:24:21] ============================================================
[13:24:21] Testing complete. Ran 3 tests: passed: 1, failed: 2
Also note that currently, these tests don't fully clean up after
themselves, as I didn't yet figure out all the right ways to set up a
fake virq and domain for the purpose of unit testing. They contain TODOs
to that effect.
Signed-off-by: Brian Norris <briannorris@...omium.org>
---
kernel/irq/Kconfig | 10 +++
kernel/irq/Makefile | 1 +
kernel/irq/irq_test.c | 162 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 173 insertions(+)
create mode 100644 kernel/irq/irq_test.c
diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
index 3f02a0e45254..9295dabea4a0 100644
--- a/kernel/irq/Kconfig
+++ b/kernel/irq/Kconfig
@@ -144,6 +144,16 @@ config GENERIC_IRQ_DEBUGFS
config GENERIC_IRQ_KEXEC_CLEAR_VM_FORWARD
bool
+config IRQ_KUNIT_TEST
+ tristate "KUnit test for IRQ management APIs" if !KUNIT_ALL_TESTS
+ depends on KUNIT
+ default KUNIT_ALL_TESTS
+ select SMP
+ help
+ Enable this option to test IRQ management APIs.
+
+ If unsure, say N.
+
endmenu
config GENERIC_IRQ_MULTI_HANDLER
diff --git a/kernel/irq/Makefile b/kernel/irq/Makefile
index c0f44c06d69d..6ab3a4055667 100644
--- a/kernel/irq/Makefile
+++ b/kernel/irq/Makefile
@@ -19,3 +19,4 @@ obj-$(CONFIG_GENERIC_IRQ_IPI_MUX) += ipi-mux.o
obj-$(CONFIG_SMP) += affinity.o
obj-$(CONFIG_GENERIC_IRQ_DEBUGFS) += debugfs.o
obj-$(CONFIG_GENERIC_IRQ_MATRIX_ALLOCATOR) += matrix.o
+obj-$(CONFIG_IRQ_KUNIT_TEST) += irq_test.o
diff --git a/kernel/irq/irq_test.c b/kernel/irq/irq_test.c
new file mode 100644
index 000000000000..24f4d8e6c433
--- /dev/null
+++ b/kernel/irq/irq_test.c
@@ -0,0 +1,162 @@
+// 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, void *)
+{
+ 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 /*virq*/, 1 /*nr_irqs*/, 0/*hwirq*/, first_online_node/*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);
+
+ /* TODO: free virq? */
+}
+
+static void irq_shutdown_depth_test(struct kunit *test)
+{
+ struct irq_desc *desc;
+ int virq, ret;
+
+ virq = irq_domain_alloc_descs(-1 /*virq*/, 1 /*nr_irqs*/, 0/*hwirq*/, first_online_node/*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);
+
+ irq_shutdown_and_deactivate(desc);
+ KUNIT_EXPECT_EQ(test, irq_activate_and_startup(desc, IRQ_NORESEND), 0);
+
+ KUNIT_EXPECT_EQ(test, desc->depth, 1);
+
+ enable_irq(virq);
+ KUNIT_EXPECT_EQ(test, desc->depth, 0);
+
+ /* TODO: free virq? */
+}
+
+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,
+ };
+
+ cpumask_copy(&affinity.mask, cpumask_of(1));
+ KUNIT_ASSERT_PTR_NE(test, get_cpu_device(1), NULL);
+ KUNIT_ASSERT_TRUE(test, cpu_is_hotpluggable(1));
+
+ virq = irq_domain_alloc_descs(-1 /*virq*/, 1 /*nr_irqs*/, 0/*hwirq*/, first_online_node/*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_EQ(test, add_cpu(1), 0);
+
+ KUNIT_EXPECT_EQ(test, desc->depth, 1);
+
+ enable_irq(virq);
+ KUNIT_EXPECT_EQ(test, desc->depth, 0);
+
+ /* TODO: free virq? */
+}
+
+static struct kunit_case irq_test_cases[] = {
+ KUNIT_CASE_SLOW(irq_disable_depth_test),
+ KUNIT_CASE_SLOW(irq_shutdown_depth_test),
+ KUNIT_CASE_SLOW(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");
--
2.49.0.1045.g170613ef41-goog
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