From: Wen Yang <[email protected]> Add KUnit tests for the panic reactor covering: - Reactor registration and unregistration lifecycle - Panic notifier chain reachability
The real rv_panic_reaction() calls vpanic(), which is __noreturn and halts the system. KUnit cannot test across that boundary. Instead, the test drives atomic_notifier_call_chain(&panic_notifier_list, ...) directly with a high-priority mock notifier that returns NOTIFY_STOP, verifying that the panic notification propagates without triggering real handlers (kdump, watchdog, reboot). The mock notifier busy-waits to simulate real handler execution time (e.g., crash_save_vmcoreinfo, emergency_restart preamble) under the panic context constraints. Signed-off-by: Wen Yang <[email protected]> --- kernel/trace/rv/Kconfig | 10 +++ kernel/trace/rv/Makefile | 1 + kernel/trace/rv/reactor_panic_kunit.c | 106 ++++++++++++++++++++++++++ 3 files changed, 117 insertions(+) create mode 100644 kernel/trace/rv/reactor_panic_kunit.c diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig index ff47895c897f..6c6c43c5f86c 100644 --- a/kernel/trace/rv/Kconfig +++ b/kernel/trace/rv/Kconfig @@ -121,3 +121,13 @@ config RV_REACT_PANIC help Enables the panic reactor. The panic reactor emits a printk() message if an exception is found and panic()s the system. + +config RV_REACT_PANIC_KUNIT + bool "KUnit tests for reactor_panic" if !KUNIT_ALL_TESTS + depends on RV_REACT_PANIC && KUNIT + default KUNIT_ALL_TESTS + help + This builds KUnit tests for the panic reactor. These are only + for development and testing, not for regular kernel use cases. + + If unsure, say N. diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile index ef0a2dcb927c..2ebfe5e5068c 100644 --- a/kernel/trace/rv/Makefile +++ b/kernel/trace/rv/Makefile @@ -25,3 +25,4 @@ obj-$(CONFIG_RV_REACTORS) += rv_reactors.o obj-$(CONFIG_RV_REACT_PRINTK) += reactor_printk.o obj-$(CONFIG_RV_REACT_PRINTK_KUNIT) += reactor_printk_kunit.o obj-$(CONFIG_RV_REACT_PANIC) += reactor_panic.o +obj-$(CONFIG_RV_REACT_PANIC_KUNIT) += reactor_panic_kunit.o diff --git a/kernel/trace/rv/reactor_panic_kunit.c b/kernel/trace/rv/reactor_panic_kunit.c new file mode 100644 index 000000000000..f9a09ae7aaad --- /dev/null +++ b/kernel/trace/rv/reactor_panic_kunit.c @@ -0,0 +1,106 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * KUnit tests for reactor_panic + * + */ + +#include <kunit/test.h> +#include <linux/rv.h> +#include <linux/panic_notifier.h> +#include <linux/notifier.h> +#include <linux/limits.h> +#include <linux/sched/clock.h> +#include <linux/processor.h> + +/* Simulated execution time for mock panic notifier (nanoseconds). */ +#define RV_PANIC_NOTIFIER_EXEC_NS 2000000ULL + +/* Test state */ +static struct { + bool notifier_called; +} panic_test_state; + +/* + * Mock panic notifier callback. + * + * Runs at INT_MAX priority and returns NOTIFY_STOP to prevent real panic + * handlers (kdump, watchdog) from executing during the test. Busy-waits + * RV_PANIC_NOTIFIER_EXEC_NS to simulate a real handler's execution time. + */ +static int mock_panic_notifier_fn(struct notifier_block *nb, + unsigned long action, void *data) +{ + char *msg = data; + u64 start = sched_clock(); + + panic_test_state.notifier_called = true; + pr_emerg("KUnit: reactor_panic test intercepted panic notifier: %s\n", + msg ? msg : "(no message)"); + + while (sched_clock() - start < RV_PANIC_NOTIFIER_EXEC_NS) + cpu_relax(); + + return NOTIFY_STOP; +} + +static struct notifier_block mock_panic_nb = { + .notifier_call = mock_panic_notifier_fn, + .priority = INT_MAX, +}; + +static struct rv_reactor mock_panic_reactor = { + .name = "test_panic", + .description = "test panic reactor", +}; + +static int reactor_panic_kunit_init(struct kunit *test) +{ + panic_test_state.notifier_called = false; + return 0; +} + +/* Test 1: register and unregister reactor */ +static void test_panic_register_unregister(struct kunit *test) +{ + int ret; + + ret = rv_register_reactor(&mock_panic_reactor); + KUNIT_EXPECT_EQ(test, ret, 0); + KUNIT_EXPECT_STREQ(test, mock_panic_reactor.name, "test_panic"); + + rv_unregister_reactor(&mock_panic_reactor); +} + +/* + * Test 2: panic notifier chain is reachable. + * + * vpanic() calls atomic_notifier_call_chain(&panic_notifier_list, ...). + * Drive the chain directly to verify panic notifiers receive the notification — + * the observable side-effect of reactor_panic without halting the system. + */ +static void test_panic_notifier_called(struct kunit *test) +{ + atomic_notifier_chain_register(&panic_notifier_list, &mock_panic_nb); + atomic_notifier_call_chain(&panic_notifier_list, 0, + "panic violation message"); + atomic_notifier_chain_unregister(&panic_notifier_list, &mock_panic_nb); + + KUNIT_EXPECT_TRUE(test, panic_test_state.notifier_called); +} + +static struct kunit_case reactor_panic_kunit_cases[] = { + KUNIT_CASE(test_panic_register_unregister), + KUNIT_CASE(test_panic_notifier_called), + {} +}; + +static struct kunit_suite reactor_panic_kunit_suite = { + .name = "rv_reactor_panic", + .init = reactor_panic_kunit_init, + .test_cases = reactor_panic_kunit_cases, +}; + +kunit_test_suite(reactor_panic_kunit_suite); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("KUnit tests for reactor_panic"); -- 2.25.1
