From: Wen Yang <[email protected]>

Add KUnit tests covering the reactor register/unregister lifecycle
(including duplicate and name-length rejection) and rv_react() dispatch
(a no-op without a callback, exactly one invocation with one; the mdelay
callback keeps the CPU busy so a timer interrupt exercises the LD_WAIT_SPIN
lockdep context).  The Kconfig entry is tristate so the tests can be built
as a module when CONFIG_KUNIT=m; only RV_REACTORS is required.

Signed-off-by: Wen Yang <[email protected]>
---
 kernel/trace/rv/Kconfig             |  12 +++
 kernel/trace/rv/Makefile            |   1 +
 kernel/trace/rv/rv_reactors_kunit.c | 143 ++++++++++++++++++++++++++++
 3 files changed, 156 insertions(+)
 create mode 100644 kernel/trace/rv/rv_reactors_kunit.c

diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig
index efa930f94ea4..9bfd429ffdea 100644
--- a/kernel/trace/rv/Kconfig
+++ b/kernel/trace/rv/Kconfig
@@ -113,6 +113,18 @@ config RV_REACT_PANIC
          Enables the panic reactor. The panic reactor emits a printk()
          message if an exception is found and panic()s the system.
 
+config RV_REACTORS_KUNIT
+       tristate "KUnit tests for RV reactors" if !KUNIT_ALL_TESTS
+       depends on KUNIT
+       depends on RV_REACTORS
+       default KUNIT_ALL_TESTS
+       help
+         Enable KUnit tests for RV reactor registration and dispatch.
+         These tests verify the register/unregister lifecycle, duplicate
+         rejection, and that rv_react() correctly invokes callbacks.
+
+         If unsure, say N.
+
 config RV_MONITORS_KUNIT_TEST
        tristate "KUnit tests for RV monitors" if !KUNIT_ALL_TESTS
        depends on KUNIT && RV && RV_REACTORS
diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile
index cdbf68c84f5a..c895d81dfdad 100644
--- a/kernel/trace/rv/Makefile
+++ b/kernel/trace/rv/Makefile
@@ -25,4 +25,5 @@ obj-$(CONFIG_RV_MON_WAKEUP) += monitors/wakeup/wakeup.o
 obj-$(CONFIG_RV_REACTORS) += rv_reactors.o
 obj-$(CONFIG_RV_REACT_PRINTK) += reactor_printk.o
 obj-$(CONFIG_RV_REACT_PANIC) += reactor_panic.o
+obj-$(CONFIG_RV_REACTORS_KUNIT) += rv_reactors_kunit.o
 obj-$(CONFIG_RV_MONITORS_KUNIT_TEST) += rv_monitors_test.o
diff --git a/kernel/trace/rv/rv_reactors_kunit.c 
b/kernel/trace/rv/rv_reactors_kunit.c
new file mode 100644
index 000000000000..32c25dcf0cb6
--- /dev/null
+++ b/kernel/trace/rv/rv_reactors_kunit.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit tests for RV reactor registration and dispatch.
+ */
+
+#include <kunit/test.h>
+#include <linux/rv.h>
+#include <linux/delay.h>
+#include <linux/atomic.h>
+#include "rv.h"
+
+static struct rv_reactor test_reactor = {
+       .name           = "kunit_test_reactor",
+       .description    = "KUnit test reactor",
+};
+
+/*
+ * rv_unregister_reactor() on a reactor that was never registered would
+ * list_del() an uninitialized list_head, so track registration and only
+ * unregister in the teardown if it is still on the list.
+ */
+static bool test_reactor_registered;
+
+static int unregister_test_reactor(void)
+{
+       int ret = 0;
+
+       if (test_reactor_registered) {
+               ret = rv_unregister_reactor(&test_reactor);
+               test_reactor_registered = false;
+       }
+
+       return ret;
+}
+
+/*
+ * The teardown action guarantees the reactor is unregistered even if a
+ * test fails mid-way, so a leftover entry cannot corrupt later tests.
+ */
+static void reactor_teardown(void *arg)
+{
+       unregister_test_reactor();
+}
+
+static void register_test_reactor(struct kunit *test)
+{
+       KUNIT_ASSERT_EQ(test, rv_register_reactor(&test_reactor), 0);
+       test_reactor_registered = true;
+       KUNIT_ASSERT_EQ(test,
+                       kunit_add_action_or_reset(test, reactor_teardown, 
NULL), 0);
+}
+
+static void test_register_unregister(struct kunit *test)
+{
+       register_test_reactor(test);
+
+       KUNIT_EXPECT_EQ(test, unregister_test_reactor(), 0);
+}
+
+static void test_double_register(struct kunit *test)
+{
+       register_test_reactor(test);
+
+       KUNIT_EXPECT_EQ(test, rv_register_reactor(&test_reactor), -EINVAL);
+
+       KUNIT_EXPECT_EQ(test, unregister_test_reactor(), 0);
+}
+
+static void test_name_too_long(struct kunit *test)
+{
+       /* Name length of MAX_RV_REACTOR_NAME_SIZE (32) must be rejected. */
+       static struct rv_reactor long_reactor = {
+               .name = "kunit_reactor_name_too_long_xxx_",
+       };
+
+       KUNIT_ASSERT_EQ(test, (int)strlen(long_reactor.name),
+                       MAX_RV_REACTOR_NAME_SIZE);
+       KUNIT_EXPECT_EQ(test, rv_register_reactor(&long_reactor), -EINVAL);
+}
+
+static struct kunit_case rv_reactor_registration_cases[] = {
+       KUNIT_CASE(test_register_unregister),
+       KUNIT_CASE(test_double_register),
+       KUNIT_CASE(test_name_too_long),
+       {}
+};
+
+static struct kunit_suite rv_reactor_registration_suite = {
+       .name           = "rv_reactor_registration",
+       .test_cases     = rv_reactor_registration_cases,
+};
+
+static atomic_t react_call_count;
+
+__printf(1, 0) static void mock_react(const char *msg, va_list args)
+{
+       atomic_inc(&react_call_count);
+       /*
+        * Hold the CPU for 5 ms so a timer interrupt is likely to fire
+        * inside rv_react()'s lockdep context, exercising the LD_WAIT_SPIN
+        * constraint.  mdelay() is a calibrated busy-wait with no scheduler
+        * interaction.
+        */
+       mdelay(5);
+}
+
+static void test_react_no_callback(struct kunit *test)
+{
+       struct rv_monitor monitor = {
+               .name = "kunit_null_react",
+       };
+
+       /* rv_react() must silently return when monitor->react is NULL. */
+       rv_react(&monitor, "no callback");
+}
+
+static void test_react_callback_invoked(struct kunit *test)
+{
+       struct rv_monitor monitor = {
+               .name   = "kunit_dispatch_monitor",
+               .react  = mock_react,
+       };
+
+       atomic_set(&react_call_count, 0);
+       rv_react(&monitor, "callback invocation test");
+       KUNIT_EXPECT_EQ(test, atomic_read(&react_call_count), 1);
+}
+
+static struct kunit_case rv_react_dispatch_cases[] = {
+       KUNIT_CASE(test_react_no_callback),
+       KUNIT_CASE(test_react_callback_invoked),
+       {}
+};
+
+static struct kunit_suite rv_react_dispatch_suite = {
+       .name           = "rv_react_dispatch",
+       .test_cases     = rv_react_dispatch_cases,
+};
+
+kunit_test_suites(&rv_reactor_registration_suite, &rv_react_dispatch_suite);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("KUnit tests for RV reactor registration and dispatch");
-- 
2.25.1


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