lib/test_trace_mq_msg: add tracepoint hook example for load/store_msg

this is a messaqge queue tracepooint tester, provide am example hook to
ensure its usability.

Signed-off-by: Jiaolong He <hejiaolong@kernelsoft.com>

lib/Kconfig.debug

@@ -2942,6 +2942,15 @@ config TEST_RT_WQ
 
 	  If unsure, say N.
 
+config TEST_TRACE_MQ_MSG
+	tristate "message queue tracepoint tester"
+	depends on TRACEPOINTS
+	help
+	  This driver provides an example hook of trace_load_msg and
+	  trace_store_msg to ensure its usability.
+
+	  If unsure, say N.
+
 endif # RUNTIME_TESTING_MENU
 
 config ARCH_USE_MEMTEST

lib/Makefile

@@ -108,6 +108,7 @@ obj-$(CONFIG_TEST_REF_TRACKER) += test_ref_tracker.o
 CFLAGS_test_fprobe.o += $(CC_FLAGS_FTRACE)
 obj-$(CONFIG_FPROBE_SANITY_TEST) += test_fprobe.o
 obj-$(CONFIG_TEST_RT_WQ) += test_rt_wq.o
+obj-$(CONFIG_TEST_TRACE_MQ_MSG) += test_trace_mq_msg.o
 
 #
 # CFLAGS for compiling floating point code inside the kernel. x86/Makefile turns

lib/test_trace_mq_msg.c

@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * messaqge queue tracepooint tester
+ * Copyright (C) 2023           Jiaolong He <hejiaolong@kernelsoft.com>
+ *
+ * This driver provides an example hook of trace_load_msg and
+ * trace_store_msg to ensure its usability.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/tracepoint.h>
+#include <linux/msg.h>
+#include <../ipc/util.h>
+
+
+
+static atomic_t load_cnt = ATOMIC_INIT(0);
+static atomic_t store_cnt = ATOMIC_INIT(0);
+
+void load_hook(void *ignore, struct msg_msg *msg, size_t len)
+{
+	atomic_inc(&load_cnt);
+}
+
+
+void store_hook(void *ignore, struct msg_msg *msg, size_t len)
+{
+	atomic_inc(&store_cnt);
+}
+
+
+static void register_tp(struct tracepoint *tp, void *priv)
+{
+	if (!strcmp(tp->name, "load_msg"))
+		WARN_ON(tracepoint_probe_register(tp, load_hook, NULL));
+	if (!strcmp(tp->name, "store_msg"))
+		WARN_ON(tracepoint_probe_register(tp, store_hook, NULL));
+}
+
+
+static void unregister_tp(struct tracepoint *tp, void *priv)
+{
+	if (!strcmp(tp->name, "load_msg"))
+		WARN_ON(tracepoint_probe_unregister(tp, load_hook, NULL));
+	if (!strcmp(tp->name, "store_msg"))
+		WARN_ON(tracepoint_probe_unregister(tp, store_hook, NULL));
+}
+
+
+static int __init test_mq_trace_init(void)
+{
+	for_each_kernel_tracepoint(register_tp, NULL);
+
+	return 0;
+}
+
+static void __exit test_mq_trace_exit(void)
+{
+	for_each_kernel_tracepoint(unregister_tp, NULL);
+	tracepoint_synchronize_unregister();
+	WARN_ON(atomic_read(&load_cnt) != atomic_read(&store_cnt));
+}
+
+module_init(test_mq_trace_init);
+module_exit(test_mq_trace_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("hejiaolong@kernelsoft.com");