tracing: tracepoints, samples

Tracepoint example code under samples/.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: 'Peter Zijlstra' <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 42 insertions, 0 deletions

diff --git a/samples/tracepoints/tracepoint-probe-sample2.c b/samples/tracepoints/tracepoint-probe-sample2.c
new file mode 100644
index 000000000000..5e9fcf4afffe
--- /dev/null
+++ b/samples/tracepoints/tracepoint-probe-sample2.c
@@ -0,0 +1,42 @@
+/*
+ * tracepoint-probe-sample2.c
+ *
+ * 2nd sample tracepoint probes.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include "tp-samples-trace.h"
+
+/*
+ * Here the caller only guarantees locking for struct file and struct inode.
+ * Locking must therefore be done in the probe to use the dentry.
+ */
+static void probe_subsys_event(struct inode *inode, struct file *file)
+{
+	printk(KERN_INFO "Event is encountered with inode number %lu\n",
+		inode->i_ino);
+}
+
+int __init tp_sample_trace_init(void)
+{
+	int ret;
+
+	ret = register_trace_subsys_event(probe_subsys_event);
+	WARN_ON(ret);
+
+	return 0;
+}
+
+module_init(tp_sample_trace_init);
+
+void __exit tp_sample_trace_exit(void)
+{
+	unregister_trace_subsys_event(probe_subsys_event);
+}
+
+module_exit(tp_sample_trace_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mathieu Desnoyers");
+MODULE_DESCRIPTION("Tracepoint Probes Samples");