tracing: tracepoints, samples

[safe/jmp/linux-2.6] / samples / tracepoints / tracepoint-probe-sample.c

diff --git a/samples/tracepoints/tracepoint-probe-sample.c b/samples/tracepoints/tracepoint-probe-sample.c
new file mode 100644 (file)
index 0000000..55abfdd
--- /dev/null
+++ b/samples/tracepoints/tracepoint-probe-sample.c
@@ -0,0 +1,55 @@
+/*
+ * tracepoint-probe-sample.c
+ *
+ * sample tracepoint probes.
+ */
+
+#include <linux/module.h>
+#include <linux/file.h>
+#include <linux/dcache.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)
+{
+       path_get(&file->f_path);
+       dget(file->f_path.dentry);
+       printk(KERN_INFO "Event is encountered with filename %s\n",
+               file->f_path.dentry->d_name.name);
+       dput(file->f_path.dentry);
+       path_put(&file->f_path);
+}
+
+static void probe_subsys_eventb(void)
+{
+       printk(KERN_INFO "Event B is encountered\n");
+}
+
+int __init tp_sample_trace_init(void)
+{
+       int ret;
+
+       ret = register_trace_subsys_event(probe_subsys_event);
+       WARN_ON(ret);
+       ret = register_trace_subsys_eventb(probe_subsys_eventb);
+       WARN_ON(ret);
+
+       return 0;
+}
+
+module_init(tp_sample_trace_init);
+
+void __exit tp_sample_trace_exit(void)
+{
+       unregister_trace_subsys_eventb(probe_subsys_eventb);
+       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");