tracing/events: add support for modules to TRACE_EVENT

Impact: allow modules to add TRACE_EVENTS on load

This patch adds the final hooks to allow modules to use the TRACE_EVENT
macro. A notifier and a data structure are used to link the TRACE_EVENTs
defined in the module to connect them with the ftrace event tracing system.

It also adds the necessary automated clean ups to the trace events when a
module is removed.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

3 files changed, 9 insertions, 0 deletions

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 17810853b4f8..75f3ac01a87c 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -7,6 +7,7 @@
 
 struct trace_array;
 struct tracer;
+struct dentry;
 
 /*
  * The trace entry - the most basic unit of tracing. This is what
@@ -87,6 +88,7 @@ struct ftrace_event_call {
         char                    *name;
         char                    *system;
         struct dentry           *dir;
+        struct trace_event      *event;
         int                     enabled;
         int                     (*regfunc)(void);
         void                    (*unregfunc)(void);
@@ -97,6 +99,7 @@ struct ftrace_event_call {
         struct list_head        fields;
         int                     n_preds;
         struct filter_pred      **preds;
+        void                    *mod;
 
 #ifdef CONFIG_EVENT_PROFILE
         atomic_t        profile_count;
diff --git a/include/linux/module.h b/include/linux/module.h
index 627ac082e2a6..6155fa44168b 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -337,6 +337,10 @@ struct module
         const char **trace_bprintk_fmt_start;
         unsigned int num_trace_bprintk_fmt;
 #endif
+#ifdef CONFIG_EVENT_TRACING
+        struct ftrace_event_call *trace_events;
+        unsigned int num_trace_events;
+#endif
 
 #ifdef CONFIG_MODULE_UNLOAD
         /* What modules depend on me? */
diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index 28051da876dd..15ca2c71af13 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -1,6 +1,8 @@
 #ifndef _LINUX_TRACE_SEQ_H
 #define _LINUX_TRACE_SEQ_H
 
+#include <linux/fs.h>
+
 /*
  * Trace sequences are used to allow a function to call several other functions
  * to create a string of data to use (up to a max of PAGE_SIZE.