1 files changed, 22 insertions, 3 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index dbff0207b213..eed732c151fc 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -337,18 +337,34 @@ struct tracer_flags {
 #define TRACER_OPT(s, b)        .name = #s, .bit = b
 
 
-/*
- * A specific tracer, represented by methods that operate on a trace array:
+/**
+ * struct tracer - a specific tracer and its callbacks to interact with debugfs
+ * @name: the name chosen to select it on the available_tracers file
+ * @init: called when one switches to this tracer (echo name > current_tracer)
+ * @reset: called when one switches to another tracer
+ * @start: called when tracing is unpaused (echo 1 > tracing_enabled)
+ * @stop: called when tracing is paused (echo 0 > tracing_enabled)
+ * @open: called when the trace file is opened
+ * @pipe_open: called when the trace_pipe file is opened
+ * @wait_pipe: override how the user waits for traces on trace_pipe
+ * @close: called when the trace file is released
+ * @read: override the default read callback on trace_pipe
+ * @splice_read: override the default splice_read callback on trace_pipe
+ * @selftest: selftest to run on boot (see trace_selftest.c)
+ * @print_headers: override the first lines that describe your columns
+ * @print_line: callback that prints a trace
+ * @set_flag: signals one of your private flags changed (trace_options file)
+ * @flags: your private flags
  */
 struct tracer {
         const char              *name;
-        /* Your tracer should raise a warning if init fails */
         int                     (*init)(struct trace_array *tr);
         void                    (*reset)(struct trace_array *tr);
         void                    (*start)(struct trace_array *tr);
         void                    (*stop)(struct trace_array *tr);
         void                    (*open)(struct trace_iterator *iter);
         void                    (*pipe_open)(struct trace_iterator *iter);
+        void                    (*wait_pipe)(struct trace_iterator *iter);
         void                    (*close)(struct trace_iterator *iter);
         ssize_t                 (*read)(struct trace_iterator *iter,
                                         struct file *filp, char __user *ubuf,
@@ -432,6 +448,9 @@ void tracing_generic_entry_update(struct trace_entry *entry,
                                   unsigned long flags,
                                   int pc);
 
+void default_wait_pipe(struct trace_iterator *iter);
+void poll_wait_pipe(struct trace_iterator *iter);
+
 void ftrace(struct trace_array *tr,
                             struct trace_array_cpu *data,
                             unsigned long ip,