commit 81698831bc462ff16f76bc11249a1e492424da4c
author Steven Rostedt <srostedt@redhat.com> Thu Oct 11 10:15:05 2012 -0400
committer Steven Rostedt <rostedt@goodmis.org> Wed Oct 31 16:45:29 2012 -0400
tree 7d980745e74be221d0fab8607ac764ee7408edb4
parent b382ede6b5eb8188926b72a9ef42fd2354342a97

tracing: Enable comm recording if trace_printk() is used

If comm recording is not enabled when trace_printk() is used then
you just get this type of output:

[ adding trace_printk("hello! %d", irq); in do_IRQ ]

           <...>-2843  [001] d.h.    80.812300: do_IRQ: hello! 14
           <...>-2734  [002] d.h2    80.824664: do_IRQ: hello! 14
           <...>-2713  [003] d.h.    80.829971: do_IRQ: hello! 14
           <...>-2814  [000] d.h.    80.833026: do_IRQ: hello! 14

By enabling the comm recorder when trace_printk is enabled:

       hackbench-6715  [001] d.h.   193.233776: do_IRQ: hello! 21
            sshd-2659  [001] d.h.   193.665862: do_IRQ: hello! 21
          <idle>-0     [001] d.h1   193.665996: do_IRQ: hello! 21

Suggested-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace.h

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index c56a233..7824a55 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -841,6 +841,7 @@
 extern const char *__stop___trace_bprintk_fmt[];
 
 void trace_printk_init_buffers(void);
+void trace_printk_start_comm(void);
 
 #undef FTRACE_ENTRY
 #define FTRACE_ENTRY(call, struct_name, id, tstruct, print, filter)	\