Commit d6726c81 authored Jul 17, 2015 by Steven Rostedt (Red Hat) Committed by Steven Rostedt Jul 17, 2015

tracing: Fix sample output of dynamic arrays

He Kuang noticed that the trace event samples for arrays was broken:

"The output result of trace_foo_bar event in traceevent samples is
 wrong. This problem can be reproduced as following:

  (Build kernel with SAMPLE_TRACE_EVENTS=m)

  $ insmod trace-events-sample.ko

  $ echo 1 > /sys/kernel/debug/tracing/events/sample-trace/foo_bar/enable

  $ cat /sys/kernel/debug/tracing/trace

  event-sample-980 [000] ....  43.649559: foo_bar: foo hello 21 0x15
  BIT1|BIT3|0x10 {0x1,0x6f6f6e53,0xff007970,0xffffffff} Snoopy
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                 The array length is not right, should be {0x1}.
  (ffffffff,ffffffff)

  event-sample-980 [000] ....  44.653827: foo_bar: foo hello 22 0x16
  BIT2|BIT3|0x10
  {0x1,0x2,0x646e6147,0x666c61,0xffffffff,0xffffffff,0x750aeffe,0x7}
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                 The array length is not right, should be {0x1,0x2}.
  Gandalf (ffffffff...

parent 6224beb1

samples/trace_events/trace-events-sample.h

+5 −2

Original line number	Diff line number	Diff line
		@@ -168,7 +168,10 @@
		*
		* For __dynamic_array(int, foo, bar) use __get_dynamic_array(foo)
		* Use __get_dynamic_array_len(foo) to get the length of the array
		* saved.
		* saved. Note, __get_dynamic_array_len() returns the total allocated
		* length of the dynamic array; __print_array() expects the second
		* parameter to be the number of elements. To get that, the array length
		* needs to be divided by the element size.
		*
		* For __string(foo, bar) use __get_str(foo)
		*
		@@ -288,7 +291,7 @@ TRACE_EVENT(foo_bar,
		* This prints out the array that is defined by __array in a nice format.
		*/
		__print_array(__get_dynamic_array(list),
		__get_dynamic_array_len(list),
		__get_dynamic_array_len(list) / sizeof(int),
		sizeof(int)),
		__get_str(str), __get_bitmask(cpus))
		);