Messages in this thread Patch in this message | | | Date | Tue, 21 Jul 2015 14:56:30 -0400 | From | Steven Rostedt <> | Subject | [GIT PULL] tracing: Fix sample output of dynamic arrays |
| |
Linus,
He Kuang noticed that the sample code using the trace_event helper function __get_dynamic_array_len() is broken. This only changes the sample code, and I'm pushing this now instead of later because I don't want others using the broken code as an example when using it for real.
Please pull the latest trace-v4.2-rc2-fix2 tree, which can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git trace-v4.2-rc2-fix2
Tag SHA1: a0fb8618a8d4841f2c75e9488700277f13f54394 Head SHA1: d6726c8145290bef950ae2538ea6ae1d96a1944b
Steven Rostedt (Red Hat) (1): tracing: Fix sample output of dynamic arrays
---- samples/trace_events/trace-events-sample.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --------------------------- commit d6726c8145290bef950ae2538ea6ae1d96a1944b Author: Steven Rostedt (Red Hat) <rostedt@goodmis.org> Date: Fri Jul 17 14:03:26 2015 -0400
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,ffffffff)" This was caused by an update to have __print_array()'s second parameter be the count of items in the array and not the size of the array. As there is already users of __print_array(), it can not change. But the sample code can and we can also improve on the documentation about __print_array() and __get_dynamic_array_len(). Link: http://lkml.kernel.org/r/1436839171-31527-2-git-send-email-hekuang@huawei.com Fixes: ac01ce1410fc2 ("tracing: Make ftrace_print_array_seq compute buf_len") Reported-by: He Kuang <hekuang@huawei.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/samples/trace_events/trace-events-sample.h b/samples/trace_events/trace-events-sample.h index 8965d1bb8811..125d6402f64f 100644 --- a/samples/trace_events/trace-events-sample.h +++ b/samples/trace_events/trace-events-sample.h @@ -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)) );
| |