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)
The event defined in samples/trace_events/trace-events-sample.h uses
this helper function to output dynamic list:
__print_array(__get_dynamic_array(list),
__get_dynamic_array_len(list),
sizeof(int))
Currently, __get_dynamic_array_len() returns the total size of the
array instead of the number of items by referencing the high 16 bits
of entry->data_loc_##item. The element size for calculating the number
of items can not be fetched by referencing fields from __entry, so
macro __get_dynamic_array_len can not return the expected value.
This patch stores array item number instead of the total size in
entry->__data_loc_##item, and makes __get_dynamic_array_len get the
right value directly. Because the function __get_bitmask() is affected
by this change, __bitmask_size is assigned to the array len by
multiplied bitmask type size.
After this patch:
event-sample-993 [000] .... 692.348562: foo_bar: foo hello 201
0xc9 BIT1|BIT4|0xc0 {0x1} Snoopy (ffffffff,ffffffff)
^^^^^
Array length fixed.
event-sample-993 [000] .... 693.349276: foo_bar: foo hello 202
0xca BIT2|BIT4|0xc0 {0x1,0x2} Gandalf (ffffffff,ffffffff)
^^^^^^^^^
Array length fixed.
Signed-off-by: He Kuang <heku...@huawei.com>
---
include/trace/trace_events.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/trace/trace_events.h b/include/trace/trace_events.h
index 43be3b0..5abe027 100644
--- a/include/trace/trace_events.h
+++ b/include/trace/trace_events.h
@@ -257,7 +257,8 @@ TRACE_MAKE_SYSTEM_STR();
({ \
void *__bitmask = __get_dynamic_array(field); \
unsigned int __bitmask_size; \
- __bitmask_size = __get_dynamic_array_len(field); \
+ __bitmask_size = (__get_dynamic_array_len(field) * \
+ sizeof(unsigned long)); \
trace_print_bitmask_seq(p, __bitmask, __bitmask_size); \
})
@@ -453,7 +454,7 @@ trace_event_define_fields_##call(struct trace_event_call
*event_call) \
__item_length = (len) * sizeof(type); \
__data_offsets->item = __data_size + \
offsetof(typeof(*entry), __data); \
- __data_offsets->item |= __item_length << 16; \
+ __data_offsets->item |= (len) << 16; \
__data_size += __item_length;
#undef __string
--
1.8.5.2
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