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Steven Rostedt (Red Hat) authored
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: ac01ce14 ("tracing: Make ftrace_print_array_seq compute buf_len") Reported-by:
He Kuang <hekuang@huawei.com> Signed-off-by:
Steven Rostedt <rostedt@goodmis.org>
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