Messages in this thread | | | Date | Wed, 14 Jul 2021 18:03:37 -0400 | From | Steven Rostedt <> | Subject | Re: [GIT PULL] tracing: Add __string_len() and __assign_str_len() helpers |
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On Wed, 14 Jul 2021 17:56:33 -0400 Steven Rostedt <rostedt@goodmis.org> wrote:
> static inline notrace int trace_event_get_offsets_foo( > struct trace_event_data_offsets_foo *__data_offsets, const char *foobar, int len) > { > int __data_size = 0; > int __maybe_unused __item_length; > struct trace_event_raw_foo __maybe_unused *entry; > > // The "(len)+1" will be used to calculate the __item_length below > > __item_length = (len + 1) * sizeof(char); > > // the dynamic fields (strings and such) are located after the static > // fields in the trace event, and the offset is recorded in the bottom > // 16 bits of a 32 bit word, and the size in the top 16 bits. > > __data_offsets->item = __data_size + > offsetof(typeof(*entry), __data); > __data_offsets->item |= __item_length << 16;
I missed a manual substitution of the macro. This should have been:
__data_offsets->str = __data_size + offsetof(typeof(*entry), __data); __data_offsets->str |= __item_length << 16;
As the macro creates the trace_event_data_offsets_foo structure (which __data_offsets is declared as), which contains a field for every __string/__string_len/__dynamic_array() in TP_STRUCT__entry.
The -">str" comes from the "str" in "__string_len(str, foobar, len)".
-- Steve
> __data_size += __item_length; > > > // Each "__string_len()" or "__string()" in the TP_STRUCT__entry is inserted > // into this macro created function. Thus, the above code is duplicated for > // each field that uses __string(), __string_len() or __dynamic_array(). > > > return __data_size; > }
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