Messages in this thread Patch in this message | | | Date | Fri, 07 Mar 2014 10:09:33 -0500 | From | Steven Rostedt <> | Subject | [for-next][PATCH 13/20] tracing: Evaluate len expression only once in __dynamic_array macro |
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From: Filipe Brandenburger <filbranden@google.com>
Use a temporary variable to store the expansion of the len expression. If the evaluation is expensive, this commit will ensure it is evaluated only once inside ftrace_get_offsets_<call>.
Link: http://lkml.kernel.org/r/1393651938-16418-3-git-send-email-filbranden@google.com
Signed-off-by: Filipe Brandenburger <filbranden@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> --- include/trace/ftrace.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h index 2125005..e15ae401 100644 --- a/include/trace/ftrace.h +++ b/include/trace/ftrace.h @@ -361,10 +361,11 @@ ftrace_define_fields_##call(struct ftrace_event_call *event_call) \ #undef __dynamic_array #define __dynamic_array(type, item, len) \ + __item_length = (len) * sizeof(type); \ __data_offsets->item = __data_size + \ offsetof(typeof(*entry), __data); \ - __data_offsets->item |= ((len) * sizeof(type)) << 16; \ - __data_size += (len) * sizeof(type); + __data_offsets->item |= __item_length << 16; \ + __data_size += __item_length; #undef __string #define __string(item, src) __dynamic_array(char, item, \ @@ -376,6 +377,7 @@ static inline notrace int ftrace_get_offsets_##call( \ struct ftrace_data_offsets_##call *__data_offsets, proto) \ { \ int __data_size = 0; \ + int __maybe_unused __item_length; \ struct ftrace_raw_##call __maybe_unused *entry; \ \ tstruct; \ -- 1.8.5.3
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