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tracing: Evaluate len expression only once in __dynamic_array macro

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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>
This commit is contained in:
Filipe Brandenburger 2014-02-28 21:32:17 -08:00 committed by Steven Rostedt
parent 5859fa1a14
commit 114e7b52de
1 changed files with 4 additions and 2 deletions
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6
include/trace/ftrace.h
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@ -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; \