tracing: Evaluate len expression only once in __dynamic_array macro
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>
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 21250056..e15ae401 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -361,10 +361,11 @@
#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 @@
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; \