tracing: Use alignof__(struct {type b;}) instead of offsetof()

commit 09794a5a6c348f629b35fc1687071a1622ef4265 upstream.

Simplify:

  #define ALIGN_STRUCTFIELD(type) ((int)(offsetof(struct {char a; type b;}, b)))

with

  #define  ALIGN_STRUCTFIELD(type) __alignof__(struct {type b;})

Which works just the same.

Link: https://lore.kernel.org/all/a7d202457150472588df0bd3b7334b3f@AcuMS.aculab.com/
Link: https://lkml.kernel.org/r/20220802154412.513c50e3@gandalf.local.home
Suggested-by: David Laight <David.Laight@ACULAB.COM>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/trace/trace_events.h b/include/trace/trace_events.h
index a77b690..7f0b91d 100644 (file)
--- a/include/trace/trace_events.h
+++ b/include/trace/trace_events.h
@@ -479,7 +479,7 @@ static struct trace_event_functions trace_event_type_funcs_##call = {       \
 
 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
 
-#define ALIGN_STRUCTFIELD(type) ((int)(offsetof(struct {char a; type b;}, b)))
+#define ALIGN_STRUCTFIELD(type) ((int)(__alignof__(struct {type b;})))
 
 #undef __field_ext
 #define __field_ext(_type, _item, _filter_type) {                      \