On Wed, 2011-02-02 at 14:15 +0000, David Laight wrote: > > +#define arch_syscall_match_sym_name(sym, name) !strcmp(sym + 3, name > + 3) > > Whenever you use a #define macro arg, you should enclose it in (). > About the only time you don't need to is when it is being > passed as an argument to another function > (ie when it's use is also ',' separated). > > So the above ought to be: > #define arch_syscall_match_sym_name(sym, name) (!strcmp((sym) + 3, > (name) + 3)) I would have mentioned this if I wanted it to stay a macro ;) > > Whether an inline function is better or worse is much more subtle! > For instance I've used: > asm volatile ( "# line " STR(__LINE__) :: ) > to stop gcc merging the tails of conditionals. > Useful when the conditional is at the end of a loop (etc), > it might increase code size slightly, but removes a branch. > > If I put one of those in an 'inline' function separate copies > of the function end up sharing code. > With a #define __LINE__ differs so they don't. > > (I had some code to get below 190 clocks, these changes > were significant!) For what you were doing, this may have helped. But the code in question is the "default" version of the function. I much more prefer it to be a static inline. The issues you experience could change from gcc to gcc. But static inlined functions are much cleaner and easier to read than macros. Using a macro for this purpose is just too messy. Again, look at include/trace/ftrace.h. If I'm saying using a macro is ugly, then don't use it! Listen to me, because I'm Mr. Ugly Macro Man. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
