Messages in this thread | | | From | Arnd Bergmann <> | Date | Wed, 7 Jun 2017 15:12:21 +0200 | Subject | Re: [RFC] clang: 'unused-function' warning on static inline functions |
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On Wed, Jun 7, 2017 at 2:58 PM, Steven Rostedt <rostedt@goodmis.org> wrote: > On Wed, 7 Jun 2017 10:17:18 +0200 > Arnd Bergmann <arnd@arndb.de> wrote:
>> > where it is truly just dead junk. I'd rather just leave the dead junk >> > than have pointless warnings, if I have to choose one of the two >> > outcomes. >> >> This is a relatively rare case, with an inline function defined by a macro, and >> I sent a patch for a similar one in 1f318a8bafcf ("modules: mark >> __inittest/__exittest >> as __maybe_unused"). I think this is a case where the __maybe_unused >> annotation is reasonable, though for the other instances of unused inline >> functions in .c files, there is often a better way: typically the only caller >> of a function is inside of an #ifdef and moving the inline function definition >> into the same #ifdef block makes it clearer what is going on. >> > > How many warnings does the TRACE_EVENT() macros produce? That macro > creates a lot of static inline functions for every event. For example, > it will create an rcuidle() version of a tracepoint for those locations > that need to be called where RCU is not watching. It also adds a > trace_#tracepoint#_enabled() function for those that want to test if > the tracepoint is enabled or not. > > That is, every tracepoint creates static inlined functions for cases > that are used by only a few. I'm sure they will cause lots of warnings > because there will be a lot of unused static inlined functions.
The TRACE_EVENT() macro is always invoked from header files, so clang does not warn about unused instances. The only other header I found that defines macros that cause unused inline functions is include/linux/interval_tree_generic.h, but I only saw two warnings from that in the whole allmodconfig build.
Arnd
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