Messages in this thread | | | From | Sedat Dilek <> | Date | Fri, 12 Jul 2019 11:16:35 +0200 | Subject | Re: [PATCH] xen/trace: avoid clang warning on function pointers |
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On Fri, Jul 12, 2019 at 10:59 AM Arnd Bergmann <arnd@arndb.de> wrote: > > clang-9 does not like the way that the is_signed_type() compares > function pointers deep inside of the trace even macros: > > In file included from arch/x86/xen/trace.c:21: > In file included from include/trace/events/xen.h:475: > In file included from include/trace/define_trace.h:102: > In file included from include/trace/trace_events.h:467: > include/trace/events/xen.h:69:7: error: ordered comparison of function pointers ('xen_mc_callback_fn_t' (aka 'void (*)(void *)') and 'xen_mc_callback_fn_t') [-Werror,-Wordered-compare-function-pointers] > __field(xen_mc_callback_fn_t, fn) > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > include/trace/trace_events.h:415:29: note: expanded from macro '__field' > #define __field(type, item) __field_ext(type, item, FILTER_OTHER) > ^ > include/trace/trace_events.h:401:6: note: expanded from macro '__field_ext' > is_signed_type(type), filter_type); \ > ^ > include/linux/trace_events.h:540:44: note: expanded from macro 'is_signed_type' > #define is_signed_type(type) (((type)(-1)) < (type)1) > ^ > note: (skipping 1 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all) > include/trace/trace_events.h:77:16: note: expanded from macro 'TRACE_EVENT' > PARAMS(tstruct), \ > ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~ > include/linux/tracepoint.h:95:25: note: expanded from macro 'PARAMS' > #define PARAMS(args...) args > ^ > include/trace/trace_events.h:455:2: note: expanded from macro 'DECLARE_EVENT_CLASS' > tstruct; \ > ^~~~~~~ > > I guess the warning is reasonable in principle, though this seems to > be the only instance we get in the entire kernel today. > Shut up the warning by making it a void pointer in the exported > structure. >
Thanks for bringing this up (again), Arnd.
As this is a known CBL issue please add...
Link: https://github.com/ClangBuiltLinux/linux/issues/97
...and...
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
For the sake of completeness see also the comments of Steven Rostedt and user "Honeybyte" in the above Link - if not known/read.
- Sedat -
P.S.: I am using this patch since 6 months in my for-5.x/clang-warningfree local Git repository.
> Fixes: c796f213a693 ("xen/trace: add multicall tracing") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > include/trace/events/xen.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/trace/events/xen.h b/include/trace/events/xen.h > index 9a0e8af21310..f75b77414ac1 100644 > --- a/include/trace/events/xen.h > +++ b/include/trace/events/xen.h > @@ -66,7 +66,7 @@ TRACE_EVENT(xen_mc_callback, > TP_PROTO(xen_mc_callback_fn_t fn, void *data), > TP_ARGS(fn, data), > TP_STRUCT__entry( > - __field(xen_mc_callback_fn_t, fn) > + __field(void *, fn) > __field(void *, data) > ), > TP_fast_assign( > -- > 2.20.0 > > -- > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20190712085908.4146364-1-arnd%40arndb.de.
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