| Message ID | 20190712085908.4146364-1-arnd@arndb.de |
|---|---|
| State | New |
| Headers | show |
| Series | xen/trace: avoid clang warning on function pointers | expand |
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.
On Fri, Jul 12, 2019 at 10:58:48AM +0200, Arnd Bergmann 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. > > Fixes: c796f213a693 ("xen/trace: add multicall tracing") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Nick suggested this as well, I think it's reasonable to work around it in this one location since this is indeed the only instance of this warning that I see in the kernel tree across all of my builds. Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
On Fri, Jul 12, 2019 at 10:41 AM Nathan Chancellor <natechancellor@gmail.com> wrote: > > On Fri, Jul 12, 2019 at 10:58:48AM +0200, Arnd Bergmann 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. > > > > Fixes: c796f213a693 ("xen/trace: add multicall tracing") > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > Nick suggested this as well, I think it's reasonable to work around it > in this one location since this is indeed the only instance of this > warning that I see in the kernel tree across all of my builds. > > Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Steven, Ingo, would one of you mind picking up this fix, please? See for multiple reports: https://github.com/ClangBuiltLinux/linux/issues/216 -- Thanks, ~Nick Desaulniers
On Mon, Sep 23, 2019 at 3:06 PM Nick Desaulniers <ndesaulniers@google.com> wrote: > Steven, Ingo, would one of you mind picking up this fix, please? See > for multiple reports: > https://github.com/ClangBuiltLinux/linux/issues/216 Sorry, https://github.com/ClangBuiltLinux/linux/issues/97 is the link. -- Thanks, ~Nick Desaulniers
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(
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. 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(-) -- 2.20.0