Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1504208

Re: [PATCH 1/3] tools lib traceevent: Add -O2 option to traceevent

Show all headers | View raw

Em Wed, Oct 19, 2016 at 02:48:45PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Tue, Oct 18, 2016 at 11:29:53AM -0400, Steven Rostedt escreveu:
> > On Tue, 18 Oct 2016 11:01:09 +0900
> > Namhyung Kim <namhyung@kernel.org> wrote:
> > 
> > > Hi Honggyu,
> > > 
> > > You need to CC relevant maintainers when you send patches to LKML.
> > > For the libtraceevent, they are Arnaldo and Steven.  You can use
> > > scripts/get_maintainer.pl for this job later.  In addition running
> > > scripts/checkpatch.pl before sending patches is a good habit.
> > > 
> > > Arnaldo and Steve,
> > > 
> > > This is from uftrace building libtraceevent with the optimization flag
> > > and we want to fix the upstream as well.
> > > 
> > 
> > Acked-by: Steven Rostedt <rostedt@goodmis.org>
> 
> So right after applying this patch I get these new warnings, investigating...

Some are the compiler not grokking logic where the compiler gets
confused with logic that tests one variable to use another and thinks it
is using garbage (uninitialized stuff), I tried to follow the logic and
I think it got slightly more confused than me, as I _think_ its not a
problem, but the one on the case entry for

  OLD_RINGBUF_TYPE_TIME_EXTEND

in old_update_pointers() looks like a bug, unless some macro magic is
taking place that updates that 'lenght' variable.

Rostedt, that -O2 unleashed some warnings, please check, I'll defer
applying those patches till it doesn't show these warnings, i.e. till
other patches fixing these issues or simply silencing the compiler with
a harmless init gets submitted,

Thanks,

- Arnaldo
 
> [acme@jouet linux]$ gcc -v
> Using built-in specs.
> COLLECT_GCC=gcc
> COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/6.2.1/lto-wrapper
> Target: x86_64-redhat-linux
> Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,objc,obj-c++,fortran,ada,go,lto --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --disable-libgcj --with-isl --enable-libmpx --enable-gnu-indirect-function --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
> Thread model: posix
> gcc version 6.2.1 20160916 (Red Hat 6.2.1-2) (GCC) 
> [acme@jouet linux]$ 
> 
>   LD       /tmp/build/perf/plugin_mac80211-in.o
> kbuffer-parse.c: In function ‘__old_next_event’:
> kbuffer-parse.c:339:27: warning: ‘length’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>   kbuf->next = kbuf->index + length;
>                ~~~~~~~~~~~~^~~~~~~~
> kbuffer-parse.c:297:15: note: ‘length’ was declared here
>   unsigned int length;
>                ^~~~~~
>   CC       /tmp/build/perf/plugin_sched_switch.o
>   CC       /tmp/build/perf/run-command.o
> event-parse.c: In function ‘pevent_find_event_by_name’:
> event-parse.c:3513:21: warning: ‘event’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>   pevent->last_event = event;
>   ~~~~~~~~~~~~~~~~~~~^~~~~~~
>   CC       /tmp/build/perf/sigchain.o
>   LD       /tmp/build/perf/plugin_sched_switch-in.o
>   CC       /tmp/build/perf/plugin_function.o
> event-parse.c: In function ‘pevent_data_lat_fmt’:
> event-parse.c:5156:4: warning: ‘migrate_disable’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>     trace_seq_printf(s, "%d", migrate_disable);
>     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> event-parse.c:5163:4: warning: ‘lock_depth’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>     trace_seq_printf(s, "%d", lock_depth);
>     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> plugin_function.c: In function ‘function_handler’:
> plugin_function.c:133:6: warning: ‘index’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>   int index;
>       ^~~~~
>   CC       /tmp/build/perf/subcmd-config.o
>   GEN      perf-archive
>   LD       /tmp/build/perf/plugin_function-in.o
>   GEN      perf-with-kcore
>   CC       /tmp/build/perf/plugin_xen.o
> event-parse.c: In function ‘pevent_event_info’:
> event-parse.c:5003:7: warning: ‘len_arg’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>        trace_seq_printf(s, format, len_arg, (char)val);
>        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> event-parse.c:4846:6: note: ‘len_arg’ was declared here
>   int len_arg;
>       ^~~~~~~
>   MKDIR    /tmp/build/perf/util/
> 

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 1/3] tools lib traceevent: Add -O2 option to traceevent Honggyu Kim <hong.gyu.kim@lge.com> - 2016-10-17 16:20 +0200
  [PATCH 2/3] tools lib traceevent: Check the return value of asprintf Honggyu Kim <hong.gyu.kim@lge.com> - 2016-10-17 16:20 +0200
    Re: [PATCH 2/3] tools lib traceevent: Check the return value of  asprintf Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-10-18 20:00 +0200
      Re: [PATCH 2/3] tools lib traceevent: Check the return value of  asprintf Namhyung Kim <namhyung@kernel.org> - 2016-10-19 02:30 +0200
  [PATCH 3/3] tools lib traceevent: Fix to set uninitialized variables Honggyu Kim <hong.gyu.kim@lge.com> - 2016-10-17 16:20 +0200
    Re: [PATCH 3/3] tools lib traceevent: Fix to set uninitialized  variables Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-10-18 20:10 +0200
  Re: [PATCH 1/3] tools lib traceevent: Add -O2 option to traceevent Namhyung Kim <namhyung@kernel.org> - 2016-10-18 04:10 +0200
    Re: [PATCH 1/3] tools lib traceevent: Add -O2 option to traceevent Steven Rostedt <rostedt@goodmis.org> - 2016-10-18 17:40 +0200
      Re: [PATCH 1/3] tools lib traceevent: Add -O2 option to traceevent Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-10-19 19:50 +0200
        Re: [PATCH 1/3] tools lib traceevent: Add -O2 option to traceevent Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-10-19 20:10 +0200
          Re: [PATCH 1/3] tools lib traceevent: Add -O2 option to traceevent Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-10-19 20:10 +0200
            Re: [PATCH 1/3] tools lib traceevent: Add -O2 option to traceevent Steven Rostedt <rostedt@goodmis.org> - 2016-10-19 21:30 +0200
          Re: [PATCH 1/3] tools lib traceevent: Add -O2 option to traceevent Steven Rostedt <rostedt@goodmis.org> - 2016-10-19 21:30 +0200
        Re: [PATCH 1/3] tools lib traceevent: Add -O2 option to traceevent Steven Rostedt <rostedt@goodmis.org> - 2016-10-19 20:30 +0200

csiph-web