Em Mon, Feb 13, 2017 at 01:24:55PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Fri, Feb 10, 2017 at 02:14:08PM -0500, Steven Rostedt escreveu:
> > On Fri, 10 Feb 2017 14:03:17 -0300
> > Arnaldo Carvalho de Melo <[email protected]> wrote:
> > > + case OLD_RINGBUF_TYPE_TIME_EXTEND:
> > > + extend = read_4(kbuf, ptr);
> > > + extend <<= TS_SHIFT;
> > > + extend += delta;
> > > + delta = extend;
> > > + ptr += 4;
> > > + /* Fall through */
>
> > No, actually, the length should be zeroed here.
>
> > length = 0;
>
> > As the ptr is placed passed the metadata. At the end of this case
> > statement, the ptr will be after the metadata. The length is
> > to represent the length of the data that is part of the event. The
> > index is the ptr - start_data + length. As there's no data to this type
> > of event, it should be zero.
>
> > When I add length = 0, I get more events from my old 2.6.30 trace.dat
> > file :-/ I'll have to update my tests.
>
> > Care to send another patch?
>
> I have this now in my tree, and since the patch is basically yours, I
> just made myself the reporter and you the author, please ack.
>
>
> commit 1fb82b6cba967afde11957099a9ef440cf8c2248
> Author: Steven Rostedt <[email protected]>
> Date: Mon Feb 13 13:18:29 2017 -0300
>
> tools lib traceevent: Initialize lenght on OLD_RING_BUFFER_TYPE_TIME_STAMP
>
> A undefined value was being used for the OLD_RING_BUFFER_TYPE_TIME_STAMP
> case entry, as the 'lenght' variable was not being initialized, fix it.
>
> Caught by the reporter when building tools/perf/ using clang, which
> emmitted
> this warning:
>
> kbuffer-parse.c:312:7: warning: variable 'length' is used uninitialized
> whenever switch case is taken [-Wsometimes-uninitialized]
> case OLD_RINGBUF_TYPE_TIME_EXTEND:
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
> kbuffer-parse.c:339:29: note: uninitialized use occurs here
> kbuf->next = kbuf->index + length;
> ^~~~~~
> kbuffer-parse.c:297:21: note: initialize the variable 'length' to
> silence this warning
> unsigned int length;
> ^
> = 0
>
> Reported-by: Arnaldo Carvalho de Melo <[email protected]>
> Cc: Adrian Hunter <[email protected]>
> Cc: David Ahern <[email protected]>
> Cc: Jiri Olsa <[email protected]>
> Cc: Namhyung Kim <[email protected]>
> Cc: Wang Nan <[email protected]>
> Link: http://lkml.kernel.org/r/[email protected]
> Signed-off-by: Steven Rostedt <[email protected]>
>
> diff --git a/tools/lib/traceevent/kbuffer-parse.c
> b/tools/lib/traceevent/kbuffer-parse.c
> index 65984f1c2974..2009cb7d9675 100644
> --- a/tools/lib/traceevent/kbuffer-parse.c
> +++ b/tools/lib/traceevent/kbuffer-parse.c
> @@ -315,6 +315,7 @@ static unsigned int old_update_pointers(struct kbuffer
> *kbuf)
> extend += delta;
> delta = extend;
> ptr += 4;
> + lenght = 0;
ouch, 'length' :-)
clang provides a really nice error message:
kbuffer-parse.c:318:3: error: use of undeclared identifier 'lenght'; did you
mean 'length'?
lenght = 0;
^~~~~~
length
kbuffer-parse.c:297:15: note: 'length' declared here
unsigned int length;
^
1 error generated.
I only had to test compile it :-)
> break;
>
> case OLD_RINGBUF_TYPE_TIME_STAMP:
>
