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SubjectRe: Re: [PATCH] perf probe: Fix --line option behavior
(2014/04/01 16:21), Namhyung Kim wrote:
> Hi Masami,
>
> (Also adding Jiri in CC and changing email of acme)
>
> On Tue, Apr 1, 2014 at 5:01 AM, Masami Hiramatsu
> <masami.hiramatsu.pt@hitachi.com> wrote:
>> (2014/04/01 13:47), Namhyung Kim wrote:
>>> The commit 5a62257a3ddd1 ("perf probe: Replace line_list with
>>> intlist") replaced line_list to intlist but it has a problem that if a
>>> same line was added again, it'd return -EEXIST rather than 1.
>>
>> Ah, right! that's a different behavior.
>>
>>> Since line_range_walk_cb() only checks the result being negative, it
>>> resulted in failure or segfault sometimes.
>>
>> Could you give me an example input of the segfault? I'd like to trace
>> it down.
>
> Just used current acme/perf/core.
>
> $ git log -1
> commit 28b5724a61cc9d84f2cbef6675e8a85ae4b1bc57
> Author: Arnaldo Carvalho de Melo <acme@redhat.com>
> Date: Thu Mar 27 17:36:14 2014 -0300
>
> MAINTAINERS: Change e-mail to kernel.org one
>
> Leaving ghostprotocols.net for old networking stuff.
>
> ...
>
> $ perf --version
> perf version 3.14.rc6.g28b572
>
> $ perf probe -x ./perf -v -L map__load
> Open Debuginfo file: /home/namhyung/project/linux/tools/perf/perf
> fname: util/map.c, lineno:153
> New line range: 153 to 2147483647
> path: (null)
> Segmentation fault (core dumped)
>
>
> It seems like find_line_range_by_line() called for multiple times,
> line_range_walk_cb returns 0 at first but as line_range_add_line()
> returns -EEXIST, it freed lr->path and __show_line_range() ended up
> accessing to NULL path.

OK, thanks for this nice report!
Hmm, line_range_inline_cb() must check the result of
find_line_range_by_line() but ignored. That should be fixed too...

Thank you,

>
>
> (gdb) bt
> #0 get_real_path (new_path=0x839ff8 <params+9272>,
> comp_dir=0x1f994f0 "/home/namhyung/project/linux/tools/perf",
> raw_path=0x0) at util/probe-event.c:518
> #1 __show_line_range (module=<optimized out>, lr=0x839fd8 <params+9240>)
> at util/probe-event.c:641
> #2 show_line_range (lr=lr@entry=0x839fd8 <params+9240>,
> module=<optimized out>) at util/probe-event.c:699
> #3 0x000000000044667b in __cmd_probe (argc=<optimized out>,
> argv=argv@entry=0x7fff7a770ba0, prefix=<optimized out>)
> at builtin-probe.c:465
> #4 0x00000000004469f4 in cmd_probe (argc=<optimized out>,
> argv=0x7fff7a770ba0, prefix=<optimized out>) at builtin-probe.c:520
> #5 0x00000000004241b5 in run_builtin (p=p@entry=0x7ebde0 <commands+384>,
> argc=argc@entry=6, argv=argv@entry=0x7fff7a770ba0) at perf.c:319
> #6 0x0000000000423a29 in handle_internal_command (argv=0x7fff7a770ba0,
> argc=6) at perf.c:376
> #7 run_argv (argv=0x7fff7a7709a0, argcp=0x7fff7a7709ac) at perf.c:420
> #8 main (argc=6, argv=0x7fff7a770ba0) at perf.c:529
>
>
> Thanks,
> Namhyung
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--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com




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