Re: [PATCH 09/14] perf ftrace: Add 'record' sub-command

From: Namhyung Kim
Date: Thu Apr 25 2013 - 02:24:24 EST


On Wed, 24 Apr 2013 16:12:41 +0200, Jiri Olsa wrote:
> I got following lockup for record command:
>
> # ./perf --no-pager ftrace record ls
> ...
> hangs
>
> in other terminal:
>
> # pstack 14237
> Thread 2 (Thread 0x7f3f1aa1d700 (LWP 14241)):
> #0 0x0000003cec20b595 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
> #1 0x0000000000446ebe in record_ftrace_raw_buffer (arg=0x21f9ce0) at builtin-ftrace.c:451
> #2 0x0000003cec207d14 in start_thread () from /lib64/libpthread.so.0
> #3 0x0000003cebaf168d in clone () from /lib64/libc.so.6
> Thread 1 (Thread 0x7f3f1ba209c0 (LWP 14237)):
> #0 0x0000003cec208e60 in pthread_join () from /lib64/libpthread.so.0
> #1 0x0000000000449c8c in do_ftrace_record (ftrace=ftrace@entry=0x7fff1377d240) at builtin-ftrace.c:682
> #2 0x000000000044a57b in __cmd_ftrace_record (argv=0x7fff1377d818, argc=<optimized out>, ftrace=0x7fff1377d240) at builtin-ftrace.c:1535
> #3 cmd_ftrace (argc=2, argv=0x7fff1377d818, prefix=<optimized out>) at builtin-ftrace.c:1655
> #4 0x000000000041a763 in run_builtin (p=p@entry=0x7d58a0, argc=argc@entry=3, argv=argv@entry=0x7fff1377d818) at perf.c:320
> #5 0x0000000000419faf in handle_internal_command (argv=0x7fff1377d818, argc=3) at perf.c:377
> #6 run_argv (argv=0x7fff1377d600, argcp=0x7fff1377d60c) at perf.c:421
> #7 main (argc=3, argv=0x7fff1377d818) at perf.c:522
>

How often can you reproduce it? I can't. :(

But it looks there's a race between cond_wait() and cond_broatcast().
I'll take a look at that.

Thanks for the test and the report,
Namhyung
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