linux-kernel - perf sched broken on tip, bisected

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Date:	Mon, 22 Feb 2010 16:09:52 -0300
From:	Arnaldo Carvalho de Melo <acme@...radead.org>
To:	Hitoshi Mitake <mitake@....info.waseda.ac.jp>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Mike Galbraith <efault@....de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: perf sched broken on tip, bisected

While testing a patch series I'm working on I noticed that 'perf sched record ;
perf sched latency' is broken on tip, bisected it down to this cset, investigating...

[acme@...a linux-2.6-tip]$ git bisect good
86d8d29634de4464d568e7c335c0da6cba64e8ab is first bad commit
commit 86d8d29634de4464d568e7c335c0da6cba64e8ab
Author: Hitoshi Mitake <mitake@....info.waseda.ac.jp>
Date:   Sat Jan 30 20:43:23 2010 +0900

    perf tools: Add __data_loc support
    
    This patch is required to test the next patch for perf lock.
    
    At 064739bc4b3d7f424b2f25547e6611bcf0132415 ,
    support for the modifier "__data_loc" of format is added.
    
    But, when I wanted to parse format of lock_acquired (or some
    event else), raw_field_ptr() did not returned correct pointer.
    
    So I modified raw_field_ptr() like this patch. Then
    raw_field_ptr() works well.
    
    Signed-off-by: Hitoshi Mitake <mitake@....info.waseda.ac.jp>
    Acked-by: Frederic Weisbecker <fweisbec@...il.com>
    Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
    Cc: Paul Mackerras <paulus@...ba.org>
    Cc: Tom Zanussi <tzanussi@...il.com>
    Cc: Steven Rostedt <srostedt@...hat.com>
    LKML-Reference: <1264851813-8413-2-git-send-email-mitake@....info.waseda.ac.jp>
    [ v3: fixed minor stylistic detail ]
    Signed-off-by: Ingo Molnar <mingo@...e.hu>

:040000 040000 8650752c9d8295e3c0ae3999b237fb86eb269e5d eb3ecfba6bfbcc80ecde51e10307fefc4d43864e M	tools
[acme@...a linux-2.6-tip]$

(gdb) run sched latency
Starting program: /root/bin/perf sched latency
[Thread debugging using libthread_db enabled]
[Detaching after fork from child process 30314. (Try `set detach-on-fork off'.)]
[New Thread 139670509008608 (LWP 30311)]

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 139670509008608 (LWP 30311)]
0x000000000040df1b in process_sched_switch_event (data=0x7f079312f9fc, session=0xcaf780, event=0xcaff50, this_cpu=3, timestamp=3964393249899, thread=0xd21ea0) at builtin-sched.c:1489
1489		FILL_ARRAY(switch_event, prev_comm, event, data);
(gdb) bt
#0  0x000000000040df1b in process_sched_switch_event (data=0x7f079312f9fc, session=0xcaf780, event=0xcaff50, this_cpu=3, timestamp=3964393249899, thread=0xd21ea0) at builtin-sched.c:1489
#1  0x000000000040e508 in process_raw_event (raw_event=0x7f079312f9d0, session=0xcaf780, data=0x7f079312f9fc, cpu=3, timestamp=3964393249899, thread=0xd21ea0) at builtin-sched.c:1594
#2  0x000000000040e7ec in process_sample_event (event=0x7f079312f9d0, session=0xcaf780) at builtin-sched.c:1639
#3  0x000000000043be6f in perf_session__process_event (self=0xcaf780, event=0x7f079312f9d0, ops=0x6878e0, offset=0, head=117200) at util/session.c:298
#4  0x000000000043c5f0 in perf_session__process_events (self=0xcaf780, ops=0x6878e0) at util/session.c:464
#5  0x000000000040e8e0 in read_events () at builtin-sched.c:1667
#6  0x000000000040edb7 in __cmd_lat () at builtin-sched.c:1708
#7  0x000000000040f355 in cmd_sched (argc=1, argv=0x7fff2a064640, prefix=0x0) at builtin-sched.c:1911
#8  0x0000000000404fdd in run_builtin (p=0x682cd0, argc=2, argv=0x7fff2a064640) at perf.c:264
#9  0x00000000004051b3 in handle_internal_command (argc=2, argv=0x7fff2a064640) at perf.c:329
#10 0x00000000004052f2 in run_argv (argcp=0x7fff2a064534, argv=0x7fff2a064528) at perf.c:373
#11 0x00000000004054ce in main (argc=2, argv=0x7fff2a064640) at perf.c:457
(gdb)
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