While updating perf to work with Python3 and Python2 I noticed that the
stat-cpi script was dumping core.
$ perf stat -e cycles,instructions record -o /tmp/perf.data /bin/false
Performance counter stats for '/bin/false':
802,148 cycles
604,622 instructions 802,148 cycles
604,622 instructions
0.001445842 seconds time elapsed
$ perf script -i /tmp/perf.data -s scripts/python/stat-cpi.py
Segmentation fault (core dumped)
...
...
rblist=rblist@entry=0xb2a200 <rt_stat>,
new_entry=new_entry@entry=0x7ffcb755c310) at util/rblist.c:33
ctx=<optimized out>, type=<optimized out>, create=<optimized out>,
cpu=<optimized out>, evsel=<optimized out>) at util/stat-shadow.c:118
ctx=<optimized out>, type=<optimized out>, st=<optimized out>)
at util/stat-shadow.c:196
count=count@entry=727442, cpu=cpu@entry=0, st=0xb2a200 <rt_stat>)
at util/stat-shadow.c:239
config=config@entry=0xafeb40 <stat_config>,
counter=counter@entry=0x133c6e0) at util/stat.c:372
...
...
The issue is that since 1fcd03946b perf_stat__update_shadow_stats now calls
update_runtime_stat passing rt_stat rather than calling update_stats but
perf_stat__init_shadow_stats has never been called to initialize rt_stat in
the script path processing recorded stat data.
Since I can't see any reason why perf_stat__init_shadow_stats() is presently
initialized like it is in builtin-script.c::perf_sample__fprint_metric()
[4bd1bef8bb] I'm proposing it instead be initialized once in __cmd_script
Committer testing:
After applying the patch:
# perf script -i /tmp/perf.data -s tools/perf/scripts/python/stat-cpi.py
0.001970: cpu -1, thread -1 -> cpi 1.709079 (1075684/629394)
#
No segfault.
Signed-off-by: Tony Jones <tonyj@suse.de>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Fixes: 1fcd03946b ("perf stat: Update per-thread shadow stats")
Link: http://lkml.kernel.org/r/20190120191414.12925-1-tonyj@suse.de
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
8bf8c6da53