<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/linux.git/tools/perf/util, branch v4.4.22</title>
<subtitle>Linux kernel stable tree (mirror)</subtitle>
<id>https://git.radix-linux.su/kernel/linux.git/atom?h=v4.4.22</id>
<link rel='self' href='https://git.radix-linux.su/kernel/linux.git/atom?h=v4.4.22'/>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/'/>
<updated>2016-05-04T21:48:53+00:00</updated>
<entry>
<title>perf tools: handle spaces in file names obtained from /proc/pid/maps</title>
<updated>2016-05-04T21:48:53+00:00</updated>
<author>
<name>Marcin Ślusarz</name>
<email>marcin.slusarz@gmail.com</email>
</author>
<published>2016-01-19T19:03:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=dcfdb38c41385bc3cb7be295eb5b9d4b00ea1177'/>
<id>urn:sha1:dcfdb38c41385bc3cb7be295eb5b9d4b00ea1177</id>
<content type='text'>
commit 89fee59b504f86925894fcc9ba79d5c933842f93 upstream.

Steam frequently puts game binaries in folders with spaces.

Note: "(deleted)" markers are now treated as part of the file name.

Signed-off-by: Marcin Ślusarz &lt;marcin.slusarz@gmail.com&gt;
Acked-by: Namhyung Kim &lt;namhyung@kernel.org&gt;
Fixes: 6064803313ba ("perf tools: Use sscanf for parsing /proc/pid/maps")
Link: http://lkml.kernel.org/r/20160119190303.GA17579@marcin-Inspiron-7720
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>perf evlist: Reference count the cpu and thread maps at set_maps()</title>
<updated>2016-05-04T21:48:52+00:00</updated>
<author>
<name>Arnaldo Carvalho de Melo</name>
<email>acme@redhat.com</email>
</author>
<published>2016-02-17T13:57:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=36828721fbbe4b53a53d62847b476f314123c819'/>
<id>urn:sha1:36828721fbbe4b53a53d62847b476f314123c819</id>
<content type='text'>
commit a55e5663761366fb883f6f25375dd68bc958b9db upstream.

We were dropping the reference we possibly held but not obtaining one
for the new maps, which we will drop at perf_evlist__delete(), fix it.

This was caught by Steven Noonan in some of the machines which would
produce this output when caught by glibc debug mechanisms:

  $ sudo perf test 21
  21: Test object code reading                                 :***
  Error in `perf': corrupted double-linked list: 0x00000000023ffcd0 ***
  ======= Backtrace: =========
  /usr/lib/libc.so.6(+0x72055)[0x7f25be0f3055]
  /usr/lib/libc.so.6(+0x779b6)[0x7f25be0f89b6]
  /usr/lib/libc.so.6(+0x7a0ed)[0x7f25be0fb0ed]
  /usr/lib/libc.so.6(__libc_calloc+0xba)[0x7f25be0fceda]
  perf(parse_events_lex_init_extra+0x38)[0x4cfff8]
  perf(parse_events+0x55)[0x4a0615]
  perf(perf_evlist__config+0xcf)[0x4eeb2f]
  perf[0x479f82]
  perf(test__code_reading+0x1e)[0x47ad4e]
  perf(cmd_test+0x5dd)[0x46452d]
  perf[0x47f4e3]
  perf(main+0x603)[0x42c723]
  /usr/lib/libc.so.6(__libc_start_main+0xf0)[0x7f25be0a1610]
  perf(_start+0x29)[0x42c859]

Further investigation using valgrind led to the reference count imbalance fixed
in this patch.

Reported-and-Tested-by: Steven Noonan &lt;steven@uplinklabs.net&gt;
Report-Link: http://lkml.kernel.org/r/CAKbGBLjC2Dx5vshxyGmQkcD+VwiAQLbHoXA9i7kvRB2-2opHZQ@mail.gmail.com
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: David Ahern &lt;dsahern@gmail.com&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Wang Nan &lt;wangnan0@huawei.com&gt;
Fixes: f30a79b012e5 ("perf tools: Add reference counting for cpu_map object")
Link: http://lkml.kernel.org/n/tip-j0u1bdhr47sa511sgg76kb8h@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>perf intel-pt: Fix segfault tracing transactions</title>
<updated>2016-05-04T21:48:47+00:00</updated>
<author>
<name>Adrian Hunter</name>
<email>adrian.hunter@intel.com</email>
</author>
<published>2016-04-18T10:57:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=0ea82073cb5e7039299350aba5bc135994c8cbda'/>
<id>urn:sha1:0ea82073cb5e7039299350aba5bc135994c8cbda</id>
<content type='text'>
commit 1342e0b7a6c1a060c593037fbac9f4b717f1cb3b upstream.

Tracing a workload that uses transactions gave a seg fault as follows:

  perf record -e intel_pt// workload
  perf report
  Program received signal SIGSEGV, Segmentation fault.
  0x000000000054b58c in intel_pt_reset_last_branch_rb (ptq=0x1a36110)
  	at util/intel-pt.c:929
  929 ptq-&gt;last_branch_rb-&gt;nr = 0;
  (gdb) p ptq-&gt;last_branch_rb
  $1 = (struct branch_stack *) 0x0
  (gdb) up
  1148 intel_pt_reset_last_branch_rb(ptq);
  (gdb) l
  1143 if (ret)
  1144 pr_err("Intel Processor Trace: failed to deliver transaction event
  1145 ret);
  1146
  1147 if (pt-&gt;synth_opts.callchain)
  1148 intel_pt_reset_last_branch_rb(ptq);
  1149
  1150 return ret;
  1151 }
  1152
  (gdb) p pt-&gt;synth_opts.callchain
  $2 = true
  (gdb)
  (gdb) bt
   #0 0x000000000054b58c in intel_pt_reset_last_branch_rb (ptq=0x1a36110)
   #1 0x000000000054c1e0 in intel_pt_synth_transaction_sample (ptq=0x1a36110)
   #2 0x000000000054c5b2 in intel_pt_sample (ptq=0x1a36110)

Caused by checking the 'callchain' flag when it should have been the
'last_branch' flag.  Fix that.

Reported-by: Andi Kleen &lt;ak@linux.intel.com&gt;
Signed-off-by: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Fixes: f14445ee72c5 ("perf intel-pt: Support generating branch stack")
Link: http://lkml.kernel.org/r/1460977068-11566-1-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>perf tools: Fix python extension build</title>
<updated>2016-04-12T16:08:35+00:00</updated>
<author>
<name>Jiri Olsa</name>
<email>jolsa@redhat.com</email>
</author>
<published>2016-02-27T20:21:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=64bf6d9705aa8724a17a137e76dc6f5b58309026'/>
<id>urn:sha1:64bf6d9705aa8724a17a137e76dc6f5b58309026</id>
<content type='text'>
commit 67d5268908283c187e0a460048a423256c2fb288 upstream.

The util/python-ext-sources file contains source files required to build
the python extension relative to $(srctree)/tools/perf,

Such a file path $(FILE).c is handed over to the python extension build
system, which builds the final object in the
$(PYTHON_EXTBUILD)/tmp/$(FILE).o path.

After the build is done all files from $(PYTHON_EXTBUILD)lib/ are
carried as the result binaries.

Above system fails when we add source file relative to ../lib, which we
do for:

  ../lib/bitmap.c
  ../lib/find_bit.c
  ../lib/hweight.c
  ../lib/rbtree.c

All above objects will be built like:

  $(PYTHON_EXTBUILD)/tmp/../lib/bitmap.c
  $(PYTHON_EXTBUILD)/tmp/../lib/find_bit.c
  $(PYTHON_EXTBUILD)/tmp/../lib/hweight.c
  $(PYTHON_EXTBUILD)/tmp/../lib/rbtree.c

which accidentally happens to be final library path:

  $(PYTHON_EXTBUILD)/lib/

Changing setup.py to pass full paths of source files to Extension build
class and thus keep all built objects under $(PYTHON_EXTBUILD)tmp
directory.

Reported-by: Jeff Bastian &lt;jbastian@redhat.com&gt;
Signed-off-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Tested-by: Josh Boyer &lt;jwboyer@fedoraproject.org&gt;
Cc: David Ahern &lt;dsahern@gmail.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Link: http://lkml.kernel.org/r/20160227201350.GB28494@krava.redhat.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>perf tools: Fix checking asprintf return value</title>
<updated>2016-04-12T16:08:35+00:00</updated>
<author>
<name>Wang Nan</name>
<email>wangnan0@huawei.com</email>
</author>
<published>2016-02-19T11:43:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=6be7771fe7242d7d4399545e0c9e2f6f3cd76725'/>
<id>urn:sha1:6be7771fe7242d7d4399545e0c9e2f6f3cd76725</id>
<content type='text'>
commit 26dee028d365fbc0e3326606a8520260b4462381 upstream.

According to man pages, asprintf returns -1 when failure. This patch
fixes two incorrect return value checker.

Signed-off-by: Wang Nan &lt;wangnan0@huawei.com&gt;
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Brendan Gregg &lt;brendan.d.gregg@gmail.com&gt;
Cc: Cody P Schafer &lt;dev@codyps.com&gt;
Cc: He Kuang &lt;hekuang@huawei.com&gt;
Cc: Jeremie Galarneau &lt;jeremie.galarneau@efficios.com&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: Kirill Smelkov &lt;kirr@nexedi.com&gt;
Cc: Li Zefan &lt;lizefan@huawei.com&gt;
Cc: Masami Hiramatsu &lt;masami.hiramatsu.pt@hitachi.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Zefan Li &lt;lizefan@huawei.com&gt;
Cc: pi3orama@163.com
Fixes: ffeb883e5662 ("perf tools: Show proper error message for wrong terms of hw/sw events")
Link: http://lkml.kernel.org/r/1455882283-79592-5-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>perf tools: Dont stop PMU parsing on alias parse error</title>
<updated>2016-04-12T16:08:35+00:00</updated>
<author>
<name>Andi Kleen</name>
<email>ak@linux.intel.com</email>
</author>
<published>2016-02-17T22:44:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=2dfe91df33715503b253563d5e6d9a816758485c'/>
<id>urn:sha1:2dfe91df33715503b253563d5e6d9a816758485c</id>
<content type='text'>
commit 940db6dcd3f4659303fdf6befe7416adc4d24118 upstream.

When an error happens during alias parsing currently the complete
parsing of all attributes of the PMU is stopped. This is breaks old perf
on a newer kernel that may have not-yet-know alias attributes (such as
.scale or .per-pkg).

Continue when some attribute is unparseable.

This is IMHO a stable candidate and should be backported to older
versions to avoid problems with newer kernels.

v2: Print warnings when something goes wrong.
v3: Change warning to debug output

Signed-off-by: Andi Kleen &lt;ak@linux.intel.com&gt;
Cc: Jiri Olsa &lt;jolsa@kernel.org&gt;
Link: http://lkml.kernel.org/r/1455749095-18358-1-git-send-email-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>perf stat: Do not clean event's private stats</title>
<updated>2016-03-03T23:07:26+00:00</updated>
<author>
<name>Jiri Olsa</name>
<email>jolsa@kernel.org</email>
</author>
<published>2016-01-20T11:56:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=e43193617315070ca9a6ca55794760e328fe4e9b'/>
<id>urn:sha1:e43193617315070ca9a6ca55794760e328fe4e9b</id>
<content type='text'>
commit 3f416f22d1e21709a631189ba169f76fd267b374 upstream.

Mel reported stddev reporting was broken due to following commit:

	106a94a0f8c2 ("perf stat: Introduce read_counters function")

This commit merged interval and overall counters reading into single
read_counters function.

The old interval code cleaned the stddev data for some reason (it's
never displayed in interval mode) and the mentioned commit kept on
cleaning the stddev data in merged function, which resulted in the
stddev not being displayed.

Removing the wrong stddev data cleanup init_stats call.

Reported-and-Tested-by: Mel Gorman &lt;mgorman@techsingularity.net&gt;
Signed-off-by: Jiri Olsa &lt;jolsa@kernel.org&gt;
Cc: David Ahern &lt;dsahern@gmail.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Fixes: 106a94a0f8c2 ("perf stat: Introduce read_counters function")
Link: http://lkml.kernel.org/r/1453290995-18485-4-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>perf kvm record/report: 'unprocessable sample' error while recording/reporting guest data</title>
<updated>2016-02-25T20:01:20+00:00</updated>
<author>
<name>Ravi Bangoria</name>
<email>ravi.bangoria@linux.vnet.ibm.com</email>
</author>
<published>2015-12-07T06:55:02+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=a6a3f3ddf6a663ab3d141f0e13f457b084a8c409'/>
<id>urn:sha1:a6a3f3ddf6a663ab3d141f0e13f457b084a8c409</id>
<content type='text'>
commit 3caeaa562733c4836e61086ec07666635006a787 upstream.

While recording guest samples in host using perf kvm record, it will
populate unprocessable sample error, though samples will be recorded
properly. While generating report using perf kvm report, no samples will
be processed and same error will populate. We have seen this behaviour
with upstream perf(4.4-rc3) on x86 and ppc64 hardware.

Reason behind this failure is, when it tries to fetch machine from
rb_tree of machines, it fails. As a part of tracing a bug, we figured
out that this code was incorrectly refactored in commit 54245fdc3576
("perf session: Remove wrappers to machines__find").

This patch will change the functionality such that if it can't fetch
machine in first trial, it will create one node of machine and add that to
rb_tree. So next time when it tries to fetch same machine from rb_tree,
it won't fail. Actually it was the case before refactoring of code in
aforementioned commit.

This patch is generated from acme perf/core branch.

Below I've mention an example that demonstrate the behaviour before and
after applying patch.

Before applying patch:
[Note: One needs to run guest before recording data in host]

  ravi@ravi-bangoria:~$ ./perf kvm record -a
  Warning:
  5903 unprocessable samples recorded.
  Do you have a KVM guest running and not using 'perf kvm'?
  [ perf record: Captured and wrote 1.409 MB perf.data.guest (285 samples) ]

  ravi@ravi-bangoria:~$ ./perf kvm report --stdio
  Warning:
  5903 unprocessable samples recorded.
  Do you have a KVM guest running and not using 'perf kvm'?
  # To display the perf.data header info, please use --header/--header-only options.
  #
  # Total Lost Samples: 0
  #
  # Samples: 285  of event 'cycles'
  # Event count (approx.): 88715406
  #
  # Overhead  Command  Shared Object  Symbol
  # ........  .......  .............  ......
  #

  # (For a higher level overview, try: perf report --sort comm,dso)
  #

After applying patch:

  ravi@ravi-bangoria:~$ ./perf kvm record -a
  [ perf record: Captured and wrote 1.188 MB perf.data.guest (17 samples) ]

  ravi@ravi-bangoria:~$ ./perf kvm report --stdio
  # To display the perf.data header info, please use --header/--header-only options.
  #
  # Total Lost Samples: 0
  #
  # Samples: 17  of event 'cycles'
  # Event count (approx.): 700746
  #
  # Overhead  Command  Shared Object     Symbol
  # ........  .......  ................  ......................
  #
      34.19%  :5758    [unknown]         [g] 0xffffffff818682ab
      22.79%  :5758    [unknown]         [g] 0xffffffff812dc7f8
      22.79%  :5758    [unknown]         [g] 0xffffffff818650d0
      14.83%  :5758    [unknown]         [g] 0xffffffff8161a1b6
       2.49%  :5758    [unknown]         [g] 0xffffffff818692bf
       0.48%  :5758    [unknown]         [g] 0xffffffff81869253
       0.05%  :5758    [unknown]         [g] 0xffffffff81869250

Signed-off-by: Ravi Bangoria &lt;ravi.bangoria@linux.vnet.ibm.com&gt;
Cc: Naveen N. Rao &lt;naveen.n.rao@linux.vnet.ibm.com&gt;
Fixes: 54245fdc3576 ("perf session: Remove wrappers to machines__find")
Link: http://lkml.kernel.org/r/1449471302-11283-1-git-send-email-ravi.bangoria@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>perf tools: tracepoint_error() can receive e=NULL, robustify it</title>
<updated>2016-02-25T20:01:16+00:00</updated>
<author>
<name>Adrian Hunter</name>
<email>adrian.hunter@intel.com</email>
</author>
<published>2016-01-26T12:05:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=6fa74f50e357b0d87fad34a4b7ccbc2beb42b859'/>
<id>urn:sha1:6fa74f50e357b0d87fad34a4b7ccbc2beb42b859</id>
<content type='text'>
commit ec183d22cc284a7a1e17f0341219d8ec8ca070cc upstream.

Fixes segmentation fault using, for instance:

  (gdb) run record -I -e intel_pt/tsc=1,noretcomp=1/u /bin/ls
  Starting program: /home/acme/bin/perf record -I -e intel_pt/tsc=1,noretcomp=1/u /bin/ls
  Missing separate debuginfos, use: dnf debuginfo-install glibc-2.22-7.fc23.x86_64
  [Thread debugging using libthread_db enabled]
  Using host libthread_db library "/lib64/libthread_db.so.1".

 Program received signal SIGSEGV, Segmentation fault.
  0 x00000000004b9ea5 in tracepoint_error (e=0x0, err=13, sys=0x19b1370 "sched", name=0x19a5d00 "sched_switch") at util/parse-events.c:410
  (gdb) bt
  #0  0x00000000004b9ea5 in tracepoint_error (e=0x0, err=13, sys=0x19b1370 "sched", name=0x19a5d00 "sched_switch") at util/parse-events.c:410
  #1  0x00000000004b9fc5 in add_tracepoint (list=0x19a5d20, idx=0x7fffffffb8c0, sys_name=0x19b1370 "sched", evt_name=0x19a5d00 "sched_switch", err=0x0, head_config=0x0)
      at util/parse-events.c:433
  #2  0x00000000004ba334 in add_tracepoint_event (list=0x19a5d20, idx=0x7fffffffb8c0, sys_name=0x19b1370 "sched", evt_name=0x19a5d00 "sched_switch", err=0x0, head_config=0x0)
      at util/parse-events.c:498
  #3  0x00000000004bb699 in parse_events_add_tracepoint (list=0x19a5d20, idx=0x7fffffffb8c0, sys=0x19b1370 "sched", event=0x19a5d00 "sched_switch", err=0x0, head_config=0x0)
      at util/parse-events.c:936
  #4  0x00000000004f6eda in parse_events_parse (_data=0x7fffffffb8b0, scanner=0x19a49d0) at util/parse-events.y:391
  #5  0x00000000004bc8e5 in parse_events__scanner (str=0x663ff2 "sched:sched_switch", data=0x7fffffffb8b0, start_token=258) at util/parse-events.c:1361
  #6  0x00000000004bca57 in parse_events (evlist=0x19a5220, str=0x663ff2 "sched:sched_switch", err=0x0) at util/parse-events.c:1401
  #7  0x0000000000518d5f in perf_evlist__can_select_event (evlist=0x19a3b90, str=0x663ff2 "sched:sched_switch") at util/record.c:253
  #8  0x0000000000553c42 in intel_pt_track_switches (evlist=0x19a3b90) at arch/x86/util/intel-pt.c:364
  #9  0x00000000005549d1 in intel_pt_recording_options (itr=0x19a2c40, evlist=0x19a3b90, opts=0x8edf68 &lt;record+232&gt;) at arch/x86/util/intel-pt.c:664
  #10 0x000000000051e076 in auxtrace_record__options (itr=0x19a2c40, evlist=0x19a3b90, opts=0x8edf68 &lt;record+232&gt;) at util/auxtrace.c:539
  #11 0x0000000000433368 in cmd_record (argc=1, argv=0x7fffffffde60, prefix=0x0) at builtin-record.c:1264
  #12 0x000000000049bec2 in run_builtin (p=0x8fa2a8 &lt;commands+168&gt;, argc=5, argv=0x7fffffffde60) at perf.c:390
  #13 0x000000000049c12a in handle_internal_command (argc=5, argv=0x7fffffffde60) at perf.c:451
  #14 0x000000000049c278 in run_argv (argcp=0x7fffffffdcbc, argv=0x7fffffffdcb0) at perf.c:495
  #15 0x000000000049c60a in main (argc=5, argv=0x7fffffffde60) at perf.c:618
(gdb)

Intel PT attempts to find the sched:sched_switch tracepoint but that seg
faults if tracefs is not readable, because the error reporting structure
is null, as errors are not reported when automatically adding
tracepoints.  Fix by checking before using.

Committer note:

This doesn't take place in a kernel that supports
perf_event_attr.context_switch, that is the default way that will be
used for tracking context switches, only in older kernels, like 4.2, in
a machine with Intel PT (e.g. Broadwell) for non-priviledged users.

Further info from a similar patch by Wang:

The error is in tracepoint_error: it assumes the 'e' parameter is valid.

However, there are many situation a parse_event() can be called without
parse_events_error. See result of

  $ grep 'parse_events(.*NULL)' ./tools/perf/ -r'

Signed-off-by: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Tested-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Josh Poimboeuf &lt;jpoimboe@redhat.com&gt;
Cc: Tong Zhang &lt;ztong@vt.edu&gt;
Cc: Wang Nan &lt;wangnan0@huawei.com&gt;
Fixes: 196581717d85 ("perf tools: Enhance parsing events tracepoint error output")
Link: http://lkml.kernel.org/r/1453809921-24596-2-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
</entry>
<entry>
<title>perf list: Robustify event printing routine</title>
<updated>2015-12-16T19:43:10+00:00</updated>
<author>
<name>Arnaldo Carvalho de Melo</name>
<email>acme@redhat.com</email>
</author>
<published>2015-11-27T19:04:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=fb202539e61b14bc63ac29af10fe5d758ecd880a'/>
<id>urn:sha1:fb202539e61b14bc63ac29af10fe5d758ecd880a</id>
<content type='text'>
When a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") added
PERF_COUNT_SW_BPF_OUTPUT we ended up with a new entry in the event_symbols_sw
array that wasn't initialized, thus set to NULL, fix print_symbol_events()
to check for that case so that we don't crash if this happens again.

  (gdb) bt
  #0  __match_glob (ignore_space=false, pat=&lt;optimized out&gt;, str=&lt;optimized out&gt;) at util/string.c:198
  #1  strglobmatch (str=&lt;optimized out&gt;, pat=pat@entry=0x7fffffffe61d "stall") at util/string.c:252
  #2  0x00000000004993a5 in print_symbol_events (type=1, syms=0x872880 &lt;event_symbols_sw+160&gt;, max=11, name_only=false, event_glob=0x7fffffffe61d "stall")
      at util/parse-events.c:1615
  #3  print_events (event_glob=event_glob@entry=0x7fffffffe61d "stall", name_only=false) at util/parse-events.c:1675
  #4  0x000000000042c79e in cmd_list (argc=1, argv=0x7fffffffe390, prefix=&lt;optimized out&gt;) at builtin-list.c:68
  #5  0x00000000004788a5 in run_builtin (p=p@entry=0x871758 &lt;commands+120&gt;, argc=argc@entry=2, argv=argv@entry=0x7fffffffe390) at perf.c:370
  #6  0x0000000000420ab0 in handle_internal_command (argv=0x7fffffffe390, argc=2) at perf.c:429
  #7  run_argv (argv=0x7fffffffe110, argcp=0x7fffffffe11c) at perf.c:473
  #8  main (argc=2, argv=0x7fffffffe390) at perf.c:588
  (gdb) p event_symbols_sw[PERF_COUNT_SW_BPF_OUTPUT]
  $4 = {symbol = 0x0, alias = 0x0}
  (gdb)

A patch to robustify perf to not segfault when the next counter gets added in
the kernel will follow this one.

Reported-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: Adrian Hunter &lt;adrian.hunter@intel.com&gt;
Cc: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: David Ahern &lt;dsahern@gmail.com&gt;
Cc: Jiri Olsa &lt;jolsa@redhat.com&gt;
Cc: Namhyung Kim &lt;namhyung@kernel.org&gt;
Cc: Wang Nan &lt;wangnan0@huawei.com&gt;
Link: http://lkml.kernel.org/n/tip-57wysblcjfrseb0zg5u7ek10@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo &lt;acme@redhat.com&gt;
</content>
</entry>
</feed>
