[tip:perf/core] perf machine: Fix machine__findnew_module_map to put dso

[tip-bot for Masami Hiramatsu]

Commit-ID:  566c69c36e6178774dd484ea4a02b76f6bd0ede4
Gitweb:     http://git.kernel.org/tip/566c69c36e6178774dd484ea4a02b76f6bd0ede4
Author:     Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
AuthorDate: Wed, 18 Nov 2015 15:40:35 +0900
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Thu, 19 Nov 2015 13:19:21 -0300

perf machine: Fix machine__findnew_module_map to put dso

Fix machine__findnew_module_map to drop the reference to the dso because
it is already referenced by both machine__findnew_module_dso() and
map__new2().

Refcnt debugger shows:

  ==== [1] ====
  Unreclaimed dso: 0x1ffd980
  Refcount +1 => 1 at
    ./perf(dso__new+0x1ff) [0x4a62df]
    ./perf(__dsos__addnew+0x29) [0x4a6e19]
    ./perf() [0x4b8b91]
    ./perf(modules__parse+0xfc) [0x4a9d5c]
    ./perf() [0x4b8460]
    ./perf(machine__create_kernel_maps+0x150) [0x4bb550]
    ./perf(machine__new_host+0xfa) [0x4bb75a]
    ./perf(init_probe_symbol_maps+0x93) [0x506623]
    ./perf() [0x455ffa]
    ./perf(cmd_probe+0x6c) [0x4566bc]
    ./perf() [0x47abc5]
    ./perf(main+0x610) [0x421f90]
    /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f1345a8eaf5]
    ./perf() [0x4220a9]

This map_groups__insert(0x4b8b91) already gets a reference to the new
dso:

  ----
  eu-addr2line -e ./perf -f 0x4b8b91
  map_groups__insert inlined at util/machine.c:586 in
  machine__create_module
  util/map.h:207
  ----

So this dso refcnt will be released when map_groups gets released.

  [snip]
  Refcount +1 => 2 at
    ./perf(dso__get+0x34) [0x4a65f4]
    ./perf() [0x4b8b35]
    ./perf(modules__parse+0xfc) [0x4a9d5c]
    ./perf() [0x4b8460]
    ./perf(machine__create_kernel_maps+0x150) [0x4bb550]
    ./perf(machine__new_host+0xfa) [0x4bb75a]
    ./perf(init_probe_symbol_maps+0x93) [0x506623]
    ./perf() [0x455ffa]
    ./perf(cmd_probe+0x6c) [0x4566bc]
    ./perf() [0x47abc5]
    ./perf(main+0x610) [0x421f90]
    /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f1345a8eaf5]
    ./perf() [0x4220a9]

Here, machine__findnew_module_dso(0x4b8b35) gets the dso (and stores it
in a local variable):

  ----
  # eu-addr2line -e ./perf -f 0x4b8b35
  machine__findnew_module_dso inlined at util/machine.c:578 in
  machine__create_module
  util/machine.c:514
  ----

  Refcount +1 => 3 at
    ./perf(dso__get+0x34) [0x4a65f4]
    ./perf(map__new2+0x76) [0x4be1c6]
    ./perf() [0x4b8b4f]
    ./perf(modules__parse+0xfc) [0x4a9d5c]
    ./perf() [0x4b8460]
    ./perf(machine__create_kernel_maps+0x150) [0x4bb550]
    ./perf(machine__new_host+0xfa) [0x4bb75a]
    ./perf(init_probe_symbol_maps+0x93) [0x506623]
    ./perf() [0x455ffa]
    ./perf(cmd_probe+0x6c) [0x4566bc]
    ./perf() [0x47abc5]
    ./perf(main+0x610) [0x421f90]
    /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f1345a8eaf5]
    ./perf() [0x4220a9]

But also map__new2() gets the dso which will be put when the map is
released.

So, we have to drop the constructor reference obtained in
machine__findnew_module_dso().

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/20151118064035.30709.58824.stgit@xxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/machine.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 0b4a05c..7f5071a 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -565,7 +565,7 @@ struct map *machine__findnew_module_map(struct machine *machine, u64 start,
 					const char *filename)
 {
 	struct map *map = NULL;
-	struct dso *dso;
+	struct dso *dso = NULL;
 	struct kmod_path m;
 
 	if (kmod_path__parse_name(&m, filename))
@@ -589,6 +589,8 @@ struct map *machine__findnew_module_map(struct machine *machine, u64 start,
 	/* Put the map here because map_groups__insert alread got it */
 	map__put(map);
 out:
+	/* put the dso here, corresponding to  machine__findnew_module_dso */
+	dso__put(dso);
 	free(m.name);
 	return map;
 }
--
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