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Subject[PATCH 28/37] perf machine: Fix machine__findnew_module_map to put dso
Date
From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

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@hitachi.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20151118064035.30709.58824.stgit@localhost.localdomain
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
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 0b4a05c14204..7f5071a4d9aa 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;
}
--
2.1.0


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