linux-kernel - [PATCH perf/core 10/13] perf: Fix __dsos__addnew to put dso after adding it to the list

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Date:	Wed, 18 Nov 2015 15:40:31 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	linux-kernel@...r.kernel.org,
	Adrian Hunter <adrian.hunter@...el.com>,
	Ingo Molnar <mingo@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Jiri Olsa <jolsa@...hat.com>
Subject: [PATCH perf/core 10/13] perf: Fix __dsos__addnew to put dso after
 adding it to the list

Fix __dsos__addnew to put dso after adding it to the list, because
__dsos__add() gets the dso refcount.
This eases refcount leaks on dso.

Refcnt debugger shows:
  ==== [0] ====
  Unreclaimed dso: 0x2fccab0
  Refcount +1 => 1 at
    ./perf(dso__new+0x1ff) [0x4a62df]
    ./perf(__dsos__addnew+0x29) [0x4a6e19]
    ./perf(dsos__findnew+0xd1) [0x4a7281]
    ./perf(machine__findnew_kernel+0x27) [0x4a5e17]
    ./perf() [0x4b8df2]
    ./perf(machine__create_kernel_maps+0x28) [0x4bb528]
    ./perf(machine__new_host+0xfa) [0x4bb84a]
    ./perf(init_probe_symbol_maps+0x93) [0x506713]
    ./perf() [0x455ffa]
    ./perf(cmd_probe+0x6c) [0x4566bc]
    ./perf() [0x47abc5]
    ./perf(main+0x610) [0x421f90]
    /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f46df132af5]
    ./perf() [0x4220a9]
  Refcount +1 => 2 at
    ./perf(__dsos__addnew+0xfb) [0x4a6eeb]
    ./perf(dsos__findnew+0xd1) [0x4a7281]
    ./perf(machine__findnew_kernel+0x27) [0x4a5e17]
    ./perf() [0x4b8df2]
    ./perf(machine__create_kernel_maps+0x28) [0x4bb528]
    ./perf(machine__new_host+0xfa) [0x4bb84a]
    ./perf(init_probe_symbol_maps+0x93) [0x506713]
    ./perf() [0x455ffa]
    ./perf(cmd_probe+0x6c) [0x4566bc]
    ./perf() [0x47abc5]
    ./perf(main+0x610) [0x421f90]
    /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f46df132af5]
    ./perf() [0x4220a9]
  Refcount +1 => 3 at
    ./perf(dsos__findnew+0x7e) [0x4a722e]
    ./perf(machine__findnew_kernel+0x27) [0x4a5e17]
    ./perf() [0x4b8df2]
    ./perf(machine__create_kernel_maps+0x28) [0x4bb528]
    ./perf(machine__new_host+0xfa) [0x4bb84a]
    ./perf(init_probe_symbol_maps+0x93) [0x506713]
    ./perf() [0x455ffa]
    ./perf(cmd_probe+0x6c) [0x4566bc]
    ./perf() [0x47abc5]
    ./perf(main+0x610) [0x421f90]
    /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f46df132af5]
    ./perf() [0x4220a9]
  [snip]

Here, __dsos__addnew() gets the dso twice, once for init,
once for adding the dso to its list. But after added, we
don't need the dso reference (since we already have).

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
---
 tools/perf/util/dso.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 28ad06a..d21057c 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -1227,6 +1227,8 @@ struct dso *__dsos__addnew(struct dsos *dsos, const char *name)
 	if (dso != NULL) {
 		__dsos__add(dsos, dso);
 		dso__set_basename(dso);
+		/* Put dso here because __dsos_add already got it */
+		dso__put(dso);
 	}
 	return dso;
 }

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