[tip:perf/core] perf tools: Clear struct machine during machine__init()

[tip-bot for Wang Nan]

Commit-ID:  93b0ba3c60da89043ce2b9f601cd2b3da408903b
Gitweb:     http://git.kernel.org/tip/93b0ba3c60da89043ce2b9f601cd2b3da408903b
Author:     Wang Nan <wangnan0@xxxxxxxxxx>
AuthorDate: Tue, 8 Dec 2015 02:25:44 +0000
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Fri, 11 Dec 2015 09:32:41 -0300

perf tools: Clear struct machine during machine__init()

There are so many test cases use stack allocated 'struct machine'.
Including:
  test__hists_link
  test__hists_filter
  test__mmap_thread_lookup
  test__thread_mg_share
  test__hists_output
  test__hists_cumulate

Also, in non-test code (for example, machine__new_host()) there are
code use 'malloc()' to alloc struct machine.

These are dangerous operations, cause some tests fail or hung in
machines__exit(). For example, in

 machines__exit ->
   machine__destroy_kernel_maps ->
     map_groups__remove ->
       maps__remove ->
         pthread_rwlock_wrlock

a incorrectly initialized lock causes unintended behavior.

This patch memset(0) that structure in machine__init() to ensure all
fields in 'struct machine' are initialized to zero.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
Link: http://lkml.kernel.org/r/1449541544-67621-17-git-send-email-wangnan0@xxxxxxxxxx
[ Use memset, see 'man bzero' ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/machine.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index f5882b8..1407d51 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -25,6 +25,7 @@ static void dsos__init(struct dsos *dsos)
 
 int machine__init(struct machine *machine, const char *root_dir, pid_t pid)
 {
+	memset(machine, 0, sizeof(*machine));
 	map_groups__init(&machine->kmaps, machine);
 	RB_CLEAR_NODE(&machine->rb_node);
 	dsos__init(&machine->dsos);
--
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