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[PATCH 9/9] perf tools: Clear struct machine during machine__init()

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From: Wang Nan <wangnan0@huawei.com>

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@huawei.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1449541544-67621-17-git-send-email-wangnan0@huawei.com
[ Use memset, see 'man bzero' ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 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 f5882b8c8db9..1407d5107480 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);
-- 
2.1.0

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[GIT PULL 0/9] perf/core improvements and fixes Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-12-11 15:30 +0100
  [PATCH 9/9] perf tools: Clear struct machine during machine__init() Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-12-11 15:30 +0100
  [PATCH 2/9] perf top: Access hists->lock only if needed Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-12-11 15:30 +0100
  [PATCH 7/9] perf data: Add u32_hex data type Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-12-11 15:30 +0100
  Re: [GIT PULL 0/9] perf/core improvements and fixes Ingo Molnar <mingo@kernel.org> - 2015-12-14 09:40 +0100

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