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

tip-bot for Wang Nan
2015-12-14T08:39:33Z

Commit-ID: 93b0ba3c60da89043ce2b9f601cd2b3da408903b
Gitweb: http://git.kernel.org/tip/93b0ba3c60da89043ce2b9f601cd2b3da408903b
Author: Wang Nan <wangnan0@huawei.com>
AuthorDate: Tue, 8 Dec 2015 02:25:44 +0000
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
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@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 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);