perf kvm: Initialize file_name var to fix segfault

The 3786063 commit:

    perf kvm: Rename perf_kvm to perf_kvm_stat

Moved the file_name from inside a local struct var that initialized some
of its members, thus zero initializing the not explicitely initialized
variables, one of which was 'file_name', to a standalone local variable,
but forgot to initialize it explicitely to NULL, so it then got some
undefined value, causing a segfault in strdup when it wasn't, by luck,
zero.

Fix it by explicitely initializing it to NULL.

Cc: David Ahern <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Xiao Guangrong <[email protected]>
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

1 files changed, 1 insertions, 2 deletions

diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index ca3f80ebc100..37a769d7f9fe 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -973,8 +973,7 @@ __cmd_buildid_list(const char *file_name, int argc, const char **argv)
 
 int cmd_kvm(int argc, const char **argv, const char *prefix __maybe_unused)
 {
-	const char *file_name;
-
+	const char *file_name = NULL;
 	const struct option kvm_options[] = {
 		OPT_STRING('i', "input", &file_name, "file",
 			   "Input file name"),