perf symbols: Do not open device files

The dso__read_binary_type_filename gets the dso's file name to open. We
need to check it for regular file before trying to open it, otherwise we
might get stuck with device file.

Signed-off-by: Jiri Olsa <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Don Zickus <[e-mail]>
Cc: Joe Mario <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: http://lkml.kernel.org/r/20160920161245.GA8995@krava
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/dso.c

···
 		return -EINVAL;
 	}
 
+	if (!is_regular_file(name))
+		return -EINVAL;
+
 	fd = do_open(name);
 	free(name);
 	return fd;