Summary: - I noticed that sometimes mqueue_test in ostest failed (i.e. mq_open failed) with rv-virt:smp. - This commit fixes this issue by replacing sched_lock with critical section. Impact: - file_mq_open() Testing: - Tested with ostest on QEMU-7.1 Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>