mtx_spin_delay
static struct lock_delay_config __read_frequently mtx_spin_delay;
&mtx_spin_delay.base, 0, "");
&mtx_spin_delay.max, 0, "");
LOCK_DELAY_SYSINIT_DEFAULT(mtx_spin_delay);
lock_delay_arg_init(&lda, &mtx_spin_delay);
lock_delay_arg_init(&lda, &mtx_spin_delay);