tasklet_sync_callback
static DEFINE_PER_CPU(struct tasklet_sync_callback, tasklet_sync_callback) = {
.cb_lock = __SPIN_LOCK_UNLOCKED(tasklet_sync_callback.cb_lock),
spin_lock(this_cpu_ptr(&tasklet_sync_callback.cb_lock));
spin_unlock(this_cpu_ptr(&tasklet_sync_callback.cb_lock));
struct tasklet_sync_callback *sync_cb = this_cpu_ptr(&tasklet_sync_callback);
struct tasklet_sync_callback *sync_cb = this_cpu_ptr(&tasklet_sync_callback);