shmem_read
shmem_read(ce->default_state, 0, state, engine->context_size);
shmem_read(ce->default_state, 0, vaddr, ce->engine->context_size);
int shmem_read(struct file *file, loff_t off, void *dst, size_t len);
err = shmem_read(file, 0, &result, sizeof(result));