static int thread_signal_callback()

in st-dma-fence.c [444:509]

• 52 lines of code
• 14 McCabe index (conditional complexity)

static int thread_signal_callback(void *arg)
{
	const struct race_thread *t = arg;
	unsigned long pass = 0;
	unsigned long miss = 0;
	int err = 0;

	while (!err && !kthread_should_stop()) {
		struct dma_fence *f1, *f2;
		struct simple_cb cb;

		f1 = mock_fence();
		if (!f1) {
			err = -ENOMEM;
			break;
		}

		rcu_assign_pointer(t->fences[t->id], f1);
		smp_wmb();

		rcu_read_lock();
		do {
			f2 = dma_fence_get_rcu_safe(&t->fences[!t->id]);
		} while (!f2 && !kthread_should_stop());
		rcu_read_unlock();

		if (t->before)
			dma_fence_signal(f1);

		smp_store_mb(cb.seen, false);
		if (!f2 ||
		    dma_fence_add_callback(f2, &cb.cb, simple_callback)) {
			miss++;
			cb.seen = true;
		}

		if (!t->before)
			dma_fence_signal(f1);

		if (!cb.seen) {
			dma_fence_wait(f2, false);
			__wait_for_callbacks(f2);
		}

		if (!READ_ONCE(cb.seen)) {
			pr_err("Callback not seen on thread %d, pass %lu (%lu misses), signaling %s add_callback; fence signaled? %s\n",
			       t->id, pass, miss,
			       t->before ? "before" : "after",
			       dma_fence_is_signaled(f2) ? "yes" : "no");
			err = -EINVAL;
		}

		dma_fence_put(f2);

		rcu_assign_pointer(t->fences[t->id], NULL);
		smp_wmb();

		dma_fence_put(f1);

		pass++;
	}

	pr_info("%s[%d] completed %lu passes, %lu misses\n",
		__func__, t->id, pass, miss);
	return err;
}