op 14-05-14 17:29, Christian König schreef:
- /* did fence get signaled after we enabled the sw irq? */
- if (atomic64_read(&fence->rdev->fence_drv[fence->ring].last_seq) >= fence->seq) {
radeon_irq_kms_sw_irq_put(fence->rdev, fence->ring);return false;- }
- fence->fence_wake.flags = 0;
- fence->fence_wake.private = NULL;
- fence->fence_wake.func = radeon_fence_check_signaled;
- __add_wait_queue(&fence->rdev->fence_queue, &fence->fence_wake);
- fence_get(f);
That looks like a race condition to me. The fence needs to be added to the wait queue before the check, not after.
Apart from that the whole approach looks like a really bad idea to me. How for example is lockup detection supposed to happen with this?
It's not a race condition because fence_queue.lock is held when this function is called.
Lockup's a bit of a weird problem, the changes wouldn't allow core ttm code to handle the lockup any more, but any driver specific wait code would still handle this. I did this by design, because in future patches the wait function may be called from outside of the radeon driver. The official wait function takes a timeout parameter, so lockups wouldn't be fatal if the timeout is set to something like 30*HZ for example, it would still return and report that the function timed out.
~Maarten