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
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