Quoting Gustavo Padovan (2018-01-31 12:32:21)
Hi,
2017-08-11 Jason Ekstrand jason@jlekstrand.net:
From: Chris Wilson chris@chris-wilson.co.uk
This is an illegal scenario, to free the fence whilst there are pending callbacks. Currently, we emit a WARN and then cast aside the callbacks leaving them dangling. Alternatively, we could set an error on the fence and then signal fence so that any dependency chains from the fence can be tidied up, and if they care they can check for the error.
The question is whether or not the cure is worse than the disease (premature fence signaling is never pretty).
Signed-off-by: Chris Wilson chris@chris-wilson.co.uk
drivers/dma-buf/dma-fence.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index 0cac367..4062708 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -172,7 +172,19 @@ void dma_fence_release(struct kref *kref)
trace_dma_fence_destroy(fence);
WARN_ON(!list_empty(&fence->cb_list));
if (WARN_ON(!list_empty(&fence->cb_list))) {unsigned long flags;/** This should never happen, but if it does make sure that we* don't leave chains dangling. We set the error flag first* so that the callbacks know this signal is due to an error.*/spin_lock_irqsave(fence->lock, flags);fence->error = -EDEADLK;dma_fence_signal_locked(fence);spin_unlock_irqrestore(fence->lock, flags);}Thanks for the patch!
Reviewed-by: Gustavo Padovan gustavo.padovan@collabora.com
If you are picking up this version, please also include a Reviewed-by: Christian König christian.koenig@amd.com given to an earlier posting, which included a discussion on the pitiful lack of EHUMAN. -Chris