On Sun, Aug 11, 2019 at 10:15:23AM +0100, Chris Wilson wrote:
> Now that dma_fence_signal always takes the spinlock to flush the
> cb_list, simply take the spinlock and call dma_fence_signal_locked() to
> avoid code repetition.
>
> Suggested-by: Christian König <christian.koe...@amd.com>
> Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
> Cc: Christian König <christian.koe...@amd.com>
Hm, I think this largely defeats the point of having the lockless signal
enabling trickery in dma_fence. Maybe that part isn't needed by anyone,
but feels like a thing that needs a notch more thought. And if we need it,
maybe a bit more cleanup.
I guess with the addition of more fancy atomic BITs we could avoid this
too ... but no idea whether that's worth the effort.
-Daniel
> ---
> drivers/dma-buf/dma-fence.c | 32 ++++++++++++--------------------
> 1 file changed, 12 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
> index ab4a456bba04..367b71084d34 100644
> --- a/drivers/dma-buf/dma-fence.c
> +++ b/drivers/dma-buf/dma-fence.c
> @@ -122,26 +122,18 @@ EXPORT_SYMBOL(dma_fence_context_alloc);
> */
> int dma_fence_signal_locked(struct dma_fence *fence)
> {
> - int ret = 0;
> -
> - lockdep_assert_held(fence->lock);
> -
> if (WARN_ON(!fence))
> return -EINVAL;
>
> - if (!__dma_fence_signal(fence)) {
> - ret = -EINVAL;
> + lockdep_assert_held(fence->lock);
>
> - /*
> - * we might have raced with the unlocked dma_fence_signal,
> - * still run through all callbacks
> - */
> - } else {
> - __dma_fence_signal__timestamp(fence, ktime_get());
> - }
> + if (!__dma_fence_signal(fence))
> + return -EINVAL;
>
> + __dma_fence_signal__timestamp(fence, ktime_get());
> __dma_fence_signal__notify(fence);
> - return ret;
> +
> + return 0;
> }
> EXPORT_SYMBOL(dma_fence_signal_locked);
>
> @@ -161,19 +153,19 @@ EXPORT_SYMBOL(dma_fence_signal_locked);
> int dma_fence_signal(struct dma_fence *fence)
> {
> unsigned long flags;
> + int ret;
>
> if (!fence)
> return -EINVAL;
>
> - if (!__dma_fence_signal(fence))
> - return -EINVAL;
> -
> - __dma_fence_signal__timestamp(fence, ktime_get());
> + if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
> + return 0;
>
> spin_lock_irqsave(fence->lock, flags);
> - __dma_fence_signal__notify(fence);
> + ret = dma_fence_signal_locked(fence);
> spin_unlock_irqrestore(fence->lock, flags);
> - return 0;
> +
> + return ret;
> }
> EXPORT_SYMBOL(dma_fence_signal);
>
> --
> 2.23.0.rc1
>
> _______________________________________________
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> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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