Re: [PATCH 1/4] dma-buf: Check status of enable-signaling bit on debug

Christian König
2022-09-05T11:21:20Z

Am 05.09.22 um 12:56 schrieb Arvind Yadav:
> The core DMA-buf framework needs to enable signaling
> before the fence is signaled. The core DMA-buf framework
> can forget to enable signaling before the fence is signaled.
> To avoid this scenario on the debug kernel, check the
> DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT status bit before checking
> the signaling bit status to confirm that enable_signaling
> is enabled.

You might want to put this patch at the end of the series to avoid
breaking the kernel in between.

>
> Signed-off-by: Arvind Yadav <Arvind.Yadav@amd.com>
> ---
> include/linux/dma-fence.h | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
> index 775cdc0b4f24..60c0e935c0b5 100644
> --- a/include/linux/dma-fence.h
> +++ b/include/linux/dma-fence.h
> @@ -428,6 +428,11 @@ dma_fence_is_signaled_locked(struct dma_fence *fence)
> static inline bool
> dma_fence_is_signaled(struct dma_fence *fence)
> {
> +#ifdef CONFIG_DEBUG_FS

CONFIG_DEBUG_FS is certainly wrong, probably better to check for
CONFIG_DEBUG_WW_MUTEX_SLOWPATH here.

Apart from that looks good to me,
Christian.

> + if (!test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags))
> + return false;
> +#endif
> +
> if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
> return true;
>