On Tue, Jul 06, 2021 at 10:05:58AM +0100, Matthew Auld wrote:
> It might be useful for drivers to annotate a path where hitting the
> actual wait path might be difficult or unlikely through normal testing.
>
> Suggested-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
> Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
> ---
> drivers/dma-buf/dma-fence.c | 19 ++++++++++++++++---
> include/linux/dma-fence.h | 2 ++
> 2 files changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
> index ce0f5eff575d..f2cd036b5243 100644
> --- a/drivers/dma-buf/dma-fence.c
> +++ b/drivers/dma-buf/dma-fence.c
> @@ -335,6 +335,21 @@ void __dma_fence_might_wait(void)
> }
> #endif
>
> +/**
> + * dma_fence_might_wait - entering a section which might wait on DMA fence
> + * critical section.
> + *
> + * This is also potentially useful for drivers to call directly, when annotating
> + * a path where hitting the actual wait path might be difficult or unlikely
> + * through normal testing.
Maybe also add a
"See also dma_fence_begin_signalling() and dma_fence_end_signalling."
here and a similar note the these two functions pointing at
dma_fence_might_wait()? I do like to link things together when there's a
group of functions.
With that: Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> + */
> +void dma_fence_might_wait(void)
> +{
> + might_sleep();
> + __dma_fence_might_wait();
> +}
> +EXPORT_SYMBOL(dma_fence_might_wait);
> +
>
> /**
> * dma_fence_signal_timestamp_locked - signal completion of a fence
> @@ -495,9 +510,7 @@ dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout)
> if (WARN_ON(timeout < 0))
> return -EINVAL;
>
> - might_sleep();
> -
> - __dma_fence_might_wait();
> + dma_fence_might_wait();
>
> trace_dma_fence_wait_start(fence);
> if (fence->ops->wait)
> diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
> index 6ffb4b2c6371..37bf4beed93f 100644
> --- a/include/linux/dma-fence.h
> +++ b/include/linux/dma-fence.h
> @@ -370,6 +370,8 @@ static inline void dma_fence_end_signalling(bool cookie) {}
> static inline void __dma_fence_might_wait(void) {}
> #endif
>
> +void dma_fence_might_wait(void);
> +
> int dma_fence_signal(struct dma_fence *fence);
> int dma_fence_signal_locked(struct dma_fence *fence);
> int dma_fence_signal_timestamp(struct dma_fence *fence, ktime_t timestamp);
> --
> 2.26.3
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
