On Tue, Jul 06, 2021 at 11:14:01AM +0200, Daniel Vetter wrote:
> 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>
Also ack for merging through drm-intel-gt-next, I don't think anything in
drm-misc plans to use this anytime soon. But please add the dma-buf Cc:
lines for the next round (dim add-missing-cc should cover you).
-Daniel
>
> > + */
> > +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
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
