Re: [PATCH 1/2] dma-fence: export dma_fence_might_wait

[Daniel Vetter <daniel@ffwll.ch>]

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@ffwll.ch>
> > Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> > Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> > ---
> >  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@ffwll.ch>

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