[Intel-gfx] [PATCH 02/28] dma-buf: add dma_resv_for_each_fence v2

[Christian König]

Good morning, could I get an rb for that patch here as well?

I've pushed the first few with Daniel's and your rbs, but this one here 
is blocking all the rest.

Thanks,
Christian.

Am 05.10.21 um 13:37 schrieb Christian König:
> A simpler version of the iterator to be used when the dma_resv object is
> locked.
>
> v2: fix index check here as well
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>   drivers/dma-buf/dma-resv.c | 49 ++++++++++++++++++++++++++++++++++++++
>   include/linux/dma-resv.h   | 19 +++++++++++++++
>   2 files changed, 68 insertions(+)
>
> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> index 3cbcf66a137e..231bae173ef1 100644
> --- a/drivers/dma-buf/dma-resv.c
> +++ b/drivers/dma-buf/dma-resv.c
> @@ -423,6 +423,55 @@ struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor)
>   }
>   EXPORT_SYMBOL(dma_resv_iter_next_unlocked);
>   
> +/**
> + * dma_resv_iter_first - first fence from a locked dma_resv object
> + * @cursor: cursor to record the current position
> + *
> + * Return all the fences in the dma_resv object while holding the
> + * &dma_resv.lock.
> + */
> +struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor)
> +{
> +	struct dma_fence *fence;
> +
> +	dma_resv_assert_held(cursor->obj);
> +
> +	cursor->index = 0;
> +	cursor->fences = dma_resv_shared_list(cursor->obj);
> +
> +	fence = dma_resv_excl_fence(cursor->obj);
> +	if (!fence)
> +		fence = dma_resv_iter_next(cursor);
> +
> +	cursor->is_restarted = true;
> +	return fence;
> +}
> +EXPORT_SYMBOL_GPL(dma_resv_iter_first);
> +
> +/**
> + * dma_resv_iter_next - next fence from a locked dma_resv object
> + * @cursor: cursor to record the current position
> + *
> + * Return all the fences in the dma_resv object while holding the
> + * &dma_resv.lock.
> + */
> +struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor)
> +{
> +	unsigned int idx;
> +
> +	dma_resv_assert_held(cursor->obj);
> +
> +	cursor->is_restarted = false;
> +	if (!cursor->all_fences || !cursor->fences ||
> +	    cursor->index >= cursor->fences->shared_count)
> +		return NULL;
> +
> +	idx = cursor->index++;
> +	return rcu_dereference_protected(cursor->fences->shared[idx],
> +					 dma_resv_held(cursor->obj));
> +}
> +EXPORT_SYMBOL_GPL(dma_resv_iter_next);
> +
>   /**
>    * dma_resv_copy_fences - Copy all fences from src to dst.
>    * @dst: the destination reservation object
> diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
> index 764138ad8583..3df7ef23712d 100644
> --- a/include/linux/dma-resv.h
> +++ b/include/linux/dma-resv.h
> @@ -179,6 +179,8 @@ struct dma_resv_iter {
>   
>   struct dma_fence *dma_resv_iter_first_unlocked(struct dma_resv_iter *cursor);
>   struct dma_fence *dma_resv_iter_next_unlocked(struct dma_resv_iter *cursor);
> +struct dma_fence *dma_resv_iter_first(struct dma_resv_iter *cursor);
> +struct dma_fence *dma_resv_iter_next(struct dma_resv_iter *cursor);
>   
>   /**
>    * dma_resv_iter_begin - initialize a dma_resv_iter object
> @@ -244,6 +246,23 @@ static inline bool dma_resv_iter_is_restarted(struct dma_resv_iter *cursor)
>   	for (fence = dma_resv_iter_first_unlocked(cursor);		\
>   	     fence; fence = dma_resv_iter_next_unlocked(cursor))
>   
> +/**
> + * dma_resv_for_each_fence - fence iterator
> + * @cursor: a struct dma_resv_iter pointer
> + * @obj: a dma_resv object pointer
> + * @all_fences: true if all fences should be returned
> + * @fence: the current fence
> + *
> + * Iterate over the fences in a struct dma_resv object while holding the
> + * &dma_resv.lock. @all_fences controls if the shared fences are returned as
> + * well. The cursor initialisation is part of the iterator and the fence stays
> + * valid as long as the lock is held.
> + */
> +#define dma_resv_for_each_fence(cursor, obj, all_fences, fence)	\
> +	for (dma_resv_iter_begin(cursor, obj, all_fences),	\
> +	     fence = dma_resv_iter_first(cursor); fence;	\
> +	     fence = dma_resv_iter_next(cursor))
> +
>   #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
>   #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
>