Deploying new iterator interface for dma-buf

Deploying new iterator interface for dma-buf

[Christian König]

Next round for that one here, maybe the CI systems are now more
gracefully with me :)

I'm pretty sure that a couple of those dma_resv_for_each_fence_unlocked
should actually be replaced with lock+dma_resv_for_each_fence, but that
needs more auditing.

Please review and comment.

Thanks,
Christian.

[Intel-gfx] Deploying new iterator interface for dma-buf

[Christian König]

Next round for that one here, maybe the CI systems are now more
gracefully with me :)

I'm pretty sure that a couple of those dma_resv_for_each_fence_unlocked
should actually be replaced with lock+dma_resv_for_each_fence, but that
needs more auditing.

Please review and comment.

Thanks,
Christian.

[PATCH 01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2

[Christian König]

Abstract the complexity of iterating over all the fences
in a dma_resv object.

The new loop handles the whole RCU and retry dance and
returns only fences where we can be sure we grabbed the
right one.

v2: fix accessing the shared fences while they might be freed,
    improve kerneldoc, rename _cursor to _iter, add
    dma_resv_iter_is_exclusive

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 62 ++++++++++++++++++++++++++++++++++++++
 include/linux/dma-resv.h   | 50 ++++++++++++++++++++++++++++++
 2 files changed, 112 insertions(+)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 84fbe60629e3..77083170ec3b 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -323,6 +323,68 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
 }
 EXPORT_SYMBOL(dma_resv_add_excl_fence);
 
+/**
+ * dma_resv_walk_unlocked - walk over fences in a dma_resv obj
+ * @obj: the dma_resv object
+ * @cursor: cursor to record the current position
+ * @all_fences: true returns also the shared fences
+ * @first: if we should start over
+ *
+ * Return all the fences in the dma_resv object which are not yet signaled.
+ * The returned fence has an extra local reference so will stay alive.
+ * If a concurrent modify is detected the whole iterator is started over again.
+ */
+struct dma_fence *dma_resv_walk_unlocked(struct dma_resv *obj,
+					 struct dma_resv_iter *cursor,
+					 bool all_fences, bool first)
+{
+	struct dma_fence *fence = NULL;
+
+	first |= read_seqcount_retry(&obj->seq, cursor->seq);
+	do {
+		/* Drop the reference from the previous round */
+		dma_fence_put(fence);
+
+		cursor->is_first = first;
+		if (first) {
+			cursor->seq = read_seqcount_begin(&obj->seq);
+			cursor->index = -1;
+			cursor->fences = dma_resv_shared_list(obj);
+
+			fence = dma_resv_excl_fence(obj);
+			if (fence && test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
+					      &fence->flags))
+				fence = NULL;
+		} else {
+			fence = NULL;
+		}
+
+		if (fence) {
+			fence = dma_fence_get_rcu(fence);
+		} else if (all_fences && cursor->fences) {
+			struct dma_resv_list *fences = cursor->fences;
+
+			while (++cursor->index < fences->shared_count) {
+				fence = rcu_dereference(
+					fences->shared[cursor->index]);
+				if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
+					      &fence->flags))
+					break;
+			}
+			if (cursor->index < fences->shared_count)
+				fence = dma_fence_get_rcu(fence);
+			else
+				fence = NULL;
+		}
+
+		/* For the eventually next round */
+		first = true;
+	} while (read_seqcount_retry(&obj->seq, cursor->seq));
+
+	return fence;
+}
+EXPORT_SYMBOL_GPL(dma_resv_walk_unlocked);
+
 /**
  * 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 9100dd3dc21f..1cd686384c71 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -149,6 +149,53 @@ struct dma_resv {
 	struct dma_resv_list __rcu *fence;
 };
 
+/**
+ * struct dma_resv_iter - current position into the dma_resv fences
+ *
+ * Don't touch this directly in the driver, use the accessor function instead.
+ */
+struct dma_resv_iter {
+	/** @seq: sequence number to check for modifications */
+	unsigned int seq;
+
+	/** @index: index into the shared fences */
+	unsigned int index;
+
+	/** @fences: the shared fences */
+	struct dma_resv_list *fences;
+
+	/** @is_first: true if this is the first returned fence */
+	bool is_first;
+};
+
+/**
+ * dma_resv_for_each_fence_unlocked - fence iterator
+ * @obj: a dma_resv object pointer
+ * @cursor: a struct dma_resv_iter pointer
+ * @all_fences: true if all fences should be returned
+ * @fence: the current fence
+ *
+ * Iterate over the fences in a struct dma_resv object without holding the
+ * dma_resv::lock. The RCU read side lock must be hold when using this, but can
+ * be dropped and re-taken as necessary inside the loop. @all_fences controls
+ * if the shared fences are returned as well.
+ */
+#define dma_resv_for_each_fence_unlocked(obj, cursor, all_fences, fence)    \
+	for (fence = dma_resv_walk_unlocked(obj, cursor, all_fences, true); \
+	     fence; dma_fence_put(fence),				    \
+	     fence = dma_resv_walk_unlocked(obj, cursor, all_fences, false))
+
+/**
+ * dma_resv_iter_is_exclusive - test if the current fence is the exclusive one
+ * @cursor: the cursor of the current position
+ *
+ * Returns true if the currently returned fence is the exclusive one.
+ */
+static inline bool dma_resv_iter_is_exclusive(struct dma_resv_iter *cursor)
+{
+	return cursor->index == -1;
+}
+
 #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
 #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
 
@@ -366,6 +413,9 @@ void dma_resv_fini(struct dma_resv *obj);
 int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
+struct dma_fence *dma_resv_walk_unlocked(struct dma_resv *obj,
+					 struct dma_resv_iter *cursor,
+					 bool first, bool all_fences);
 int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl,
 			unsigned *pshared_count, struct dma_fence ***pshared);
 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
-- 
2.25.1

[Intel-gfx] [PATCH 01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2

[Christian König]

Abstract the complexity of iterating over all the fences
in a dma_resv object.

The new loop handles the whole RCU and retry dance and
returns only fences where we can be sure we grabbed the
right one.

v2: fix accessing the shared fences while they might be freed,
    improve kerneldoc, rename _cursor to _iter, add
    dma_resv_iter_is_exclusive

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 62 ++++++++++++++++++++++++++++++++++++++
 include/linux/dma-resv.h   | 50 ++++++++++++++++++++++++++++++
 2 files changed, 112 insertions(+)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 84fbe60629e3..77083170ec3b 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -323,6 +323,68 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
 }
 EXPORT_SYMBOL(dma_resv_add_excl_fence);
 
+/**
+ * dma_resv_walk_unlocked - walk over fences in a dma_resv obj
+ * @obj: the dma_resv object
+ * @cursor: cursor to record the current position
+ * @all_fences: true returns also the shared fences
+ * @first: if we should start over
+ *
+ * Return all the fences in the dma_resv object which are not yet signaled.
+ * The returned fence has an extra local reference so will stay alive.
+ * If a concurrent modify is detected the whole iterator is started over again.
+ */
+struct dma_fence *dma_resv_walk_unlocked(struct dma_resv *obj,
+					 struct dma_resv_iter *cursor,
+					 bool all_fences, bool first)
+{
+	struct dma_fence *fence = NULL;
+
+	first |= read_seqcount_retry(&obj->seq, cursor->seq);
+	do {
+		/* Drop the reference from the previous round */
+		dma_fence_put(fence);
+
+		cursor->is_first = first;
+		if (first) {
+			cursor->seq = read_seqcount_begin(&obj->seq);
+			cursor->index = -1;
+			cursor->fences = dma_resv_shared_list(obj);
+
+			fence = dma_resv_excl_fence(obj);
+			if (fence && test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
+					      &fence->flags))
+				fence = NULL;
+		} else {
+			fence = NULL;
+		}
+
+		if (fence) {
+			fence = dma_fence_get_rcu(fence);
+		} else if (all_fences && cursor->fences) {
+			struct dma_resv_list *fences = cursor->fences;
+
+			while (++cursor->index < fences->shared_count) {
+				fence = rcu_dereference(
+					fences->shared[cursor->index]);
+				if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
+					      &fence->flags))
+					break;
+			}
+			if (cursor->index < fences->shared_count)
+				fence = dma_fence_get_rcu(fence);
+			else
+				fence = NULL;
+		}
+
+		/* For the eventually next round */
+		first = true;
+	} while (read_seqcount_retry(&obj->seq, cursor->seq));
+
+	return fence;
+}
+EXPORT_SYMBOL_GPL(dma_resv_walk_unlocked);
+
 /**
  * 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 9100dd3dc21f..1cd686384c71 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -149,6 +149,53 @@ struct dma_resv {
 	struct dma_resv_list __rcu *fence;
 };
 
+/**
+ * struct dma_resv_iter - current position into the dma_resv fences
+ *
+ * Don't touch this directly in the driver, use the accessor function instead.
+ */
+struct dma_resv_iter {
+	/** @seq: sequence number to check for modifications */
+	unsigned int seq;
+
+	/** @index: index into the shared fences */
+	unsigned int index;
+
+	/** @fences: the shared fences */
+	struct dma_resv_list *fences;
+
+	/** @is_first: true if this is the first returned fence */
+	bool is_first;
+};
+
+/**
+ * dma_resv_for_each_fence_unlocked - fence iterator
+ * @obj: a dma_resv object pointer
+ * @cursor: a struct dma_resv_iter pointer
+ * @all_fences: true if all fences should be returned
+ * @fence: the current fence
+ *
+ * Iterate over the fences in a struct dma_resv object without holding the
+ * dma_resv::lock. The RCU read side lock must be hold when using this, but can
+ * be dropped and re-taken as necessary inside the loop. @all_fences controls
+ * if the shared fences are returned as well.
+ */
+#define dma_resv_for_each_fence_unlocked(obj, cursor, all_fences, fence)    \
+	for (fence = dma_resv_walk_unlocked(obj, cursor, all_fences, true); \
+	     fence; dma_fence_put(fence),				    \
+	     fence = dma_resv_walk_unlocked(obj, cursor, all_fences, false))
+
+/**
+ * dma_resv_iter_is_exclusive - test if the current fence is the exclusive one
+ * @cursor: the cursor of the current position
+ *
+ * Returns true if the currently returned fence is the exclusive one.
+ */
+static inline bool dma_resv_iter_is_exclusive(struct dma_resv_iter *cursor)
+{
+	return cursor->index == -1;
+}
+
 #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
 #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
 
@@ -366,6 +413,9 @@ void dma_resv_fini(struct dma_resv *obj);
 int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
+struct dma_fence *dma_resv_walk_unlocked(struct dma_resv *obj,
+					 struct dma_resv_iter *cursor,
+					 bool first, bool all_fences);
 int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl,
 			unsigned *pshared_count, struct dma_fence ***pshared);
 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
-- 
2.25.1

Re: [PATCH 01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2

[Daniel Vetter]

On Thu, Sep 16, 2021 at 01:30:17PM +0200, Christian König wrote:
> Abstract the complexity of iterating over all the fences
> in a dma_resv object.
> 
> The new loop handles the whole RCU and retry dance and
> returns only fences where we can be sure we grabbed the
> right one.
> 
> v2: fix accessing the shared fences while they might be freed,
>     improve kerneldoc, rename _cursor to _iter, add
>     dma_resv_iter_is_exclusive
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>

Replied in the other thread with the fully typed out example, this really
needs iter_init/next/end here. Or it's just way too fragile and tricky for
a generic helper that we roll out everywhere.
-Daniel

> ---
>  drivers/dma-buf/dma-resv.c | 62 ++++++++++++++++++++++++++++++++++++++
>  include/linux/dma-resv.h   | 50 ++++++++++++++++++++++++++++++
>  2 files changed, 112 insertions(+)
> 
> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> index 84fbe60629e3..77083170ec3b 100644
> --- a/drivers/dma-buf/dma-resv.c
> +++ b/drivers/dma-buf/dma-resv.c
> @@ -323,6 +323,68 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
>  }
>  EXPORT_SYMBOL(dma_resv_add_excl_fence);
>  
> +/**
> + * dma_resv_walk_unlocked - walk over fences in a dma_resv obj
> + * @obj: the dma_resv object
> + * @cursor: cursor to record the current position
> + * @all_fences: true returns also the shared fences
> + * @first: if we should start over
> + *
> + * Return all the fences in the dma_resv object which are not yet signaled.
> + * The returned fence has an extra local reference so will stay alive.
> + * If a concurrent modify is detected the whole iterator is started over again.
> + */
> +struct dma_fence *dma_resv_walk_unlocked(struct dma_resv *obj,
> +					 struct dma_resv_iter *cursor,
> +					 bool all_fences, bool first)
> +{
> +	struct dma_fence *fence = NULL;
> +
> +	first |= read_seqcount_retry(&obj->seq, cursor->seq);
> +	do {
> +		/* Drop the reference from the previous round */
> +		dma_fence_put(fence);
> +
> +		cursor->is_first = first;
> +		if (first) {
> +			cursor->seq = read_seqcount_begin(&obj->seq);
> +			cursor->index = -1;
> +			cursor->fences = dma_resv_shared_list(obj);
> +
> +			fence = dma_resv_excl_fence(obj);
> +			if (fence && test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
> +					      &fence->flags))
> +				fence = NULL;
> +		} else {
> +			fence = NULL;
> +		}
> +
> +		if (fence) {
> +			fence = dma_fence_get_rcu(fence);
> +		} else if (all_fences && cursor->fences) {
> +			struct dma_resv_list *fences = cursor->fences;
> +
> +			while (++cursor->index < fences->shared_count) {
> +				fence = rcu_dereference(
> +					fences->shared[cursor->index]);
> +				if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
> +					      &fence->flags))
> +					break;
> +			}
> +			if (cursor->index < fences->shared_count)
> +				fence = dma_fence_get_rcu(fence);
> +			else
> +				fence = NULL;
> +		}
> +
> +		/* For the eventually next round */
> +		first = true;
> +	} while (read_seqcount_retry(&obj->seq, cursor->seq));
> +
> +	return fence;
> +}
> +EXPORT_SYMBOL_GPL(dma_resv_walk_unlocked);
> +
>  /**
>   * 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 9100dd3dc21f..1cd686384c71 100644
> --- a/include/linux/dma-resv.h
> +++ b/include/linux/dma-resv.h
> @@ -149,6 +149,53 @@ struct dma_resv {
>  	struct dma_resv_list __rcu *fence;
>  };
>  
> +/**
> + * struct dma_resv_iter - current position into the dma_resv fences
> + *
> + * Don't touch this directly in the driver, use the accessor function instead.
> + */
> +struct dma_resv_iter {
> +	/** @seq: sequence number to check for modifications */
> +	unsigned int seq;
> +
> +	/** @index: index into the shared fences */
> +	unsigned int index;
> +
> +	/** @fences: the shared fences */
> +	struct dma_resv_list *fences;
> +
> +	/** @is_first: true if this is the first returned fence */
> +	bool is_first;
> +};
> +
> +/**
> + * dma_resv_for_each_fence_unlocked - fence iterator
> + * @obj: a dma_resv object pointer
> + * @cursor: a struct dma_resv_iter pointer
> + * @all_fences: true if all fences should be returned
> + * @fence: the current fence
> + *
> + * Iterate over the fences in a struct dma_resv object without holding the
> + * dma_resv::lock. The RCU read side lock must be hold when using this, but can
> + * be dropped and re-taken as necessary inside the loop. @all_fences controls
> + * if the shared fences are returned as well.
> + */
> +#define dma_resv_for_each_fence_unlocked(obj, cursor, all_fences, fence)    \
> +	for (fence = dma_resv_walk_unlocked(obj, cursor, all_fences, true); \
> +	     fence; dma_fence_put(fence),				    \
> +	     fence = dma_resv_walk_unlocked(obj, cursor, all_fences, false))
> +
> +/**
> + * dma_resv_iter_is_exclusive - test if the current fence is the exclusive one
> + * @cursor: the cursor of the current position
> + *
> + * Returns true if the currently returned fence is the exclusive one.
> + */
> +static inline bool dma_resv_iter_is_exclusive(struct dma_resv_iter *cursor)
> +{
> +	return cursor->index == -1;
> +}
> +
>  #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
>  #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
>  
> @@ -366,6 +413,9 @@ void dma_resv_fini(struct dma_resv *obj);
>  int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
>  void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
>  void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
> +struct dma_fence *dma_resv_walk_unlocked(struct dma_resv *obj,
> +					 struct dma_resv_iter *cursor,
> +					 bool first, bool all_fences);
>  int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl,
>  			unsigned *pshared_count, struct dma_fence ***pshared);
>  int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Re: [Intel-gfx] [PATCH 01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2

[Daniel Vetter]

On Thu, Sep 16, 2021 at 01:30:17PM +0200, Christian König wrote:
> Abstract the complexity of iterating over all the fences
> in a dma_resv object.
> 
> The new loop handles the whole RCU and retry dance and
> returns only fences where we can be sure we grabbed the
> right one.
> 
> v2: fix accessing the shared fences while they might be freed,
>     improve kerneldoc, rename _cursor to _iter, add
>     dma_resv_iter_is_exclusive
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>

Replied in the other thread with the fully typed out example, this really
needs iter_init/next/end here. Or it's just way too fragile and tricky for
a generic helper that we roll out everywhere.
-Daniel

> ---
>  drivers/dma-buf/dma-resv.c | 62 ++++++++++++++++++++++++++++++++++++++
>  include/linux/dma-resv.h   | 50 ++++++++++++++++++++++++++++++
>  2 files changed, 112 insertions(+)
> 
> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> index 84fbe60629e3..77083170ec3b 100644
> --- a/drivers/dma-buf/dma-resv.c
> +++ b/drivers/dma-buf/dma-resv.c
> @@ -323,6 +323,68 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
>  }
>  EXPORT_SYMBOL(dma_resv_add_excl_fence);
>  
> +/**
> + * dma_resv_walk_unlocked - walk over fences in a dma_resv obj
> + * @obj: the dma_resv object
> + * @cursor: cursor to record the current position
> + * @all_fences: true returns also the shared fences
> + * @first: if we should start over
> + *
> + * Return all the fences in the dma_resv object which are not yet signaled.
> + * The returned fence has an extra local reference so will stay alive.
> + * If a concurrent modify is detected the whole iterator is started over again.
> + */
> +struct dma_fence *dma_resv_walk_unlocked(struct dma_resv *obj,
> +					 struct dma_resv_iter *cursor,
> +					 bool all_fences, bool first)
> +{
> +	struct dma_fence *fence = NULL;
> +
> +	first |= read_seqcount_retry(&obj->seq, cursor->seq);
> +	do {
> +		/* Drop the reference from the previous round */
> +		dma_fence_put(fence);
> +
> +		cursor->is_first = first;
> +		if (first) {
> +			cursor->seq = read_seqcount_begin(&obj->seq);
> +			cursor->index = -1;
> +			cursor->fences = dma_resv_shared_list(obj);
> +
> +			fence = dma_resv_excl_fence(obj);
> +			if (fence && test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
> +					      &fence->flags))
> +				fence = NULL;
> +		} else {
> +			fence = NULL;
> +		}
> +
> +		if (fence) {
> +			fence = dma_fence_get_rcu(fence);
> +		} else if (all_fences && cursor->fences) {
> +			struct dma_resv_list *fences = cursor->fences;
> +
> +			while (++cursor->index < fences->shared_count) {
> +				fence = rcu_dereference(
> +					fences->shared[cursor->index]);
> +				if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
> +					      &fence->flags))
> +					break;
> +			}
> +			if (cursor->index < fences->shared_count)
> +				fence = dma_fence_get_rcu(fence);
> +			else
> +				fence = NULL;
> +		}
> +
> +		/* For the eventually next round */
> +		first = true;
> +	} while (read_seqcount_retry(&obj->seq, cursor->seq));
> +
> +	return fence;
> +}
> +EXPORT_SYMBOL_GPL(dma_resv_walk_unlocked);
> +
>  /**
>   * 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 9100dd3dc21f..1cd686384c71 100644
> --- a/include/linux/dma-resv.h
> +++ b/include/linux/dma-resv.h
> @@ -149,6 +149,53 @@ struct dma_resv {
>  	struct dma_resv_list __rcu *fence;
>  };
>  
> +/**
> + * struct dma_resv_iter - current position into the dma_resv fences
> + *
> + * Don't touch this directly in the driver, use the accessor function instead.
> + */
> +struct dma_resv_iter {
> +	/** @seq: sequence number to check for modifications */
> +	unsigned int seq;
> +
> +	/** @index: index into the shared fences */
> +	unsigned int index;
> +
> +	/** @fences: the shared fences */
> +	struct dma_resv_list *fences;
> +
> +	/** @is_first: true if this is the first returned fence */
> +	bool is_first;
> +};
> +
> +/**
> + * dma_resv_for_each_fence_unlocked - fence iterator
> + * @obj: a dma_resv object pointer
> + * @cursor: a struct dma_resv_iter pointer
> + * @all_fences: true if all fences should be returned
> + * @fence: the current fence
> + *
> + * Iterate over the fences in a struct dma_resv object without holding the
> + * dma_resv::lock. The RCU read side lock must be hold when using this, but can
> + * be dropped and re-taken as necessary inside the loop. @all_fences controls
> + * if the shared fences are returned as well.
> + */
> +#define dma_resv_for_each_fence_unlocked(obj, cursor, all_fences, fence)    \
> +	for (fence = dma_resv_walk_unlocked(obj, cursor, all_fences, true); \
> +	     fence; dma_fence_put(fence),				    \
> +	     fence = dma_resv_walk_unlocked(obj, cursor, all_fences, false))
> +
> +/**
> + * dma_resv_iter_is_exclusive - test if the current fence is the exclusive one
> + * @cursor: the cursor of the current position
> + *
> + * Returns true if the currently returned fence is the exclusive one.
> + */
> +static inline bool dma_resv_iter_is_exclusive(struct dma_resv_iter *cursor)
> +{
> +	return cursor->index == -1;
> +}
> +
>  #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
>  #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
>  
> @@ -366,6 +413,9 @@ void dma_resv_fini(struct dma_resv *obj);
>  int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
>  void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
>  void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
> +struct dma_fence *dma_resv_walk_unlocked(struct dma_resv *obj,
> +					 struct dma_resv_iter *cursor,
> +					 bool first, bool all_fences);
>  int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl,
>  			unsigned *pshared_count, struct dma_fence ***pshared);
>  int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

[PATCH 02/26] dma-buf: add dma_resv_for_each_fence

[Christian König]

A simpler version of the iterator to be used when the dma_resv object is
locked.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 37 +++++++++++++++++++++++++++++++++++++
 include/linux/dma-resv.h   | 18 ++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 77083170ec3b..bbf36a08ced0 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -323,6 +323,43 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
 }
 EXPORT_SYMBOL(dma_resv_add_excl_fence);
 
+/**
+ * dma_resv_walk - walk over fences in a dma_resv obj
+ * @obj: the dma_resv object
+ * @cursor: cursor to record the current position
+ * @all_fences: true returns also the shared fences
+ * @first: if we should start over
+ *
+ * Return all the fences in the dma_resv object while holding the
+ * dma_resv::lock.
+ */
+struct dma_fence *dma_resv_walk(struct dma_resv *obj,
+				struct dma_resv_iter *cursor,
+				bool all_fences, bool first)
+{
+	dma_resv_assert_held(obj);
+
+	cursor->is_first = first;
+	if (first) {
+		struct dma_fence *fence;
+
+		cursor->index = -1;
+		cursor->fences = dma_resv_shared_list(obj);
+
+		fence = dma_resv_excl_fence(obj);
+		if (fence)
+			return fence;
+	}
+
+	if (!all_fences || !cursor->fences ||
+	    ++cursor->index >= cursor->fences->shared_count)
+		return NULL;
+
+	return rcu_dereference_protected(cursor->fences->shared[cursor->index],
+					 dma_resv_held(obj));
+}
+EXPORT_SYMBOL_GPL(dma_resv_walk);
+
 /**
  * dma_resv_walk_unlocked - walk over fences in a dma_resv obj
  * @obj: the dma_resv object
diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
index 1cd686384c71..6761512ba662 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -168,6 +168,21 @@ struct dma_resv_iter {
 	bool is_first;
 };
 
+/**
+ * dma_resv_for_each_fence - fence iterator
+ * @obj: a dma_resv object pointer
+ * @cursor: a struct dma_resv_iter 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.
+ */
+#define dma_resv_for_each_fence(obj, cursor, all_fences, fence)		  \
+	for (fence = dma_resv_walk(obj, cursor, all_fences, true); fence; \
+	     fence = dma_resv_walk(obj, cursor, all_fences, false))
+
 /**
  * dma_resv_for_each_fence_unlocked - fence iterator
  * @obj: a dma_resv object pointer
@@ -413,6 +428,9 @@ void dma_resv_fini(struct dma_resv *obj);
 int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
+struct dma_fence *dma_resv_walk(struct dma_resv *obj,
+				struct dma_resv_iter *cursor,
+				bool first, bool all_fences);
 struct dma_fence *dma_resv_walk_unlocked(struct dma_resv *obj,
 					 struct dma_resv_iter *cursor,
 					 bool first, bool all_fences);
-- 
2.25.1

[Intel-gfx] [PATCH 02/26] dma-buf: add dma_resv_for_each_fence

[Christian König]

A simpler version of the iterator to be used when the dma_resv object is
locked.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 37 +++++++++++++++++++++++++++++++++++++
 include/linux/dma-resv.h   | 18 ++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 77083170ec3b..bbf36a08ced0 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -323,6 +323,43 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
 }
 EXPORT_SYMBOL(dma_resv_add_excl_fence);
 
+/**
+ * dma_resv_walk - walk over fences in a dma_resv obj
+ * @obj: the dma_resv object
+ * @cursor: cursor to record the current position
+ * @all_fences: true returns also the shared fences
+ * @first: if we should start over
+ *
+ * Return all the fences in the dma_resv object while holding the
+ * dma_resv::lock.
+ */
+struct dma_fence *dma_resv_walk(struct dma_resv *obj,
+				struct dma_resv_iter *cursor,
+				bool all_fences, bool first)
+{
+	dma_resv_assert_held(obj);
+
+	cursor->is_first = first;
+	if (first) {
+		struct dma_fence *fence;
+
+		cursor->index = -1;
+		cursor->fences = dma_resv_shared_list(obj);
+
+		fence = dma_resv_excl_fence(obj);
+		if (fence)
+			return fence;
+	}
+
+	if (!all_fences || !cursor->fences ||
+	    ++cursor->index >= cursor->fences->shared_count)
+		return NULL;
+
+	return rcu_dereference_protected(cursor->fences->shared[cursor->index],
+					 dma_resv_held(obj));
+}
+EXPORT_SYMBOL_GPL(dma_resv_walk);
+
 /**
  * dma_resv_walk_unlocked - walk over fences in a dma_resv obj
  * @obj: the dma_resv object
diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
index 1cd686384c71..6761512ba662 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -168,6 +168,21 @@ struct dma_resv_iter {
 	bool is_first;
 };
 
+/**
+ * dma_resv_for_each_fence - fence iterator
+ * @obj: a dma_resv object pointer
+ * @cursor: a struct dma_resv_iter 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.
+ */
+#define dma_resv_for_each_fence(obj, cursor, all_fences, fence)		  \
+	for (fence = dma_resv_walk(obj, cursor, all_fences, true); fence; \
+	     fence = dma_resv_walk(obj, cursor, all_fences, false))
+
 /**
  * dma_resv_for_each_fence_unlocked - fence iterator
  * @obj: a dma_resv object pointer
@@ -413,6 +428,9 @@ void dma_resv_fini(struct dma_resv *obj);
 int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
 void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
 void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
+struct dma_fence *dma_resv_walk(struct dma_resv *obj,
+				struct dma_resv_iter *cursor,
+				bool first, bool all_fences);
 struct dma_fence *dma_resv_walk_unlocked(struct dma_resv *obj,
 					 struct dma_resv_iter *cursor,
 					 bool first, bool all_fences);
-- 
2.25.1

[PATCH 03/26] dma-buf: use new iterator in dma_resv_copy_fences

[Christian König]

This makes the function much simpler since the complex
retry logic is now handled else where.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 81 +++++++++++++++-----------------------
 1 file changed, 32 insertions(+), 49 deletions(-)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index bbf36a08ced0..91c040cb7d63 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -431,74 +431,57 @@ EXPORT_SYMBOL_GPL(dma_resv_walk_unlocked);
  */
 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
 {
-	struct dma_resv_list *src_list, *dst_list;
-	struct dma_fence *old, *new;
-	unsigned int i;
+	struct dma_resv_iter cursor;
+	struct dma_resv_list *list;
+	struct dma_fence *f, *excl;
 
 	dma_resv_assert_held(dst);
 
-	rcu_read_lock();
-	src_list = dma_resv_shared_list(src);
+	list = NULL;
+	excl = NULL;
 
-retry:
-	if (src_list) {
-		unsigned int shared_count = src_list->shared_count;
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(dst, &cursor, true, f) {
 
-		rcu_read_unlock();
+		if (cursor.is_first) {
+			dma_resv_list_free(list);
+			dma_fence_put(excl);
 
-		dst_list = dma_resv_list_alloc(shared_count);
-		if (!dst_list)
-			return -ENOMEM;
+			if (cursor.fences) {
+				unsigned int cnt = cursor.fences->shared_count;
 
-		rcu_read_lock();
-		src_list = dma_resv_shared_list(src);
-		if (!src_list || src_list->shared_count > shared_count) {
-			kfree(dst_list);
-			goto retry;
-		}
+				rcu_read_unlock();
+				list = dma_resv_list_alloc(cnt);
+				if (!list)
+					return -ENOMEM;
 
-		dst_list->shared_count = 0;
-		for (i = 0; i < src_list->shared_count; ++i) {
-			struct dma_fence __rcu **dst;
-			struct dma_fence *fence;
+				list->shared_count = 0;
+				rcu_read_lock();
 
-			fence = rcu_dereference(src_list->shared[i]);
-			if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
-				     &fence->flags))
-				continue;
-
-			if (!dma_fence_get_rcu(fence)) {
-				dma_resv_list_free(dst_list);
-				src_list = dma_resv_shared_list(src);
-				goto retry;
+			} else {
+				list = NULL;
 			}
+			excl = NULL;
+		}
 
-			if (dma_fence_is_signaled(fence)) {
-				dma_fence_put(fence);
-				continue;
-			}
+		if (dma_resv_iter_is_exclusive(&cursor))
+			excl = f;
+		else
+			RCU_INIT_POINTER(list->shared[list->shared_count++], f);
 
-			dst = &dst_list->shared[dst_list->shared_count++];
-			rcu_assign_pointer(*dst, fence);
-		}
-	} else {
-		dst_list = NULL;
+		/* Don't drop the reference */
+		f = NULL;
 	}
 
-	new = dma_fence_get_rcu_safe(&src->fence_excl);
 	rcu_read_unlock();
 
-	src_list = dma_resv_shared_list(dst);
-	old = dma_resv_excl_fence(dst);
-
 	write_seqcount_begin(&dst->seq);
-	/* write_seqcount_begin provides the necessary memory barrier */
-	RCU_INIT_POINTER(dst->fence_excl, new);
-	RCU_INIT_POINTER(dst->fence, dst_list);
+	excl = rcu_replace_pointer(dst->fence_excl, excl, dma_resv_held(dst));
+	list = rcu_replace_pointer(dst->fence, list, dma_resv_held(dst));
 	write_seqcount_end(&dst->seq);
 
-	dma_resv_list_free(src_list);
-	dma_fence_put(old);
+	dma_resv_list_free(list);
+	dma_fence_put(excl);
 
 	return 0;
 }
-- 
2.25.1

[Intel-gfx] [PATCH 03/26] dma-buf: use new iterator in dma_resv_copy_fences

[Christian König]

This makes the function much simpler since the complex
retry logic is now handled else where.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 81 +++++++++++++++-----------------------
 1 file changed, 32 insertions(+), 49 deletions(-)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index bbf36a08ced0..91c040cb7d63 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -431,74 +431,57 @@ EXPORT_SYMBOL_GPL(dma_resv_walk_unlocked);
  */
 int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src)
 {
-	struct dma_resv_list *src_list, *dst_list;
-	struct dma_fence *old, *new;
-	unsigned int i;
+	struct dma_resv_iter cursor;
+	struct dma_resv_list *list;
+	struct dma_fence *f, *excl;
 
 	dma_resv_assert_held(dst);
 
-	rcu_read_lock();
-	src_list = dma_resv_shared_list(src);
+	list = NULL;
+	excl = NULL;
 
-retry:
-	if (src_list) {
-		unsigned int shared_count = src_list->shared_count;
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(dst, &cursor, true, f) {
 
-		rcu_read_unlock();
+		if (cursor.is_first) {
+			dma_resv_list_free(list);
+			dma_fence_put(excl);
 
-		dst_list = dma_resv_list_alloc(shared_count);
-		if (!dst_list)
-			return -ENOMEM;
+			if (cursor.fences) {
+				unsigned int cnt = cursor.fences->shared_count;
 
-		rcu_read_lock();
-		src_list = dma_resv_shared_list(src);
-		if (!src_list || src_list->shared_count > shared_count) {
-			kfree(dst_list);
-			goto retry;
-		}
+				rcu_read_unlock();
+				list = dma_resv_list_alloc(cnt);
+				if (!list)
+					return -ENOMEM;
 
-		dst_list->shared_count = 0;
-		for (i = 0; i < src_list->shared_count; ++i) {
-			struct dma_fence __rcu **dst;
-			struct dma_fence *fence;
+				list->shared_count = 0;
+				rcu_read_lock();
 
-			fence = rcu_dereference(src_list->shared[i]);
-			if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
-				     &fence->flags))
-				continue;
-
-			if (!dma_fence_get_rcu(fence)) {
-				dma_resv_list_free(dst_list);
-				src_list = dma_resv_shared_list(src);
-				goto retry;
+			} else {
+				list = NULL;
 			}
+			excl = NULL;
+		}
 
-			if (dma_fence_is_signaled(fence)) {
-				dma_fence_put(fence);
-				continue;
-			}
+		if (dma_resv_iter_is_exclusive(&cursor))
+			excl = f;
+		else
+			RCU_INIT_POINTER(list->shared[list->shared_count++], f);
 
-			dst = &dst_list->shared[dst_list->shared_count++];
-			rcu_assign_pointer(*dst, fence);
-		}
-	} else {
-		dst_list = NULL;
+		/* Don't drop the reference */
+		f = NULL;
 	}
 
-	new = dma_fence_get_rcu_safe(&src->fence_excl);
 	rcu_read_unlock();
 
-	src_list = dma_resv_shared_list(dst);
-	old = dma_resv_excl_fence(dst);
-
 	write_seqcount_begin(&dst->seq);
-	/* write_seqcount_begin provides the necessary memory barrier */
-	RCU_INIT_POINTER(dst->fence_excl, new);
-	RCU_INIT_POINTER(dst->fence, dst_list);
+	excl = rcu_replace_pointer(dst->fence_excl, excl, dma_resv_held(dst));
+	list = rcu_replace_pointer(dst->fence, list, dma_resv_held(dst));
 	write_seqcount_end(&dst->seq);
 
-	dma_resv_list_free(src_list);
-	dma_fence_put(old);
+	dma_resv_list_free(list);
+	dma_fence_put(excl);
 
 	return 0;
 }
-- 
2.25.1

[PATCH 04/26] dma-buf: use new iterator in dma_resv_get_fences v2

[Christian König]

This makes the function much simpler since the complex
retry logic is now handled elsewhere.

v2: use sizeof(void*) instead

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 110 +++++++++++++------------------------
 1 file changed, 37 insertions(+), 73 deletions(-)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 91c040cb7d63..bba328475304 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -491,99 +491,63 @@ EXPORT_SYMBOL(dma_resv_copy_fences);
  * dma_resv_get_fences - Get an object's shared and exclusive
  * fences without update side lock held
  * @obj: the reservation object
- * @pfence_excl: the returned exclusive fence (or NULL)
- * @pshared_count: the number of shared fences returned
- * @pshared: the array of shared fence ptrs returned (array is krealloc'd to
+ * @fence_excl: the returned exclusive fence (or NULL)
+ * @shared_count: the number of shared fences returned
+ * @shared: the array of shared fence ptrs returned (array is krealloc'd to
  * the required size, and must be freed by caller)
  *
  * Retrieve all fences from the reservation object. If the pointer for the
  * exclusive fence is not specified the fence is put into the array of the
  * shared fences as well. Returns either zero or -ENOMEM.
  */
-int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl,
-			unsigned int *pshared_count,
-			struct dma_fence ***pshared)
+int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **fence_excl,
+			unsigned int *shared_count, struct dma_fence ***shared)
 {
-	struct dma_fence **shared = NULL;
-	struct dma_fence *fence_excl;
-	unsigned int shared_count;
-	int ret = 1;
-
-	do {
-		struct dma_resv_list *fobj;
-		unsigned int i, seq;
-		size_t sz = 0;
-
-		shared_count = i = 0;
-
-		rcu_read_lock();
-		seq = read_seqcount_begin(&obj->seq);
-
-		fence_excl = dma_resv_excl_fence(obj);
-		if (fence_excl && !dma_fence_get_rcu(fence_excl))
-			goto unlock;
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
 
-		fobj = dma_resv_shared_list(obj);
-		if (fobj)
-			sz += sizeof(*shared) * fobj->shared_max;
+	*shared_count = 0;
+	*shared = NULL;
 
-		if (!pfence_excl && fence_excl)
-			sz += sizeof(*shared);
+	if (fence_excl)
+		*fence_excl = NULL;
 
-		if (sz) {
-			struct dma_fence **nshared;
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(obj, &cursor, true, fence) {
 
-			nshared = krealloc(shared, sz,
-					   GFP_NOWAIT | __GFP_NOWARN);
-			if (!nshared) {
-				rcu_read_unlock();
+		if (cursor.is_first) {
+			unsigned int count;
 
-				dma_fence_put(fence_excl);
-				fence_excl = NULL;
+			while (*shared_count)
+				dma_fence_put((*shared)[--(*shared_count)]);
 
-				nshared = krealloc(shared, sz, GFP_KERNEL);
-				if (nshared) {
-					shared = nshared;
-					continue;
-				}
+			if (fence_excl)
+				dma_fence_put(*fence_excl);
 
-				ret = -ENOMEM;
-				break;
-			}
-			shared = nshared;
-			shared_count = fobj ? fobj->shared_count : 0;
-			for (i = 0; i < shared_count; ++i) {
-				shared[i] = rcu_dereference(fobj->shared[i]);
-				if (!dma_fence_get_rcu(shared[i]))
-					break;
-			}
-		}
+			count = cursor.fences ? cursor.fences->shared_count : 0;
+			count += fence_excl ? 0 : 1;
+			rcu_read_unlock();
 
-		if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) {
-			while (i--)
-				dma_fence_put(shared[i]);
-			dma_fence_put(fence_excl);
-			goto unlock;
+			/* Eventually re-allocate the array */
+			*shared = krealloc_array(*shared, count,
+						 sizeof(void *),
+						 GFP_KERNEL);
+			if (count && !*shared)
+				return -ENOMEM;
+			rcu_read_lock();
 		}
 
-		ret = 0;
-unlock:
-		rcu_read_unlock();
-	} while (ret);
-
-	if (pfence_excl)
-		*pfence_excl = fence_excl;
-	else if (fence_excl)
-		shared[shared_count++] = fence_excl;
+		if (dma_resv_iter_is_exclusive(&cursor) && fence_excl)
+			*fence_excl = fence;
+		else
+			(*shared)[(*shared_count)++] = fence;
 
-	if (!shared_count) {
-		kfree(shared);
-		shared = NULL;
+		/* Don't drop the reference */
+		fence = NULL;
 	}
+	rcu_read_unlock();
 
-	*pshared_count = shared_count;
-	*pshared = shared;
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(dma_resv_get_fences);
 
-- 
2.25.1

[Intel-gfx] [PATCH 04/26] dma-buf: use new iterator in dma_resv_get_fences v2

[Christian König]

This makes the function much simpler since the complex
retry logic is now handled elsewhere.

v2: use sizeof(void*) instead

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 110 +++++++++++++------------------------
 1 file changed, 37 insertions(+), 73 deletions(-)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 91c040cb7d63..bba328475304 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -491,99 +491,63 @@ EXPORT_SYMBOL(dma_resv_copy_fences);
  * dma_resv_get_fences - Get an object's shared and exclusive
  * fences without update side lock held
  * @obj: the reservation object
- * @pfence_excl: the returned exclusive fence (or NULL)
- * @pshared_count: the number of shared fences returned
- * @pshared: the array of shared fence ptrs returned (array is krealloc'd to
+ * @fence_excl: the returned exclusive fence (or NULL)
+ * @shared_count: the number of shared fences returned
+ * @shared: the array of shared fence ptrs returned (array is krealloc'd to
  * the required size, and must be freed by caller)
  *
  * Retrieve all fences from the reservation object. If the pointer for the
  * exclusive fence is not specified the fence is put into the array of the
  * shared fences as well. Returns either zero or -ENOMEM.
  */
-int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl,
-			unsigned int *pshared_count,
-			struct dma_fence ***pshared)
+int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **fence_excl,
+			unsigned int *shared_count, struct dma_fence ***shared)
 {
-	struct dma_fence **shared = NULL;
-	struct dma_fence *fence_excl;
-	unsigned int shared_count;
-	int ret = 1;
-
-	do {
-		struct dma_resv_list *fobj;
-		unsigned int i, seq;
-		size_t sz = 0;
-
-		shared_count = i = 0;
-
-		rcu_read_lock();
-		seq = read_seqcount_begin(&obj->seq);
-
-		fence_excl = dma_resv_excl_fence(obj);
-		if (fence_excl && !dma_fence_get_rcu(fence_excl))
-			goto unlock;
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
 
-		fobj = dma_resv_shared_list(obj);
-		if (fobj)
-			sz += sizeof(*shared) * fobj->shared_max;
+	*shared_count = 0;
+	*shared = NULL;
 
-		if (!pfence_excl && fence_excl)
-			sz += sizeof(*shared);
+	if (fence_excl)
+		*fence_excl = NULL;
 
-		if (sz) {
-			struct dma_fence **nshared;
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(obj, &cursor, true, fence) {
 
-			nshared = krealloc(shared, sz,
-					   GFP_NOWAIT | __GFP_NOWARN);
-			if (!nshared) {
-				rcu_read_unlock();
+		if (cursor.is_first) {
+			unsigned int count;
 
-				dma_fence_put(fence_excl);
-				fence_excl = NULL;
+			while (*shared_count)
+				dma_fence_put((*shared)[--(*shared_count)]);
 
-				nshared = krealloc(shared, sz, GFP_KERNEL);
-				if (nshared) {
-					shared = nshared;
-					continue;
-				}
+			if (fence_excl)
+				dma_fence_put(*fence_excl);
 
-				ret = -ENOMEM;
-				break;
-			}
-			shared = nshared;
-			shared_count = fobj ? fobj->shared_count : 0;
-			for (i = 0; i < shared_count; ++i) {
-				shared[i] = rcu_dereference(fobj->shared[i]);
-				if (!dma_fence_get_rcu(shared[i]))
-					break;
-			}
-		}
+			count = cursor.fences ? cursor.fences->shared_count : 0;
+			count += fence_excl ? 0 : 1;
+			rcu_read_unlock();
 
-		if (i != shared_count || read_seqcount_retry(&obj->seq, seq)) {
-			while (i--)
-				dma_fence_put(shared[i]);
-			dma_fence_put(fence_excl);
-			goto unlock;
+			/* Eventually re-allocate the array */
+			*shared = krealloc_array(*shared, count,
+						 sizeof(void *),
+						 GFP_KERNEL);
+			if (count && !*shared)
+				return -ENOMEM;
+			rcu_read_lock();
 		}
 
-		ret = 0;
-unlock:
-		rcu_read_unlock();
-	} while (ret);
-
-	if (pfence_excl)
-		*pfence_excl = fence_excl;
-	else if (fence_excl)
-		shared[shared_count++] = fence_excl;
+		if (dma_resv_iter_is_exclusive(&cursor) && fence_excl)
+			*fence_excl = fence;
+		else
+			(*shared)[(*shared_count)++] = fence;
 
-	if (!shared_count) {
-		kfree(shared);
-		shared = NULL;
+		/* Don't drop the reference */
+		fence = NULL;
 	}
+	rcu_read_unlock();
 
-	*pshared_count = shared_count;
-	*pshared = shared;
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(dma_resv_get_fences);
 
-- 
2.25.1

[PATCH 05/26] dma-buf: use new iterator in dma_resv_wait_timeout

[Christian König]

This makes the function much simpler since the complex
retry logic is now handled elsewhere.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 64 +++++---------------------------------
 1 file changed, 7 insertions(+), 57 deletions(-)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index bba328475304..764a71ec2347 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -569,74 +569,24 @@ long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr,
 			   unsigned long timeout)
 {
 	long ret = timeout ? timeout : 1;
-	unsigned int seq, shared_count;
+	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
-	int i;
 
-retry:
-	shared_count = 0;
-	seq = read_seqcount_begin(&obj->seq);
 	rcu_read_lock();
-	i = -1;
-
-	fence = dma_resv_excl_fence(obj);
-	if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
-		if (!dma_fence_get_rcu(fence))
-			goto unlock_retry;
+	dma_resv_for_each_fence_unlocked(obj, &cursor, wait_all, fence) {
+		rcu_read_unlock();
 
-		if (dma_fence_is_signaled(fence)) {
+		ret = dma_fence_wait_timeout(fence, intr, ret);
+		if (ret <= 0) {
 			dma_fence_put(fence);
-			fence = NULL;
+			return ret;
 		}
 
-	} else {
-		fence = NULL;
-	}
-
-	if (wait_all) {
-		struct dma_resv_list *fobj = dma_resv_shared_list(obj);
-
-		if (fobj)
-			shared_count = fobj->shared_count;
-
-		for (i = 0; !fence && i < shared_count; ++i) {
-			struct dma_fence *lfence;
-
-			lfence = rcu_dereference(fobj->shared[i]);
-			if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
-				     &lfence->flags))
-				continue;
-
-			if (!dma_fence_get_rcu(lfence))
-				goto unlock_retry;
-
-			if (dma_fence_is_signaled(lfence)) {
-				dma_fence_put(lfence);
-				continue;
-			}
-
-			fence = lfence;
-			break;
-		}
+		rcu_read_lock();
 	}
-
 	rcu_read_unlock();
-	if (fence) {
-		if (read_seqcount_retry(&obj->seq, seq)) {
-			dma_fence_put(fence);
-			goto retry;
-		}
 
-		ret = dma_fence_wait_timeout(fence, intr, ret);
-		dma_fence_put(fence);
-		if (ret > 0 && wait_all && (i + 1 < shared_count))
-			goto retry;
-	}
 	return ret;
-
-unlock_retry:
-	rcu_read_unlock();
-	goto retry;
 }
 EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
 
-- 
2.25.1

[Intel-gfx] [PATCH 05/26] dma-buf: use new iterator in dma_resv_wait_timeout

[Christian König]

This makes the function much simpler since the complex
retry logic is now handled elsewhere.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 64 +++++---------------------------------
 1 file changed, 7 insertions(+), 57 deletions(-)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index bba328475304..764a71ec2347 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -569,74 +569,24 @@ long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr,
 			   unsigned long timeout)
 {
 	long ret = timeout ? timeout : 1;
-	unsigned int seq, shared_count;
+	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
-	int i;
 
-retry:
-	shared_count = 0;
-	seq = read_seqcount_begin(&obj->seq);
 	rcu_read_lock();
-	i = -1;
-
-	fence = dma_resv_excl_fence(obj);
-	if (fence && !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
-		if (!dma_fence_get_rcu(fence))
-			goto unlock_retry;
+	dma_resv_for_each_fence_unlocked(obj, &cursor, wait_all, fence) {
+		rcu_read_unlock();
 
-		if (dma_fence_is_signaled(fence)) {
+		ret = dma_fence_wait_timeout(fence, intr, ret);
+		if (ret <= 0) {
 			dma_fence_put(fence);
-			fence = NULL;
+			return ret;
 		}
 
-	} else {
-		fence = NULL;
-	}
-
-	if (wait_all) {
-		struct dma_resv_list *fobj = dma_resv_shared_list(obj);
-
-		if (fobj)
-			shared_count = fobj->shared_count;
-
-		for (i = 0; !fence && i < shared_count; ++i) {
-			struct dma_fence *lfence;
-
-			lfence = rcu_dereference(fobj->shared[i]);
-			if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
-				     &lfence->flags))
-				continue;
-
-			if (!dma_fence_get_rcu(lfence))
-				goto unlock_retry;
-
-			if (dma_fence_is_signaled(lfence)) {
-				dma_fence_put(lfence);
-				continue;
-			}
-
-			fence = lfence;
-			break;
-		}
+		rcu_read_lock();
 	}
-
 	rcu_read_unlock();
-	if (fence) {
-		if (read_seqcount_retry(&obj->seq, seq)) {
-			dma_fence_put(fence);
-			goto retry;
-		}
 
-		ret = dma_fence_wait_timeout(fence, intr, ret);
-		dma_fence_put(fence);
-		if (ret > 0 && wait_all && (i + 1 < shared_count))
-			goto retry;
-	}
 	return ret;
-
-unlock_retry:
-	rcu_read_unlock();
-	goto retry;
 }
 EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
 
-- 
2.25.1

[PATCH 06/26] dma-buf: use new iterator in dma_resv_test_signaled

[Christian König]

This makes the function much simpler since the complex
retry logic is now handled elsewhere.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 54 +++++---------------------------------
 1 file changed, 7 insertions(+), 47 deletions(-)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 764a71ec2347..fae881a5d336 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -591,22 +591,6 @@ long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr,
 EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
 
 
-static inline int dma_resv_test_signaled_single(struct dma_fence *passed_fence)
-{
-	struct dma_fence *fence, *lfence = passed_fence;
-	int ret = 1;
-
-	if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &lfence->flags)) {
-		fence = dma_fence_get_rcu(lfence);
-		if (!fence)
-			return -1;
-
-		ret = !!dma_fence_is_signaled(fence);
-		dma_fence_put(fence);
-	}
-	return ret;
-}
-
 /**
  * dma_resv_test_signaled - Test if a reservation object's fences have been
  * signaled.
@@ -623,43 +607,19 @@ static inline int dma_resv_test_signaled_single(struct dma_fence *passed_fence)
  */
 bool dma_resv_test_signaled(struct dma_resv *obj, bool test_all)
 {
+	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
-	unsigned int seq;
-	int ret;
 
 	rcu_read_lock();
-retry:
-	ret = true;
-	seq = read_seqcount_begin(&obj->seq);
-
-	if (test_all) {
-		struct dma_resv_list *fobj = dma_resv_shared_list(obj);
-		unsigned int i, shared_count;
-
-		shared_count = fobj ? fobj->shared_count : 0;
-		for (i = 0; i < shared_count; ++i) {
-			fence = rcu_dereference(fobj->shared[i]);
-			ret = dma_resv_test_signaled_single(fence);
-			if (ret < 0)
-				goto retry;
-			else if (!ret)
-				break;
+	dma_resv_for_each_fence_unlocked(obj, &cursor, test_all, fence) {
+		if (!dma_fence_is_signaled(fence)) {
+			rcu_read_unlock();
+			dma_fence_put(fence);
+			return false;
 		}
 	}
-
-	fence = dma_resv_excl_fence(obj);
-	if (ret && fence) {
-		ret = dma_resv_test_signaled_single(fence);
-		if (ret < 0)
-			goto retry;
-
-	}
-
-	if (read_seqcount_retry(&obj->seq, seq))
-		goto retry;
-
 	rcu_read_unlock();
-	return ret;
+	return true;
 }
 EXPORT_SYMBOL_GPL(dma_resv_test_signaled);
 
-- 
2.25.1

[Intel-gfx] [PATCH 06/26] dma-buf: use new iterator in dma_resv_test_signaled

[Christian König]

This makes the function much simpler since the complex
retry logic is now handled elsewhere.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 54 +++++---------------------------------
 1 file changed, 7 insertions(+), 47 deletions(-)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 764a71ec2347..fae881a5d336 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -591,22 +591,6 @@ long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr,
 EXPORT_SYMBOL_GPL(dma_resv_wait_timeout);
 
 
-static inline int dma_resv_test_signaled_single(struct dma_fence *passed_fence)
-{
-	struct dma_fence *fence, *lfence = passed_fence;
-	int ret = 1;
-
-	if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &lfence->flags)) {
-		fence = dma_fence_get_rcu(lfence);
-		if (!fence)
-			return -1;
-
-		ret = !!dma_fence_is_signaled(fence);
-		dma_fence_put(fence);
-	}
-	return ret;
-}
-
 /**
  * dma_resv_test_signaled - Test if a reservation object's fences have been
  * signaled.
@@ -623,43 +607,19 @@ static inline int dma_resv_test_signaled_single(struct dma_fence *passed_fence)
  */
 bool dma_resv_test_signaled(struct dma_resv *obj, bool test_all)
 {
+	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
-	unsigned int seq;
-	int ret;
 
 	rcu_read_lock();
-retry:
-	ret = true;
-	seq = read_seqcount_begin(&obj->seq);
-
-	if (test_all) {
-		struct dma_resv_list *fobj = dma_resv_shared_list(obj);
-		unsigned int i, shared_count;
-
-		shared_count = fobj ? fobj->shared_count : 0;
-		for (i = 0; i < shared_count; ++i) {
-			fence = rcu_dereference(fobj->shared[i]);
-			ret = dma_resv_test_signaled_single(fence);
-			if (ret < 0)
-				goto retry;
-			else if (!ret)
-				break;
+	dma_resv_for_each_fence_unlocked(obj, &cursor, test_all, fence) {
+		if (!dma_fence_is_signaled(fence)) {
+			rcu_read_unlock();
+			dma_fence_put(fence);
+			return false;
 		}
 	}
-
-	fence = dma_resv_excl_fence(obj);
-	if (ret && fence) {
-		ret = dma_resv_test_signaled_single(fence);
-		if (ret < 0)
-			goto retry;
-
-	}
-
-	if (read_seqcount_retry(&obj->seq, seq))
-		goto retry;
-
 	rcu_read_unlock();
-	return ret;
+	return true;
 }
 EXPORT_SYMBOL_GPL(dma_resv_test_signaled);
 
-- 
2.25.1

[PATCH 07/26] drm/ttm: use the new iterator in ttm_bo_flush_all_fences

[Christian König]

This is probably a fix since we didn't even grabed a reference to the
fences.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 3b22c0013dbf..d5912f5b5953 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -269,19 +269,11 @@ static int ttm_bo_individualize_resv(struct ttm_buffer_object *bo)
 static void ttm_bo_flush_all_fences(struct ttm_buffer_object *bo)
 {
 	struct dma_resv *resv = &bo->base._resv;
-	struct dma_resv_list *fobj;
+	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
-	int i;
 
 	rcu_read_lock();
-	fobj = dma_resv_shared_list(resv);
-	fence = dma_resv_excl_fence(resv);
-	if (fence && !fence->ops->signaled)
-		dma_fence_enable_sw_signaling(fence);
-
-	for (i = 0; fobj && i < fobj->shared_count; ++i) {
-		fence = rcu_dereference(fobj->shared[i]);
-
+	dma_resv_for_each_fence_unlocked(resv, &cursor, true, fence) {
 		if (!fence->ops->signaled)
 			dma_fence_enable_sw_signaling(fence);
 	}
-- 
2.25.1

[Intel-gfx] [PATCH 07/26] drm/ttm: use the new iterator in ttm_bo_flush_all_fences

[Christian König]

This is probably a fix since we didn't even grabed a reference to the
fences.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 3b22c0013dbf..d5912f5b5953 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -269,19 +269,11 @@ static int ttm_bo_individualize_resv(struct ttm_buffer_object *bo)
 static void ttm_bo_flush_all_fences(struct ttm_buffer_object *bo)
 {
 	struct dma_resv *resv = &bo->base._resv;
-	struct dma_resv_list *fobj;
+	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
-	int i;
 
 	rcu_read_lock();
-	fobj = dma_resv_shared_list(resv);
-	fence = dma_resv_excl_fence(resv);
-	if (fence && !fence->ops->signaled)
-		dma_fence_enable_sw_signaling(fence);
-
-	for (i = 0; fobj && i < fobj->shared_count; ++i) {
-		fence = rcu_dereference(fobj->shared[i]);
-
+	dma_resv_for_each_fence_unlocked(resv, &cursor, true, fence) {
 		if (!fence->ops->signaled)
 			dma_fence_enable_sw_signaling(fence);
 	}
-- 
2.25.1

[PATCH 08/26] drm/amdgpu: use the new iterator in amdgpu_sync_resv

[Christian König]

Simplifying the code a bit.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c | 44 ++++++++----------------
 1 file changed, 14 insertions(+), 30 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
index 862eb3c1c4c5..e5d8bb11a14a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
@@ -252,41 +252,25 @@ int amdgpu_sync_resv(struct amdgpu_device *adev, struct amdgpu_sync *sync,
 		     struct dma_resv *resv, enum amdgpu_sync_mode mode,
 		     void *owner)
 {
-	struct dma_resv_list *flist;
+	struct dma_resv_iter cursor;
 	struct dma_fence *f;
-	unsigned i;
-	int r = 0;
+	int r;
 
 	if (resv == NULL)
 		return -EINVAL;
 
-	/* always sync to the exclusive fence */
-	f = dma_resv_excl_fence(resv);
-	dma_fence_chain_for_each(f, f) {
-		struct dma_fence_chain *chain = to_dma_fence_chain(f);
-
-		if (amdgpu_sync_test_fence(adev, mode, owner, chain ?
-					   chain->fence : f)) {
-			r = amdgpu_sync_fence(sync, f);
-			dma_fence_put(f);
-			if (r)
-				return r;
-			break;
-		}
-	}
-
-	flist = dma_resv_shared_list(resv);
-	if (!flist)
-		return 0;
-
-	for (i = 0; i < flist->shared_count; ++i) {
-		f = rcu_dereference_protected(flist->shared[i],
-					      dma_resv_held(resv));
-
-		if (amdgpu_sync_test_fence(adev, mode, owner, f)) {
-			r = amdgpu_sync_fence(sync, f);
-			if (r)
-				return r;
+	dma_resv_for_each_fence(resv, &cursor, true, f) {
+		dma_fence_chain_for_each(f, f) {
+			struct dma_fence_chain *chain = to_dma_fence_chain(f);
+
+			if (amdgpu_sync_test_fence(adev, mode, owner, chain ?
+						   chain->fence : f)) {
+				r = amdgpu_sync_fence(sync, f);
+				dma_fence_put(f);
+				if (r)
+					return r;
+				break;
+			}
 		}
 	}
 	return 0;
-- 
2.25.1

[Intel-gfx] [PATCH 08/26] drm/amdgpu: use the new iterator in amdgpu_sync_resv

[Christian König]

Simplifying the code a bit.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c | 44 ++++++++----------------
 1 file changed, 14 insertions(+), 30 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
index 862eb3c1c4c5..e5d8bb11a14a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c
@@ -252,41 +252,25 @@ int amdgpu_sync_resv(struct amdgpu_device *adev, struct amdgpu_sync *sync,
 		     struct dma_resv *resv, enum amdgpu_sync_mode mode,
 		     void *owner)
 {
-	struct dma_resv_list *flist;
+	struct dma_resv_iter cursor;
 	struct dma_fence *f;
-	unsigned i;
-	int r = 0;
+	int r;
 
 	if (resv == NULL)
 		return -EINVAL;
 
-	/* always sync to the exclusive fence */
-	f = dma_resv_excl_fence(resv);
-	dma_fence_chain_for_each(f, f) {
-		struct dma_fence_chain *chain = to_dma_fence_chain(f);
-
-		if (amdgpu_sync_test_fence(adev, mode, owner, chain ?
-					   chain->fence : f)) {
-			r = amdgpu_sync_fence(sync, f);
-			dma_fence_put(f);
-			if (r)
-				return r;
-			break;
-		}
-	}
-
-	flist = dma_resv_shared_list(resv);
-	if (!flist)
-		return 0;
-
-	for (i = 0; i < flist->shared_count; ++i) {
-		f = rcu_dereference_protected(flist->shared[i],
-					      dma_resv_held(resv));
-
-		if (amdgpu_sync_test_fence(adev, mode, owner, f)) {
-			r = amdgpu_sync_fence(sync, f);
-			if (r)
-				return r;
+	dma_resv_for_each_fence(resv, &cursor, true, f) {
+		dma_fence_chain_for_each(f, f) {
+			struct dma_fence_chain *chain = to_dma_fence_chain(f);
+
+			if (amdgpu_sync_test_fence(adev, mode, owner, chain ?
+						   chain->fence : f)) {
+				r = amdgpu_sync_fence(sync, f);
+				dma_fence_put(f);
+				if (r)
+					return r;
+				break;
+			}
 		}
 	}
 	return 0;
-- 
2.25.1

[PATCH 09/26] drm/amdgpu: use new iterator in amdgpu_ttm_bo_eviction_valuable

[Christian König]

Simplifying the code a bit.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 1129e17e9f09..b3859c8ded85 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1332,10 +1332,9 @@ static bool amdgpu_ttm_bo_eviction_valuable(struct ttm_buffer_object *bo,
 					    const struct ttm_place *place)
 {
 	unsigned long num_pages = bo->resource->num_pages;
+	struct dma_resv_iter resv_cursor;
 	struct amdgpu_res_cursor cursor;
-	struct dma_resv_list *flist;
 	struct dma_fence *f;
-	int i;
 
 	/* Swapout? */
 	if (bo->resource->mem_type == TTM_PL_SYSTEM)
@@ -1349,14 +1348,9 @@ static bool amdgpu_ttm_bo_eviction_valuable(struct ttm_buffer_object *bo,
 	 * If true, then return false as any KFD process needs all its BOs to
 	 * be resident to run successfully
 	 */
-	flist = dma_resv_shared_list(bo->base.resv);
-	if (flist) {
-		for (i = 0; i < flist->shared_count; ++i) {
-			f = rcu_dereference_protected(flist->shared[i],
-				dma_resv_held(bo->base.resv));
-			if (amdkfd_fence_check_mm(f, current->mm))
-				return false;
-		}
+	dma_resv_for_each_fence(bo->base.resv, &resv_cursor, true, f) {
+		if (amdkfd_fence_check_mm(f, current->mm))
+			return false;
 	}
 
 	switch (bo->resource->mem_type) {
-- 
2.25.1

[Intel-gfx] [PATCH 09/26] drm/amdgpu: use new iterator in amdgpu_ttm_bo_eviction_valuable

[Christian König]

Simplifying the code a bit.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 1129e17e9f09..b3859c8ded85 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1332,10 +1332,9 @@ static bool amdgpu_ttm_bo_eviction_valuable(struct ttm_buffer_object *bo,
 					    const struct ttm_place *place)
 {
 	unsigned long num_pages = bo->resource->num_pages;
+	struct dma_resv_iter resv_cursor;
 	struct amdgpu_res_cursor cursor;
-	struct dma_resv_list *flist;
 	struct dma_fence *f;
-	int i;
 
 	/* Swapout? */
 	if (bo->resource->mem_type == TTM_PL_SYSTEM)
@@ -1349,14 +1348,9 @@ static bool amdgpu_ttm_bo_eviction_valuable(struct ttm_buffer_object *bo,
 	 * If true, then return false as any KFD process needs all its BOs to
 	 * be resident to run successfully
 	 */
-	flist = dma_resv_shared_list(bo->base.resv);
-	if (flist) {
-		for (i = 0; i < flist->shared_count; ++i) {
-			f = rcu_dereference_protected(flist->shared[i],
-				dma_resv_held(bo->base.resv));
-			if (amdkfd_fence_check_mm(f, current->mm))
-				return false;
-		}
+	dma_resv_for_each_fence(bo->base.resv, &resv_cursor, true, f) {
+		if (amdkfd_fence_check_mm(f, current->mm))
+			return false;
 	}
 
 	switch (bo->resource->mem_type) {
-- 
2.25.1

[PATCH 10/26] drm/msm: use new iterator in msm_gem_describe

[Christian König]

Simplifying the code a bit. Also drop the RCU read side lock since the
object is locked anyway.

Untested since I can't get the driver to compile on !ARM.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/msm/msm_gem.c | 19 +++++--------------
 1 file changed, 5 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 22308a1b66fc..5bece4600e41 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -880,7 +880,7 @@ void msm_gem_describe(struct drm_gem_object *obj, struct seq_file *m,
 {
 	struct msm_gem_object *msm_obj = to_msm_bo(obj);
 	struct dma_resv *robj = obj->resv;
-	struct dma_resv_list *fobj;
+	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
 	struct msm_gem_vma *vma;
 	uint64_t off = drm_vma_node_start(&obj->vma_node);
@@ -955,22 +955,13 @@ void msm_gem_describe(struct drm_gem_object *obj, struct seq_file *m,
 		seq_puts(m, "\n");
 	}
 
-	rcu_read_lock();
-	fobj = dma_resv_shared_list(robj);
-	if (fobj) {
-		unsigned int i, shared_count = fobj->shared_count;
-
-		for (i = 0; i < shared_count; i++) {
-			fence = rcu_dereference(fobj->shared[i]);
+	dma_resv_for_each_fence(robj, &cursor, true, fence) {
+		if (dma_resv_iter_is_exclusive(&cursor))
+			describe_fence(fence, "Exclusive", m);
+		else
 			describe_fence(fence, "Shared", m);
-		}
 	}
 
-	fence = dma_resv_excl_fence(robj);
-	if (fence)
-		describe_fence(fence, "Exclusive", m);
-	rcu_read_unlock();
-
 	msm_gem_unlock(obj);
 }
 
-- 
2.25.1

[Intel-gfx] [PATCH 10/26] drm/msm: use new iterator in msm_gem_describe

[Christian König]

Simplifying the code a bit. Also drop the RCU read side lock since the
object is locked anyway.

Untested since I can't get the driver to compile on !ARM.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/msm/msm_gem.c | 19 +++++--------------
 1 file changed, 5 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 22308a1b66fc..5bece4600e41 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -880,7 +880,7 @@ void msm_gem_describe(struct drm_gem_object *obj, struct seq_file *m,
 {
 	struct msm_gem_object *msm_obj = to_msm_bo(obj);
 	struct dma_resv *robj = obj->resv;
-	struct dma_resv_list *fobj;
+	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
 	struct msm_gem_vma *vma;
 	uint64_t off = drm_vma_node_start(&obj->vma_node);
@@ -955,22 +955,13 @@ void msm_gem_describe(struct drm_gem_object *obj, struct seq_file *m,
 		seq_puts(m, "\n");
 	}
 
-	rcu_read_lock();
-	fobj = dma_resv_shared_list(robj);
-	if (fobj) {
-		unsigned int i, shared_count = fobj->shared_count;
-
-		for (i = 0; i < shared_count; i++) {
-			fence = rcu_dereference(fobj->shared[i]);
+	dma_resv_for_each_fence(robj, &cursor, true, fence) {
+		if (dma_resv_iter_is_exclusive(&cursor))
+			describe_fence(fence, "Exclusive", m);
+		else
 			describe_fence(fence, "Shared", m);
-		}
 	}
 
-	fence = dma_resv_excl_fence(robj);
-	if (fence)
-		describe_fence(fence, "Exclusive", m);
-	rcu_read_unlock();
-
 	msm_gem_unlock(obj);
 }
 
-- 
2.25.1

[PATCH 11/26] drm/radeon: use new iterator in radeon_sync_resv

[Christian König]

Simplifying the code a bit.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/radeon/radeon_sync.c | 22 +++-------------------
 1 file changed, 3 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_sync.c b/drivers/gpu/drm/radeon/radeon_sync.c
index 9257b60144c4..23fa98dfe04b 100644
--- a/drivers/gpu/drm/radeon/radeon_sync.c
+++ b/drivers/gpu/drm/radeon/radeon_sync.c
@@ -91,33 +91,17 @@ int radeon_sync_resv(struct radeon_device *rdev,
 		     struct dma_resv *resv,
 		     bool shared)
 {
-	struct dma_resv_list *flist;
-	struct dma_fence *f;
+	struct dma_resv_iter cursor;
 	struct radeon_fence *fence;
-	unsigned i;
+	struct dma_fence *f;
 	int r = 0;
 
-	/* always sync to the exclusive fence */
-	f = dma_resv_excl_fence(resv);
-	fence = f ? to_radeon_fence(f) : NULL;
-	if (fence && fence->rdev == rdev)
-		radeon_sync_fence(sync, fence);
-	else if (f)
-		r = dma_fence_wait(f, true);
-
-	flist = dma_resv_shared_list(resv);
-	if (shared || !flist || r)
-		return r;
-
-	for (i = 0; i < flist->shared_count; ++i) {
-		f = rcu_dereference_protected(flist->shared[i],
-					      dma_resv_held(resv));
+	dma_resv_for_each_fence(resv, &cursor, shared, f) {
 		fence = to_radeon_fence(f);
 		if (fence && fence->rdev == rdev)
 			radeon_sync_fence(sync, fence);
 		else
 			r = dma_fence_wait(f, true);
-
 		if (r)
 			break;
 	}
-- 
2.25.1

[Intel-gfx] [PATCH 11/26] drm/radeon: use new iterator in radeon_sync_resv

[Christian König]

Simplifying the code a bit.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/radeon/radeon_sync.c | 22 +++-------------------
 1 file changed, 3 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_sync.c b/drivers/gpu/drm/radeon/radeon_sync.c
index 9257b60144c4..23fa98dfe04b 100644
--- a/drivers/gpu/drm/radeon/radeon_sync.c
+++ b/drivers/gpu/drm/radeon/radeon_sync.c
@@ -91,33 +91,17 @@ int radeon_sync_resv(struct radeon_device *rdev,
 		     struct dma_resv *resv,
 		     bool shared)
 {
-	struct dma_resv_list *flist;
-	struct dma_fence *f;
+	struct dma_resv_iter cursor;
 	struct radeon_fence *fence;
-	unsigned i;
+	struct dma_fence *f;
 	int r = 0;
 
-	/* always sync to the exclusive fence */
-	f = dma_resv_excl_fence(resv);
-	fence = f ? to_radeon_fence(f) : NULL;
-	if (fence && fence->rdev == rdev)
-		radeon_sync_fence(sync, fence);
-	else if (f)
-		r = dma_fence_wait(f, true);
-
-	flist = dma_resv_shared_list(resv);
-	if (shared || !flist || r)
-		return r;
-
-	for (i = 0; i < flist->shared_count; ++i) {
-		f = rcu_dereference_protected(flist->shared[i],
-					      dma_resv_held(resv));
+	dma_resv_for_each_fence(resv, &cursor, shared, f) {
 		fence = to_radeon_fence(f);
 		if (fence && fence->rdev == rdev)
 			radeon_sync_fence(sync, fence);
 		else
 			r = dma_fence_wait(f, true);
-
 		if (r)
 			break;
 	}
-- 
2.25.1

[PATCH 12/26] drm/scheduler: use new iterator in drm_sched_job_add_implicit_dependencies v2

[Christian König]

Simplifying the code a bit.

v2: use dma_resv_for_each_fence

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/scheduler/sched_main.c | 26 ++++++--------------------
 1 file changed, 6 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index 042c16b5d54a..ee2fe37ee724 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -699,30 +699,16 @@ int drm_sched_job_add_implicit_dependencies(struct drm_sched_job *job,
 					    struct drm_gem_object *obj,
 					    bool write)
 {
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
 	int ret;
-	struct dma_fence **fences;
-	unsigned int i, fence_count;
-
-	if (!write) {
-		struct dma_fence *fence = dma_resv_get_excl_unlocked(obj->resv);
-
-		return drm_sched_job_add_dependency(job, fence);
-	}
-
-	ret = dma_resv_get_fences(obj->resv, NULL, &fence_count, &fences);
-	if (ret || !fence_count)
-		return ret;
 
-	for (i = 0; i < fence_count; i++) {
-		ret = drm_sched_job_add_dependency(job, fences[i]);
+	dma_resv_for_each_fence(obj->resv, &cursor, write, fence) {
+		ret = drm_sched_job_add_dependency(job, fence);
 		if (ret)
-			break;
+			return ret;
 	}
-
-	for (; i < fence_count; i++)
-		dma_fence_put(fences[i]);
-	kfree(fences);
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL(drm_sched_job_add_implicit_dependencies);
 
-- 
2.25.1

[Intel-gfx] [PATCH 12/26] drm/scheduler: use new iterator in drm_sched_job_add_implicit_dependencies v2

[Christian König]

Simplifying the code a bit.

v2: use dma_resv_for_each_fence

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/scheduler/sched_main.c | 26 ++++++--------------------
 1 file changed, 6 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index 042c16b5d54a..ee2fe37ee724 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -699,30 +699,16 @@ int drm_sched_job_add_implicit_dependencies(struct drm_sched_job *job,
 					    struct drm_gem_object *obj,
 					    bool write)
 {
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
 	int ret;
-	struct dma_fence **fences;
-	unsigned int i, fence_count;
-
-	if (!write) {
-		struct dma_fence *fence = dma_resv_get_excl_unlocked(obj->resv);
-
-		return drm_sched_job_add_dependency(job, fence);
-	}
-
-	ret = dma_resv_get_fences(obj->resv, NULL, &fence_count, &fences);
-	if (ret || !fence_count)
-		return ret;
 
-	for (i = 0; i < fence_count; i++) {
-		ret = drm_sched_job_add_dependency(job, fences[i]);
+	dma_resv_for_each_fence(obj->resv, &cursor, write, fence) {
+		ret = drm_sched_job_add_dependency(job, fence);
 		if (ret)
-			break;
+			return ret;
 	}
-
-	for (; i < fence_count; i++)
-		dma_fence_put(fences[i]);
-	kfree(fences);
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL(drm_sched_job_add_implicit_dependencies);
 
-- 
2.25.1

[PATCH 13/26] drm/i915: use the new iterator in i915_gem_busy_ioctl

[Christian König]

This makes the function much simpler since the complex
retry logic is now handled else where.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_busy.c | 30 +++++++-----------------
 1 file changed, 9 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_busy.c b/drivers/gpu/drm/i915/gem/i915_gem_busy.c
index 6234e17259c1..adf9a8413446 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_busy.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_busy.c
@@ -82,8 +82,8 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
 {
 	struct drm_i915_gem_busy *args = data;
 	struct drm_i915_gem_object *obj;
-	struct dma_resv_list *list;
-	unsigned int seq;
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
 	int err;
 
 	err = -ENOENT;
@@ -109,28 +109,16 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
 	 * to report the overall busyness. This is what the wait-ioctl does.
 	 *
 	 */
-retry:
-	seq = raw_read_seqcount(&obj->base.resv->seq);
-
-	/* Translate the exclusive fence to the READ *and* WRITE engine */
-	args->busy = busy_check_writer(dma_resv_excl_fence(obj->base.resv));
-
-	/* Translate shared fences to READ set of engines */
-	list = dma_resv_shared_list(obj->base.resv);
-	if (list) {
-		unsigned int shared_count = list->shared_count, i;
-
-		for (i = 0; i < shared_count; ++i) {
-			struct dma_fence *fence =
-				rcu_dereference(list->shared[i]);
-
+	args->busy = false;
+	dma_resv_for_each_fence_unlocked(obj->base.resv, &cursor, true, fence) {
+		if (dma_resv_iter_is_exclusive(&cursor))
+			/* Translate the exclusive fence to the READ *and* WRITE engine */
+			args->busy = busy_check_writer(fence);
+		else
+			/* Translate shared fences to READ set of engines */
 			args->busy |= busy_check_reader(fence);
-		}
 	}
 
-	if (args->busy && read_seqcount_retry(&obj->base.resv->seq, seq))
-		goto retry;
-
 	err = 0;
 out:
 	rcu_read_unlock();
-- 
2.25.1

[Intel-gfx] [PATCH 13/26] drm/i915: use the new iterator in i915_gem_busy_ioctl

[Christian König]

This makes the function much simpler since the complex
retry logic is now handled else where.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_busy.c | 30 +++++++-----------------
 1 file changed, 9 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_busy.c b/drivers/gpu/drm/i915/gem/i915_gem_busy.c
index 6234e17259c1..adf9a8413446 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_busy.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_busy.c
@@ -82,8 +82,8 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
 {
 	struct drm_i915_gem_busy *args = data;
 	struct drm_i915_gem_object *obj;
-	struct dma_resv_list *list;
-	unsigned int seq;
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
 	int err;
 
 	err = -ENOENT;
@@ -109,28 +109,16 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
 	 * to report the overall busyness. This is what the wait-ioctl does.
 	 *
 	 */
-retry:
-	seq = raw_read_seqcount(&obj->base.resv->seq);
-
-	/* Translate the exclusive fence to the READ *and* WRITE engine */
-	args->busy = busy_check_writer(dma_resv_excl_fence(obj->base.resv));
-
-	/* Translate shared fences to READ set of engines */
-	list = dma_resv_shared_list(obj->base.resv);
-	if (list) {
-		unsigned int shared_count = list->shared_count, i;
-
-		for (i = 0; i < shared_count; ++i) {
-			struct dma_fence *fence =
-				rcu_dereference(list->shared[i]);
-
+	args->busy = false;
+	dma_resv_for_each_fence_unlocked(obj->base.resv, &cursor, true, fence) {
+		if (dma_resv_iter_is_exclusive(&cursor))
+			/* Translate the exclusive fence to the READ *and* WRITE engine */
+			args->busy = busy_check_writer(fence);
+		else
+			/* Translate shared fences to READ set of engines */
 			args->busy |= busy_check_reader(fence);
-		}
 	}
 
-	if (args->busy && read_seqcount_retry(&obj->base.resv->seq, seq))
-		goto retry;
-
 	err = 0;
 out:
 	rcu_read_unlock();
-- 
2.25.1

[PATCH 14/26] drm/i915: use the new iterator in i915_sw_fence_await_reservation v2

[Christian König]

Simplifying the code a bit.

v2: use dma_resv_for_each_fence instead, according to Tvrtko the lock is
    held here anyway.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/i915/i915_sw_fence.c | 51 +++++-----------------------
 1 file changed, 9 insertions(+), 42 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
index c589a681da77..86eb9ece71e0 100644
--- a/drivers/gpu/drm/i915/i915_sw_fence.c
+++ b/drivers/gpu/drm/i915/i915_sw_fence.c
@@ -572,56 +572,23 @@ int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
 				    unsigned long timeout,
 				    gfp_t gfp)
 {
-	struct dma_fence *excl;
+	struct dma_resv_iter cursor;
+	struct dma_fence *f;
 	int ret = 0, pending;
 
 	debug_fence_assert(fence);
 	might_sleep_if(gfpflags_allow_blocking(gfp));
 
-	if (write) {
-		struct dma_fence **shared;
-		unsigned int count, i;
-
-		ret = dma_resv_get_fences(resv, &excl, &count, &shared);
-		if (ret)
-			return ret;
-
-		for (i = 0; i < count; i++) {
-			if (shared[i]->ops == exclude)
-				continue;
-
-			pending = i915_sw_fence_await_dma_fence(fence,
-								shared[i],
-								timeout,
-								gfp);
-			if (pending < 0) {
-				ret = pending;
-				break;
-			}
-
-			ret |= pending;
-		}
-
-		for (i = 0; i < count; i++)
-			dma_fence_put(shared[i]);
-		kfree(shared);
-	} else {
-		excl = dma_resv_get_excl_unlocked(resv);
-	}
-
-	if (ret >= 0 && excl && excl->ops != exclude) {
-		pending = i915_sw_fence_await_dma_fence(fence,
-							excl,
-							timeout,
+	dma_resv_for_each_fence(resv, &cursor, write, f) {
+		pending = i915_sw_fence_await_dma_fence(fence, f, timeout,
 							gfp);
-		if (pending < 0)
+		if (pending < 0) {
 			ret = pending;
-		else
-			ret |= pending;
-	}
-
-	dma_fence_put(excl);
+			break;
+		}
 
+		ret |= pending;
+	}
 	return ret;
 }
 
-- 
2.25.1

[Intel-gfx] [PATCH 14/26] drm/i915: use the new iterator in i915_sw_fence_await_reservation v2

[Christian König]

Simplifying the code a bit.

v2: use dma_resv_for_each_fence instead, according to Tvrtko the lock is
    held here anyway.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/i915/i915_sw_fence.c | 51 +++++-----------------------
 1 file changed, 9 insertions(+), 42 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c
index c589a681da77..86eb9ece71e0 100644
--- a/drivers/gpu/drm/i915/i915_sw_fence.c
+++ b/drivers/gpu/drm/i915/i915_sw_fence.c
@@ -572,56 +572,23 @@ int i915_sw_fence_await_reservation(struct i915_sw_fence *fence,
 				    unsigned long timeout,
 				    gfp_t gfp)
 {
-	struct dma_fence *excl;
+	struct dma_resv_iter cursor;
+	struct dma_fence *f;
 	int ret = 0, pending;
 
 	debug_fence_assert(fence);
 	might_sleep_if(gfpflags_allow_blocking(gfp));
 
-	if (write) {
-		struct dma_fence **shared;
-		unsigned int count, i;
-
-		ret = dma_resv_get_fences(resv, &excl, &count, &shared);
-		if (ret)
-			return ret;
-
-		for (i = 0; i < count; i++) {
-			if (shared[i]->ops == exclude)
-				continue;
-
-			pending = i915_sw_fence_await_dma_fence(fence,
-								shared[i],
-								timeout,
-								gfp);
-			if (pending < 0) {
-				ret = pending;
-				break;
-			}
-
-			ret |= pending;
-		}
-
-		for (i = 0; i < count; i++)
-			dma_fence_put(shared[i]);
-		kfree(shared);
-	} else {
-		excl = dma_resv_get_excl_unlocked(resv);
-	}
-
-	if (ret >= 0 && excl && excl->ops != exclude) {
-		pending = i915_sw_fence_await_dma_fence(fence,
-							excl,
-							timeout,
+	dma_resv_for_each_fence(resv, &cursor, write, f) {
+		pending = i915_sw_fence_await_dma_fence(fence, f, timeout,
 							gfp);
-		if (pending < 0)
+		if (pending < 0) {
 			ret = pending;
-		else
-			ret |= pending;
-	}
-
-	dma_fence_put(excl);
+			break;
+		}
 
+		ret |= pending;
+	}
 	return ret;
 }
 
-- 
2.25.1

[PATCH 15/26] drm/i915: use the new iterator in i915_request_await_object v2

[Christian König]

Simplifying the code a bit.

v2: add missing rcu_read_lock()/rcu_read_unlock()

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/i915/i915_request.c | 40 ++++++++---------------------
 1 file changed, 11 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index ce446716d092..221df2edcf02 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -1509,39 +1509,21 @@ i915_request_await_object(struct i915_request *to,
 			  struct drm_i915_gem_object *obj,
 			  bool write)
 {
-	struct dma_fence *excl;
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
 	int ret = 0;
 
-	if (write) {
-		struct dma_fence **shared;
-		unsigned int count, i;
-
-		ret = dma_resv_get_fences(obj->base.resv, &excl, &count,
-					  &shared);
-		if (ret)
-			return ret;
-
-		for (i = 0; i < count; i++) {
-			ret = i915_request_await_dma_fence(to, shared[i]);
-			if (ret)
-				break;
-
-			dma_fence_put(shared[i]);
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(obj->base.resv, &cursor, write, fence) {
+		rcu_read_unlock();
+		ret = i915_request_await_dma_fence(to, fence);
+		rcu_read_lock();
+		if (ret) {
+			dma_fence_put(fence);
+			break;
 		}
-
-		for (; i < count; i++)
-			dma_fence_put(shared[i]);
-		kfree(shared);
-	} else {
-		excl = dma_resv_get_excl_unlocked(obj->base.resv);
-	}
-
-	if (excl) {
-		if (ret == 0)
-			ret = i915_request_await_dma_fence(to, excl);
-
-		dma_fence_put(excl);
 	}
+	rcu_read_unlock();
 
 	return ret;
 }
-- 
2.25.1

[Intel-gfx] [PATCH 15/26] drm/i915: use the new iterator in i915_request_await_object v2

[Christian König]

Simplifying the code a bit.

v2: add missing rcu_read_lock()/rcu_read_unlock()

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/i915/i915_request.c | 40 ++++++++---------------------
 1 file changed, 11 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index ce446716d092..221df2edcf02 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -1509,39 +1509,21 @@ i915_request_await_object(struct i915_request *to,
 			  struct drm_i915_gem_object *obj,
 			  bool write)
 {
-	struct dma_fence *excl;
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
 	int ret = 0;
 
-	if (write) {
-		struct dma_fence **shared;
-		unsigned int count, i;
-
-		ret = dma_resv_get_fences(obj->base.resv, &excl, &count,
-					  &shared);
-		if (ret)
-			return ret;
-
-		for (i = 0; i < count; i++) {
-			ret = i915_request_await_dma_fence(to, shared[i]);
-			if (ret)
-				break;
-
-			dma_fence_put(shared[i]);
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(obj->base.resv, &cursor, write, fence) {
+		rcu_read_unlock();
+		ret = i915_request_await_dma_fence(to, fence);
+		rcu_read_lock();
+		if (ret) {
+			dma_fence_put(fence);
+			break;
 		}
-
-		for (; i < count; i++)
-			dma_fence_put(shared[i]);
-		kfree(shared);
-	} else {
-		excl = dma_resv_get_excl_unlocked(obj->base.resv);
-	}
-
-	if (excl) {
-		if (ret == 0)
-			ret = i915_request_await_dma_fence(to, excl);
-
-		dma_fence_put(excl);
 	}
+	rcu_read_unlock();
 
 	return ret;
 }
-- 
2.25.1

[PATCH 16/26] drm/i915: use new iterator in i915_gem_object_wait_reservation v2

[Christian König]

Simplifying the code a bit.

v2: add missing rcu read unlock.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_wait.c | 57 +++++++-----------------
 1 file changed, 15 insertions(+), 42 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_wait.c b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
index f909aaa09d9c..a75dee9d7790 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_wait.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
@@ -37,55 +37,28 @@ i915_gem_object_wait_reservation(struct dma_resv *resv,
 				 unsigned int flags,
 				 long timeout)
 {
-	struct dma_fence *excl;
-	bool prune_fences = false;
-
-	if (flags & I915_WAIT_ALL) {
-		struct dma_fence **shared;
-		unsigned int count, i;
-		int ret;
-
-		ret = dma_resv_get_fences(resv, &excl, &count, &shared);
-		if (ret)
-			return ret;
-
-		for (i = 0; i < count; i++) {
-			timeout = i915_gem_object_wait_fence(shared[i],
-							     flags, timeout);
-			if (timeout < 0)
-				break;
-
-			dma_fence_put(shared[i]);
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
+
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(resv, &cursor, flags & I915_WAIT_ALL,
+					 fence) {
+
+		rcu_read_unlock();
+		timeout = i915_gem_object_wait_fence(fence, flags, timeout);
+		rcu_read_lock();
+		if (timeout < 0) {
+			dma_fence_put(fence);
+			break;
 		}
-
-		for (; i < count; i++)
-			dma_fence_put(shared[i]);
-		kfree(shared);
-
-		/*
-		 * If both shared fences and an exclusive fence exist,
-		 * then by construction the shared fences must be later
-		 * than the exclusive fence. If we successfully wait for
-		 * all the shared fences, we know that the exclusive fence
-		 * must all be signaled. If all the shared fences are
-		 * signaled, we can prune the array and recover the
-		 * floating references on the fences/requests.
-		 */
-		prune_fences = count && timeout >= 0;
-	} else {
-		excl = dma_resv_get_excl_unlocked(resv);
 	}
-
-	if (excl && timeout >= 0)
-		timeout = i915_gem_object_wait_fence(excl, flags, timeout);
-
-	dma_fence_put(excl);
+	rcu_read_unlock();
 
 	/*
 	 * Opportunistically prune the fences iff we know they have *all* been
 	 * signaled.
 	 */
-	if (prune_fences)
+	if (timeout > 0)
 		dma_resv_prune(resv);
 
 	return timeout;
-- 
2.25.1

[Intel-gfx] [PATCH 16/26] drm/i915: use new iterator in i915_gem_object_wait_reservation v2

[Christian König]

Simplifying the code a bit.

v2: add missing rcu read unlock.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_wait.c | 57 +++++++-----------------
 1 file changed, 15 insertions(+), 42 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_wait.c b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
index f909aaa09d9c..a75dee9d7790 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_wait.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
@@ -37,55 +37,28 @@ i915_gem_object_wait_reservation(struct dma_resv *resv,
 				 unsigned int flags,
 				 long timeout)
 {
-	struct dma_fence *excl;
-	bool prune_fences = false;
-
-	if (flags & I915_WAIT_ALL) {
-		struct dma_fence **shared;
-		unsigned int count, i;
-		int ret;
-
-		ret = dma_resv_get_fences(resv, &excl, &count, &shared);
-		if (ret)
-			return ret;
-
-		for (i = 0; i < count; i++) {
-			timeout = i915_gem_object_wait_fence(shared[i],
-							     flags, timeout);
-			if (timeout < 0)
-				break;
-
-			dma_fence_put(shared[i]);
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
+
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(resv, &cursor, flags & I915_WAIT_ALL,
+					 fence) {
+
+		rcu_read_unlock();
+		timeout = i915_gem_object_wait_fence(fence, flags, timeout);
+		rcu_read_lock();
+		if (timeout < 0) {
+			dma_fence_put(fence);
+			break;
 		}
-
-		for (; i < count; i++)
-			dma_fence_put(shared[i]);
-		kfree(shared);
-
-		/*
-		 * If both shared fences and an exclusive fence exist,
-		 * then by construction the shared fences must be later
-		 * than the exclusive fence. If we successfully wait for
-		 * all the shared fences, we know that the exclusive fence
-		 * must all be signaled. If all the shared fences are
-		 * signaled, we can prune the array and recover the
-		 * floating references on the fences/requests.
-		 */
-		prune_fences = count && timeout >= 0;
-	} else {
-		excl = dma_resv_get_excl_unlocked(resv);
 	}
-
-	if (excl && timeout >= 0)
-		timeout = i915_gem_object_wait_fence(excl, flags, timeout);
-
-	dma_fence_put(excl);
+	rcu_read_unlock();
 
 	/*
 	 * Opportunistically prune the fences iff we know they have *all* been
 	 * signaled.
 	 */
-	if (prune_fences)
+	if (timeout > 0)
 		dma_resv_prune(resv);
 
 	return timeout;
-- 
2.25.1

[PATCH 17/26] drm/i915: use new iterator in i915_gem_object_wait_priority v2

[Christian König]

Simplifying the code a bit.

v2: add missing rcu_read_lock()/unlock()

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_wait.c | 33 +++++++-----------------
 1 file changed, 9 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_wait.c b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
index a75dee9d7790..db8a72556338 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_wait.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
@@ -124,32 +124,17 @@ i915_gem_object_wait_priority(struct drm_i915_gem_object *obj,
 			      unsigned int flags,
 			      const struct i915_sched_attr *attr)
 {
-	struct dma_fence *excl;
-
-	if (flags & I915_WAIT_ALL) {
-		struct dma_fence **shared;
-		unsigned int count, i;
-		int ret;
-
-		ret = dma_resv_get_fences(obj->base.resv, &excl, &count,
-					  &shared);
-		if (ret)
-			return ret;
-
-		for (i = 0; i < count; i++) {
-			i915_gem_fence_wait_priority(shared[i], attr);
-			dma_fence_put(shared[i]);
-		}
-
-		kfree(shared);
-	} else {
-		excl = dma_resv_get_excl_unlocked(obj->base.resv);
-	}
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
 
-	if (excl) {
-		i915_gem_fence_wait_priority(excl, attr);
-		dma_fence_put(excl);
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(obj->base.resv, &cursor,
+					 flags & I915_WAIT_ALL, fence) {
+		rcu_read_unlock();
+		i915_gem_fence_wait_priority(fence, attr);
+		rcu_read_lock();
 	}
+	rcu_read_unlock();
 	return 0;
 }
 
-- 
2.25.1

[Intel-gfx] [PATCH 17/26] drm/i915: use new iterator in i915_gem_object_wait_priority v2

[Christian König]

Simplifying the code a bit.

v2: add missing rcu_read_lock()/unlock()

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_wait.c | 33 +++++++-----------------
 1 file changed, 9 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_wait.c b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
index a75dee9d7790..db8a72556338 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_wait.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
@@ -124,32 +124,17 @@ i915_gem_object_wait_priority(struct drm_i915_gem_object *obj,
 			      unsigned int flags,
 			      const struct i915_sched_attr *attr)
 {
-	struct dma_fence *excl;
-
-	if (flags & I915_WAIT_ALL) {
-		struct dma_fence **shared;
-		unsigned int count, i;
-		int ret;
-
-		ret = dma_resv_get_fences(obj->base.resv, &excl, &count,
-					  &shared);
-		if (ret)
-			return ret;
-
-		for (i = 0; i < count; i++) {
-			i915_gem_fence_wait_priority(shared[i], attr);
-			dma_fence_put(shared[i]);
-		}
-
-		kfree(shared);
-	} else {
-		excl = dma_resv_get_excl_unlocked(obj->base.resv);
-	}
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
 
-	if (excl) {
-		i915_gem_fence_wait_priority(excl, attr);
-		dma_fence_put(excl);
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(obj->base.resv, &cursor,
+					 flags & I915_WAIT_ALL, fence) {
+		rcu_read_unlock();
+		i915_gem_fence_wait_priority(fence, attr);
+		rcu_read_lock();
 	}
+	rcu_read_unlock();
 	return 0;
 }
 
-- 
2.25.1

[PATCH 18/26] drm/i915: use new iterator in i915_gem_object_last_write_engine v2

[Christian König]

This is maybe even a fix since the RCU usage here looks incorrect.

v2: add missing rcu_read_lock()/unlock()

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_object.h | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index 48112b9d76df..7ff0027af7d9 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -507,16 +507,17 @@ static inline struct intel_engine_cs *
 i915_gem_object_last_write_engine(struct drm_i915_gem_object *obj)
 {
 	struct intel_engine_cs *engine = NULL;
+	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
 
 	rcu_read_lock();
-	fence = dma_resv_get_excl_unlocked(obj->base.resv);
+	dma_resv_for_each_fence_unlocked(obj->base.resv, &cursor, false,
+					 fence) {
+		if (fence && dma_fence_is_i915(fence) &&
+		    !dma_fence_is_signaled(fence))
+			engine = to_request(fence)->engine;
+	}
 	rcu_read_unlock();
-
-	if (fence && dma_fence_is_i915(fence) && !dma_fence_is_signaled(fence))
-		engine = to_request(fence)->engine;
-	dma_fence_put(fence);
-
 	return engine;
 }
 
-- 
2.25.1

[Intel-gfx] [PATCH 18/26] drm/i915: use new iterator in i915_gem_object_last_write_engine v2

[Christian König]

This is maybe even a fix since the RCU usage here looks incorrect.

v2: add missing rcu_read_lock()/unlock()

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_object.h | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index 48112b9d76df..7ff0027af7d9 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -507,16 +507,17 @@ static inline struct intel_engine_cs *
 i915_gem_object_last_write_engine(struct drm_i915_gem_object *obj)
 {
 	struct intel_engine_cs *engine = NULL;
+	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
 
 	rcu_read_lock();
-	fence = dma_resv_get_excl_unlocked(obj->base.resv);
+	dma_resv_for_each_fence_unlocked(obj->base.resv, &cursor, false,
+					 fence) {
+		if (fence && dma_fence_is_i915(fence) &&
+		    !dma_fence_is_signaled(fence))
+			engine = to_request(fence)->engine;
+	}
 	rcu_read_unlock();
-
-	if (fence && dma_fence_is_i915(fence) && !dma_fence_is_signaled(fence))
-		engine = to_request(fence)->engine;
-	dma_fence_put(fence);
-
 	return engine;
 }
 
-- 
2.25.1

[PATCH 19/26] drm/i915: use new cursor in intel_prepare_plane_fb v2

[Christian König]

Simplifying the code a bit.

v2: add rcu_read_lock()/unlock()

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/i915/display/intel_display.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 134a6acbd8fb..fa73a6754373 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -11290,6 +11290,7 @@ intel_prepare_plane_fb(struct drm_plane *_plane,
 	i915_gem_object_flush_frontbuffer(obj, ORIGIN_DIRTYFB);
 
 	if (!new_plane_state->uapi.fence) { /* implicit fencing */
+		struct dma_resv_iter cursor;
 		struct dma_fence *fence;
 
 		ret = i915_sw_fence_await_reservation(&state->commit_ready,
@@ -11300,12 +11301,15 @@ intel_prepare_plane_fb(struct drm_plane *_plane,
 		if (ret < 0)
 			goto unpin_fb;
 
-		fence = dma_resv_get_excl_unlocked(obj->base.resv);
-		if (fence) {
+		rcu_read_lock();
+		dma_resv_for_each_fence_unlocked(obj->base.resv, &cursor, false,
+						 fence) {
+			rcu_read_unlock();
 			add_rps_boost_after_vblank(new_plane_state->hw.crtc,
 						   fence);
-			dma_fence_put(fence);
+			rcu_read_lock();
 		}
+		rcu_read_unlock();
 	} else {
 		add_rps_boost_after_vblank(new_plane_state->hw.crtc,
 					   new_plane_state->uapi.fence);
-- 
2.25.1

[Intel-gfx] [PATCH 19/26] drm/i915: use new cursor in intel_prepare_plane_fb v2

[Christian König]

Simplifying the code a bit.

v2: add rcu_read_lock()/unlock()

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/i915/display/intel_display.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 134a6acbd8fb..fa73a6754373 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -11290,6 +11290,7 @@ intel_prepare_plane_fb(struct drm_plane *_plane,
 	i915_gem_object_flush_frontbuffer(obj, ORIGIN_DIRTYFB);
 
 	if (!new_plane_state->uapi.fence) { /* implicit fencing */
+		struct dma_resv_iter cursor;
 		struct dma_fence *fence;
 
 		ret = i915_sw_fence_await_reservation(&state->commit_ready,
@@ -11300,12 +11301,15 @@ intel_prepare_plane_fb(struct drm_plane *_plane,
 		if (ret < 0)
 			goto unpin_fb;
 
-		fence = dma_resv_get_excl_unlocked(obj->base.resv);
-		if (fence) {
+		rcu_read_lock();
+		dma_resv_for_each_fence_unlocked(obj->base.resv, &cursor, false,
+						 fence) {
+			rcu_read_unlock();
 			add_rps_boost_after_vblank(new_plane_state->hw.crtc,
 						   fence);
-			dma_fence_put(fence);
+			rcu_read_lock();
 		}
+		rcu_read_unlock();
 	} else {
 		add_rps_boost_after_vblank(new_plane_state->hw.crtc,
 					   new_plane_state->uapi.fence);
-- 
2.25.1

[PATCH 20/26] drm: use new iterator in drm_gem_fence_array_add_implicit v2

[Christian König]

Simplifying the code a bit.

v2: add missing rcu_read_lock()/unlock()

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/drm_gem.c | 36 +++++++++++++-----------------------
 1 file changed, 13 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 09c820045859..8c3ff098e49e 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -1340,31 +1340,21 @@ int drm_gem_fence_array_add_implicit(struct xarray *fence_array,
 				     struct drm_gem_object *obj,
 				     bool write)
 {
-	int ret;
-	struct dma_fence **fences;
-	unsigned int i, fence_count;
-
-	if (!write) {
-		struct dma_fence *fence =
-			dma_resv_get_excl_unlocked(obj->resv);
-
-		return drm_gem_fence_array_add(fence_array, fence);
-	}
-
-	ret = dma_resv_get_fences(obj->resv, NULL,
-						&fence_count, &fences);
-	if (ret || !fence_count)
-		return ret;
-
-	for (i = 0; i < fence_count; i++) {
-		ret = drm_gem_fence_array_add(fence_array, fences[i]);
-		if (ret)
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
+	int ret = 0;
+
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(obj->resv, &cursor, write, fence) {
+		rcu_read_unlock();
+		ret = drm_gem_fence_array_add(fence_array, fence);
+		rcu_read_lock();
+		if (ret) {
+			dma_fence_put(fence);
 			break;
+		}
 	}
-
-	for (; i < fence_count; i++)
-		dma_fence_put(fences[i]);
-	kfree(fences);
+	rcu_read_unlock();
 	return ret;
 }
 EXPORT_SYMBOL(drm_gem_fence_array_add_implicit);
-- 
2.25.1

[Intel-gfx] [PATCH 20/26] drm: use new iterator in drm_gem_fence_array_add_implicit v2

[Christian König]

Simplifying the code a bit.

v2: add missing rcu_read_lock()/unlock()

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/drm_gem.c | 36 +++++++++++++-----------------------
 1 file changed, 13 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 09c820045859..8c3ff098e49e 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -1340,31 +1340,21 @@ int drm_gem_fence_array_add_implicit(struct xarray *fence_array,
 				     struct drm_gem_object *obj,
 				     bool write)
 {
-	int ret;
-	struct dma_fence **fences;
-	unsigned int i, fence_count;
-
-	if (!write) {
-		struct dma_fence *fence =
-			dma_resv_get_excl_unlocked(obj->resv);
-
-		return drm_gem_fence_array_add(fence_array, fence);
-	}
-
-	ret = dma_resv_get_fences(obj->resv, NULL,
-						&fence_count, &fences);
-	if (ret || !fence_count)
-		return ret;
-
-	for (i = 0; i < fence_count; i++) {
-		ret = drm_gem_fence_array_add(fence_array, fences[i]);
-		if (ret)
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
+	int ret = 0;
+
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(obj->resv, &cursor, write, fence) {
+		rcu_read_unlock();
+		ret = drm_gem_fence_array_add(fence_array, fence);
+		rcu_read_lock();
+		if (ret) {
+			dma_fence_put(fence);
 			break;
+		}
 	}
-
-	for (; i < fence_count; i++)
-		dma_fence_put(fences[i]);
-	kfree(fences);
+	rcu_read_unlock();
 	return ret;
 }
 EXPORT_SYMBOL(drm_gem_fence_array_add_implicit);
-- 
2.25.1

[PATCH 21/26] drm: use new iterator in drm_gem_plane_helper_prepare_fb v2

[Christian König]

Makes the handling a bit more complex, but avoids the use of
dma_resv_get_excl_unlocked().

v2: add missing rcu_read_lock()/unlock()

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/drm_gem_atomic_helper.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_atomic_helper.c b/drivers/gpu/drm/drm_gem_atomic_helper.c
index e570398abd78..86df75b2f8eb 100644
--- a/drivers/gpu/drm/drm_gem_atomic_helper.c
+++ b/drivers/gpu/drm/drm_gem_atomic_helper.c
@@ -143,6 +143,7 @@
  */
 int drm_gem_plane_helper_prepare_fb(struct drm_plane *plane, struct drm_plane_state *state)
 {
+	struct dma_resv_iter cursor;
 	struct drm_gem_object *obj;
 	struct dma_fence *fence;
 
@@ -150,9 +151,16 @@ int drm_gem_plane_helper_prepare_fb(struct drm_plane *plane, struct drm_plane_st
 		return 0;
 
 	obj = drm_gem_fb_get_obj(state->fb, 0);
-	fence = dma_resv_get_excl_unlocked(obj->resv);
-	drm_atomic_set_fence_for_plane(state, fence);
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(obj->resv, &cursor, false, fence) {
+		rcu_read_unlock();
+		/* TODO: We only use the first write fence here */
+		drm_atomic_set_fence_for_plane(state, fence);
+		return 0;
+	}
+	rcu_read_unlock();
 
+	drm_atomic_set_fence_for_plane(state, NULL);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(drm_gem_plane_helper_prepare_fb);
-- 
2.25.1

[Intel-gfx] [PATCH 21/26] drm: use new iterator in drm_gem_plane_helper_prepare_fb v2

[Christian König]

Makes the handling a bit more complex, but avoids the use of
dma_resv_get_excl_unlocked().

v2: add missing rcu_read_lock()/unlock()

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/drm_gem_atomic_helper.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_atomic_helper.c b/drivers/gpu/drm/drm_gem_atomic_helper.c
index e570398abd78..86df75b2f8eb 100644
--- a/drivers/gpu/drm/drm_gem_atomic_helper.c
+++ b/drivers/gpu/drm/drm_gem_atomic_helper.c
@@ -143,6 +143,7 @@
  */
 int drm_gem_plane_helper_prepare_fb(struct drm_plane *plane, struct drm_plane_state *state)
 {
+	struct dma_resv_iter cursor;
 	struct drm_gem_object *obj;
 	struct dma_fence *fence;
 
@@ -150,9 +151,16 @@ int drm_gem_plane_helper_prepare_fb(struct drm_plane *plane, struct drm_plane_st
 		return 0;
 
 	obj = drm_gem_fb_get_obj(state->fb, 0);
-	fence = dma_resv_get_excl_unlocked(obj->resv);
-	drm_atomic_set_fence_for_plane(state, fence);
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(obj->resv, &cursor, false, fence) {
+		rcu_read_unlock();
+		/* TODO: We only use the first write fence here */
+		drm_atomic_set_fence_for_plane(state, fence);
+		return 0;
+	}
+	rcu_read_unlock();
 
+	drm_atomic_set_fence_for_plane(state, NULL);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(drm_gem_plane_helper_prepare_fb);
-- 
2.25.1

[PATCH 22/26] drm/nouveau: use the new iterator in nouveau_fence_sync

[Christian König]

Simplifying the code a bit.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/nouveau/nouveau_fence.c | 48 +++++++------------------
 1 file changed, 12 insertions(+), 36 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c
index 05d0b3eb3690..f3584d840edc 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fence.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fence.c
@@ -339,14 +339,15 @@ nouveau_fence_wait(struct nouveau_fence *fence, bool lazy, bool intr)
 }
 
 int
-nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan, bool exclusive, bool intr)
+nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan,
+		   bool exclusive, bool intr)
 {
 	struct nouveau_fence_chan *fctx = chan->fence;
-	struct dma_fence *fence;
 	struct dma_resv *resv = nvbo->bo.base.resv;
-	struct dma_resv_list *fobj;
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
 	struct nouveau_fence *f;
-	int ret = 0, i;
+	int ret;
 
 	if (!exclusive) {
 		ret = dma_resv_reserve_shared(resv, 1);
@@ -355,10 +356,7 @@ nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan, bool e
 			return ret;
 	}
 
-	fobj = dma_resv_shared_list(resv);
-	fence = dma_resv_excl_fence(resv);
-
-	if (fence) {
+	dma_resv_for_each_fence(resv, &cursor, exclusive, fence) {
 		struct nouveau_channel *prev = NULL;
 		bool must_wait = true;
 
@@ -366,41 +364,19 @@ nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan, bool e
 		if (f) {
 			rcu_read_lock();
 			prev = rcu_dereference(f->channel);
-			if (prev && (prev == chan || fctx->sync(f, prev, chan) == 0))
+			if (prev && (prev == chan ||
+				     fctx->sync(f, prev, chan) == 0))
 				must_wait = false;
 			rcu_read_unlock();
 		}
 
-		if (must_wait)
+		if (must_wait) {
 			ret = dma_fence_wait(fence, intr);
-
-		return ret;
-	}
-
-	if (!exclusive || !fobj)
-		return ret;
-
-	for (i = 0; i < fobj->shared_count && !ret; ++i) {
-		struct nouveau_channel *prev = NULL;
-		bool must_wait = true;
-
-		fence = rcu_dereference_protected(fobj->shared[i],
-						dma_resv_held(resv));
-
-		f = nouveau_local_fence(fence, chan->drm);
-		if (f) {
-			rcu_read_lock();
-			prev = rcu_dereference(f->channel);
-			if (prev && (prev == chan || fctx->sync(f, prev, chan) == 0))
-				must_wait = false;
-			rcu_read_unlock();
+			if (ret)
+				return ret;
 		}
-
-		if (must_wait)
-			ret = dma_fence_wait(fence, intr);
 	}
-
-	return ret;
+	return 0;
 }
 
 void
-- 
2.25.1

[Intel-gfx] [PATCH 22/26] drm/nouveau: use the new iterator in nouveau_fence_sync

[Christian König]

Simplifying the code a bit.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/nouveau/nouveau_fence.c | 48 +++++++------------------
 1 file changed, 12 insertions(+), 36 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c
index 05d0b3eb3690..f3584d840edc 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fence.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fence.c
@@ -339,14 +339,15 @@ nouveau_fence_wait(struct nouveau_fence *fence, bool lazy, bool intr)
 }
 
 int
-nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan, bool exclusive, bool intr)
+nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan,
+		   bool exclusive, bool intr)
 {
 	struct nouveau_fence_chan *fctx = chan->fence;
-	struct dma_fence *fence;
 	struct dma_resv *resv = nvbo->bo.base.resv;
-	struct dma_resv_list *fobj;
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
 	struct nouveau_fence *f;
-	int ret = 0, i;
+	int ret;
 
 	if (!exclusive) {
 		ret = dma_resv_reserve_shared(resv, 1);
@@ -355,10 +356,7 @@ nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan, bool e
 			return ret;
 	}
 
-	fobj = dma_resv_shared_list(resv);
-	fence = dma_resv_excl_fence(resv);
-
-	if (fence) {
+	dma_resv_for_each_fence(resv, &cursor, exclusive, fence) {
 		struct nouveau_channel *prev = NULL;
 		bool must_wait = true;
 
@@ -366,41 +364,19 @@ nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan, bool e
 		if (f) {
 			rcu_read_lock();
 			prev = rcu_dereference(f->channel);
-			if (prev && (prev == chan || fctx->sync(f, prev, chan) == 0))
+			if (prev && (prev == chan ||
+				     fctx->sync(f, prev, chan) == 0))
 				must_wait = false;
 			rcu_read_unlock();
 		}
 
-		if (must_wait)
+		if (must_wait) {
 			ret = dma_fence_wait(fence, intr);
-
-		return ret;
-	}
-
-	if (!exclusive || !fobj)
-		return ret;
-
-	for (i = 0; i < fobj->shared_count && !ret; ++i) {
-		struct nouveau_channel *prev = NULL;
-		bool must_wait = true;
-
-		fence = rcu_dereference_protected(fobj->shared[i],
-						dma_resv_held(resv));
-
-		f = nouveau_local_fence(fence, chan->drm);
-		if (f) {
-			rcu_read_lock();
-			prev = rcu_dereference(f->channel);
-			if (prev && (prev == chan || fctx->sync(f, prev, chan) == 0))
-				must_wait = false;
-			rcu_read_unlock();
+			if (ret)
+				return ret;
 		}
-
-		if (must_wait)
-			ret = dma_fence_wait(fence, intr);
 	}
-
-	return ret;
+	return 0;
 }
 
 void
-- 
2.25.1

[PATCH 23/26] drm/nouveau: use the new interator in nv50_wndw_prepare_fb v2

[Christian König]

Makes the handling a bit more complex, but avoids the use of
dma_resv_get_excl_unlocked().

v2: add missing rcu_read_lock()/unlock()

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/nouveau/dispnv50/wndw.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv50/wndw.c b/drivers/gpu/drm/nouveau/dispnv50/wndw.c
index 8d048bacd6f0..0f5cdb897f06 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/wndw.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/wndw.c
@@ -539,6 +539,8 @@ nv50_wndw_prepare_fb(struct drm_plane *plane, struct drm_plane_state *state)
 	struct nouveau_bo *nvbo;
 	struct nv50_head_atom *asyh;
 	struct nv50_wndw_ctxdma *ctxdma;
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
 	int ret;
 
 	NV_ATOMIC(drm, "%s prepare: %p\n", plane->name, fb);
@@ -561,7 +563,14 @@ nv50_wndw_prepare_fb(struct drm_plane *plane, struct drm_plane_state *state)
 			asyw->image.handle[0] = ctxdma->object.handle;
 	}
 
-	asyw->state.fence = dma_resv_get_excl_unlocked(nvbo->bo.base.resv);
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(nvbo->bo.base.resv, &cursor, false,
+					 fence) {
+		/* TODO: We only use the first writer here */
+		asyw->state.fence = fence;
+		break;
+	}
+	rcu_read_unlock();
 	asyw->image.offset[0] = nvbo->offset;
 
 	if (wndw->func->prepare) {
-- 
2.25.1

[Intel-gfx] [PATCH 23/26] drm/nouveau: use the new interator in nv50_wndw_prepare_fb v2

[Christian König]

Makes the handling a bit more complex, but avoids the use of
dma_resv_get_excl_unlocked().

v2: add missing rcu_read_lock()/unlock()

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/nouveau/dispnv50/wndw.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv50/wndw.c b/drivers/gpu/drm/nouveau/dispnv50/wndw.c
index 8d048bacd6f0..0f5cdb897f06 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/wndw.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/wndw.c
@@ -539,6 +539,8 @@ nv50_wndw_prepare_fb(struct drm_plane *plane, struct drm_plane_state *state)
 	struct nouveau_bo *nvbo;
 	struct nv50_head_atom *asyh;
 	struct nv50_wndw_ctxdma *ctxdma;
+	struct dma_resv_iter cursor;
+	struct dma_fence *fence;
 	int ret;
 
 	NV_ATOMIC(drm, "%s prepare: %p\n", plane->name, fb);
@@ -561,7 +563,14 @@ nv50_wndw_prepare_fb(struct drm_plane *plane, struct drm_plane_state *state)
 			asyw->image.handle[0] = ctxdma->object.handle;
 	}
 
-	asyw->state.fence = dma_resv_get_excl_unlocked(nvbo->bo.base.resv);
+	rcu_read_lock();
+	dma_resv_for_each_fence_unlocked(nvbo->bo.base.resv, &cursor, false,
+					 fence) {
+		/* TODO: We only use the first writer here */
+		asyw->state.fence = fence;
+		break;
+	}
+	rcu_read_unlock();
 	asyw->image.offset[0] = nvbo->offset;
 
 	if (wndw->func->prepare) {
-- 
2.25.1

[PATCH 24/26] drm/etnaviv: use new iterator in etnaviv_gem_describe

[Christian König]

Instead of hand rolling the logic.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/etnaviv/etnaviv_gem.c | 27 +++++++++------------------
 1 file changed, 9 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index 8f1b5af47dd6..dc2a2615db38 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -428,19 +428,17 @@ int etnaviv_gem_wait_bo(struct etnaviv_gpu *gpu, struct drm_gem_object *obj,
 static void etnaviv_gem_describe_fence(struct dma_fence *fence,
 	const char *type, struct seq_file *m)
 {
-	if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
-		seq_printf(m, "\t%9s: %s %s seq %llu\n",
-			   type,
-			   fence->ops->get_driver_name(fence),
-			   fence->ops->get_timeline_name(fence),
-			   fence->seqno);
+	seq_printf(m, "\t%9s: %s %s seq %llu\n", type,
+		   fence->ops->get_driver_name(fence),
+		   fence->ops->get_timeline_name(fence),
+		   fence->seqno);
 }
 
 static void etnaviv_gem_describe(struct drm_gem_object *obj, struct seq_file *m)
 {
 	struct etnaviv_gem_object *etnaviv_obj = to_etnaviv_bo(obj);
 	struct dma_resv *robj = obj->resv;
-	struct dma_resv_list *fobj;
+	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
 	unsigned long off = drm_vma_node_start(&obj->vma_node);
 
@@ -450,19 +448,12 @@ static void etnaviv_gem_describe(struct drm_gem_object *obj, struct seq_file *m)
 			off, etnaviv_obj->vaddr, obj->size);
 
 	rcu_read_lock();
-	fobj = dma_resv_shared_list(robj);
-	if (fobj) {
-		unsigned int i, shared_count = fobj->shared_count;
-
-		for (i = 0; i < shared_count; i++) {
-			fence = rcu_dereference(fobj->shared[i]);
+	dma_resv_for_each_fence_unlocked(robj, &cursor, true, fence) {
+		if (dma_resv_iter_is_exclusive(&cursor))
+			etnaviv_gem_describe_fence(fence, "Exclusive", m);
+		else
 			etnaviv_gem_describe_fence(fence, "Shared", m);
-		}
 	}
-
-	fence = dma_resv_excl_fence(robj);
-	if (fence)
-		etnaviv_gem_describe_fence(fence, "Exclusive", m);
 	rcu_read_unlock();
 }
 
-- 
2.25.1

[Intel-gfx] [PATCH 24/26] drm/etnaviv: use new iterator in etnaviv_gem_describe

[Christian König]

Instead of hand rolling the logic.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/etnaviv/etnaviv_gem.c | 27 +++++++++------------------
 1 file changed, 9 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index 8f1b5af47dd6..dc2a2615db38 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -428,19 +428,17 @@ int etnaviv_gem_wait_bo(struct etnaviv_gpu *gpu, struct drm_gem_object *obj,
 static void etnaviv_gem_describe_fence(struct dma_fence *fence,
 	const char *type, struct seq_file *m)
 {
-	if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
-		seq_printf(m, "\t%9s: %s %s seq %llu\n",
-			   type,
-			   fence->ops->get_driver_name(fence),
-			   fence->ops->get_timeline_name(fence),
-			   fence->seqno);
+	seq_printf(m, "\t%9s: %s %s seq %llu\n", type,
+		   fence->ops->get_driver_name(fence),
+		   fence->ops->get_timeline_name(fence),
+		   fence->seqno);
 }
 
 static void etnaviv_gem_describe(struct drm_gem_object *obj, struct seq_file *m)
 {
 	struct etnaviv_gem_object *etnaviv_obj = to_etnaviv_bo(obj);
 	struct dma_resv *robj = obj->resv;
-	struct dma_resv_list *fobj;
+	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
 	unsigned long off = drm_vma_node_start(&obj->vma_node);
 
@@ -450,19 +448,12 @@ static void etnaviv_gem_describe(struct drm_gem_object *obj, struct seq_file *m)
 			off, etnaviv_obj->vaddr, obj->size);
 
 	rcu_read_lock();
-	fobj = dma_resv_shared_list(robj);
-	if (fobj) {
-		unsigned int i, shared_count = fobj->shared_count;
-
-		for (i = 0; i < shared_count; i++) {
-			fence = rcu_dereference(fobj->shared[i]);
+	dma_resv_for_each_fence_unlocked(robj, &cursor, true, fence) {
+		if (dma_resv_iter_is_exclusive(&cursor))
+			etnaviv_gem_describe_fence(fence, "Exclusive", m);
+		else
 			etnaviv_gem_describe_fence(fence, "Shared", m);
-		}
 	}
-
-	fence = dma_resv_excl_fence(robj);
-	if (fence)
-		etnaviv_gem_describe_fence(fence, "Exclusive", m);
 	rcu_read_unlock();
 }
 
-- 
2.25.1

[PATCH 25/26] drm/etnaviv: replace dma_resv_get_excl_unlocked

[Christian König]

We certainly hold the reservation lock here, no need for the RCU dance.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
index 4dd7d9d541c0..7e17bc2b5df1 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
@@ -195,7 +195,7 @@ static int submit_fence_sync(struct etnaviv_gem_submit *submit)
 			if (ret)
 				return ret;
 		} else {
-			bo->excl = dma_resv_get_excl_unlocked(robj);
+			bo->excl = dma_fence_get(dma_resv_excl_fence(robj));
 		}
 
 	}
-- 
2.25.1

[Intel-gfx] [PATCH 25/26] drm/etnaviv: replace dma_resv_get_excl_unlocked

[Christian König]

We certainly hold the reservation lock here, no need for the RCU dance.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
index 4dd7d9d541c0..7e17bc2b5df1 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c
@@ -195,7 +195,7 @@ static int submit_fence_sync(struct etnaviv_gem_submit *submit)
 			if (ret)
 				return ret;
 		} else {
-			bo->excl = dma_resv_get_excl_unlocked(robj);
+			bo->excl = dma_fence_get(dma_resv_excl_fence(robj));
 		}
 
 	}
-- 
2.25.1

[PATCH 26/26] dma-buf: nuke dma_resv_get_excl_unlocked

[Christian König]

Heureka, that's finally not used any more.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 include/linux/dma-resv.h | 26 --------------------------
 1 file changed, 26 deletions(-)

diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
index 6761512ba662..3e6ffba0af70 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -384,32 +384,6 @@ dma_resv_excl_fence(struct dma_resv *obj)
 	return rcu_dereference_check(obj->fence_excl, dma_resv_held(obj));
 }
 
-/**
- * dma_resv_get_excl_unlocked - get the reservation object's
- * exclusive fence, without lock held.
- * @obj: the reservation object
- *
- * If there is an exclusive fence, this atomically increments it's
- * reference count and returns it.
- *
- * RETURNS
- * The exclusive fence or NULL if none
- */
-static inline struct dma_fence *
-dma_resv_get_excl_unlocked(struct dma_resv *obj)
-{
-	struct dma_fence *fence;
-
-	if (!rcu_access_pointer(obj->fence_excl))
-		return NULL;
-
-	rcu_read_lock();
-	fence = dma_fence_get_rcu_safe(&obj->fence_excl);
-	rcu_read_unlock();
-
-	return fence;
-}
-
 /**
  * dma_resv_shared_list - get the reservation object's shared fence list
  * @obj: the reservation object
-- 
2.25.1

[Intel-gfx] [PATCH 26/26] dma-buf: nuke dma_resv_get_excl_unlocked

[Christian König]

Heureka, that's finally not used any more.

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 include/linux/dma-resv.h | 26 --------------------------
 1 file changed, 26 deletions(-)

diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h
index 6761512ba662..3e6ffba0af70 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -384,32 +384,6 @@ dma_resv_excl_fence(struct dma_resv *obj)
 	return rcu_dereference_check(obj->fence_excl, dma_resv_held(obj));
 }
 
-/**
- * dma_resv_get_excl_unlocked - get the reservation object's
- * exclusive fence, without lock held.
- * @obj: the reservation object
- *
- * If there is an exclusive fence, this atomically increments it's
- * reference count and returns it.
- *
- * RETURNS
- * The exclusive fence or NULL if none
- */
-static inline struct dma_fence *
-dma_resv_get_excl_unlocked(struct dma_resv *obj)
-{
-	struct dma_fence *fence;
-
-	if (!rcu_access_pointer(obj->fence_excl))
-		return NULL;
-
-	rcu_read_lock();
-	fence = dma_fence_get_rcu_safe(&obj->fence_excl);
-	rcu_read_unlock();
-
-	return fence;
-}
-
 /**
  * dma_resv_shared_list - get the reservation object's shared fence list
  * @obj: the reservation object
-- 
2.25.1

[Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with [01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2

[Patchwork]

== Series Details ==

Series: series starting with [01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2
URL   : https://patchwork.freedesktop.org/series/94750/
State : warning

== Summary ==

$ dim checkpatch origin/drm-tip
79becb99fccc dma-buf: add dma_resv_for_each_fence_unlocked v2
-:72: CHECK:OPEN_ENDED_LINE: Lines should not end with a '('
#72: FILE: drivers/dma-buf/dma-resv.c:368:
+				fence = rcu_dereference(

-:134: CHECK:MACRO_ARG_REUSE: Macro argument reuse 'obj' - possible side-effects?
#134: FILE: include/linux/dma-resv.h:183:
+#define dma_resv_for_each_fence_unlocked(obj, cursor, all_fences, fence)    \
+	for (fence = dma_resv_walk_unlocked(obj, cursor, all_fences, true); \
+	     fence; dma_fence_put(fence),				    \
+	     fence = dma_resv_walk_unlocked(obj, cursor, all_fences, false))

-:134: CHECK:MACRO_ARG_REUSE: Macro argument reuse 'cursor' - possible side-effects?
#134: FILE: include/linux/dma-resv.h:183:
+#define dma_resv_for_each_fence_unlocked(obj, cursor, all_fences, fence)    \
+	for (fence = dma_resv_walk_unlocked(obj, cursor, all_fences, true); \
+	     fence; dma_fence_put(fence),				    \
+	     fence = dma_resv_walk_unlocked(obj, cursor, all_fences, false))

-:134: CHECK:MACRO_ARG_REUSE: Macro argument reuse 'all_fences' - possible side-effects?
#134: FILE: include/linux/dma-resv.h:183:
+#define dma_resv_for_each_fence_unlocked(obj, cursor, all_fences, fence)    \
+	for (fence = dma_resv_walk_unlocked(obj, cursor, all_fences, true); \
+	     fence; dma_fence_put(fence),				    \
+	     fence = dma_resv_walk_unlocked(obj, cursor, all_fences, false))

-:134: CHECK:MACRO_ARG_REUSE: Macro argument reuse 'fence' - possible side-effects?
#134: FILE: include/linux/dma-resv.h:183:
+#define dma_resv_for_each_fence_unlocked(obj, cursor, all_fences, fence)    \
+	for (fence = dma_resv_walk_unlocked(obj, cursor, all_fences, true); \
+	     fence; dma_fence_put(fence),				    \
+	     fence = dma_resv_walk_unlocked(obj, cursor, all_fences, false))

-:162: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 5 checks, 130 lines checked
43fd9d11fcd6 dma-buf: add dma_resv_for_each_fence
-:81: CHECK:MACRO_ARG_REUSE: Macro argument reuse 'obj' - possible side-effects?
#81: FILE: include/linux/dma-resv.h:182:
+#define dma_resv_for_each_fence(obj, cursor, all_fences, fence)		  \
+	for (fence = dma_resv_walk(obj, cursor, all_fences, true); fence; \
+	     fence = dma_resv_walk(obj, cursor, all_fences, false))

-:81: CHECK:MACRO_ARG_REUSE: Macro argument reuse 'cursor' - possible side-effects?
#81: FILE: include/linux/dma-resv.h:182:
+#define dma_resv_for_each_fence(obj, cursor, all_fences, fence)		  \
+	for (fence = dma_resv_walk(obj, cursor, all_fences, true); fence; \
+	     fence = dma_resv_walk(obj, cursor, all_fences, false))

-:81: CHECK:MACRO_ARG_REUSE: Macro argument reuse 'all_fences' - possible side-effects?
#81: FILE: include/linux/dma-resv.h:182:
+#define dma_resv_for_each_fence(obj, cursor, all_fences, fence)		  \
+	for (fence = dma_resv_walk(obj, cursor, all_fences, true); fence; \
+	     fence = dma_resv_walk(obj, cursor, all_fences, false))

-:81: CHECK:MACRO_ARG_REUSE: Macro argument reuse 'fence' - possible side-effects?
#81: FILE: include/linux/dma-resv.h:182:
+#define dma_resv_for_each_fence(obj, cursor, all_fences, fence)		  \
+	for (fence = dma_resv_walk(obj, cursor, all_fences, true); fence; \
+	     fence = dma_resv_walk(obj, cursor, all_fences, false))

-:97: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 4 checks, 73 lines checked
a8b725463938 dma-buf: use new iterator in dma_resv_copy_fences
-:124: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 106 lines checked
20181be832c0 dma-buf: use new iterator in dma_resv_get_fences v2
-:156: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 136 lines checked
d07cfed64ece dma-buf: use new iterator in dma_resv_wait_timeout
-:99: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 81 lines checked
f26d368dba9c dma-buf: use new iterator in dma_resv_test_signaled
-:91: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 72 lines checked
bd71df193561 drm/ttm: use the new iterator in ttm_bo_flush_all_fences
-:39: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 21 lines checked
174500546b2b drm/amdgpu: use the new iterator in amdgpu_sync_resv
-:72: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 55 lines checked
f8f742ac41e1 drm/amdgpu: use new iterator in amdgpu_ttm_bo_eviction_valuable
-:47: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 28 lines checked
cc28ebf6dea3 drm/msm: use new iterator in msm_gem_describe
-:55: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 34 lines checked
8fe08b573247 drm/radeon: use new iterator in radeon_sync_resv
-:53: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 36 lines checked
d5ec3add7f52 drm/scheduler: use new iterator in drm_sched_job_add_implicit_dependencies v2
-:56: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 36 lines checked
f4e64617226b drm/i915: use the new iterator in i915_gem_busy_ioctl
-:64: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 45 lines checked
77c552340892 drm/i915: use the new iterator in i915_sw_fence_await_reservation v2
-:86: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 65 lines checked
3b3d6edc3ec1 drm/i915: use the new iterator in i915_request_await_object v2
-:70: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 50 lines checked
fbe3139fe0d5 drm/i915: use new iterator in i915_gem_object_wait_reservation v2
-:49: CHECK:BRACES: Blank lines aren't necessary after an open brace '{'
#49: FILE: drivers/gpu/drm/i915/gem/i915_gem_wait.c:46:
+					 fence) {
+

-:90: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 1 checks, 70 lines checked
01cb40f10c37 drm/i915: use new iterator in i915_gem_object_wait_priority v2
-:61: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 41 lines checked
e4c67e16e633 drm/i915: use new iterator in i915_gem_object_last_write_engine v2
-:43: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 23 lines checked
36237da723df drm/i915: use new cursor in intel_prepare_plane_fb v2
-:45: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 25 lines checked
92c356444b7b drm: use new iterator in drm_gem_fence_array_add_implicit v2
-:63: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 44 lines checked
ee7a40d3c32d drm: use new iterator in drm_gem_plane_helper_prepare_fb v2
-:46: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 25 lines checked
cf5d087e77ef drm/nouveau: use the new iterator in nouveau_fence_sync
-:96: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 77 lines checked
aa6d699f8f59 drm/nouveau: use the new interator in nv50_wndw_prepare_fb v2
-:44: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 23 lines checked
10b96c40fe4f drm/etnaviv: use new iterator in etnaviv_gem_describe
-:65: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 47 lines checked
fc9b5ce671ec drm/etnaviv: replace dma_resv_get_excl_unlocked
-:25: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 8 lines checked
a648c89556c2 dma-buf: nuke dma_resv_get_excl_unlocked
-:49: WARNING:FROM_SIGN_OFF_MISMATCH: From:/Signed-off-by: email address mismatch: 'From: "Christian König" <ckoenig.leichtzumerken@gmail.com>' != 'Signed-off-by: Christian König <christian.koenig@amd.com>'

total: 0 errors, 1 warnings, 0 checks, 32 lines checked

[Intel-gfx] ✗ Fi.CI.BAT: failure for series starting with [01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2

[Patchwork]

[-- Attachment #1: Type: text/plain, Size: 9715 bytes --]

== Series Details ==

Series: series starting with [01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2
URL   : https://patchwork.freedesktop.org/series/94750/
State : failure

== Summary ==

CI Bug Log - changes from CI_DRM_10596 -> Patchwork_21073
====================================================

Summary
-------

  **FAILURE**

  Serious unknown changes coming with Patchwork_21073 absolutely need to be
  verified manually.
  
  If you think the reported changes have nothing to do with the changes
  introduced in Patchwork_21073, please notify your bug team to allow them
  to document this new failure mode, which will reduce false positives in CI.

  External URL: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/index.html

Possible new issues
-------------------

  Here are the unknown changes that may have been introduced in Patchwork_21073:

### IGT changes ###

#### Possible regressions ####

  * igt@kms_force_connector_basic@force-connector-state:
    - fi-kbl-7567u:       [PASS][1] -> [DMESG-WARN][2]
   [1]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_10596/fi-kbl-7567u/igt@kms_force_connector_basic@force-connector-state.html
   [2]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-kbl-7567u/igt@kms_force_connector_basic@force-connector-state.html
    - fi-kbl-8809g:       [PASS][3] -> [DMESG-WARN][4]
   [3]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_10596/fi-kbl-8809g/igt@kms_force_connector_basic@force-connector-state.html
   [4]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-kbl-8809g/igt@kms_force_connector_basic@force-connector-state.html
    - fi-kbl-guc:         [PASS][5] -> [DMESG-WARN][6]
   [5]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_10596/fi-kbl-guc/igt@kms_force_connector_basic@force-connector-state.html
   [6]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-kbl-guc/igt@kms_force_connector_basic@force-connector-state.html

  * igt@runner@aborted:
    - fi-rkl-11600:       NOTRUN -> [FAIL][7]
   [7]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-rkl-11600/igt@runner@aborted.html
    - fi-bwr-2160:        NOTRUN -> [FAIL][8]
   [8]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-bwr-2160/igt@runner@aborted.html

  
#### Warnings ####

  * igt@runner@aborted:
    - fi-rkl-guc:         [FAIL][9] ([i915#2426]) -> [FAIL][10]
   [9]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_10596/fi-rkl-guc/igt@runner@aborted.html
   [10]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-rkl-guc/igt@runner@aborted.html

  
#### Suppressed ####

  The following results come from untrusted machines, tests, or statuses.
  They do not affect the overall result.

  * igt@runner@aborted:
    - {fi-tgl-dsi}:       [FAIL][11] ([i915#2932] / [i915#3690]) -> [FAIL][12]
   [11]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_10596/fi-tgl-dsi/igt@runner@aborted.html
   [12]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-tgl-dsi/igt@runner@aborted.html
    - {fi-jsl-1}:         NOTRUN -> [FAIL][13]
   [13]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-jsl-1/igt@runner@aborted.html

  
Known issues
------------

  Here are the changes found in Patchwork_21073 that come from known issues:

### IGT changes ###

#### Issues hit ####

  * igt@runner@aborted:
    - fi-pnv-d510:        NOTRUN -> [FAIL][14] ([i915#2403])
   [14]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-pnv-d510/igt@runner@aborted.html
    - fi-cfl-8700k:       NOTRUN -> [FAIL][15] ([i915#3363] / [k.org#202107] / [k.org#202109])
   [15]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-cfl-8700k/igt@runner@aborted.html
    - fi-skl-6600u:       NOTRUN -> [FAIL][16] ([i915#3363])
   [16]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-skl-6600u/igt@runner@aborted.html
    - fi-cfl-8109u:       NOTRUN -> [FAIL][17] ([i915#3363] / [k.org#202107] / [k.org#202109])
   [17]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-cfl-8109u/igt@runner@aborted.html
    - fi-icl-u2:          NOTRUN -> [FAIL][18] ([i915#1569] / [i915#3363])
   [18]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-icl-u2/igt@runner@aborted.html
    - fi-kbl-8809g:       NOTRUN -> [FAIL][19] ([i915#3363])
   [19]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-kbl-8809g/igt@runner@aborted.html
    - fi-kbl-r:           NOTRUN -> [FAIL][20] ([i915#1569] / [i915#192] / [i915#193] / [i915#194] / [i915#3363])
   [20]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-kbl-r/igt@runner@aborted.html
    - fi-kbl-7500u:       NOTRUN -> [FAIL][21] ([i915#1569] / [i915#192] / [i915#193] / [i915#194] / [i915#3363])
   [21]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-kbl-7500u/igt@runner@aborted.html
    - fi-kbl-guc:         NOTRUN -> [FAIL][22] ([i915#3363])
   [22]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-kbl-guc/igt@runner@aborted.html
    - fi-cml-u2:          NOTRUN -> [FAIL][23] ([i915#3363])
   [23]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-cml-u2/igt@runner@aborted.html
    - fi-cfl-guc:         NOTRUN -> [FAIL][24] ([i915#3363] / [k.org#202107] / [k.org#202109])
   [24]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-cfl-guc/igt@runner@aborted.html
    - fi-icl-y:           NOTRUN -> [FAIL][25] ([i915#1569])
   [25]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-icl-y/igt@runner@aborted.html
    - fi-kbl-7567u:       NOTRUN -> [FAIL][26] ([i915#3363])
   [26]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-kbl-7567u/igt@runner@aborted.html

  
#### Warnings ####

  * igt@runner@aborted:
    - fi-kbl-soraka:      [FAIL][27] ([i915#2426] / [i915#3363]) -> [FAIL][28] ([i915#1569] / [i915#192] / [i915#193] / [i915#194] / [i915#3363])
   [27]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_10596/fi-kbl-soraka/igt@runner@aborted.html
   [28]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-kbl-soraka/igt@runner@aborted.html
    - fi-skl-6700k2:      [FAIL][29] ([i915#2426] / [i915#3363]) -> [FAIL][30] ([i915#3363])
   [29]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_10596/fi-skl-6700k2/igt@runner@aborted.html
   [30]: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/fi-skl-6700k2/igt@runner@aborted.html

  
  {name}: This element is suppressed. This means it is ignored when computing
          the status of the difference (SUCCESS, WARNING, or FAILURE).

  [i915#1569]: https://gitlab.freedesktop.org/drm/intel/issues/1569
  [i915#192]: https://gitlab.freedesktop.org/drm/intel/issues/192
  [i915#193]: https://gitlab.freedesktop.org/drm/intel/issues/193
  [i915#194]: https://gitlab.freedesktop.org/drm/intel/issues/194
  [i915#2403]: https://gitlab.freedesktop.org/drm/intel/issues/2403
  [i915#2426]: https://gitlab.freedesktop.org/drm/intel/issues/2426
  [i915#2932]: https://gitlab.freedesktop.org/drm/intel/issues/2932
  [i915#3363]: https://gitlab.freedesktop.org/drm/intel/issues/3363
  [i915#3690]: https://gitlab.freedesktop.org/drm/intel/issues/3690
  [k.org#202107]: https://bugzilla.kernel.org/show_bug.cgi?id=202107
  [k.org#202109]: https://bugzilla.kernel.org/show_bug.cgi?id=202109


Participating hosts (37 -> 35)
------------------------------

  Missing    (2): fi-bsw-cyan fi-bdw-samus 


Build changes
-------------

  * Linux: CI_DRM_10596 -> Patchwork_21073

  CI-20190529: 20190529
  CI_DRM_10596: 3e450101ba783c61e51898a84b7758efbb505e8f @ git://anongit.freedesktop.org/gfx-ci/linux
  IGT_6209: 07d6594ed02f55b68d64fa6dd7f80cfbc1ce4ef8 @ https://gitlab.freedesktop.org/drm/igt-gpu-tools.git
  Patchwork_21073: a648c89556c265b0c3c9882534c36c14c8982f39 @ git://anongit.freedesktop.org/gfx-ci/linux


== Linux commits ==

a648c89556c2 dma-buf: nuke dma_resv_get_excl_unlocked
fc9b5ce671ec drm/etnaviv: replace dma_resv_get_excl_unlocked
10b96c40fe4f drm/etnaviv: use new iterator in etnaviv_gem_describe
aa6d699f8f59 drm/nouveau: use the new interator in nv50_wndw_prepare_fb v2
cf5d087e77ef drm/nouveau: use the new iterator in nouveau_fence_sync
ee7a40d3c32d drm: use new iterator in drm_gem_plane_helper_prepare_fb v2
92c356444b7b drm: use new iterator in drm_gem_fence_array_add_implicit v2
36237da723df drm/i915: use new cursor in intel_prepare_plane_fb v2
e4c67e16e633 drm/i915: use new iterator in i915_gem_object_last_write_engine v2
01cb40f10c37 drm/i915: use new iterator in i915_gem_object_wait_priority v2
fbe3139fe0d5 drm/i915: use new iterator in i915_gem_object_wait_reservation v2
3b3d6edc3ec1 drm/i915: use the new iterator in i915_request_await_object v2
77c552340892 drm/i915: use the new iterator in i915_sw_fence_await_reservation v2
f4e64617226b drm/i915: use the new iterator in i915_gem_busy_ioctl
d5ec3add7f52 drm/scheduler: use new iterator in drm_sched_job_add_implicit_dependencies v2
8fe08b573247 drm/radeon: use new iterator in radeon_sync_resv
cc28ebf6dea3 drm/msm: use new iterator in msm_gem_describe
f8f742ac41e1 drm/amdgpu: use new iterator in amdgpu_ttm_bo_eviction_valuable
174500546b2b drm/amdgpu: use the new iterator in amdgpu_sync_resv
bd71df193561 drm/ttm: use the new iterator in ttm_bo_flush_all_fences
f26d368dba9c dma-buf: use new iterator in dma_resv_test_signaled
d07cfed64ece dma-buf: use new iterator in dma_resv_wait_timeout
20181be832c0 dma-buf: use new iterator in dma_resv_get_fences v2
a8b725463938 dma-buf: use new iterator in dma_resv_copy_fences
43fd9d11fcd6 dma-buf: add dma_resv_for_each_fence
79becb99fccc dma-buf: add dma_resv_for_each_fence_unlocked v2

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21073/index.html

[-- Attachment #2: Type: text/html, Size: 12852 bytes --]

Deploying new iterator interface for dma-buf

[Christian König]

Hopefully the last round for this.

Added dma_resv_iter_begin/end as requested by Daniel. Fixed a bunch of
problems pointed out by the CI systems and found a few more myselve.

Please review and/or comment,
Christian.

[PATCH 01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2

[Christian König]

Abstract the complexity of iterating over all the fences
in a dma_resv object.

The new loop handles the whole RCU and retry dance and
returns only fences where we can be sure we grabbed the
right one.

v2: fix accessing the shared fences while they might be freed,
    improve kerneldoc, rename _cursor to _iter, add
    dma_resv_iter_is_exclusive, add dma_resv_iter_begin/end

Signed-off-by: Christian König <christian.koenig@amd.com>
---
 drivers/dma-buf/dma-resv.c | 61 +++++++++++++++++++++++++++
 include/linux/dma-resv.h   | 84 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 145 insertions(+)

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index 84fbe60629e3..3e77cad2c9d4 100644
--- a/drivers/dma-buf/dma-resv.c
+++ b/drivers/dma-buf/dma-resv.c
@@ -323,6 +323,67 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
 }
 EXPORT_SYMBOL(dma_resv_add_excl_fence);
 
+/**
+ * dma_resv_iter_walk_unlocked - walk over fences in a dma_resv obj
+ * @cursor: cursor to record the current position
+ * @first: if we should start over
+ *
+ * Return all the fences in the dma_resv object which are not yet signaled.
+ * The returned fence has an extra local reference so will stay alive.
+ * If a concurrent modify is detected the whole iterration is started over again.
+ */
+struct dma_fence *dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor,
+					      bool first)
+{
+	struct dma_resv *obj = cursor->obj;
+
+	first |= read_seqcount_retry(&obj->seq, cursor->seq);
+	do {
+		/* Drop the reference from the previous round */
+		dma_fence_put(cursor->fence);
+
+		cursor->is_first = first;
+		if (first) {
+			cursor->seq = read_seqcount_begin(&obj->seq);
+			cursor->index = -1;
+			cursor->fences = dma_resv_shared_list(obj);
+
+			cursor->fence = dma_resv_excl_fence(obj);
+			if (cursor->fence &&
+			    test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
+				     &cursor->fence->flags))
+				cursor->fence = NULL;
+		} else {
+			cursor->fence = NULL;
+		}
+
+		if (cursor->fence) {
+			cursor->fence = dma_fence_get_rcu(cursor->fence);
+		} else if (cursor->all_fences && cursor->fences) {
+			struct dma_resv_list *fences = cursor->fences;
+
+			while (++cursor->index < fences->shared_count) {
+				cursor->fence = rcu_dereference(
+					fences->shared[cursor->index]);
+				if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
+					      &cursor->fence->flags))
+					break;
+			}
+			if (cursor->index < fences->shared_count)
+				cursor->fence =
+					dma_fence_get_rcu(cursor->fence);
+			else
+				cursor->fence = NULL;
+		}
+
+		/* For the eventually next round */
+		first = true;
+	} while (read_seqcount_retry(&obj->seq, cursor->seq));
+
+	return cursor->fence;
+}
+EXPORT_SYMBOL_GPL(dma_resv_iter_walk_unlocked);
+
 /**
  * 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 9100dd3dc21f..693d16117153 100644
--- a/include/linux/dma-resv.h
+++ b/include/linux/dma-resv.h
@@ -149,6 +149,90 @@ struct dma_resv {
 	struct dma_resv_list __rcu *fence;
 };
 
+/**
+ * struct dma_resv_iter - current position into the dma_resv fences
+ *
+ * Don't touch this directly in the driver, use the accessor function instead.
+ */
+struct dma_resv_iter {
+	/** @obj: The dma_resv object we iterate over */
+	struct dma_resv *obj;
+
+	/** @all_fences: If all fences should be returned */
+	bool all_fences;
+
+	/** @fence: the currently handled fence */
+	struct dma_fence *fence;
+
+	/** @seq: sequence number to check for modifications */
+	unsigned int seq;
+
+	/** @index: index into the shared fences */
+	unsigned int index;
+
+	/** @fences: the shared fences */
+	struct dma_resv_list *fences;
+
+	/** @is_first: true if this is the first returned fence */
+	bool is_first;
+};
+
+struct dma_fence *dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor,
+					      bool first);
+
+/**
+ * dma_resv_iter_begin - initialize a dma_resv_iter object
+ * @cursor: The dma_resv_iter object to initialize
+ * @obj: The dma_resv object which we want to iterator over
+ * @all_fences: If all fences should be returned or just the exclusive one
+ */
+static inline void dma_resv_iter_begin(struct dma_resv_iter *cursor,
+					struct dma_resv *obj,
+					bool all_fences)
+{
+	cursor->obj = obj;
+	cursor->all_fences = all_fences;
+	cursor->fence = NULL;
+}
+
+/**
+ * dma_resv_iter_end - cleanup a dma_resv_iter object
+ * @cursor: the dma_resv_iter object which should be cleaned up
+ *
+ * Make sure that the reference to the fence in the cursor is properly
+ * dropped.
+ */
+static inline void dma_resv_iter_end(struct dma_resv_iter *cursor)
+{
+	dma_fence_put(cursor->fence);
+}
+
+/**
+ * dma_resv_iter_is_exclusive - test if the current fence is the exclusive one
+ * @cursor: the cursor of the current position
+ *
+ * Returns true if the currently returned fence is the exclusive one.
+ */
+static inline bool dma_resv_iter_is_exclusive(struct dma_resv_iter *cursor)
+{
+	return cursor->index == -1;
+}
+
+/**
+ * dma_resv_for_each_fence_unlocked - unlocked fence iterator
+ * @cursor: a struct dma_resv_iter pointer
+ * @fence: the current fence
+ *
+ * Iterate over the fences in a struct dma_resv object without holding the
+ * dma_resv::lock. The RCU read side lock must be hold when using this, but can
+ * be dropped and re-taken as necessary inside the loop. The cursor needs to be
+ * initialized with dma_resv_iter_begin_unlocked() and cleaned up with
+ * dma_resv_iter_end_unlocked().
+ */
+#define dma_resv_for_each_fence_unlocked(cursor, fence)			\
+	for (fence = dma_resv_iter_walk_unlocked(cursor, true);		\
+	     fence; fence = dma_resv_iter_walk_unlocked(cursor, false))
+
 #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
 #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
 
-- 
2.25.1

Re: [PATCH 01/26] dma-buf: add dma_resv_for_each_fence_unlocked v2

[Daniel Vetter]

On Fri, Sep 17, 2021 at 02:34:48PM +0200, Christian König wrote:
> Abstract the complexity of iterating over all the fences
> in a dma_resv object.
> 
> The new loop handles the whole RCU and retry dance and
> returns only fences where we can be sure we grabbed the
> right one.
> 
> v2: fix accessing the shared fences while they might be freed,
>     improve kerneldoc, rename _cursor to _iter, add
>     dma_resv_iter_is_exclusive, add dma_resv_iter_begin/end
> 
> Signed-off-by: Christian König <christian.koenig@amd.com>
> ---
>  drivers/dma-buf/dma-resv.c | 61 +++++++++++++++++++++++++++
>  include/linux/dma-resv.h   | 84 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 145 insertions(+)
> 
> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> index 84fbe60629e3..3e77cad2c9d4 100644
> --- a/drivers/dma-buf/dma-resv.c
> +++ b/drivers/dma-buf/dma-resv.c
> @@ -323,6 +323,67 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence)
>  }
>  EXPORT_SYMBOL(dma_resv_add_excl_fence);
>  
> +/**
> + * dma_resv_iter_walk_unlocked - walk over fences in a dma_resv obj
> + * @cursor: cursor to record the current position
> + * @first: if we should start over
> + *
> + * Return all the fences in the dma_resv object which are not yet signaled.
> + * The returned fence has an extra local reference so will stay alive.
> + * If a concurrent modify is detected the whole iterration is started over again.
> + */
> +struct dma_fence *dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor,

Bit ocd, but I'd still just call that iter_next.

> +					      bool first)

Hm I'd put all the init code into iter_begin ...

> +{
> +	struct dma_resv *obj = cursor->obj;

Aren't we missing rcu_read_lock() around the entire thing here?

> +
> +	first |= read_seqcount_retry(&obj->seq, cursor->seq);
> +	do {
> +		/* Drop the reference from the previous round */
> +		dma_fence_put(cursor->fence);
> +
> +		cursor->is_first = first;
> +		if (first) {
> +			cursor->seq = read_seqcount_begin(&obj->seq);
> +			cursor->index = -1;
> +			cursor->fences = dma_resv_shared_list(obj);

And then also call iter_begin from here. That way we guarantee that
read_seqcount_begin is always called before _retry(). It's not a problem
with the seqcount implementation (I think at least), but it definitely
looks funny.

Calling iter_begin here also makes it clear that we're essentially
restarting.

> +
> +			cursor->fence = dma_resv_excl_fence(obj);
> +			if (cursor->fence &&
> +			    test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,

Please use the right dma_fence wrapper here for this and don't look at the
bits/flags outside of dma_fence.[hc] code. I just realized that we don't
have the right amount of barriers in there for the fastpath, i.e. if we
have:

x = 0; /* static initializer */

thread a
	x = 1;
	dma_fence_signal(fence);


thread b;
	if (dma_fence_is_signalled(fence))
		printk("%i\n", x);

Then you might actually be able to observe x == 0 in thread b. Which is
not what we want at all.

So no open-coding of dma_fence flag bits code outside of drm_fence.[hc]
please. And yes i915-gem code is unfortunately a disaster.

> +				     &cursor->fence->flags))
> +				cursor->fence = NULL;
> +		} else {
> +			cursor->fence = NULL;
> +		}
> +
> +		if (cursor->fence) {
> +			cursor->fence = dma_fence_get_rcu(cursor->fence);
> +		} else if (cursor->all_fences && cursor->fences) {
> +			struct dma_resv_list *fences = cursor->fences;
> +
> +			while (++cursor->index < fences->shared_count) {
> +				cursor->fence = rcu_dereference(
> +					fences->shared[cursor->index]);
> +				if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
> +					      &cursor->fence->flags))
> +					break;
> +			}
> +			if (cursor->index < fences->shared_count)
> +				cursor->fence =
> +					dma_fence_get_rcu(cursor->fence);
> +			else
> +				cursor->fence = NULL;
> +		}

The control flow here is very hairy, but I'm not sure how to best do this.
With my suggestion to move the read_seqcount_begin into iter_begin maybe
something like this:

iter_next()
{
	do {
		dma_fence_put(cursor->fence)
		cursor->fence = NULL;

		if (cursor->index == -1) { /* reset by iter_begin()
			cursor->fence = get_exclusive();
			cusor->index++;
		} else {
			cursor->fence = shared_fences[++cursor->index]
		}

		if (!dma_fence_is_signalled(cursor->fence))
			continue; /* just grab the next fence. */

		cursor->fence =  dma_fence_get_rcu(cursor->fence);

		if (!cursor->fence || read_seqcount_retry()) {
			/* we lost the race, restart completely */
			iter_begin(); /* ->fence will be cleaned up at beginning of the loop */
			continue;
		}

		return cursor->fence;
	} while (true);
}

Maybe I missed something, but that avoids the duplication of all the
tricky code, i.e. checking for signalling, rcu protected conditional
fence_get, and the retry is also nicely at the end.
> +
> +		/* For the eventually next round */
> +		first = true;
> +	} while (read_seqcount_retry(&obj->seq, cursor->seq));
> +
> +	return cursor->fence;
> +}
> +EXPORT_SYMBOL_GPL(dma_resv_iter_walk_unlocked);
> +
>  /**
>   * 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 9100dd3dc21f..693d16117153 100644
> --- a/include/linux/dma-resv.h
> +++ b/include/linux/dma-resv.h
> @@ -149,6 +149,90 @@ struct dma_resv {
>  	struct dma_resv_list __rcu *fence;
>  };
>  
> +/**
> + * struct dma_resv_iter - current position into the dma_resv fences
> + *
> + * Don't touch this directly in the driver, use the accessor function instead.
> + */
> +struct dma_resv_iter {
> +	/** @obj: The dma_resv object we iterate over */
> +	struct dma_resv *obj;
> +
> +	/** @all_fences: If all fences should be returned */
> +	bool all_fences;
> +
> +	/** @fence: the currently handled fence */
> +	struct dma_fence *fence;
> +
> +	/** @seq: sequence number to check for modifications */
> +	unsigned int seq;
> +
> +	/** @index: index into the shared fences */

If you go with my suggestion (assuming it works): Please add "-1 indicates
to pick the exclusive fence instead."

> +	unsigned int index;
> +
> +	/** @fences: the shared fences */
> +	struct dma_resv_list *fences;
> +
> +	/** @is_first: true if this is the first returned fence */
> +	bool is_first;

I think if we just rely on -1 == exclusive fence/is_first we don't need
this one here?

> +};
> +
> +struct dma_fence *dma_resv_iter_walk_unlocked(struct dma_resv_iter *cursor,
> +					      bool first);
> +
> +/**
> + * dma_resv_iter_begin - initialize a dma_resv_iter object
> + * @cursor: The dma_resv_iter object to initialize
> + * @obj: The dma_resv object which we want to iterator over
> + * @all_fences: If all fences should be returned or just the exclusive one

Please add: "Callers must clean up the iterator with dma_resv_iter_end()."

> + */
> +static inline void dma_resv_iter_begin(struct dma_resv_iter *cursor,
> +					struct dma_resv *obj,
> +					bool all_fences)
> +{
> +	cursor->obj = obj;
> +	cursor->all_fences = all_fences;
> +	cursor->fence = NULL;
> +}
> +
> +/**
> + * dma_resv_iter_end - cleanup a dma_resv_iter object
> + * @cursor: the dma_resv_iter object which should be cleaned up
> + *
> + * Make sure that the reference to the fence in the cursor is properly
> + * dropped.

Please add:

"This function must be called every time dma_resv_iter_begin() was called
to clean up any references."
> + */
> +static inline void dma_resv_iter_end(struct dma_resv_iter *cursor)
> +{
> +	dma_fence_put(cursor->fence);
> +}
> +
> +/**
> + * dma_resv_iter_is_exclusive - test if the current fence is the exclusive one
> + * @cursor: the cursor of the current position
> + *
> + * Returns true if the currently returned fence is the exclusive one.
> + */
> +static inline bool dma_resv_iter_is_exclusive(struct dma_resv_iter *cursor)
> +{
> +	return cursor->index == -1;
> +}
> +
> +/**
> + * dma_resv_for_each_fence_unlocked - unlocked fence iterator
> + * @cursor: a struct dma_resv_iter pointer
> + * @fence: the current fence
> + *
> + * Iterate over the fences in a struct dma_resv object without holding the
> + * dma_resv::lock. The RCU read side lock must be hold when using this, but can
> + * be dropped and re-taken as necessary inside the loop. The cursor needs to be
> + * initialized with dma_resv_iter_begin_unlocked() and cleaned up with

We don't have an _unlocked version?

> + * dma_resv_iter_end_unlocked().
> + */
> +#define dma_resv_for_each_fence_unlocked(cursor, fence)			\
> +	for (fence = dma_resv_iter_walk_unlocked(cursor, true);		\
> +	     fence; fence = dma_resv_iter_walk_unlocked(cursor, false))
> +
>  #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
>  #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
>  
> -- 
> 2.25.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch