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[PATCH v2 1/8] dma-buf/dma-fence: Add dma_fence_test_signaled_flag()

Philipp Stanner posted 6 patches 2 months, 1 week ago
[PATCH v2 1/8] dma-buf/dma-fence: Add dma_fence_test_signaled_flag()
Posted by Philipp Stanner 2 months, 1 week ago 
The dma_fence framework checks at many places whether the signaled flag
of a fence is already set. The code can be simplified and made more
readable by providing a helper function for that.

Add dma_fence_test_signaled_flag(), which only checks whether a fence is
signaled. Use it internally.

Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Signed-off-by: Philipp Stanner <phasta@kernel.org>
---
 drivers/dma-buf/dma-fence.c | 16 ++++++++--------
 include/linux/dma-fence.h   | 24 ++++++++++++++++++++++--
 2 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 39e6f93dc310..96d72ffc0750 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -545,7 +545,7 @@ void dma_fence_release(struct kref *kref)
 	trace_dma_fence_destroy(fence);
 
 	if (!list_empty(&fence->cb_list) &&
-	    !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
+	    !dma_fence_test_signaled_flag(fence)) {
 		const char __rcu *timeline;
 		const char __rcu *driver;
 		unsigned long flags;
@@ -602,7 +602,7 @@ static bool __dma_fence_enable_signaling(struct dma_fence *fence)
 	was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
 				   &fence->flags);
 
-	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+	if (dma_fence_test_signaled_flag(fence))
 		return false;
 
 	if (!was_set && fence->ops->enable_signaling) {
@@ -666,7 +666,7 @@ int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb,
 	if (WARN_ON(!fence || !func))
 		return -EINVAL;
 
-	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
+	if (dma_fence_test_signaled_flag(fence)) {
 		INIT_LIST_HEAD(&cb->node);
 		return -ENOENT;
 	}
@@ -783,7 +783,7 @@ dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
 
 	spin_lock_irqsave(fence->lock, flags);
 
-	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+	if (dma_fence_test_signaled_flag(fence))
 		goto out;
 
 	if (intr && signal_pending(current)) {
@@ -800,7 +800,7 @@ dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
 	cb.task = current;
 	list_add(&cb.base.node, &fence->cb_list);
 
-	while (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
+	while (!dma_fence_test_signaled_flag(fence) && ret > 0) {
 		if (intr)
 			__set_current_state(TASK_INTERRUPTIBLE);
 		else
@@ -832,7 +832,7 @@ dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
 
 	for (i = 0; i < count; ++i) {
 		struct dma_fence *fence = fences[i];
-		if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
+		if (dma_fence_test_signaled_flag(fence)) {
 			if (idx)
 				*idx = i;
 			return true;
@@ -1108,7 +1108,7 @@ const char __rcu *dma_fence_driver_name(struct dma_fence *fence)
 	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
 			 "RCU protection is required for safe access to returned string");
 
-	if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+	if (!dma_fence_test_signaled_flag(fence))
 		return fence->ops->get_driver_name(fence);
 	else
 		return "detached-driver";
@@ -1140,7 +1140,7 @@ const char __rcu *dma_fence_timeline_name(struct dma_fence *fence)
 	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
 			 "RCU protection is required for safe access to returned string");
 
-	if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+	if (!dma_fence_test_signaled_flag(fence))
 		return fence->ops->get_timeline_name(fence);
 	else
 		return "signaled-timeline";
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index 64639e104110..19972f5d176f 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -401,6 +401,26 @@ void dma_fence_enable_sw_signaling(struct dma_fence *fence);
 const char __rcu *dma_fence_driver_name(struct dma_fence *fence);
 const char __rcu *dma_fence_timeline_name(struct dma_fence *fence);
 
+/*
+ * dma_fence_test_signaled_flag - Only check whether a fence is signaled yet.
+ * @fence: the fence to check
+ *
+ * This function just checks whether @fence is signaled, without interacting
+ * with the fence in any way. The user must, therefore, ensure through other
+ * means that fences get signaled eventually.
+ *
+ * This function uses test_bit(), which is thread-safe. Naturally, this function
+ * should be used opportunistically; a fence could get signaled at any moment
+ * after the check is done.
+ *
+ * Return: true if signaled, false otherwise.
+ */
+static inline bool
+dma_fence_test_signaled_flag(struct dma_fence *fence)
+{
+	return test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags);
+}
+
 /**
  * dma_fence_is_signaled_locked - Return an indication if the fence
  *                                is signaled yet.
@@ -418,7 +438,7 @@ const char __rcu *dma_fence_timeline_name(struct dma_fence *fence);
 static inline bool
 dma_fence_is_signaled_locked(struct dma_fence *fence)
 {
-	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+	if (dma_fence_test_signaled_flag(fence))
 		return true;
 
 	if (fence->ops->signaled && fence->ops->signaled(fence)) {
@@ -448,7 +468,7 @@ dma_fence_is_signaled_locked(struct dma_fence *fence)
 static inline bool
 dma_fence_is_signaled(struct dma_fence *fence)
 {
-	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
+	if (dma_fence_test_signaled_flag(fence))
 		return true;
 
 	if (fence->ops->signaled && fence->ops->signaled(fence)) {
-- 
2.49.0
Re: [PATCH v2 1/8] dma-buf/dma-fence: Add dma_fence_test_signaled_flag()
Posted by Christian König 2 months ago 
On 12/1/25 11:50, Philipp Stanner wrote:
> The dma_fence framework checks at many places whether the signaled flag
> of a fence is already set. The code can be simplified and made more
> readable by providing a helper function for that.
> 
> Add dma_fence_test_signaled_flag(), which only checks whether a fence is
> signaled. Use it internally.
> 
> Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
> Signed-off-by: Philipp Stanner <phasta@kernel.org>

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
>  drivers/dma-buf/dma-fence.c | 16 ++++++++--------
>  include/linux/dma-fence.h   | 24 ++++++++++++++++++++++--
>  2 files changed, 30 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
> index 39e6f93dc310..96d72ffc0750 100644
> --- a/drivers/dma-buf/dma-fence.c
> +++ b/drivers/dma-buf/dma-fence.c
> @@ -545,7 +545,7 @@ void dma_fence_release(struct kref *kref)
>  	trace_dma_fence_destroy(fence);
>  
>  	if (!list_empty(&fence->cb_list) &&
> -	    !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
> +	    !dma_fence_test_signaled_flag(fence)) {
>  		const char __rcu *timeline;
>  		const char __rcu *driver;
>  		unsigned long flags;
> @@ -602,7 +602,7 @@ static bool __dma_fence_enable_signaling(struct dma_fence *fence)
>  	was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
>  				   &fence->flags);
>  
> -	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
> +	if (dma_fence_test_signaled_flag(fence))
>  		return false;
>  
>  	if (!was_set && fence->ops->enable_signaling) {
> @@ -666,7 +666,7 @@ int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb,
>  	if (WARN_ON(!fence || !func))
>  		return -EINVAL;
>  
> -	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
> +	if (dma_fence_test_signaled_flag(fence)) {
>  		INIT_LIST_HEAD(&cb->node);
>  		return -ENOENT;
>  	}
> @@ -783,7 +783,7 @@ dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
>  
>  	spin_lock_irqsave(fence->lock, flags);
>  
> -	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
> +	if (dma_fence_test_signaled_flag(fence))
>  		goto out;
>  
>  	if (intr && signal_pending(current)) {
> @@ -800,7 +800,7 @@ dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
>  	cb.task = current;
>  	list_add(&cb.base.node, &fence->cb_list);
>  
> -	while (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) {
> +	while (!dma_fence_test_signaled_flag(fence) && ret > 0) {
>  		if (intr)
>  			__set_current_state(TASK_INTERRUPTIBLE);
>  		else
> @@ -832,7 +832,7 @@ dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count,
>  
>  	for (i = 0; i < count; ++i) {
>  		struct dma_fence *fence = fences[i];
> -		if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) {
> +		if (dma_fence_test_signaled_flag(fence)) {
>  			if (idx)
>  				*idx = i;
>  			return true;
> @@ -1108,7 +1108,7 @@ const char __rcu *dma_fence_driver_name(struct dma_fence *fence)
>  	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
>  			 "RCU protection is required for safe access to returned string");
>  
> -	if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
> +	if (!dma_fence_test_signaled_flag(fence))
>  		return fence->ops->get_driver_name(fence);
>  	else
>  		return "detached-driver";
> @@ -1140,7 +1140,7 @@ const char __rcu *dma_fence_timeline_name(struct dma_fence *fence)
>  	RCU_LOCKDEP_WARN(!rcu_read_lock_held(),
>  			 "RCU protection is required for safe access to returned string");
>  
> -	if (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
> +	if (!dma_fence_test_signaled_flag(fence))
>  		return fence->ops->get_timeline_name(fence);
>  	else
>  		return "signaled-timeline";
> diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
> index 64639e104110..19972f5d176f 100644
> --- a/include/linux/dma-fence.h
> +++ b/include/linux/dma-fence.h
> @@ -401,6 +401,26 @@ void dma_fence_enable_sw_signaling(struct dma_fence *fence);
>  const char __rcu *dma_fence_driver_name(struct dma_fence *fence);
>  const char __rcu *dma_fence_timeline_name(struct dma_fence *fence);
>  
> +/*
> + * dma_fence_test_signaled_flag - Only check whether a fence is signaled yet.
> + * @fence: the fence to check
> + *
> + * This function just checks whether @fence is signaled, without interacting
> + * with the fence in any way. The user must, therefore, ensure through other
> + * means that fences get signaled eventually.
> + *
> + * This function uses test_bit(), which is thread-safe. Naturally, this function
> + * should be used opportunistically; a fence could get signaled at any moment
> + * after the check is done.
> + *
> + * Return: true if signaled, false otherwise.
> + */
> +static inline bool
> +dma_fence_test_signaled_flag(struct dma_fence *fence)
> +{
> +	return test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags);
> +}
> +
>  /**
>   * dma_fence_is_signaled_locked - Return an indication if the fence
>   *                                is signaled yet.
> @@ -418,7 +438,7 @@ const char __rcu *dma_fence_timeline_name(struct dma_fence *fence);
>  static inline bool
>  dma_fence_is_signaled_locked(struct dma_fence *fence)
>  {
> -	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
> +	if (dma_fence_test_signaled_flag(fence))
>  		return true;
>  
>  	if (fence->ops->signaled && fence->ops->signaled(fence)) {
> @@ -448,7 +468,7 @@ dma_fence_is_signaled_locked(struct dma_fence *fence)
>  static inline bool
>  dma_fence_is_signaled(struct dma_fence *fence)
>  {
> -	if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
> +	if (dma_fence_test_signaled_flag(fence))
>  		return true;
>  
>  	if (fence->ops->signaled && fence->ops->signaled(fence)) {

Patchew 2.1-devel-b67e4c2

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