drm/amdgpu: drop userq fence driver refs out of fence process()

amdgpu_userq_wait_ioctl() takes extra references on waited-on fence
drivers and stores them in waitq->fence_drv_xa. When a new userq fence is
created, those references are transferred into userq_fence->fence_drv_array
so they can be released when the fence completes.

However, those inherited references are currently only dropped from
amdgpu_userq_fence_driver_process(). If a fence never reaches that path,
such as it is already signaled when created, so we need to explicitly release
those fences in that case.

v2: use a list(list_cut_before) for managing the signal userq driver fences.(Christian)
    Link: https://patchwork.freedesktop.org/patch/718078/?series=164763&rev=2
v3: Doesn't cache the userq first unsignaled fence and use the cut before list
    head directly.(Christian)

Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Prike Liang <Prike.Liang@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 33 insertions, 14 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
index 5784f2b3ecae..da39ac862f37 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
@@ -145,13 +145,22 @@ amdgpu_userq_fence_driver_free(struct amdgpu_usermode_queue *userq)
 	amdgpu_userq_fence_driver_put(userq->fence_drv);
 }
 
+static void
+amdgpu_userq_fence_put_fence_drv_array(struct amdgpu_userq_fence *userq_fence)
+{
+	unsigned long i;
+	for (i = 0; i < userq_fence->fence_drv_array_count; i++)
+		amdgpu_userq_fence_driver_put(userq_fence->fence_drv_array[i]);
+	userq_fence->fence_drv_array_count = 0;
+}
+
 void amdgpu_userq_fence_driver_process(struct amdgpu_userq_fence_driver *fence_drv)
 {
 	struct amdgpu_userq_fence *userq_fence, *tmp;
+	LIST_HEAD(to_be_signaled);
 	struct dma_fence *fence;
 	unsigned long flags;
 	u64 rptr;
-	int i;
 
 	if (!fence_drv)
 		return;
@@ -159,21 +168,26 @@ void amdgpu_userq_fence_driver_process(struct amdgpu_userq_fence_driver *fence_d
 	spin_lock_irqsave(&fence_drv->fence_list_lock, flags);
 	rptr = amdgpu_userq_fence_read(fence_drv);
 
-	list_for_each_entry_safe(userq_fence, tmp, &fence_drv->fences, link) {
-		fence = &userq_fence->base;
-
-		if (rptr < fence->seqno)
+	list_for_each_entry(userq_fence, &fence_drv->fences, link) {
+		if (rptr < userq_fence->base.seqno)
 			break;
+	}
 
-		dma_fence_signal(fence);
-
-		for (i = 0; i < userq_fence->fence_drv_array_count; i++)
-			amdgpu_userq_fence_driver_put(userq_fence->fence_drv_array[i]);
+	list_cut_before(&to_be_signaled, &fence_drv->fences,
+				&userq_fence->link);
+	spin_unlock_irqrestore(&fence_drv->fence_list_lock, flags);
 
-		list_del(&userq_fence->link);
+	list_for_each_entry_safe(userq_fence, tmp, &to_be_signaled, link) {
+		fence = &userq_fence->base;
+		list_del_init(&userq_fence->link);
+		dma_fence_signal(fence);
+		/* Drop fence_drv_array outside fence_list_lock
+		 * to avoid the recursion lock.
+		 */
+		amdgpu_userq_fence_put_fence_drv_array(userq_fence);
 		dma_fence_put(fence);
 	}
-	spin_unlock_irqrestore(&fence_drv->fence_list_lock, flags);
+
 }
 
 void amdgpu_userq_fence_driver_destroy(struct kref *ref)
@@ -228,6 +242,7 @@ static int amdgpu_userq_fence_create(struct amdgpu_usermode_queue *userq,
 	struct amdgpu_userq_fence_driver *fence_drv;
 	struct dma_fence *fence;
 	unsigned long flags;
+	bool signaled = false;
 
 	fence_drv = userq->fence_drv;
 	if (!fence_drv)
@@ -274,13 +289,17 @@ static int amdgpu_userq_fence_create(struct amdgpu_usermode_queue *userq,
 
 	/* Check if hardware has already processed the job */
 	spin_lock_irqsave(&fence_drv->fence_list_lock, flags);
-	if (!dma_fence_is_signaled(fence))
+	if (!dma_fence_is_signaled(fence)) {
 		list_add_tail(&userq_fence->link, &fence_drv->fences);
-	else
+	} else {
+		signaled = true;
 		dma_fence_put(fence);
-
+	}
 	spin_unlock_irqrestore(&fence_drv->fence_list_lock, flags);
 
+	if (signaled)
+		amdgpu_userq_fence_put_fence_drv_array(userq_fence);
+
 	*f = fence;
 
 	return 0;