From 96c4104523a6a38f763dbdb3015d87aa5acca706 Mon Sep 17 00:00:00 2001
From: Evan Hemsley <[EMAIL REDACTED]>
Date: Tue, 10 Mar 2026 13:33:07 -0700
Subject: [PATCH] GPU: Refcount Vulkan allocations to fix transfer corruption
on defrag (#15127)
---
src/gpu/vulkan/SDL_gpu_vulkan.c | 163 +++++++++++++++++++++++++++++---
1 file changed, 149 insertions(+), 14 deletions(-)
diff --git a/src/gpu/vulkan/SDL_gpu_vulkan.c b/src/gpu/vulkan/SDL_gpu_vulkan.c
index 102fc166c3c2e..f05c03973cb42 100644
--- a/src/gpu/vulkan/SDL_gpu_vulkan.c
+++ b/src/gpu/vulkan/SDL_gpu_vulkan.c
@@ -500,6 +500,7 @@ struct VulkanMemoryAllocation
VkDeviceSize usedSpace;
Uint8 *mapPointer;
SDL_Mutex *memoryLock;
+ SDL_AtomicInt referenceCount; // Used to avoid defrag races
};
typedef struct VulkanMemoryAllocator
@@ -1040,10 +1041,18 @@ typedef struct VulkanCommandBuffer
Sint32 usedBufferCount;
Sint32 usedBufferCapacity;
+ VulkanBuffer **buffersUsedInPendingTransfers;
+ Sint32 buffersUsedInPendingTransfersCount;
+ Sint32 buffersUsedInPendingTransfersCapacity;
+
VulkanTexture **usedTextures;
Sint32 usedTextureCount;
Sint32 usedTextureCapacity;
+ VulkanTexture **texturesUsedInPendingTransfers;
+ Sint32 texturesUsedInPendingTransfersCount;
+ Sint32 texturesUsedInPendingTransfersCapacity;
+
VulkanSampler **usedSamplers;
Sint32 usedSamplerCount;
Sint32 usedSamplerCapacity;
@@ -1205,6 +1214,10 @@ struct VulkanRenderer
SDL_Mutex *descriptorSetLayoutFetchLock;
SDL_Mutex *windowLock;
+ // We don't want transfer commands to block each other,
+ // but we want all transfers to block during defrag.
+ SDL_RWLock *defragLock;
+
Uint8 defragInProgress;
VulkanMemoryAllocation **allocationsToDefrag;
@@ -1836,6 +1849,8 @@ static Uint8 VULKAN_INTERNAL_AllocateMemory(
allocation->freeRegionCount = 0;
allocation->freeRegionCapacity = 1;
+ SDL_SetAtomicInt(&allocation->referenceCount, 0);
+
allocation->allocator = allocator;
result = renderer->vkAllocateMemory(
@@ -2373,7 +2388,7 @@ static Uint8 VULKAN_INTERNAL_BindMemoryForBuffer(
// Resource tracking
-#define TRACK_RESOURCE(resource, type, array, count, capacity) \
+#define TRACK_RESOURCE(resource, type, array, count, capacity, refcountvar) \
for (Sint32 i = commandBuffer->count - 1; i >= 0; i -= 1) { \
if (commandBuffer->array[i] == resource) { \
return; \
@@ -2388,7 +2403,8 @@ static Uint8 VULKAN_INTERNAL_BindMemoryForBuffer(
} \
commandBuffer->array[commandBuffer->count] = resource; \
commandBuffer->count += 1; \
- SDL_AtomicIncRef(&resource->referenceCount);
+ SDL_AtomicIncRef(&refcountvar)
+
static void VULKAN_INTERNAL_TrackBuffer(
VulkanCommandBuffer *commandBuffer,
@@ -2399,7 +2415,23 @@ static void VULKAN_INTERNAL_TrackBuffer(
VulkanBuffer *,
usedBuffers,
usedBufferCount,
- usedBufferCapacity)
+ usedBufferCapacity,
+ buffer->referenceCount);
+}
+
+// Use this function when a GPU buffer is part of a transfer operation.
+// Note that this isn't for transfer buffers, those don't need to refcount their allocations.
+static void VULKAN_INTERNAL_TrackBufferTransfer(
+ VulkanCommandBuffer *commandBuffer,
+ VulkanBuffer *buffer)
+{
+ TRACK_RESOURCE(
+ buffer,
+ VulkanBuffer *,
+ buffersUsedInPendingTransfers,
+ buffersUsedInPendingTransfersCount,
+ buffersUsedInPendingTransfersCapacity,
+ buffer->usedRegion->allocation->referenceCount);
}
static void VULKAN_INTERNAL_TrackTexture(
@@ -2411,7 +2443,22 @@ static void VULKAN_INTERNAL_TrackTexture(
VulkanTexture *,
usedTextures,
usedTextureCount,
- usedTextureCapacity)
+ usedTextureCapacity,
+ texture->referenceCount);
+}
+
+// Use this when a texture is part of a transfer operation.
+static void VULKAN_INTERNAL_TrackTextureTransfer(
+ VulkanCommandBuffer *commandBuffer,
+ VulkanTexture *texture)
+{
+ TRACK_RESOURCE(
+ texture,
+ VulkanTexture *,
+ texturesUsedInPendingTransfers,
+ texturesUsedInPendingTransfersCount,
+ texturesUsedInPendingTransfersCapacity,
+ texture->usedRegion->allocation->referenceCount);
}
static void VULKAN_INTERNAL_TrackSampler(
@@ -2423,7 +2470,8 @@ static void VULKAN_INTERNAL_TrackSampler(
VulkanSampler *,
usedSamplers,
usedSamplerCount,
- usedSamplerCapacity)
+ usedSamplerCapacity,
+ sampler->referenceCount);
}
static void VULKAN_INTERNAL_TrackGraphicsPipeline(
@@ -2435,7 +2483,8 @@ static void VULKAN_INTERNAL_TrackGraphicsPipeline(
VulkanGraphicsPipeline *,
usedGraphicsPipelines,
usedGraphicsPipelineCount,
- usedGraphicsPipelineCapacity)
+ usedGraphicsPipelineCapacity,
+ graphicsPipeline->referenceCount);
}
static void VULKAN_INTERNAL_TrackComputePipeline(
@@ -2447,7 +2496,8 @@ static void VULKAN_INTERNAL_TrackComputePipeline(
VulkanComputePipeline *,
usedComputePipelines,
usedComputePipelineCount,
- usedComputePipelineCapacity)
+ usedComputePipelineCapacity,
+ computePipeline->referenceCount);
}
static void VULKAN_INTERNAL_TrackFramebuffer(
@@ -2459,7 +2509,8 @@ static void VULKAN_INTERNAL_TrackFramebuffer(
VulkanFramebuffer *,
usedFramebuffers,
usedFramebufferCount,
- usedFramebufferCapacity);
+ usedFramebufferCapacity,
+ framebuffer->referenceCount);
}
static void VULKAN_INTERNAL_TrackUniformBuffer(
@@ -6844,7 +6895,7 @@ static SDL_GPUTexture *VULKAN_CreateTexture(
texture);
VULKAN_INTERNAL_TrackTexture(barrierCommandBuffer, texture);
if (!VULKAN_Submit((SDL_GPUCommandBuffer *)barrierCommandBuffer)) {
- VULKAN_ReleaseTexture((SDL_GPURenderer *)renderer, (SDL_GPUTexture *)container);
+ VULKAN_ReleaseTexture((SDL_GPURenderer *)renderer, (SDL_GPUTexture *)container);
return NULL;
}
}
@@ -8742,8 +8793,9 @@ static void VULKAN_UploadToTexture(
VulkanTextureSubresource *vulkanTextureSubresource;
VkBufferImageCopy imageCopy;
- // Note that the transfer buffer does not need a barrier, as it is synced by the client
+ SDL_LockRWLockForReading(renderer->defragLock);
+ // Note that the transfer buffer does not need a barrier, as it is synced by the client
vulkanTextureSubresource = VULKAN_INTERNAL_PrepareTextureSubresourceForWrite(
renderer,
vulkanCommandBuffer,
@@ -8783,6 +8835,9 @@ static void VULKAN_UploadToTexture(
VULKAN_INTERNAL_TrackBuffer(vulkanCommandBuffer, transferBufferContainer->activeBuffer);
VULKAN_INTERNAL_TrackTexture(vulkanCommandBuffer, vulkanTextureSubresource->parent);
+ VULKAN_INTERNAL_TrackTextureTransfer(vulkanCommandBuffer, vulkanTextureSubresource->parent);
+
+ SDL_UnlockRWLock(renderer->defragLock);
}
static void VULKAN_UploadToBuffer(
@@ -8797,8 +8852,9 @@ static void VULKAN_UploadToBuffer(
VulkanBufferContainer *bufferContainer = (VulkanBufferContainer *)destination->buffer;
VkBufferCopy bufferCopy;
- // Note that the transfer buffer does not need a barrier, as it is synced by the client
+ SDL_LockRWLockForReading(renderer->defragLock);
+ // Note that the transfer buffer does not need a barrier, as it is synced by the client
VulkanBuffer *vulkanBuffer = VULKAN_INTERNAL_PrepareBufferForWrite(
renderer,
vulkanCommandBuffer,
@@ -8806,6 +8862,7 @@ static void VULKAN_UploadToBuffer(
cycle,
VULKAN_BUFFER_USAGE_MODE_COPY_DESTINATION);
+
bufferCopy.srcOffset = source->offset;
bufferCopy.dstOffset = destination->offset;
bufferCopy.size = destination->size;
@@ -8825,6 +8882,9 @@ static void VULKAN_UploadToBuffer(
VULKAN_INTERNAL_TrackBuffer(vulkanCommandBuffer, transferBufferContainer->activeBuffer);
VULKAN_INTERNAL_TrackBuffer(vulkanCommandBuffer, vulkanBuffer);
+ VULKAN_INTERNAL_TrackBufferTransfer(vulkanCommandBuffer, vulkanBuffer);
+
+ SDL_UnlockRWLock(renderer->defragLock);
}
// Readback
@@ -8840,6 +8900,9 @@ static void VULKAN_DownloadFromTexture(
VulkanTextureSubresource *vulkanTextureSubresource;
VulkanBufferContainer *transferBufferContainer = (VulkanBufferContainer *)destination->transfer_buffer;
VkBufferImageCopy imageCopy;
+
+ SDL_LockRWLockForReading(renderer->defragLock);
+
vulkanTextureSubresource = VULKAN_INTERNAL_FetchTextureSubresource(
textureContainer,
source->layer,
@@ -8883,6 +8946,9 @@ static void VULKAN_DownloadFromTexture(
VULKAN_INTERNAL_TrackBuffer(vulkanCommandBuffer, transferBufferContainer->activeBuffer);
VULKAN_INTERNAL_TrackTexture(vulkanCommandBuffer, vulkanTextureSubresource->parent);
+ VULKAN_INTERNAL_TrackTextureTransfer(vulkanCommandBuffer, vulkanTextureSubresource->parent);
+
+ SDL_UnlockRWLock(renderer->defragLock);
}
static void VULKAN_DownloadFromBuffer(
@@ -8896,8 +8962,9 @@ static void VULKAN_DownloadFromBuffer(
VulkanBufferContainer *transferBufferContainer = (VulkanBufferContainer *)destination->transfer_buffer;
VkBufferCopy bufferCopy;
- // Note that transfer buffer does not need a barrier, as it is synced by the client
+ SDL_LockRWLockForReading(renderer->defragLock);
+ // Note that transfer buffer does not need a barrier, as it is synced by the client
VULKAN_INTERNAL_BufferTransitionFromDefaultUsage(
renderer,
vulkanCommandBuffer,
@@ -8923,6 +8990,9 @@ static void VULKAN_DownloadFromBuffer(
VULKAN_INTERNAL_TrackBuffer(vulkanCommandBuffer, transferBufferContainer->activeBuffer);
VULKAN_INTERNAL_TrackBuffer(vulkanCommandBuffer, bufferContainer->activeBuffer);
+ VULKAN_INTERNAL_TrackBufferTransfer(vulkanCommandBuffer, bufferContainer->activeBuffer);
+
+ SDL_UnlockRWLock(renderer->defragLock);
}
static void VULKAN_CopyTextureToTexture(
@@ -8940,6 +9010,8 @@ static void VULKAN_CopyTextureToTexture(
VulkanTextureSubresource *dstSubresource;
VkImageCopy imageCopy;
+ SDL_LockRWLockForReading(renderer->defragLock);
+
srcSubresource = VULKAN_INTERNAL_FetchTextureSubresource(
(VulkanTextureContainer *)source->texture,
source->layer,
@@ -9001,6 +9073,10 @@ static void VULKAN_CopyTextureToTexture(
VULKAN_INTERNAL_TrackTexture(vulkanCommandBuffer, srcSubresource->parent);
VULKAN_INTERNAL_TrackTexture(vulkanCommandBuffer, dstSubresource->parent);
+ VULKAN_INTERNAL_TrackTextureTransfer(vulkanCommandBuffer, srcSubresource->parent);
+ VULKAN_INTERNAL_TrackTextureTransfer(vulkanCommandBuffer, dstSubresource->parent);
+
+ SDL_UnlockRWLock(renderer->defragLock);
}
static void VULKAN_CopyBufferToBuffer(
@@ -9016,6 +9092,8 @@ static void VULKAN_CopyBufferToBuffer(
VulkanBufferContainer *dstContainer = (VulkanBufferContainer *)destination->buffer;
VkBufferCopy bufferCopy;
+ SDL_LockRWLockForReading(renderer->defragLock);
+
VulkanBuffer *dstBuffer = VULKAN_INTERNAL_PrepareBufferForWrite(
renderer,
vulkanCommandBuffer,
@@ -9054,6 +9132,10 @@ static void VULKAN_CopyBufferToBuffer(
VULKAN_INTERNAL_TrackBuffer(vulkanCommandBuffer, srcContainer->activeBuffer);
VULKAN_INTERNAL_TrackBuffer(vulkanCommandBuffer, dstBuffer);
+ VULKAN_INTERNAL_TrackBufferTransfer(vulkanCommandBuffer, srcContainer->activeBuffer);
+ VULKAN_INTERNAL_TrackBufferTransfer(vulkanCommandBuffer, dstBuffer);
+
+ SDL_UnlockRWLock(renderer->defragLock);
}
static void VULKAN_GenerateMipmaps(
@@ -9067,8 +9149,10 @@ static void VULKAN_GenerateMipmaps(
VulkanTextureSubresource *dstTextureSubresource;
VkImageBlit blit;
+ SDL_LockRWLockForReading(renderer->defragLock);
+
// Blit each slice sequentially. Barriers, barriers everywhere!
- for (Uint32 layerOrDepthIndex = 0; layerOrDepthIndex < container->header.info.layer_count_or_depth; layerOrDepthIndex += 1)
+ for (Uint32 layerOrDepthIndex = 0; layerOrDepthIndex < container->header.info.layer_count_or_depth; layerOrDepthIndex += 1) {
for (Uint32 level = 1; level < container->header.info.num_levels; level += 1) {
Uint32 layer = container->header.info.type == SDL_GPU_TEXTURETYPE_3D ? 0 : layerOrDepthIndex;
Uint32 depth = container->header.info.type == SDL_GPU_TEXTURETYPE_3D ? layerOrDepthIndex : 0;
@@ -9147,7 +9231,13 @@ static void VULKAN_GenerateMipmaps(
VULKAN_INTERNAL_TrackTexture(vulkanCommandBuffer, srcTextureSubresource->parent);
VULKAN_INTERNAL_TrackTexture(vulkanCommandBuffer, dstTextureSubresource->parent);
+ VULKAN_INTERNAL_TrackTextureTransfer(vulkanCommandBuffer, srcTextureSubresource->parent);
+ VULKAN_INTERNAL_TrackTextureTransfer(vulkanCommandBuffer, dstTextureSubresource->parent);
+
}
+ }
+
+ SDL_UnlockRWLock(renderer->defragLock);
}
static void VULKAN_EndCopyPass(
@@ -9357,11 +9447,21 @@ static bool VULKAN_INTERNAL_AllocateCommandBuffer(
commandBuffer->usedBuffers = SDL_malloc(
commandBuffer->usedBufferCapacity * sizeof(VulkanBuffer *));
+ commandBuffer->buffersUsedInPendingTransfersCapacity = 4;
+ commandBuffer->buffersUsedInPendingTransfersCount = 0;
+ commandBuffer->buffersUsedInPendingTransfers = SDL_malloc(
+ commandBuffer->buffersUsedInPendingTransfersCapacity * sizeof(VulkanBuffer *));
+
commandBuffer->usedTextureCapacity = 4;
commandBuffer->usedTextureCount = 0;
commandBuffer->usedTextures = SDL_malloc(
commandBuffer->usedTextureCapacity * sizeof(VulkanTexture *));
+ commandBuffer->texturesUsedInPendingTransfersCapacity = 4;
+ commandBuffer->texturesUsedInPendingTransfersCount = 0;
+ commandBuffer->texturesUsedInPendingTransfers = SDL_malloc(
+ commandBuffer->texturesUsedInPendingTransfersCapacity * sizeof(VulkanTexture *));
+
commandBuffer->usedSamplerCapacity = 4;
commandBuffer->usedSamplerCount = 0;
commandBuffer->usedSamplers = SDL_malloc(
@@ -10430,11 +10530,21 @@ static void VULKAN_INTERNAL_CleanCommandBuffer(
}
commandBuffer->usedBufferCount = 0;
+ for (Sint32 i = 0; i < commandBuffer->buffersUsedInPendingTransfersCount; i += 1) {
+ (void)SDL_AtomicDecRef(&commandBuffer->usedBuffers[i]->usedRegion->allocation->referenceCount);
+ }
+ commandBuffer->buffersUsedInPendingTransfersCount = 0;
+
for (Sint32 i = 0; i < commandBuffer->usedTextureCount; i += 1) {
(void)SDL_AtomicDecRef(&commandBuffer->usedTextures[i]->referenceCount);
}
commandBuffer->usedTextureCount = 0;
+ for (Sint32 i = 0; i < commandBuffer->texturesUsedInPendingTransfersCount; i += 1){
+ (void)SDL_AtomicDecRef(&commandBuffer->usedTextures[i]->usedRegion->allocation->referenceCount);
+ }
+ commandBuffer->texturesUsedInPendingTransfersCount = 0;
+
for (Sint32 i = 0; i < commandBuffer->usedSamplerCount; i += 1) {
(void)SDL_AtomicDecRef(&commandBuffer->usedSamplers[i]->referenceCount);
}
@@ -10820,8 +10930,30 @@ static bool VULKAN_INTERNAL_DefragmentMemory(
commandBuffer->isDefrag = 1;
SDL_LockMutex(renderer->allocatorLock);
+ SDL_LockRWLockForWriting(renderer->defragLock);
+
+ // Find an allocation that doesn't have any pending transfer operations
+ Sint32 indexToDefrag = -1;
+ for (Sint32 i = renderer->allocationsToDefragCount - 1; i >= 0; i -= 1) {
+ if (SDL_GetAtomicInt(&renderer->allocationsToDefrag[i]->referenceCount) == 0) {
+ indexToDefrag = i;
+ break;
+ }
+ }
- VulkanMemoryAllocation *allocation = renderer->allocationsToDefrag[renderer->allocationsToDefragCount - 1];
+ if (indexToDefrag == -1) {
+ // Nothing is available to defrag, but it's not an error
+ SDL_UnlockRWLock(renderer->defragLock);
+ SDL_UnlockMutex(renderer->allocatorLock);
+ return true;
+ }
+
+ VulkanMemoryAllocation *allocation = renderer->allocationsToDefrag[indexToDefrag];
+
+ // Plug the hole
+ if ((Uint32) indexToDefrag != renderer->allocationsToDefragCount - 1) {
+ renderer->allocationsToDefrag[indexToDefrag] = renderer->allocationsToDefrag[renderer->allocationsToDefragCount - 1];
+ }
renderer->allocationsToDefragCount -= 1;
/* For each used region in the allocation
@@ -10841,6 +10973,7 @@ static bool VULKAN_INTERNAL_DefragmentMemory(
currentRegion->vulkanBuffer->container != NULL ? currentRegion->vulkanBuffer->container->debugName : NULL);
if (newBuffer == NULL) {
+ SDL_UnlockRWLock(renderer->defragLock);
SDL_UnlockMutex(renderer->allocatorLock);
SDL_LogError(SDL_LOG_CATEGORY_GPU, "%s", "Failed to allocate defrag buffer!");
return false;
@@ -10906,6 +11039,7 @@ static bool VULKAN_INTERNAL_DefragmentMemory(
¤tRegion->vulkanTexture->container->header.info);
if (newTexture == NULL) {
+ SDL_UnlockRWLock(renderer->defragLock);
SDL_UnlockMutex(renderer->allocatorLock);
SDL_LogError(SDL_LOG_CATEGORY_GPU, "%s", "Failed to allocate defrag buffer!");
return false;
@@ -10980,6 +11114,7 @@ static bool VULKAN_INTERNAL_DefragmentMemory(
}
}
+ SDL_UnlockRWLock(renderer->defragLock);
SDL_UnlockMutex(renderer->allocatorLock);
return true;