[FFmpeg-devel] [PATCH 1/2] vulkan: synchronize access to execution pool fences

[Lynne]

vkResetFences is specified as being user-synchronized
(yet vkWaitFences, is not).

Patch attached.

>From c79aa3ed01033f515cbb21251e83cb5bafdf83d7 Mon Sep 17 00:00:00 2001
From: Lynne <d...@lynne.ee>
Date: Wed, 7 Jun 2023 00:24:43 +0200
Subject: [PATCH 1/2] vulkan: synchronize access to execution pool fences

vkResetFences is specified as being user-synchronized
(yet vkWaitFences, is not).
---
 libavcodec/vulkan_decode.c |  2 +-
 libavutil/vulkan.c         | 12 ++++++++++--
 libavutil/vulkan.h         |  2 ++
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/libavcodec/vulkan_decode.c b/libavcodec/vulkan_decode.c
index 889c67a15f..9e3ebf6770 100644
--- a/libavcodec/vulkan_decode.c
+++ b/libavcodec/vulkan_decode.c
@@ -1106,7 +1106,7 @@ int ff_vk_decode_init(AVCodecContext *avctx)
 
     /* Create decode exec context.
      * 4 async contexts per thread seems like a good number. */
-    err = ff_vk_exec_pool_init(s, &qf_dec, &ctx->exec_pool, 4*avctx->thread_count,
+    err = ff_vk_exec_pool_init(s, &qf_dec, &ctx->exec_pool, 1,
                                nb_q, VK_QUERY_TYPE_RESULT_STATUS_ONLY_KHR, 0,
                                session_create.pVideoProfile);
     if (err < 0)
diff --git a/libavutil/vulkan.c b/libavutil/vulkan.c
index bc4466e6c9..4b96c0c200 100644
--- a/libavutil/vulkan.c
+++ b/libavutil/vulkan.c
@@ -241,6 +241,7 @@ void ff_vk_exec_pool_free(FFVulkanContext *s, FFVkExecPool *pool)
             vk->WaitForFences(s->hwctx->act_dev, 1, &e->fence, VK_TRUE, UINT64_MAX);
             vk->DestroyFence(s->hwctx->act_dev, e->fence, s->hwctx->alloc);
         }
+        pthread_mutex_destroy(&e->lock);
 
         ff_vk_exec_discard_deps(s, e);
 
@@ -379,12 +380,17 @@ int ff_vk_exec_pool_init(FFVulkanContext *s, FFVkQueueFamilyCtx *qf,
     /* Init contexts */
     for (int i = 0; i < pool->pool_size; i++) {
         FFVkExecContext *e = &pool->contexts[i];
-
-        /* Fence */
         VkFenceCreateInfo fence_create = {
             .sType = VK_STRUCTURE_TYPE_FENCE_CREATE_INFO,
             .flags = VK_FENCE_CREATE_SIGNALED_BIT,
         };
+
+        /* Mutex */
+        err = pthread_mutex_init(&e->lock, NULL);
+        if (err != 0)
+            return AVERROR(err);
+
+        /* Fence */
         ret = vk->CreateFence(s->hwctx->act_dev, &fence_create, s->hwctx->alloc,
                               &e->fence);
         if (ret != VK_SUCCESS) {
@@ -489,8 +495,10 @@ int ff_vk_exec_start(FFVulkanContext *s, FFVkExecContext *e)
     };
 
     /* Create the fence and don't wait for it initially */
+    pthread_mutex_lock(&e->lock);
     vk->WaitForFences(s->hwctx->act_dev, 1, &e->fence, VK_TRUE, UINT64_MAX);
     vk->ResetFences(s->hwctx->act_dev, 1, &e->fence);
+    pthread_mutex_unlock(&e->lock);
 
     /* Discard queue dependencies */
     ff_vk_exec_discard_deps(s, e);
diff --git a/libavutil/vulkan.h b/libavutil/vulkan.h
index 58da720a1c..bbbc9374ae 100644
--- a/libavutil/vulkan.h
+++ b/libavutil/vulkan.h
@@ -23,6 +23,7 @@
 
 #include <stdatomic.h>
 
+#include "thread.h"
 #include "pixdesc.h"
 #include "bprint.h"
 #include "hwcontext.h"
@@ -152,6 +153,7 @@ typedef struct FFVulkanPipeline {
 typedef struct FFVkExecContext {
     int idx;
     const struct FFVkExecPool *parent;
+    pthread_mutex_t lock;
 
     /* Queue for the execution context */
     VkQueue queue;
-- 
2.40.1


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