dnn/Vulkan: make thread safe

Use a global dedicated mutex to make sure initialize once and
protect command buffer pool and queue.

Signed-off-by: Wu Zhiwen <zhiwen.wu@intel.com>

modules/dnn/src/vkcom/src/common.hpp

@@ -33,6 +33,7 @@ extern VkPhysicalDevice kPhysicalDevice;
 extern VkDevice kDevice;
 extern VkQueue kQueue;
 extern VkCommandPool kCmdPool;
+extern cv::Mutex kContextMtx;
 
 enum ShapeIdx
 {

modules/dnn/src/vkcom/src/context.cpp

@@ -25,6 +25,7 @@ VkDebugReportCallbackEXT kDebugReportCallback;
 uint32_t kQueueFamilyIndex;
 std::vector<const char *> kEnabledLayers;
 std::map<std::string, std::vector<uint32_t>> kShaders;
+cv::Mutex kContextMtx;
 
 static uint32_t getComputeQueueFamilyIndex()
 {
@@ -86,7 +87,7 @@ VKAPI_ATTR VkBool32 VKAPI_CALL debugReportCallbackFn(
 // internally used
 void createContext()
 {
-    cv::AutoLock lock(getInitializationMutex());
+    cv::AutoLock lock(kContextMtx);
     if (!kCtx)
     {
         kCtx.reset(new Context());

modules/dnn/src/vkcom/src/op_base.cpp

@@ -150,6 +150,7 @@ void OpBase::recordCommandBuffer(void* push_constants, size_t push_constants_siz
     VkCommandBufferBeginInfo beginInfo = {};
     beginInfo.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
     beginInfo.flags = VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT;
+    cv::AutoLock lock(kContextMtx);
     VK_CHECK_RESULT(vkBeginCommandBuffer(cmd_buffer_, &beginInfo));
     if (push_constants)
         vkCmdPushConstants(cmd_buffer_, pipeline_layout_,
@@ -176,7 +177,10 @@ void OpBase::runCommandBuffer()
     fence_create_info_.flags = 0;
 
     VK_CHECK_RESULT(vkCreateFence(device_, &fence_create_info_, NULL, &fence));
-    VK_CHECK_RESULT(vkQueueSubmit(kQueue, 1, &submit_info, fence));
+    {
+        cv::AutoLock lock(kContextMtx);
+        VK_CHECK_RESULT(vkQueueSubmit(kQueue, 1, &submit_info, fence));
+    }
     VK_CHECK_RESULT(vkWaitForFences(device_, 1, &fence, VK_TRUE, 100000000000));
     vkDestroyFence(device_, fence, NULL);
 }