dnn/dnn_backend_native_layer_conv2d: Avoid separate, unchecked allocations

Reviewed-by: Guo, Yejun <yejun.guo@intel.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavfilter/dnn/dnn_backend_native_layer_conv2d.c

@@ -191,7 +191,7 @@ int ff_dnn_execute_layer_conv2d(DnnOperand *operands, const int32_t *input_opera
     int thread_num = (ctx->options.conv2d_threads <= 0 || ctx->options.conv2d_threads > av_cpu_count())
         ? (av_cpu_count() + 1) : (ctx->options.conv2d_threads);
     int thread_stride;
-    ThreadParam **thread_param;
+    ThreadParam *thread_param;
 #else
     ThreadParam thread_param = { 0 };
 #endif
@@ -231,22 +231,18 @@ int ff_dnn_execute_layer_conv2d(DnnOperand *operands, const int32_t *input_opera
     thread_stride = (height - pad_size * 2) / thread_num;
     //create threads
     for (int i = 0; i < thread_num; i++){
-        thread_param[i] = av_malloc(sizeof(*thread_param[0]));
-        thread_param[i]->thread_common_param = &thread_common_param;
-        thread_param[i]->thread_start = thread_stride * i + pad_size;
-        thread_param[i]->thread_end = (i == thread_num - 1) ? (height - pad_size) : (thread_param[i]->thread_start + thread_stride);
-        pthread_create(&thread_param[i]->thread, NULL, dnn_execute_layer_conv2d_thread, (void *)thread_param[i]);
+        thread_param[i].thread_common_param = &thread_common_param;
+        thread_param[i].thread_start = thread_stride * i + pad_size;
+        thread_param[i].thread_end = (i == thread_num - 1) ? (height - pad_size) : (thread_param[i].thread_start + thread_stride);
+        pthread_create(&thread_param[i].thread, NULL, dnn_execute_layer_conv2d_thread, &thread_param[i]);
     }
 
     //join threads, res gets function return
     for (int i = 0; i < thread_num; i++){
-        pthread_join(thread_param[i]->thread, NULL);
+        pthread_join(thread_param[i].thread, NULL);
     }
 
     //release memory
-    for (int i = 0; i < thread_num; i++){
-        av_freep(&thread_param[i]);
-    }
     av_freep(&thread_param);
 #else
     thread_param.thread_common_param = &thread_common_param;