get_data_ptr_ipc.cu

// Copyright (c) 2025 PaddlePaddle Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <cstring>
#include "cuda_multiprocess.h"
#include "helper.h"

namespace {
#if !defined(_WIN32)
int sharedMemoryOpen2(const char *name, size_t sz, sharedMemoryInfo *info) {
  info->size = sz;
  info->shmFd = shm_open(name, O_RDWR, 0777);
  if (info->shmFd < 0) {
    return errno;
  }

  info->addr = mmap(0, sz, PROT_READ | PROT_WRITE, MAP_SHARED, info->shmFd, 0);
  if (info->addr == NULL) {
    return errno;
  }

  return 0;
}
#endif
}  // namespace

std::vector<paddle::Tensor> GetDataPtrIpc(const paddle::Tensor &tmp_input,
                                          const std::string &shm_name) {
#if defined(_WIN32)
  PD_THROW(
      "GetDataPtrIpc is not supported on Windows "
      "(POSIX shared memory required).");
#else
  auto out_data_ptr_tensor =
      paddle::full({1}, 0, paddle::DataType::INT64, paddle::CPUPlace());
  auto out_data_ptr_tensor_ptr = out_data_ptr_tensor.data<int64_t>();
  volatile shmStruct *shm = NULL;
  sharedMemoryInfo info;
  if (sharedMemoryOpen2(shm_name.c_str(), sizeof(shmStruct), &info) != 0) {
    throw std::runtime_error(
        "Failed to open shared memory slab in GetDataPtrIpc, shm_name: " +
        shm_name + ", errno: " + std::string(strerror(errno)));
  }
  shm = (volatile shmStruct *)info.addr;
  void *ptr = nullptr;
  checkCudaErrors(cudaIpcOpenMemHandle(&ptr,
                                       *(cudaIpcMemHandle_t *)&shm->memHandle,
                                       cudaIpcMemLazyEnablePeerAccess));

  out_data_ptr_tensor_ptr[0] = reinterpret_cast<int64_t>(ptr);
  return {out_data_ptr_tensor};
#endif
}

PD_BUILD_STATIC_OP(get_data_ptr_ipc)
    .Inputs({"tmp_input"})
    .Attrs({"shm_name: std::string"})
    .Outputs({"data_ptr"})
    .SetKernelFn(PD_KERNEL(GetDataPtrIpc));