[SYCL][CUDA] Fixes device leak (#1175)

This also makes `cuda_piDevicesGet` return all available CUDA devices.

Signed-off-by: Steffen Larsen <steffen.larsen@codeplay.com>

Author: steffenlarsen

sycl/plugins/cuda/pi_cuda.cpp

@@ -542,9 +542,28 @@ pi_result cuda_piPlatformsGet(pi_uint32 num_entries, pi_platform *platforms,
 
       static std::once_flag initFlag;
       static _pi_platform platformId;
-      std::call_once(initFlag,
-                     [](pi_result &err) { err = PI_CHECK_ERROR(cuInit(0)); },
-                     err);
+      std::call_once(
+          initFlag,
+          [](pi_result &err) {
+            err = PI_CHECK_ERROR(cuInit(0));
+
+            int numDevices = 0;
+            err = PI_CHECK_ERROR(cuDeviceGetCount(&numDevices));
+            platformId.devices_.reserve(numDevices);
+            try {
+              for (int i = 0; i < numDevices; ++i) {
+                CUdevice device;
+                err = PI_CHECK_ERROR(cuDeviceGet(&device, i));
+                platformId.devices_.emplace_back(
+                    new _pi_device{device, &platformId});
+              }
+            } catch (...) {
+              // Clear and rethrow to allow retry
+              platformId.devices_.clear();
+              throw;
+            }
+          },
+          err);
 
       *platforms = &platformId;
     }
@@ -594,22 +613,16 @@ pi_result cuda_piDevicesGet(pi_platform platform, pi_device_type device_type,
 
   pi_result err = PI_SUCCESS;
   const bool askingForGPU = (device_type & PI_DEVICE_TYPE_GPU);
-  size_t numDevices = askingForGPU ? 1 : 0;
+  size_t numDevices = askingForGPU ? platform->devices_.size() : 0;
 
   try {
     if (num_devices) {
       *num_devices = numDevices;
     }
 
-    if (askingForGPU) {
-      if (devices) {
-        CUdevice device;
-        err = PI_CHECK_ERROR(cuDeviceGet(&device, 0));
-        *devices = new _pi_device{device, platform};
-      }
-    } else {
-      if (devices) {
-        *devices = nullptr;
+    if (askingForGPU && devices) {
+      for (size_t i = 0; i < std::min(size_t(num_entries), numDevices); ++i) {
+        devices[i] = platform->devices_[i].get();
       }
     }
 

sycl/plugins/cuda/pi_cuda.hpp

@@ -46,6 +46,7 @@ pi_result cuda_piKernelRelease(pi_kernel);
 }
 
 struct _pi_platform {
+  std::vector<std::unique_ptr<_pi_device>> devices_;
 };
 
 struct _pi_device {