[Openmp-commits] [PATCH] D84381: [OpenMP] Fixed an issue that memory free might be called inappropriately when the kernel is still running

[Shilei Tian via Phabricator via Openmp-commits]

tianshilei1992 created this revision.
Herald added subscribers: openmp-commits, sstefan1, guansong, yaxunl.
Herald added a reviewer: jdoerfert.
Herald added a project: OpenMP.

In the function `target`, memory deallocation and target_data_end is called
immediately returning from launching kernel. This might cause a race condition
that the corresponding memory is still being used by the kernel, and a optential
issue that when the kernel starts to execute, its required data have already
been deallocated, especially when multiple kernels running concurrently. Since
nevertheless we will block the thread issuing the target offloading at the end
of `target`, we just move the synchronization ahead a little bit to make sure
the correctness.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D84381

Files:
  openmp/libomptarget/src/omptarget.cpp


Index: openmp/libomptarget/src/omptarget.cpp
===================================================================
--- openmp/libomptarget/src/omptarget.cpp
+++ openmp/libomptarget/src/omptarget.cpp
@@ -927,6 +927,14 @@
     return OFFLOAD_FAIL;
   }
 
+  if (Device.RTL->synchronize) {
+    rc = Device.RTL->synchronize(device_id, &AsyncInfo);
+    if (rc != OFFLOAD_SUCCESS) {
+      DP("Failed to synchronize.\n");
+      return OFFLOAD_FAIL;
+    }
+  }
+
   // Deallocate (first-)private arrays
   for (auto it : fpArrays) {
     int rt = Device.RTL->data_delete(Device.RTLDeviceID, it);
@@ -944,8 +952,5 @@
     return OFFLOAD_FAIL;
   }
 
-  if (Device.RTL->synchronize)
-    return Device.RTL->synchronize(device_id, &AsyncInfo);
-
   return OFFLOAD_SUCCESS;
 }


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