[all-commits] [llvm/llvm-project] 667c10: [libc] Fix the implementation of exit on the GPU

[Joseph Huber via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 667c10353e87d2be5b981cdac0a698c93946cc92
      https://github.com/llvm/llvm-project/commit/667c10353e87d2be5b981cdac0a698c93946cc92
  Author: Joseph Huber <jhuber6 at vols.utk.edu>
  Date:   2023-06-29 (Thu, 29 Jun 2023)

  Changed paths:
    M libc/docs/gpu/support.rst
    M libc/src/__support/OSUtil/gpu/quick_exit.cpp
    M libc/utils/gpu/server/rpc_server.cpp

  Log Message:
  -----------
  [libc] Fix the implementation of exit on the GPU

The RPC calls all have delays associated with them. Currently the `exit`
function does an async send and immediately exits the GPU. This can have
the effect that the RPC server never sees the exit call and we continue.
This patch changes that to first sync with the server before continuing
to perform its exit. There is still a hazard here, where the kernel can
complete before the RPC call reads back its response, but this is simply
multi-threaded hazards. This change ensures that the server *will*
always exit some time after the GPU exits.

Reviewed By: JonChesterfield

Differential Revision: https://reviews.llvm.org/D154112