[all-commits] [llvm/llvm-project] 6eb576: Add a mutex to guard access to the ThreadPlanStack...

[jimingham via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 6eb576dcff45fa53e8ceb30c7648b903c1413e05
      https://github.com/llvm/llvm-project/commit/6eb576dcff45fa53e8ceb30c7648b903c1413e05
  Author: Jim Ingham <jingham at apple.com>
  Date:   2021-07-16 (Fri, 16 Jul 2021)

  Changed paths:
    M lldb/include/lldb/Target/ThreadPlanStack.h
    M lldb/source/Target/ThreadPlanStack.cpp

  Log Message:
  -----------
  Add a mutex to guard access to the ThreadPlanStack class

We've seen reports of crashes (none we've been able to reproduce
locally) that look like they are caused by concurrent access to a
thread plan stack.  It looks like there are error paths when an
interrupt request to debugserver times out that cause this problem.

The thread plan stack access is never in a hot loop, and there
aren't enough of them for the extra data member to matter, so
there's really no good reason not to protect the access.

Adding the mutex revealed a couple of places where we were
using "auto" in an iteration when we should have been using
"auto &" - we didn't intend to copy the stack - and I fixed
those as well.

Except for preventing crashes this should be NFC.

Differential Revision: https\://reviews.llvm.org/D106122