[Lldb-commits] [lldb] [lldb] Make sure the process is stopped when computing the symbol context (PR #135458)

[Jonas Devlieghere via lldb-commits]

https://github.com/JDevlieghere created https://github.com/llvm/llvm-project/pull/135458

Make sure the process is stopped when computing the symbol context. Both
Adrian and Felipe reported a handful of crashes in GetSymbolContext
called from Statusline::Redraw on the default event thread.

Given that we're handling a StackFrameSP, it's not clear to me how that
could have gotten invalidated, but Jim points out that it doesn't make
sense to compute the symbol context for the frame when the process isn't
stopped.

Depends on  #135455

>From 19d761478bdad5615e3f3c7f4a1b71c1c698725b Mon Sep 17 00:00:00 2001
From: Jonas Devlieghere <jonas at devlieghere.com>
Date: Fri, 11 Apr 2025 16:56:53 -0700
Subject: [PATCH] =?UTF-8?q?Revert=20"Revert=20"[lldb]=20Make=20sure=20the?=
 =?UTF-8?q?=20process=20is=20stopped=20when=20computing=20the=20sy?=
 =?UTF-8?q?=E2=80=A6"?=
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Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This reverts commit 179d30f8c3fddd3c85056fd2b8e877a4a8513158.
---
 lldb/source/Core/Statusline.cpp | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/lldb/source/Core/Statusline.cpp b/lldb/source/Core/Statusline.cpp
index ed5308ef53eb0..e14691e2538a2 100644
--- a/lldb/source/Core/Statusline.cpp
+++ b/lldb/source/Core/Statusline.cpp
@@ -12,6 +12,7 @@
 #include "lldb/Host/StreamFile.h"
 #include "lldb/Interpreter/CommandInterpreter.h"
 #include "lldb/Symbol/SymbolContext.h"
+#include "lldb/Target/Process.h"
 #include "lldb/Target/StackFrame.h"
 #include "lldb/Utility/AnsiTerminal.h"
 #include "lldb/Utility/StreamString.h"
@@ -134,8 +135,15 @@ void Statusline::Redraw(bool update) {
     exe_ctx.SetTargetPtr(&m_debugger.GetSelectedOrDummyTarget());
 
   SymbolContext symbol_ctx;
-  if (auto frame_sp = exe_ctx.GetFrameSP())
-    symbol_ctx = frame_sp->GetSymbolContext(eSymbolContextEverything);
+  if (ProcessSP process_sp = exe_ctx.GetProcessSP()) {
+    // Check if the process is stopped, and if it is, make sure it remains
+    // stopped until we've computed the symbol context.
+    Process::StopLocker stop_locker;
+    if (stop_locker.TryLock(&process_sp->GetRunLock())) {
+      if (auto frame_sp = exe_ctx.GetFrameSP())
+        symbol_ctx = frame_sp->GetSymbolContext(eSymbolContextEverything);
+    }
+  }
 
   StreamString stream;
   if (auto *format = m_debugger.GetStatuslineFormat())