[Lldb-commits] [lldb] r268828 - Take the API lock in SBThread::IsValid & SBFrame::IsValid.

[Jim Ingham via lldb-commits]

Author: jingham
Date: Fri May  6 19:54:56 2016
New Revision: 268828

URL: http://llvm.org/viewvc/llvm-project?rev=268828&view=rev
Log:
Take the API lock in SBThread::IsValid & SBFrame::IsValid.

The IsValid calls can try to reconstruct the thread & frame, which can 
take various internal locks.  This can cause A/B locking issues with
the Target lock, so these calls need to that the Target lock.

Modified:
    lldb/trunk/source/API/SBFrame.cpp
    lldb/trunk/source/API/SBThread.cpp

Modified: lldb/trunk/source/API/SBFrame.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/API/SBFrame.cpp?rev=268828&r1=268827&r2=268828&view=diff
==============================================================================
--- lldb/trunk/source/API/SBFrame.cpp (original)
+++ lldb/trunk/source/API/SBFrame.cpp Fri May  6 19:54:56 2016
@@ -105,7 +105,20 @@ SBFrame::SetFrameSP (const StackFrameSP
 bool
 SBFrame::IsValid() const
 {
-    return GetFrameSP().get() != nullptr;
+    Mutex::Locker api_locker;
+    ExecutionContext exe_ctx (m_opaque_sp.get(), api_locker);
+
+    Target *target = exe_ctx.GetTargetPtr();
+    Process *process = exe_ctx.GetProcessPtr();
+    if (target && process)
+    {
+        Process::StopLocker stop_locker;
+        if (stop_locker.TryLock(&process->GetRunLock()))
+        return GetFrameSP().get() != nullptr;
+    }
+    
+    // Without a target & process we can't have a valid stack frame.
+    return false;
 }
 
 SBSymbolContext

Modified: lldb/trunk/source/API/SBThread.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/API/SBThread.cpp?rev=268828&r1=268827&r2=268828&view=diff
==============================================================================
--- lldb/trunk/source/API/SBThread.cpp (original)
+++ lldb/trunk/source/API/SBThread.cpp Fri May  6 19:54:56 2016
@@ -130,7 +130,19 @@ SBThread::GetQueue () const
 bool
 SBThread::IsValid() const
 {
-    return m_opaque_sp->GetThreadSP().get() != NULL;
+    Mutex::Locker api_locker;
+    ExecutionContext exe_ctx (m_opaque_sp.get(), api_locker);
+
+    Target *target = exe_ctx.GetTargetPtr();
+    Process *process = exe_ctx.GetProcessPtr();
+    if (target && process)
+    {
+        Process::StopLocker stop_locker;
+        if (stop_locker.TryLock(&process->GetRunLock()))
+        return m_opaque_sp->GetThreadSP().get() != NULL;
+    }
+    // Without a valid target & process, this thread can't be valid.
+    return false;
 }
 
 void