[Lldb-commits] [lldb] r228844 - Lock mutex in the same order.

[Hafiz Abid Qadeer]

Author: abidh
Date: Wed Feb 11 10:37:17 2015
New Revision: 228844

URL: http://llvm.org/viewvc/llvm-project?rev=228844&view=rev
Log:
Lock mutex in the same order.
SBProcess uses 2 mutexex; RunLock and APILock. Apart from 2 places, RunLock
is locked before API lock. I have fixed the 2 places where order was different.
I observed a deadlock due to this different order in lldb-mi once. Although
lldb-mi command and event thread dont run at the same time now. So it can not deadlock
there but can still be problem for some other clients.

Pre-approved by Greg in http://lists.cs.uiuc.edu/pipermail/lldb-dev/2015-February/006509.html



Modified:
    lldb/trunk/source/API/SBProcess.cpp

Modified: lldb/trunk/source/API/SBProcess.cpp
URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/API/SBProcess.cpp?rev=228844&r1=228843&r2=228844&view=diff
==============================================================================
--- lldb/trunk/source/API/SBProcess.cpp (original)
+++ lldb/trunk/source/API/SBProcess.cpp Wed Feb 11 10:37:17 2015
@@ -918,9 +918,9 @@ SBProcess::GetThreadByID (tid_t tid)
     ProcessSP process_sp(GetSP());
     if (process_sp)
     {
-        Mutex::Locker api_locker (process_sp->GetTarget().GetAPIMutex());
         Process::StopLocker stop_locker;
         const bool can_update = stop_locker.TryLock(&process_sp->GetRunLock());
+        Mutex::Locker api_locker (process_sp->GetTarget().GetAPIMutex());
         thread_sp = process_sp->GetThreadList().FindThreadByID (tid, can_update);
         sb_thread.SetThread (thread_sp);
     }
@@ -942,9 +942,9 @@ SBProcess::GetThreadByIndexID (uint32_t
     ProcessSP process_sp(GetSP());
     if (process_sp)
     {
-        Mutex::Locker api_locker (process_sp->GetTarget().GetAPIMutex());
         Process::StopLocker stop_locker;
         const bool can_update = stop_locker.TryLock(&process_sp->GetRunLock());
+        Mutex::Locker api_locker (process_sp->GetTarget().GetAPIMutex());
         thread_sp = process_sp->GetThreadList().FindThreadByIndexID (index_id, can_update);
         sb_thread.SetThread (thread_sp);
     }