Add a lock in the UnwindTable class so two Targets won't try

to modify the same UnwindTable object simultaneously.  Fix
HistoryThread and HistoryUnwind's mutex lock acqusition to
retain the lock for the duration of the operation instead of
releasing the temporary immediately.
<rdar://problem/17055023>

llvm-svn: 211241

diff --git a/lldb/include/lldb/Symbol/UnwindTable.h b/lldb/include/lldb/Symbol/UnwindTable.h
index 684cd19..3a89f9f 100644 (file)
--- a/lldb/include/lldb/Symbol/UnwindTable.h
+++ b/lldb/include/lldb/Symbol/UnwindTable.h
@@ -14,6 +14,7 @@
 #include <map>
 
 #include "lldb/lldb-private.h" 
+#include "lldb/Host/Mutex.h"
 
 namespace lldb_private {
 
@@ -59,6 +60,7 @@ private:
     collection          m_unwinds;
 
     bool                m_initialized;  // delay some initialization until ObjectFile is set up
+    Mutex               m_mutex;
 
     DWARFCallFrameInfo* m_eh_frame;
     

diff --git a/lldb/source/Plugins/Process/Utility/HistoryThread.cpp b/lldb/source/Plugins/Process/Utility/HistoryThread.cpp
index 11ad815..cdb0528 100644 (file)
--- a/lldb/source/Plugins/Process/Utility/HistoryThread.cpp
+++ b/lldb/source/Plugins/Process/Utility/HistoryThread.cpp
@@ -78,7 +78,7 @@ HistoryThread::CreateRegisterContextForFrame (StackFrame *frame)
 lldb::StackFrameListSP
 HistoryThread::GetStackFrameList ()
 {
-    Mutex::Locker (m_framelist_mutex);
+    Mutex::Locker locker(m_framelist_mutex);
     if (m_framelist.get() == NULL)
     {
         m_framelist.reset (new StackFrameList (*this, StackFrameListSP(), true));

diff --git a/lldb/source/Plugins/Process/Utility/HistoryUnwind.cpp b/lldb/source/Plugins/Process/Utility/HistoryUnwind.cpp
index 4659e48..bf8b3f5 100644 (file)
--- a/lldb/source/Plugins/Process/Utility/HistoryUnwind.cpp
+++ b/lldb/source/Plugins/Process/Utility/HistoryUnwind.cpp
@@ -66,7 +66,7 @@ HistoryUnwind::DoCreateRegisterContextForFrame (StackFrame *frame)
 bool
 HistoryUnwind::DoGetFrameInfoAtIndex (uint32_t frame_idx, lldb::addr_t& cfa, lldb::addr_t& pc)
 {
-    Mutex::Locker (m_unwind_mutex);
+    Mutex::Locker locker(m_unwind_mutex);
     if (frame_idx < m_pcs.size())
     {
         cfa = frame_idx;

diff --git a/lldb/source/Symbol/UnwindTable.cpp b/lldb/source/Symbol/UnwindTable.cpp
index 9aaacb3..df9f5b9 100644 (file)
--- a/lldb/source/Symbol/UnwindTable.cpp
+++ b/lldb/source/Symbol/UnwindTable.cpp
@@ -29,6 +29,7 @@ UnwindTable::UnwindTable (ObjectFile& objfile) :
     m_object_file (objfile), 
     m_unwinds (),
     m_initialized (false),
+    m_mutex (),
     m_eh_frame (nullptr)
 {
 }
@@ -42,6 +43,11 @@ UnwindTable::Initialize ()
     if (m_initialized)
         return;
 
+    Mutex::Locker locker(m_mutex);
+
+    if (m_initialized) // check again once we've acquired the lock
+        return;
+
     SectionList* sl = m_object_file.GetSectionList ();
     if (sl)
     {
@@ -68,6 +74,8 @@ UnwindTable::GetFuncUnwindersContainingAddress (const Address& addr, SymbolConte
 
     Initialize();
 
+    Mutex::Locker locker(m_mutex);
+
     // There is an UnwindTable per object file, so we can safely use file handles
     addr_t file_addr = addr.GetFileAddress();
     iterator end = m_unwinds.end ();
@@ -128,6 +136,7 @@ UnwindTable::GetUncachedFuncUnwindersContainingAddress (const Address& addr, Sym
 void
 UnwindTable::Dump (Stream &s)
 {
+    Mutex::Locker locker(m_mutex);
     s.Printf("UnwindTable for '%s':\n", m_object_file.GetFileSpec().GetPath().c_str());
     const_iterator begin = m_unwinds.begin();
     const_iterator end = m_unwinds.end();