Fixed a case where we might be able to acquire a mutex with a try lock and
not release it by making sure a mutex locker object is appropriately used.
git-svn-id: https://llvm.org/svn/llvm-project/llvdb/trunk@112996 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/source/Host/posix/Mutex.cpp b/source/Host/posix/Mutex.cpp
index 3f1c830..e038102 100644
--- a/source/Host/posix/Mutex.cpp
+++ b/source/Host/posix/Mutex.cpp
@@ -78,8 +78,7 @@
//----------------------------------------------------------------------
Mutex::Locker::~Locker ()
{
- if (m_mutex_ptr)
- Mutex::Unlock (m_mutex_ptr);
+ Reset();
}
//----------------------------------------------------------------------
@@ -89,6 +88,10 @@
void
Mutex::Locker::Reset (pthread_mutex_t *mutex_ptr)
{
+ // We already have this mutex locked or both are NULL...
+ if (m_mutex_ptr == mutex_ptr)
+ return;
+
if (m_mutex_ptr)
Mutex::Unlock (m_mutex_ptr);
@@ -100,9 +103,12 @@
bool
Mutex::Locker::TryLock (pthread_mutex_t *mutex_ptr)
{
- if (m_mutex_ptr)
- Mutex::Unlock (m_mutex_ptr);
- m_mutex_ptr = NULL;
+ // We already have this mutex locked!
+ if (m_mutex_ptr == mutex_ptr)
+ return true;
+
+ Reset ();
+
if (mutex_ptr)
{
if (Mutex::TryLock (mutex_ptr) == 0)
diff --git a/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp b/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
index 062bd25..0f7787b 100644
--- a/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
+++ b/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
@@ -124,7 +124,7 @@
timeout_time = TimeValue::Now();
timeout_time.OffsetWithSeconds (timeout_seconds);
- if (locker.TryLock (m_sequence_mutex.GetMutex()))
+ if (GetSequenceMutex (locker))
{
if (SendPacketNoLock (payload, strlen(payload)))
return WaitForPacketNoLock (response, &timeout_time);
@@ -139,7 +139,7 @@
m_async_packet_predicate.SetValue (true, eBroadcastNever);
bool timed_out = false;
- if (SendInterrupt(1, &timed_out))
+ if (SendInterrupt(locker, 1, &timed_out))
{
if (m_async_packet_predicate.WaitForValueEqualTo (false, &timeout_time, &timed_out))
{
@@ -396,14 +396,25 @@
{
m_async_signal = signo;
bool timed_out = false;
- if (SendInterrupt(1, &timed_out))
+ Mutex::Locker locker;
+ if (SendInterrupt (locker, 1, &timed_out))
return true;
m_async_signal = -1;
return false;
}
+// This function takes a mutex locker as a parameter in case the GetSequenceMutex
+// actually succeeds. If it doesn't succeed in acquiring the sequence mutex
+// (the expected result), then it will send the halt packet. If it does succeed
+// then the caller that requested the interrupt will want to keep the sequence
+// locked down so that no one else can send packets while the caller has control.
+// This function usually gets called when we are running and need to stop the
+// target. It can also be used when we are running and and we need to do something
+// else (like read/write memory), so we need to interrupt the running process
+// (gdb remote protocol requires this), and do what we need to do, then resume.
+
bool
-GDBRemoteCommunication::SendInterrupt (uint32_t seconds_to_wait_for_stop, bool *timed_out)
+GDBRemoteCommunication::SendInterrupt (Mutex::Locker& locker, uint32_t seconds_to_wait_for_stop, bool *timed_out)
{
if (timed_out)
*timed_out = false;
@@ -411,7 +422,7 @@
if (IsConnected() && IsRunning())
{
// Only send an interrupt if our debugserver is running...
- if (m_sequence_mutex.TryLock() != 0)
+ if (GetSequenceMutex (locker) == false)
{
// Someone has the mutex locked waiting for a response or for the
// inferior to stop, so send the interrupt on the down low...
diff --git a/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.h b/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.h
index 9351c6a..e556072 100644
--- a/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.h
+++ b/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.h
@@ -99,7 +99,9 @@
SendAsyncSignal (int signo);
bool
- SendInterrupt (uint32_t seconds_to_wait_for_stop, bool *timed_out = NULL);
+ SendInterrupt (lldb_private::Mutex::Locker &locker,
+ uint32_t seconds_to_wait_for_stop,
+ bool *timed_out = NULL);
bool
GetSequenceMutex(lldb_private::Mutex::Locker& locker);
diff --git a/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp b/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
index aa3cf6b..815cece 100644
--- a/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ b/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -1117,7 +1117,8 @@
if (m_gdb_comm.IsRunning())
{
bool timed_out = false;
- if (!m_gdb_comm.SendInterrupt (2, &timed_out))
+ Mutex::Locker locker;
+ if (!m_gdb_comm.SendInterrupt (locker, 2, &timed_out))
{
if (timed_out)
error.SetErrorString("timed out sending interrupt packet");
@@ -1150,7 +1151,8 @@
log->Printf ("ProcessGDBRemote::DoDestroy()");
// Interrupt if our inferior is running...
- m_gdb_comm.SendInterrupt (1);
+ Mutex::Locker locker;
+ m_gdb_comm.SendInterrupt (locker, 1);
DisableAllBreakpointSites ();
SetExitStatus(-1, "process killed");