From 495a4188841c20f74a8f581beca1e1dad1240203 Mon Sep 17 00:00:00 2001
From: Glenn Maynard <gmaynard@users.sourceforge.net>
Date: Tue, 7 Dec 2004 00:06:59 +0000
Subject: [PATCH] Previously, the main mount loop was unlocking the thread and
 then immediately re-locking it.  In some threads implementations (Linux 2.6),
 this causes the mount thread to hog the lock, which causes
 SetMountThreadState to hang.  Move the "check and delay" part of the mount
 thread outside of the lock, so other threads have opportunity to get the
 lock.

---
 .../MemoryCard/MemoryCardDriverThreaded.cpp   |  9 +++++
 .../MemoryCard/MemoryCardDriverThreaded.h     |  1 +
 .../MemoryCardDriverThreaded_Linux.cpp        | 37 +++++++++----------
 .../MemoryCardDriverThreaded_Linux.h          |  1 +
 4 files changed, 28 insertions(+), 20 deletions(-)

diff --git a/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded.cpp b/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded.cpp
index 20adf1da42..42747cc592 100644
--- a/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded.cpp
+++ b/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded.cpp
@@ -79,11 +79,20 @@ void MemoryCardDriverThreaded::MountThreadMain()
 
 	while( !m_bShutdownNextUpdate )
 	{      
+		if( !this->MountThreadWaitForUpdate() )
+			continue;
+
 		LockMut( m_mutexPause );	// wait until we're unpaused
 		this->MountThreadDoOneUpdate();
 	}
 }
 
+bool MemoryCardDriverThreaded::MountThreadWaitForUpdate()
+{
+	usleep( 100000 );
+	return true;
+}
+
 bool MemoryCardDriverThreaded::StorageDevicesChanged()
 {
 	CHECKPOINT;
diff --git a/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded.h b/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded.h
index dad7b6a2b6..61848c1acf 100644
--- a/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded.h
+++ b/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded.h
@@ -33,6 +33,7 @@ protected:
 	void StartThread();	// call this in the derived constructor to start the mounting thread
 	void StopThread(); // call this in the derived desstructor to stop the mounting thread
 	virtual void MountThreadDoOneUpdate() = 0;	// this will get called as fast as possible
+	virtual bool MountThreadWaitForUpdate();
 	virtual void Mount( UsbStorageDevice* pDevice, CString sMountPoint ) = 0;
 	bool ShouldDoOsMount() { return m_MountThreadState==detect_and_mount; }
 
diff --git a/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_Linux.cpp b/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_Linux.cpp
index fc64498e63..e07b647dc0 100644
--- a/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_Linux.cpp
+++ b/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_Linux.cpp
@@ -187,32 +187,29 @@ bool UsbStorageDevicesChanged()
   return bChanged;
 }
 
-void MemoryCardDriverThreaded_Linux::MountThreadDoOneUpdate()
+/* Return true if MountThreadDoOneUpdate should be called. */
+bool MemoryCardDriverThreaded_Linux::MountThreadWaitForUpdate()
 {
-	bool bNeedToDoAnyMounts = false;
+	/* Check if any devices need a write test. */
 	for( unsigned i=0; i<m_vDevicesLastSeen.size(); i++ )
 	{
 		UsbStorageDevice &d = m_vDevicesLastSeen[i];
 		if( d.bNeedsWriteTest )
-		{
-			bNeedToDoAnyMounts = true;
-			break;
-		}
+			return true;
 	}
-	
-	if( bNeedToDoAnyMounts )
-	{
-		// fall through
-	}
-	else
-	{
-	  if( !UsbStorageDevicesChanged() )
-	    {
-	      usleep(1000*300);  // 300 ms
-	      return;
-	    }
-	}
-	
+
+	/* Nothing needs a write test.  If no devices have changed, either,
+	 * delay. */
+	if( UsbStorageDevicesChanged() )
+		return true;
+
+	/* Nothing to do.  Delay, so we don't busy loop. */
+	usleep(1000*300);  // 300 ms
+	return false;
+}
+
+void MemoryCardDriverThreaded_Linux::MountThreadDoOneUpdate()
+{
 	// TRICKY: We're waiting for a change in the USB device list, but 
 	// the usb-storage descriptors take a bit longer to update.  It's more convenient to wait
 	// on the USB device list because the usb-storage descriptors are separate files per 
diff --git a/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_Linux.h b/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_Linux.h
index aa42499920..ca657ff8b0 100644
--- a/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_Linux.h
+++ b/stepmania/src/arch/MemoryCard/MemoryCardDriverThreaded_Linux.h
@@ -15,6 +15,7 @@ protected:
 	virtual void Mount( UsbStorageDevice* pDevice, CString sMountPoint );
 	virtual void ResetUsbStorage();
 	virtual void MountThreadDoOneUpdate();
+	virtual bool MountThreadWaitForUpdate();
 
 	vector<UsbStorageDevice> m_vDevicesLastSeen;
 };