From 9d64454b70e47aa5c29077e4dd59d28e14ca3bf2 Mon Sep 17 00:00:00 2001
From: "John Hodge (sonata)" <tpg@mutabah.net>
Date: Sat, 19 Jan 2013 22:09:45 +0800
Subject: [PATCH] Kernel - Added (possibly buggy) support for WaitTID(TID>0)

---
 KernelLand/Kernel/include/events.h      |  2 +
 KernelLand/Kernel/include/threads_int.h |  5 +-
 KernelLand/Kernel/threads.c             | 64 +++++++++++++------------
 3 files changed, 40 insertions(+), 31 deletions(-)

diff --git a/KernelLand/Kernel/include/events.h b/KernelLand/Kernel/include/events.h
index dc9d6543..17143e86 100644
--- a/KernelLand/Kernel/include/events.h
+++ b/KernelLand/Kernel/include/events.h
@@ -25,6 +25,8 @@
 //! General purpose event for short waits
 //! e.g. waiting for an IRQ in a Read() call
 #define THREAD_EVENT_SHORTWAIT	0x00000010
+//! Fired when a child process quits
+#define THREAD_EVENT_DEADCHILD	0x00000020
 
 #define THREAD_EVENT_USER1	0x10000000
 #define THREAD_EVENT_USER2	0x20000000
diff --git a/KernelLand/Kernel/include/threads_int.h b/KernelLand/Kernel/include/threads_int.h
index 578fdcf1..48452649 100644
--- a/KernelLand/Kernel/include/threads_int.h
+++ b/KernelLand/Kernel/include/threads_int.h
@@ -71,7 +71,10 @@ struct sThread
 	struct sProcess	*Process;	//!< Thread Group / Process
 	struct sThread	*Parent;	//!< Parent Thread
 	char	*ThreadName;	//!< Name of thread
-	
+
+	struct sThread	*LastDeadChild;	//!< Last child to die (will have the \a DeadChildren lock)
+	tMutex	DeadChildLock;	//!< Lock to prevent clobbering of \a LastDeadChild, acquired by child, released by parent
+
 	// --- arch/proc.c's responsibility
 	//! Kernel Stack Base
 	tVAddr	KernelStack;
diff --git a/KernelLand/Kernel/threads.c b/KernelLand/Kernel/threads.c
index 92a7a576..a8697d63 100644
--- a/KernelLand/Kernel/threads.c
+++ b/KernelLand/Kernel/threads.c
@@ -11,6 +11,7 @@
 #include <hal_proc.h>
 #include <semaphore.h>
 #include <vfs_threads.h>	// VFS Handle maintainence
+#include <events.h>
 
 // Configuration
 #define DEBUG_TRACE_TICKETS	0	// Trace ticket counts
@@ -442,9 +443,30 @@ tThread *Threads_CloneThreadZero(void)
 tTID Threads_WaitTID(int TID, int *Status)
 {	
 	// Any Child
-	if(TID == -1) {
-		Log_Error("Threads", "TODO: Threads_WaitTID(TID=-1) - Any Child");
-		return -1;
+	if(TID == -1)
+	{
+		Uint32 ev = Threads_WaitEvents(THREAD_EVENT_DEADCHILD);
+		tTID	ret = -1;
+		if( ev & THREAD_EVENT_DEADCHILD )
+		{
+			// A child died, get the TID
+			tThread	*us = Proc_GetCurThread();
+			ASSERT(us->LastDeadChild);
+			ret = us->LastDeadChild->TID;
+			// - Mark as dead (as opposed to undead)
+			ASSERT(us->LastDeadChild->Status == THREAD_STAT_ZOMBIE);
+			us->LastDeadChild->Status = THREAD_STAT_DEAD;
+			// - Set return status
+			if(Status)
+				*Status = us->LastDeadChild->RetStatus;
+			us->LastDeadChild = NULL;
+			Mutex_Release(&us->DeadChildLock);
+		}
+		else
+		{
+			Log_Error("Threads", "TODO: Threads_WaitTID(TID=-1) - Any Child");
+		}
+		return ret;
 	}
 	
 	// Any peer/child thread
@@ -460,33 +482,13 @@ tTID Threads_WaitTID(int TID, int *Status)
 	}
 	
 	// Specific Thread
-	if(TID > 0) {
-		tThread	*t = Threads_GetThread(TID);
+	if(TID > 0)
+	{
 		tTID	ret;
-		
-		// Wait for the thread to die!
-		// TODO: Handle child also being suspended if wanted
-		while(t->Status != THREAD_STAT_ZOMBIE) {
-			Threads_Sleep();
-			Log_Debug("Threads", "%i waiting for %i, t->Status = %i",
-				Threads_GetTID(), t->TID, t->Status);
-		}
-		
-		// Set return status
-		ret = t->TID;
-		switch(t->Status)
+		while( (ret = Threads_WaitTID(-1, Status)) != TID )
 		{
-		case THREAD_STAT_ZOMBIE:
-			// Kill the thread
-			t->Status = THREAD_STAT_DEAD;
-			// TODO: Child return value?
-			if(Status)	*Status = t->RetStatus;
-			// add to delete queue
-			Threads_Delete( t );
-			break;
-		default:
-			if(Status)	*Status = -1;
-			break;
+			if( ret == -1 )
+				break;
 		}
 		return ret;
 	}
@@ -685,8 +687,10 @@ void Threads_Kill(tThread *Thread, int Status)
 
 	Thread->Status = THREAD_STAT_ZOMBIE;
 	SHORTREL( &glThreadListLock );
-	// TODO: Send something like SIGCHLD
-	Threads_Wake( Thread->Parent );
+	// TODO: It's possible that we could be timer-preempted here, should disable that... somehow
+	Mutex_Acquire( &Thread->Parent->DeadChildLock );	// released by parent
+	Thread->Parent->LastDeadChild = Thread;
+	Threads_PostEvent( Thread->Parent, THREAD_EVENT_DEADCHILD );
 	
 	Log("Thread %i went *hurk* (%i)", Thread->TID, Status);
 	
-- 
2.20.1