From fdbc5adf83741d7e3af0c3f0ffdb59bdf42493b6 Mon Sep 17 00:00:00 2001
From: Kimplul <kimi.h.kuparinen@gmail.com>
Date: Thu, 4 Jul 2024 22:52:47 +0300
Subject: generalize orphants

+ Allow threads to make themselves become orphants
---
 include/arch/tcb.h      |  8 ++++++--
 include/kmi/orphanage.h |  9 ++++++++-
 include/kmi/syscalls.h  |  3 +++
 include/kmi/tcb.h       | 20 ++++++++------------
 include/kmi/uapi.h      | 15 +++++++++++++++
 5 files changed, 40 insertions(+), 15 deletions(-)

(limited to 'include')

diff --git a/include/arch/tcb.h b/include/arch/tcb.h
index 115f49d..22d3b59 100644
--- a/include/arch/tcb.h
+++ b/include/arch/tcb.h
@@ -40,12 +40,16 @@ void setup_rpc_stack(struct tcb *t);
 void destroy_rpc_stack(struct tcb *t);
 
 /**
- * Maximum size of one individual RPC stack instance.
- *
  * @return Max size of one individual RPC stack instance.
  */
 size_t max_rpc_size();
 
+/**
+ * @param addr Address of current top of stack, generally from `ctx->rpc_stack`.
+ * @return \ref true if next rpc return would be into the root process.
+ */
+bool rpc_stack_empty(pm_t addr);
+
 /**
  * Current highest address in RPC stack. Allowed to be inaccurate to one base page.
  *
diff --git a/include/kmi/orphanage.h b/include/kmi/orphanage.h
index 530d10c..09e36b3 100644
--- a/include/kmi/orphanage.h
+++ b/include/kmi/orphanage.h
@@ -22,6 +22,13 @@
  */
 bool orphan(struct tcb *t);
 
+/**
+ * Mark \p t orphaned.
+ *
+ * @param t Thread to orphanize.
+ */
+void orphanize(struct tcb *t);
+
 /**
  * Assign \p t to the init process and jump to it.
  * \p t must be an orphan!
@@ -30,6 +37,6 @@ bool orphan(struct tcb *t);
  *
  * @param t Orphaned thread.
  */
-__noreturn void orphanize(struct tcb *t);
+__noreturn void unorphanize(struct tcb *t);
 
 #endif /* KMI_OPRHANAGE_H */
diff --git a/include/kmi/syscalls.h b/include/kmi/syscalls.h
index 3619469..93d0ac9 100644
--- a/include/kmi/syscalls.h
+++ b/include/kmi/syscalls.h
@@ -157,6 +157,9 @@ enum sys_code {
 	/** Request a thread exits. */
 	SYS_EXIT,
 
+	/** Detach a thread from its root process, becoming an orphant. */
+	SYS_DETACH,
+
 	/** @} */
 
 	SYS_NUM,
diff --git a/include/kmi/tcb.h b/include/kmi/tcb.h
index fac9df7..df161b3 100644
--- a/include/kmi/tcb.h
+++ b/include/kmi/tcb.h
@@ -72,16 +72,13 @@ struct tcb_ctx {
 	struct vmem *vmem;
 };
 
-/** Enum for notification states. */
-enum tcb_notify {
-	/** Thread is free to be notified. */
-	NOTIFY_WAITING = 0,
+/** State of thread. */
+enum tcb_state {
+	/** Thread is a zombie. */
+	TCB_ZOMBIE = (1 << 0),
 
-	/** Thread has notifcations queued. */
-	NOTIFY_QUEUED,
-
-	/** Thread is running notification handler. */
-	NOTIFY_RUNNING,
+	/** Thread is an orphan. */
+	TCB_ORPHAN = (1 << 1),
 };
 
 /** Thread control block. Main way to handle threads. */
@@ -180,9 +177,8 @@ struct tcb {
 	/** Queue that connects together threads waiting for an ipi */
 	struct queue_head ipi_queue;
 
-	/** Whether thread is dead. If thread is process, then corresponds to
-	 * whole process. */
-	bool dead;
+	/** Current state of thread. */
+	enum tcb_state state;
 };
 
 /**
diff --git a/include/kmi/uapi.h b/include/kmi/uapi.h
index 684f0da..76a759f 100644
--- a/include/kmi/uapi.h
+++ b/include/kmi/uapi.h
@@ -841,6 +841,21 @@ SYSCALL_DECLARE1(irq_req, id);
  */
 SYSCALL_DECLARE1(exit, tid);
 
+/**
+ * Request that a thread becomes orphant, i.e. eventually attached to the init
+ * process. Can be used to stop threads within a process by sending an
+ * appropriate signal to the troublesome thread which then detaches itself from
+ * its root process.
+ *
+ * @param t Current tcb.
+ * @param a Unused.
+ * @param b Unused.
+ * @param c Unused.
+ * @param d Unused.
+ * @param e Unused.
+ */
+SYSCALL_DECLARE0(detach);
+
 /** @} */
 
 /**
-- 
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