From 2094122f8670d9cff4fb4a42eba295970cd9522f Mon Sep 17 00:00:00 2001
From: julian <julian@FreeBSD.org>
Date: Tue, 5 Oct 2004 20:39:26 +0000
Subject: [PATCH] Break out to a separate function, the code to revert a
 multithreaded process back to officially being a non-threaded program.

MFC after:	4 days
---
 sys/kern/kern_kse.c    |  3 +--
 sys/kern/kern_thread.c | 40 ++++++++++++++++++++++++++--------------
 sys/sys/proc.h         |  1 +
 3 files changed, 28 insertions(+), 16 deletions(-)

diff --git a/sys/kern/kern_kse.c b/sys/kern/kern_kse.c
index 85732daf2c88..7ed6380c0d4b 100644
--- a/sys/kern/kern_kse.c
+++ b/sys/kern/kern_kse.c
@@ -347,8 +347,7 @@ kse_exit(struct thread *td, struct kse_exit_args *uap)
 	 * One possibility is to return to the user. It may not cope well.
 	 * The other possibility would be to let the process exit.
 	 */
-	p->p_flag &= ~(P_SA|P_HADTHREADS);
-	sched_set_concurrency(td->td_ksegrp, 1);
+	thread_unthread(td);
 	mtx_unlock_spin(&sched_lock);
 	PROC_UNLOCK(p);
 #if 1
diff --git a/sys/kern/kern_thread.c b/sys/kern/kern_thread.c
index b8535209f047..28dcb137053b 100644
--- a/sys/kern/kern_thread.c
+++ b/sys/kern/kern_thread.c
@@ -708,6 +708,29 @@ thread_link(struct thread *td, struct ksegrp *kg)
 	kg->kg_numthreads++;
 }
 
+/*
+ * Convert a process with one thread to an unthreaded process.
+ * Called from:
+ *  thread_single(exit)  (called from execve and exit)
+ *  kse_exit()		XXX may need cleaning up wrt KSE stuff
+ */
+void
+thread_unthread(struct thread *td)
+{
+	struct proc *p = td->td_proc;
+
+	KASSERT((p->p_numthreads == 1), ("Unthreading with >1 threads"));
+	upcall_remove(td);
+	p->p_flag &= ~(P_SA|P_HADTHREADS);
+	td->td_mailbox = NULL;
+	td->td_pflags &= ~(TDP_SA | TDP_CAN_UNBIND);
+	if (td->td_standin != NULL) {
+		thread_stash(td->td_standin);
+		td->td_standin = NULL;
+	}
+	sched_set_concurrency(td->td_ksegrp, 1);
+}
+
 /*
  * Called from:
  *  thread_exit()
@@ -835,21 +858,11 @@ thread_single(int force_exit)
 		 * we try our utmost  to revert to being a non-threaded
 		 * process.
 		 */
-		upcall_remove(td);
-		p->p_flag &= ~(P_SA|P_HADTHREADS);
-		td->td_mailbox = NULL;
-		td->td_pflags &= ~(TDP_SA | TDP_CAN_UNBIND);
-		p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT);
 		p->p_singlethread = NULL;
-		if (td->td_standin != NULL) {
-			thread_stash(td->td_standin);
-			td->td_standin = NULL;
-		}
-		sched_set_concurrency(td->td_ksegrp, 1);
-		mtx_unlock_spin(&sched_lock);
-	} else {
-		mtx_unlock_spin(&sched_lock);
+		p->p_flag &= ~(P_STOPPED_SINGLE | P_SINGLE_EXIT);
+		thread_unthread(td);
 	}
+	mtx_unlock_spin(&sched_lock);
 	return (0);
 }
 
@@ -1004,7 +1017,6 @@ thread_unsuspend(struct proc *p)
 
 /*
  * End the single threading mode..
- * Part of this is duplicated in thread-single in the SINGLE_EXIT case.
  */
 void
 thread_single_end(void)
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index 9d75c927dd40..cdaa8f518cc9 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -915,6 +915,7 @@ void	thread_unlink(struct thread *td);
 void	thread_unsuspend(struct proc *p);
 void	thread_unsuspend_one(struct thread *td);
 int	thread_upcall_check(struct thread *td);
+void	thread_unthread(struct thread *td);
 int	thread_userret(struct thread *td, struct trapframe *frame);
 void	thread_user_enter(struct thread *td);
 void	thread_wait(struct proc *p);