Add thread_run_flash() helper

(cherry picked from commit af928fd)

sys/kern/kern_thread.c

@@ -1514,6 +1514,31 @@ thread_unsuspend_one(struct thread *td, struct proc *p, bool boundary)
 	return (setrunnable(td, 0));
 }
 
+void
+thread_run_flash(struct thread *td)
+{
+	struct proc *p;
+
+	p = td->td_proc;
+	PROC_LOCK_ASSERT(p, MA_OWNED);
+
+	if (TD_ON_SLEEPQ(td))
+		sleepq_remove_nested(td);
+	else
+		thread_lock(td);
+
+	THREAD_LOCK_ASSERT(td, MA_OWNED);
+	KASSERT(TD_IS_SUSPENDED(td), ("Thread not suspended"));
+
+	TD_CLR_SUSPENDED(td);
+	PROC_SLOCK(p);
+	MPASS(p->p_suspcount > 0);
+	p->p_suspcount--;
+	PROC_SUNLOCK(p);
+	if (setrunnable(td, 0))
+		kick_proc0();
+}
+
 /*
  * Allow all threads blocked by single threading to continue running.
  */

sys/sys/proc.h

@@ -1179,6 +1179,7 @@ void	thread_stopped(struct proc *p);
 void	childproc_stopped(struct proc *child, int reason);
 void	childproc_continued(struct proc *child);
 void	childproc_exited(struct proc *child);
+void	thread_run_flash(struct thread *td);
 int	thread_suspend_check(int how);
 bool	thread_suspend_check_needed(void);
 void	thread_suspend_switch(struct thread *, struct proc *p);