From: Tim Leslie <tleslie@protonmail.com>
Subject: Re: Remove last callers of the lbolt sleep channel
To: Claudio Jeker <cjeker@diehard.n-r-g.com>
Cc: Vitaliy Makkoveev <mvs@openbsd.org>, "tech@openbsd.org" <tech@openbsd.org>
Date: Wed, 24 Sep 2025 16:20:08 +0000

> > So I prefer to use `nowake', because this 100% exclude the fallout from
> > current or hypothetical newly introduced wakeup(pr->ps_pgrp).
> 
> 
> I agree with this. Replacing this with 'nowake' is the right way since
> only the 1sec timer should wake up these ttysleeps.

Updated diff below.

Tim

--



diff --git a/sys/kern/sched_bsd.c b/sys/kern/sched_bsd.c
--- a/sys/kern/sched_bsd.c
+++ b/sys/kern/sched_bsd.c
@@ -55,7 +55,6 @@
 #endif
 
 uint64_t roundrobin_period;	/* [I] roundrobin period (ns) */
-int	lbolt;			/* once a second sleep address */
 
 struct mutex sched_lock;
 
@@ -282,7 +281,6 @@ schedcpu(void *unused)
 		}
 		SCHED_UNLOCK();
 	}
-	wakeup(&lbolt);
 	timeout_add_sec(&to, 1);
 }
 
diff --git a/sys/kern/tty.c b/sys/kern/tty.c
--- a/sys/kern/tty.c
+++ b/sys/kern/tty.c
@@ -747,8 +747,8 @@ ttioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct proc *p)
 			if (pr->ps_pgrp->pg_jobc == 0)
 				return (EIO);
 			pgsignal(pr->ps_pgrp, SIGTTOU, 1);
-			error = ttysleep(tp, &lbolt, TTOPRI | PCATCH,
-			    ttybg);
+			error = ttysleep_nsec(tp, &nowake, TTOPRI | PCATCH,
+				ttybg, SEC_TO_NSEC(1));
 			if (error)
 				return (error);
 		}
@@ -1515,7 +1515,8 @@ loop:	lflag = tp->t_lflag;
 			goto out;
 		}
 		pgsignal(pr->ps_pgrp, SIGTTIN, 1);
-		error = ttysleep(tp, &lbolt, TTIPRI | PCATCH, ttybg);
+		error = ttysleep_nsec(tp, &nowake, TTIPRI | PCATCH, ttybg, 
+			SEC_TO_NSEC(1));
 		if (error)
 			goto out;
 		goto loop;
@@ -1613,8 +1614,8 @@ read:
 		    ISSET(lflag, IEXTEN | ISIG) == (IEXTEN | ISIG)) {
 			pgsignal(tp->t_pgrp, SIGTSTP, 1);
 			if (first) {
-				error = ttysleep(tp, &lbolt, TTIPRI | PCATCH,
-				    ttybg);
+				error = ttysleep_nsec(tp, &nowake, TTIPRI | PCATCH, 
+					ttybg, SEC_TO_NSEC(1));
 				if (error)
 					break;
 				goto loop;
@@ -1765,7 +1766,8 @@ loop:
 			goto out;
 		}
 		pgsignal(pr->ps_pgrp, SIGTTOU, 1);
-		error = ttysleep(tp, &lbolt, TTIPRI | PCATCH, ttybg);
+		error = ttysleep_nsec(tp, &nowake, TTIPRI | PCATCH, ttybg, 
+			SEC_TO_NSEC(1));
 		if (error)
 			goto out;
 		goto loop;
diff --git a/sys/kern/tty_pty.c b/sys/kern/tty_pty.c
--- a/sys/kern/tty_pty.c
+++ b/sys/kern/tty_pty.c
@@ -294,7 +294,8 @@ again:
 			    pr->ps_flags & PS_PPWAIT)
 				return (EIO);
 			pgsignal(pr->ps_pgrp, SIGTTIN, 1);
-			error = ttysleep(tp, &lbolt, TTIPRI | PCATCH, ttybg);
+			error = ttysleep_nsec(tp, &nowake, TTIPRI | PCATCH, 
+				ttybg, SEC_TO_NSEC(1));
 			if (error)
 				return (error);
 		}
diff --git a/sys/sys/kernel.h b/sys/sys/kernel.h
--- a/sys/sys/kernel.h
+++ b/sys/sys/kernel.h
@@ -55,7 +55,6 @@ extern int ticks;		/* # of hardclock ticks */
 extern int hz;			/* system clock's frequency */
 extern int stathz;		/* statistics clock's frequency */
 extern int profhz;		/* profiling clock's frequency */
-extern int lbolt;		/* once a second sleep address */
 
 #ifndef HZ
 #define HZ 100
diff --git a/sys/sys/tty.h b/sys/sys/tty.h
--- a/sys/sys/tty.h
+++ b/sys/sys/tty.h
@@ -290,6 +290,7 @@ void	 ttypend(struct tty *tp);
 int	 ttyretype(struct tty *tp);
 int	 ttyrub(int c, struct tty *tp);
 int	 ttysleep(struct tty *tp, void *chan, int pri, char *wmesg);
+int	 ttysleep_nsec(struct tty *, void *, int, char *, uint64_t);
 int	 ttywait(struct tty *tp);
 int	 ttywflush(struct tty *tp);
 void	 ttytstamp(struct tty *tp, int octs, int ncts, int odcd, int ndcd);