Path: utzoo!utgpu!water!watmath!clyde!rutgers!cmcl2!brl-adm!umd5!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.unix.wizards
Subject: Re: 4.3BSD bug query
Summary: ^C during `<fs>: file system full
Message-ID: <10361@mimsy.UUCP>
Date: 27 Jan 88 11:42:42 GMT
References: <1960@bsu-cs.UUCP>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 130

In article <1960@bsu-cs.UUCP> dhesi@bsu-cs.UUCP (Rahul Dhesi) writes:
>Is anybody aware of a bug (and possibly a fix) in 4.3BSD as distributed
>by UCB for VAX machines that causes the system to undergo silent death
>(no error messages of any kind, just hangs up until rebooted) if one or
>more disk partitions get close to being full (but not actually full)?

No, but if one *does* get full (to 100%---110% is not necessary) and
someone types ^C or some other flush character while the system is
printing `/usr: file system full', that can do it.  `ps' on the crash
dump will show various processes stuck in inode wait (`STAT' D).

From: bostic@OKEEFFE.BERKELEY.EDU (Keith Bostic)
Newsgroups: comp.bugs.4bsd.ucb-fixes
Subject: V1.21 (ttycheckoutq)
Message-ID: <8704302022.AA22430@okeeffe.Berkeley.EDU>
Date: 30 Apr 87 20:22:06 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: The ARPA Internet
Lines: 105
Approved: ucb-fixes@okeeffe.berkeley.edu

Subject: ^C during 'file system full' messages can hang your system
Index: sys/{tty.c,subr_prf.c} 4.3BSD

Description:
	While printing "file system full" messages, ttycheckoutq()
	allows the system call to be interrupted, leaving inodes locked.

Fix:

echo x - subr_prf.c.diff
sed 's/^X//' >subr_prf.c.diff << 'END-of-subr_prf.c.diff'
X*** subr_prf.c	Thu Apr 30 13:17:12 1987
X--- subr_prf.c.new	Thu Apr 30 12:29:15 1987
X***************
X*** 67,72 ****
X--- 67,74 ----
X  /*
X   * Uprintf prints to the current user's terminal.
X   * It may block if the tty queue is overfull.
X+  * No message is printed if the queue does not clear
X+  * in a reasonable time.
X   * Should determine whether current terminal user is related
X   * to this process.
X   */
X***************
X*** 87,94 ****
X  		if (p->p_uid != u.u_uid)	/* doesn't account for setuid */
X  			return;
X  #endif
X! 	(void)ttycheckoutq(tp, 1);
X! 	prf(fmt, &x1, TOTTY, tp);
X  }
X  
X  /*
X--- 89,96 ----
X  		if (p->p_uid != u.u_uid)	/* doesn't account for setuid */
X  			return;
X  #endif
X! 	if (ttycheckoutq(tp, 1))
X! 		prf(fmt, &x1, TOTTY, tp);
X  }
X  
X  /*
END-of-subr_prf.c.diff
echo x - tty.c.diff
sed 's/^X//' >tty.c.diff << 'END-of-tty.c.diff'
X*** tty.c	Thu Apr 30 13:17:12 1987
X--- tty.c.new	Thu Apr 30 12:25:12 1987
X***************
X*** 1256,1279 ****
X   * (from uprintf/tprintf).  Allow some space over the normal
X   * hiwater mark so we don't lose messages due to normal flow
X   * control, but don't let the tty run amok.
X   */
X  ttycheckoutq(tp, wait)
X  	register struct tty *tp;
X  	int wait;
X  {
X! 	int hiwat, s;
X  
X  	hiwat = TTHIWAT(tp);
X  	s = spltty();
X  	if (tp->t_outq.c_cc > hiwat + 200)
X  	    while (tp->t_outq.c_cc > hiwat) {
X  		ttstart(tp);
X! 		if (wait == 0) {
X  			splx(s);
X  			return (0);
X  		}
X  		tp->t_state |= TS_ASLEEP;
X! 		sleep((caddr_t)&tp->t_outq, TTOPRI);
X  	}
X  	splx(s);
X  	return (1);
X--- 1256,1283 ----
X   * (from uprintf/tprintf).  Allow some space over the normal
X   * hiwater mark so we don't lose messages due to normal flow
X   * control, but don't let the tty run amok.
X+  * Sleeps here are not interruptible, but we return permaturely
X+  * if new signals come in.
X   */
X  ttycheckoutq(tp, wait)
X  	register struct tty *tp;
X  	int wait;
X  {
X! 	int hiwat, s, oldsig;
X  
X  	hiwat = TTHIWAT(tp);
X  	s = spltty();
X+ 	oldsig = u.u_procp->p_sig;
X  	if (tp->t_outq.c_cc > hiwat + 200)
X  	    while (tp->t_outq.c_cc > hiwat) {
X  		ttstart(tp);
X! 		if (wait == 0 || u.u_procp->p_sig != oldsig) {
X  			splx(s);
X  			return (0);
X  		}
X+ 		timeout(wakeup, (caddr_t)&tp->t_outq, hz);
X  		tp->t_state |= TS_ASLEEP;
X! 		sleep((caddr_t)&tp->t_outq, PZERO - 1);
X  	}
X  	splx(s);
X  	return (1);
END-of-tty.c.diff
exit
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris