From owner-freebsd-hackers  Thu Nov 20 00:21:31 1997
Return-Path: <owner-freebsd-hackers>
Received: (from root@localhost)
          by hub.freebsd.org (8.8.7/8.8.7) id AAA20282
          for hackers-outgoing; Thu, 20 Nov 1997 00:21:31 -0800 (PST)
          (envelope-from owner-freebsd-hackers)
Received: from sax.sax.de (sax.sax.de [193.175.26.33])
          by hub.freebsd.org (8.8.7/8.8.7) with SMTP id AAA20269
          for <hackers@freebsd.org>; Thu, 20 Nov 1997 00:21:26 -0800 (PST)
          (envelope-from j@uriah.heep.sax.de)
Received: (from uucp@localhost) by sax.sax.de (8.6.12/8.6.12-s1) with UUCP id JAA06210 for hackers@freebsd.org; Thu, 20 Nov 1997 09:21:19 +0100
Received: (from j@localhost)
	by uriah.heep.sax.de (8.8.8/8.8.5) id JAA01342;
	Thu, 20 Nov 1997 09:06:11 +0100 (MET)
Message-ID: <19971120090611.FW37911@uriah.heep.sax.de>
Date: Thu, 20 Nov 1997 09:06:11 +0100
From: j@uriah.heep.sax.de (J Wunsch)
To: hackers@freebsd.org
Subject: Re: vnode.h and IO_NDELAY (help!!)
References: <Pine.BSF.3.96.971118192251.175A-100000@trojanhorse.ml.org>
X-Mailer: Mutt 0.60_p2-3,5,8-9
Mime-Version: 1.0
X-Phone: +49-351-2012 669
X-PGP-Fingerprint: DC 47 E6 E4 FF A6 E9 8F  93 21 E0 7D F9 12 D6 4E
Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch)
In-Reply-To: <Pine.BSF.3.96.971118192251.175A-100000@trojanhorse.ml.org>; from Jamil J. Weatherbee on Nov 18, 1997 19:28:41 -0800
Sender: owner-freebsd-hackers@freebsd.org
X-Loop: FreeBSD.org
Precedence: bulk

As Jamil J. Weatherbee wrote:

> I can't find a single code fragment in any device driver that checks
> ioflags in the read routine to see if IO_NDELAY is set.

That's work-in-progress, but i know the non-delay stuff does what it's
supposed to do:

static int
rtcread(dev_t dev, struct uio *uio, int flag)
{
	int rv = 0;
	size_t amnt;

	if (flag & IO_NDELAY) {
		/* O_NONBLOCK requests to pull previous data if available */
		if ((rtc_softc.sc_flags & RTC_UPDATED) == 0)
			rv = EWOULDBLOCK;
	} else {
		rv = tsleep((caddr_t)&rtc_softc, RTCPRI | PCATCH, "rtc", 0);

		if (rv == ERESTART)
			rv = EINTR;
	}

	if (rv == 0) {
		amnt = MIN(uio->uio_resid, RTC_DATALEN);
		rv = uiomove((caddr_t)&rtc_softc.sc_data, amnt, uio);
	}

	return rv;
}

Also, don't forget that you need to allow the FIONBIO ioctl command.

-- 
cheers, J"org

joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)