Date: Tue, 13 Feb 1996 20:04:54 +1030 (CST) From: Michael Smith <msmith@atrad.adelaide.edu.au> To: bde@zeta.org.au (Bruce Evans) Cc: msmith@atrad.adelaide.edu.au, hackers@FreeBSD.org Subject: Re: device driver ioctl for nonblocking IO? Message-ID: <199602130934.UAA10882@genesis.atrad.adelaide.edu.au> In-Reply-To: <199602130909.UAA19799@godzilla.zeta.org.au> from "Bruce Evans" at Feb 13, 96 08:09:43 pm
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Bruce Evans stands accused of saying: > >> If I open an fd on the device and fcntl(fd, F_SETFL, O_NONBLOCK), I get > >> a mystery ioctl sent to my device. > > >Argh. FIONBIO. Not enough coffee. Sorry. > > FIONBIO should be ignored unless you want to handle the races that can > result when a process changes the flag while another process is blocked > in an i/o. The O_NONBLOCK flag (aka the O_NDELAY flag) (aka the FNDELAY I'm only allowing one open (no more make any sense), so that's not a problem. > flag) is better aka the FNONBLOCK flag in the kernel. It is stored in > the file descriptor flags and passed to all read and write functions > after converting it to the IO_NDELAY. It is also passed to the open, > ioctl and close functions without conversion. That makes it much easier than keeping state in the unit structure; thanks. > Bruce -- ]] Mike Smith, Software Engineer msmith@atrad.adelaide.edu.au [[ ]] Genesis Software genesis@atrad.adelaide.edu.au [[ ]] High-speed data acquisition and (GSM mobile) 0411-222-496 [[ ]] realtime instrument control (ph/fax) +61-8-267-3039 [[ ]] Collector of old Unix hardware. "I seek PEZ!" - The Tick [[
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