COMEDI_LOCK(3)

✨ COMEDI_LOCK ✨

okay bestie, welcome to COMEDI_LOCK(3) from the Comedi reference 💖 this is the one about claiming a subdevice so nobody else can touch it. lets get into it 🫶

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🌸 NAME 🌸

comedi_lock — subdevice reservation 👑

like literally you're reserving a subdevice. calling dibs. putting your name on it in glitter pen 💅

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✨ SYNOPSIS ✨

#include <comedilib.h>

int comedi_lock(comedi_t * device, unsigned int subdevice);

so you pass in your device (a comedi_t *) and a subdevice (an unsigned int) and it hands you back an int. tidy ✨

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💖 DESCRIPTION 💖

so the function comedi_lock reserves a subdevice for use by the current process. it's giving "this is mine now" but in a polite, kernel-sanctioned way 🎀

while the lock is held, no other process is allowed to read, write, or configure that subdevice — periodt. not reading, not writing, not configuring. none of it 🚫

but here's the nuance, bestie, and it's important: other processes can read information about the subdevice. so they can peek at the metadata, they just can't actually read/write/configure the thing itself. iykyk 👀

the lock gets released by comedi_unlock, orrr it just evaporates when comedi_close is called on device. so if you forget to unlock, closing the device is your safety net 🧚 (still unlock though, bestie, be a good citizen 💜)

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🔥 RETURN VALUE 🔥

• if it works → 0 comes back. slay ✨
• if something goes wrong → -1 comes back. not slay 😭

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👑 AUTHORS 👑

the icons who made this happen 🌈

• David Schleef <ds@schleef.org> — Author.
• Frank Mori Hess <fmhess@users.sourceforge.net> — Author.
• Herman Bruyninckx <Herman.Bruyninckx@mech.kuleuven.ac.be> — Author.
• Bernd Porr <tech@linux-usb-daq.co.uk> — Author.
• Ian Abbott <abbotti@mev.co.uk> — Author.
• Éric Piel <piel@delmic.com> — Author.

main character energy, all six of them 💅

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🎀 COPYRIGHT 🎀

Copyright © 1998-2003 David Schleef
Copyright © 2001-2003, 2005, 2008 Frank Mori Hess
Copyright © 2002-2003 Herman Bruyninckx
Copyright © 2012 Bernd Porr
Copyright © 2012 Ian Abbott
Copyright © 2012, 2015 Éric Piel

This document is part of Comedilib. In the context of this document, the term "source code" as defined by the license is interpreted as the XML source.

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, version 2.1 of the License.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

ngl the all-caps warranty bit is the dramatic part — it literally says NO WARRANTY and that's not a vibe, that's a legally binding fact 💀 read it, don't skip it.

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that's the whole page, bestie 🦋 this one's from the Comedi reference, dated 03/20/2026, and it's COMEDI_LOCK(3) — go forth and reserve your subdevices responsibly 💖✨🎀