BUS_RELEASE_RESOURCE(9)

📦 version 12.2, in debian bookworm, debian trixie, ubuntu jammy, ubuntu noble, ubuntu questing, ubuntu resolute, ubuntu stonking

💖 BUS_RELEASE_RESOURCE(9) 💖

okay so bestie, welcome to the Kernel Developer's Manual entry for bus_release_resource — yes it's a real manpage, yes it's giving ✨responsible cleanup era✨, and yes you're gonna slay it.

🌸 NAME 🌸

bus_release_resource — release resources on a bus 🚌💅

✨ SYNOPSIS ✨

#include <sys/param.h>
#include <sys/bus.h>

#include <machine/bus.h>
#include <sys/rman.h>
#include <machine/resource.h>

int
bus_release_resource(device_t dev, int type, int rid,
    struct resource *r);

like. look at that signature. gorgeous. no notes. 🫶

🎀 DESCRIPTION 🎀

So what this bad boy does is free a resource that was allocated by bus_alloc_resource(9). that's literally it. that's the whole vibe. it's the goodbye text after the situationship.

⚠️ BUT — and this is the important part, no cap — the resource must not be in use on release. like, call the appropriate function before you let it go (for example, bus_teardown_intr(9) if it's an IRQ). don't be out here releasing stuff mid-use, it's not the move, it's giving chaos. 😭

Now let's break down the args, bestie:

  • dev — the device that owns the resource. it's their resource. their name is on it. 👑
  • type — the type of resource you're releasing. it must be the same type you allocated it as before, don't switch up on it. check bus_alloc_resource(9) for the valid types if you need a refresher. 📝
  • rid — the resource ID of the resource. and listen, the rid value must be the exact same one that bus_alloc_resource(9) handed you back. same. one. no substitutions. 🚫
  • r — the pointer to struct resource, aka the resource itself, the one and only, returned by bus_alloc_resource(9). hold onto it and give it back exactly as received. 🎁

💀 RETURN VALUES 💀

  • EINVAL gets returned if the device dev has no parent. yep. no parent, no dice.
  • 0 otherwise. clean. iconic. a little win. ✨
🚨 and heads up: the kernel will PANIC if it cannot release the resource. not a vibe check you want to fail. panic = bad. be careful. 😭💀

🌈 EXAMPLES 🌈

here's the whole little routine, verbatim, because we do not gatekeep:

    /* deactivate IRQ */
    bus_teardown_intr(dev, foosoftc->irqres, foosoftc->irqid);

    /* release IRQ resource */
    bus_release_resource(dev, SYS_RES_IRQ, foosoftc->irqid,
        foosoftc->irqres);

    /* release I/O port resource */
    bus_release_resource(dev, SYS_RES_IOPORT, foosoftc->portid,
        foosoftc->portres);

see how it tears down the intr first? that's the whole point bestie. deactivate, then release. order matters. periodt. 💅

👀 SEE ALSO 👀

(the group chat, basically. read the whole thread. iykyk. 🦋)

🫶 AUTHORS 🫶

This manual page was written by Alexander Langer <alex@big.endian.de>. absolute legend behavior. we thank them. 🌸

and that's the page, bestie — go release your resources responsibly, keep your rids matching, and never panic the kernel 💖✨🎀🦋

Debian · May 18, 2000 · BUS_RELEASE_RESOURCE(9) — mwah, signing off 💅⭐

📦 where this page comes from