PHOLD(9)

💅 PHOLD(9) — the "hold a process" manual, bestie edition 💅

okay so this is a Kernel Developer's Manual page, and today's main character is PHOLD — the macro that literally just holds a process. iconic behaviour honestly.

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🌸 NAME 🌸

PHOLD — hold a process 🫶

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✨ SYNOPSIS ✨

like, here's the whole cast, no cap:

#include <sys/proc.h>

PHOLD(struct proc *p);

_PHOLD(struct proc *p);

PRELE(struct proc *p);

_PRELE(struct proc *p);

PROC_ASSERT_HELD(struct proc *p);

PROC_ASSERT_NOT_HELD(struct proc *p);

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💖 DESCRIPTION 💖

so the PHOLD() macro increments the hold count of a process, and the PRELE() macro decrements the hold count of a process. that's it, that's the vibe. 💅

and here's the part where it gets kind of serious, so listen up bestie 🫶 — if a process with a non-zero hold count tries to exit, it will sleep until its hold count has reached zero before the kernel begins releasing resources associated with the process. the way I think about it: nobody leaves the group chat until everyone's done holding. 😭

once a process has started exiting, it is invalid to increase its hold count. so callers must not attempt to hold a process that has the P_WEXIT flag set. 🚫 (fr fr, don't do it.)

also the VM daemon will not swap out the kernel stack of a thread belonging to a process with a non-zero hold count. so that stack is staying right where it is, periodt. 👑

The _PHOLD() and _PRELE() macros are identical to PHOLD() and PRELE(), except that they must be called with the process lock held. 🔒 iykyk.

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🎀 AUTHORS 🎀

This manual page was written by Mark Johnston <markj@FreeBSD.org>. slay, thank you Mark. 💖

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that's the whole page, bestie — go forth and hold those processes responsibly ✨🦋🌸

Debian · November 7, 2015 🎀 — mwah, that's a wrap on the PHOLD(9) page, version and date and all 💜