NAME

PHOLD — hold a process

SYNOPSIS

#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);

DESCRIPTION

The PHOLD() macro increments the hold count of a process, and the PRELE() macro decrements the hold count of a process.

If a process with a non-zero hold count attempts to exit, it will sleep until its hold count has reached zero before the kernel begins releasing resources associated with the process. Once a process has started exiting, it is invalid to increase its hold count. Thus, callers must not attempt to hold a process that has the P_WEXIT flag set. The VM daemon will not swap out the kernel stack of a thread belonging to a process with a non-zero hold count.

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

AUTHORS

This manual page was written by Mark Johnston <markj@FreeBSD.org>.