linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 *  linux/kernel/acct.c

 *

 *  BSD Process Accounting for Linux

 *

 *  Author: Marco van Wieringen <mvw@planets.elm.net>

 *

 *  Some code based on ideas and code from:

 *  Thomas K. Dyas <tdyas@eden.rutgers.edu>

 *

 *  This file implements BSD-style process accounting. Whenever any

 *  process exits, an accounting record of type "struct acct" is

 *  written to the file specified with the acct() system call. It is

 *  up to user-level programs to do useful things with the accounting

 *  log. The kernel just provides the raw accounting information.

 *

 * (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.

 *

 *  Plugged two leaks. 1) It didn't return acct_file into the free_filps if

 *  the file happened to be read-only. 2) If the accounting was suspended

 *  due to the lack of space it happily allowed to reopen it and completely

 *  lost the old acct_file. 3/10/98, Al Viro.

 *

 *  Now we silently close acct_file on attempt to reopen. Cleaned sys_acct().

 *  XTerms and EMACS are manifestations of pure evil. 21/10/98, AV.

 *

 *  Fixed a nasty interaction with with sys_umount(). If the accointing

 *  was suspeneded we failed to stop it on umount(). Messy.

 *  Another one: remount to readonly didn't stop accounting.

 *  Question: what should we do if we have CAP_SYS_ADMIN but not

 *  CAP_SYS_PACCT? Current code does the following: umount returns -EBUSY

 *  unless we are messing with the root. In that case we are getting a

 *  real mess with do_remount_sb(). 9/11/98, AV.

 *

 *  Fixed a bunch of races (and pair of leaks). Probably not the best way,

 *  but this one obviously doesn't introduce deadlocks. Later. BTW, found

 *  one race (and leak) in BSD implementation.

 *  OK, that's better. ANOTHER race and leak in BSD variant. There always

 *  is one more bug... 10/11/98, AV.

 *

 *  Oh, fsck... Oopsable SMP race in do_process_acct() - we must hold

 * ->mmap_sem to walk the vma list of current->mm. Nasty, since it leaks

 * a struct file opened for write. Fixed. 2/6/2000, AV.

 */

​

#include <linux/mm.h>

#include <linux/slab.h>

#include <linux/acct.h>

#include <linux/capability.h>

#include <linux/file.h>

#include <linux/tty.h>

#include <linux/security.h>

#include <linux/vfs.h>

#include <linux/jiffies.h>

#include <linux/times.h>

#include <linux/syscalls.h>

#include <linux/mount.h>

#include <linux/uaccess.h>

#include <linux/sched/cputime.h>

​

#include <asm/div64.h>

#include <linux/blkdev.h> /* sector_div */

#include <linux/pid_namespace.h>

#include <linux/fs_pin.h>

​

/*

 * These constants control the amount of freespace that suspend and

 * resume the process accounting system, and the time delay between

 * each check.

 * Turned into sysctl-controllable parameters. AV, 12/11/98

 */

​

int acct_parm[3] = {4, 2, 30};

#define RESUME      (acct_parm[0])  /* >foo% free space - resume */

#define SUSPEND     (acct_parm[1])  /* <foo% free space - suspend */

#define ACCT_TIMEOUT    (acct_parm[2])  /* foo second timeout between checks */

​

/*

 * External references and all of the globals.

 */

​

struct bsd_acct_struct {

    struct fs_pin       pin;

    atomic_long_t       count;

    struct rcu_head     rcu;

    struct mutex        lock;

    int         active;

    unsigned long       needcheck;

    struct file     *file;

    struct pid_namespace    *ns;

    struct work_struct  work;