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4 * BSD Process Accounting for Linux
6 * Author: Marco van Wieringen <mvw@planets.elm.net>
8 * Some code based on ideas and code from:
9 * Thomas K. Dyas <tdyas@eden.rutgers.edu>
11 * This file implements BSD-style process accounting. Whenever any
12 * process exits, an accounting record of type "struct acct" is
13 * written to the file specified with the acct() system call. It is
14 * up to user-level programs to do useful things with the accounting
15 * log. The kernel just provides the raw accounting information.
17 * (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V.
19 * Plugged two leaks. 1) It didn't return acct_file into the free_filps if
20 * the file happened to be read-only. 2) If the accounting was suspended
21 * due to the lack of space it happily allowed to reopen it and completely
22 * lost the old acct_file. 3/10/98, Al Viro.
24 * Now we silently close acct_file on attempt to reopen. Cleaned sys_acct().
25 * XTerms and EMACS are manifestations of pure evil. 21/10/98, AV.
27 * Fixed a nasty interaction with with sys_umount(). If the accointing
28 * was suspeneded we failed to stop it on umount(). Messy.
29 * Another one: remount to readonly didn't stop accounting.
30 * Question: what should we do if we have CAP_SYS_ADMIN but not
31 * CAP_SYS_PACCT? Current code does the following: umount returns -EBUSY
32 * unless we are messing with the root. In that case we are getting a
33 * real mess with do_remount_sb(). 9/11/98, AV.
35 * Fixed a bunch of races (and pair of leaks). Probably not the best way,
36 * but this one obviously doesn't introduce deadlocks. Later. BTW, found
37 * one race (and leak) in BSD implementation.
38 * OK, that's better. ANOTHER race and leak in BSD variant. There always
39 * is one more bug... 10/11/98, AV.
41 * Oh, fsck... Oopsable SMP race in do_process_acct() - we must hold
42 * ->mmap_sem to walk the vma list of current->mm. Nasty, since it leaks
43 * a struct file opened for write. Fixed. 2/6/2000, AV.
47 #include <linux/slab.h>
48 #include <linux/acct.h>
49 #include <linux/capability.h>
50 #include <linux/file.h>
51 #include <linux/tty.h>
52 #include <linux/security.h>
53 #include <linux/vfs.h>
54 #include <linux/jiffies.h>
55 #include <linux/times.h>
56 #include <linux/syscalls.h>
57 #include <linux/mount.h>
58 #include <asm/uaccess.h>
59 #include <asm/div64.h>
60 #include <linux/blkdev.h> /* sector_div */
61 #include <linux/pid_namespace.h>
64 * These constants control the amount of freespace that suspend and
65 * resume the process accounting system, and the time delay between
67 * Turned into sysctl-controllable parameters. AV, 12/11/98
70 int acct_parm
[3] = {4, 2, 30};
71 #define RESUME (acct_parm[0]) /* >foo% free space - resume */
72 #define SUSPEND (acct_parm[1]) /* <foo% free space - suspend */
73 #define ACCT_TIMEOUT (acct_parm[2]) /* foo second timeout between checks */
76 * External references and all of the globals.
78 static void do_acct_process(struct bsd_acct_struct
*acct
,
79 struct pid_namespace
*ns
, struct file
*);
82 * This structure is used so that all the data protected by lock
83 * can be placed in the same cache line as the lock. This primes
84 * the cache line to have the data after getting the lock.
86 struct bsd_acct_struct
{
88 volatile int needcheck
;
90 struct pid_namespace
*ns
;
91 struct timer_list timer
;
92 struct list_head list
;
95 static DEFINE_SPINLOCK(acct_lock
);
96 static LIST_HEAD(acct_list
);
99 * Called whenever the timer says to check the free space.
101 static void acct_timeout(unsigned long x
)
103 struct bsd_acct_struct
*acct
= (struct bsd_acct_struct
*)x
;
108 * Check the amount of free space and suspend/resume accordingly.
110 static int check_free_space(struct bsd_acct_struct
*acct
, struct file
*file
)
118 spin_lock(&acct_lock
);
120 if (!file
|| !acct
->needcheck
)
122 spin_unlock(&acct_lock
);
125 if (vfs_statfs(file
->f_path
.dentry
, &sbuf
))
127 suspend
= sbuf
.f_blocks
* SUSPEND
;
128 resume
= sbuf
.f_blocks
* RESUME
;
130 sector_div(suspend
, 100);
131 sector_div(resume
, 100);
133 if (sbuf
.f_bavail
<= suspend
)
135 else if (sbuf
.f_bavail
>= resume
)
141 * If some joker switched acct->file under us we'ld better be
142 * silent and _not_ touch anything.
144 spin_lock(&acct_lock
);
145 if (file
!= acct
->file
) {
154 printk(KERN_INFO
"Process accounting paused\n");
159 printk(KERN_INFO
"Process accounting resumed\n");
163 del_timer(&acct
->timer
);
165 acct
->timer
.expires
= jiffies
+ ACCT_TIMEOUT
*HZ
;
166 add_timer(&acct
->timer
);
169 spin_unlock(&acct_lock
);
174 * Close the old accounting file (if currently open) and then replace
175 * it with file (if non-NULL).
177 * NOTE: acct_lock MUST be held on entry and exit.
179 static void acct_file_reopen(struct bsd_acct_struct
*acct
, struct file
*file
,
180 struct pid_namespace
*ns
)
182 struct file
*old_acct
= NULL
;
183 struct pid_namespace
*old_ns
= NULL
;
186 old_acct
= acct
->file
;
188 del_timer(&acct
->timer
);
193 list_del(&acct
->list
);
200 list_add(&acct
->list
, &acct_list
);
201 /* It's been deleted if it was used before so this is safe */
202 setup_timer(&acct
->timer
, acct_timeout
, (unsigned long)acct
);
203 acct
->timer
.expires
= jiffies
+ ACCT_TIMEOUT
*HZ
;
204 add_timer(&acct
->timer
);
207 mnt_unpin(old_acct
->f_path
.mnt
);
208 spin_unlock(&acct_lock
);
209 do_acct_process(acct
, old_ns
, old_acct
);
210 filp_close(old_acct
, NULL
);
211 spin_lock(&acct_lock
);
215 static int acct_on(char *name
)
218 struct vfsmount
*mnt
;
220 struct pid_namespace
*ns
;
221 struct bsd_acct_struct
*acct
= NULL
;
223 /* Difference from BSD - they don't do O_APPEND */
224 file
= filp_open(name
, O_WRONLY
|O_APPEND
|O_LARGEFILE
, 0);
226 return PTR_ERR(file
);
228 if (!S_ISREG(file
->f_path
.dentry
->d_inode
->i_mode
)) {
229 filp_close(file
, NULL
);
233 if (!file
->f_op
->write
) {
234 filp_close(file
, NULL
);
238 ns
= task_active_pid_ns(current
);
239 if (ns
->bacct
== NULL
) {
240 acct
= kzalloc(sizeof(struct bsd_acct_struct
), GFP_KERNEL
);
242 filp_close(file
, NULL
);
247 error
= security_acct(file
);
250 filp_close(file
, NULL
);
254 spin_lock(&acct_lock
);
255 if (ns
->bacct
== NULL
) {
260 mnt
= file
->f_path
.mnt
;
262 acct_file_reopen(ns
->bacct
, file
, ns
);
263 spin_unlock(&acct_lock
);
265 mntput(mnt
); /* it's pinned, now give up active reference */
272 * sys_acct - enable/disable process accounting
273 * @name: file name for accounting records or NULL to shutdown accounting
275 * Returns 0 for success or negative errno values for failure.
277 * sys_acct() is the only system call needed to implement process
278 * accounting. It takes the name of the file where accounting records
279 * should be written. If the filename is NULL, accounting will be
282 SYSCALL_DEFINE1(acct
, const char __user
*, name
)
286 if (!capable(CAP_SYS_PACCT
))
290 char *tmp
= getname(name
);
292 return (PTR_ERR(tmp
));
293 error
= acct_on(tmp
);
296 struct bsd_acct_struct
*acct
;
298 acct
= task_active_pid_ns(current
)->bacct
;
302 error
= security_acct(NULL
);
304 spin_lock(&acct_lock
);
305 acct_file_reopen(acct
, NULL
, NULL
);
306 spin_unlock(&acct_lock
);
313 * acct_auto_close - turn off a filesystem's accounting if it is on
314 * @m: vfsmount being shut down
316 * If the accounting is turned on for a file in the subtree pointed to
317 * to by m, turn accounting off. Done when m is about to die.
319 void acct_auto_close_mnt(struct vfsmount
*m
)
321 struct bsd_acct_struct
*acct
;
323 spin_lock(&acct_lock
);
325 list_for_each_entry(acct
, &acct_list
, list
)
326 if (acct
->file
&& acct
->file
->f_path
.mnt
== m
) {
327 acct_file_reopen(acct
, NULL
, NULL
);
330 spin_unlock(&acct_lock
);
334 * acct_auto_close - turn off a filesystem's accounting if it is on
335 * @sb: super block for the filesystem
337 * If the accounting is turned on for a file in the filesystem pointed
338 * to by sb, turn accounting off.
340 void acct_auto_close(struct super_block
*sb
)
342 struct bsd_acct_struct
*acct
;
344 spin_lock(&acct_lock
);
346 list_for_each_entry(acct
, &acct_list
, list
)
347 if (acct
->file
&& acct
->file
->f_path
.mnt
->mnt_sb
== sb
) {
348 acct_file_reopen(acct
, NULL
, NULL
);
351 spin_unlock(&acct_lock
);
354 void acct_exit_ns(struct pid_namespace
*ns
)
356 struct bsd_acct_struct
*acct
;
358 spin_lock(&acct_lock
);
361 if (acct
->file
!= NULL
)
362 acct_file_reopen(acct
, NULL
, NULL
);
366 spin_unlock(&acct_lock
);
370 * encode an unsigned long into a comp_t
372 * This routine has been adopted from the encode_comp_t() function in
373 * the kern_acct.c file of the FreeBSD operating system. The encoding
374 * is a 13-bit fraction with a 3-bit (base 8) exponent.
377 #define MANTSIZE 13 /* 13 bit mantissa. */
378 #define EXPSIZE 3 /* Base 8 (3 bit) exponent. */
379 #define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */
381 static comp_t
encode_comp_t(unsigned long value
)
386 while (value
> MAXFRACT
) {
387 rnd
= value
& (1 << (EXPSIZE
- 1)); /* Round up? */
388 value
>>= EXPSIZE
; /* Base 8 exponent == 3 bit shift. */
393 * If we need to round up, do it (and handle overflow correctly).
395 if (rnd
&& (++value
> MAXFRACT
)) {
401 * Clean it up and polish it off.
403 exp
<<= MANTSIZE
; /* Shift the exponent into place */
404 exp
+= value
; /* and add on the mantissa. */
408 #if ACCT_VERSION==1 || ACCT_VERSION==2
410 * encode an u64 into a comp2_t (24 bits)
412 * Format: 5 bit base 2 exponent, 20 bits mantissa.
413 * The leading bit of the mantissa is not stored, but implied for
414 * non-zero exponents.
415 * Largest encodable value is 50 bits.
418 #define MANTSIZE2 20 /* 20 bit mantissa. */
419 #define EXPSIZE2 5 /* 5 bit base 2 exponent. */
420 #define MAXFRACT2 ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */
421 #define MAXEXP2 ((1 <<EXPSIZE2) - 1) /* Maximum exponent. */
423 static comp2_t
encode_comp2_t(u64 value
)
427 exp
= (value
> (MAXFRACT2
>>1));
429 while (value
> MAXFRACT2
) {
436 * If we need to round up, do it (and handle overflow correctly).
438 if (rnd
&& (++value
> MAXFRACT2
)) {
444 /* Overflow. Return largest representable number instead. */
445 return (1ul << (MANTSIZE2
+EXPSIZE2
-1)) - 1;
447 return (value
& (MAXFRACT2
>>1)) | (exp
<< (MANTSIZE2
-1));
454 * encode an u64 into a 32 bit IEEE float
456 static u32
encode_float(u64 value
)
461 if (value
==0) return 0;
462 while ((s64
)value
> 0){
466 u
= (u32
)(value
>> 40) & 0x7fffffu
;
467 return u
| (exp
<< 23);
472 * Write an accounting entry for an exiting process
474 * The acct_process() call is the workhorse of the process
475 * accounting system. The struct acct is built here and then written
476 * into the accounting file. This function should only be called from
477 * do_exit() or when switching to a different output file.
481 * do_acct_process does all actual work. Caller holds the reference to file.
483 static void do_acct_process(struct bsd_acct_struct
*acct
,
484 struct pid_namespace
*ns
, struct file
*file
)
486 struct pacct_struct
*pacct
= ¤t
->signal
->pacct
;
492 struct timespec uptime
;
493 struct tty_struct
*tty
;
496 * First check to see if there is enough free_space to continue
497 * the process accounting system.
499 if (!check_free_space(acct
, file
))
503 * Fill the accounting struct with the needed info as recorded
504 * by the different kernel functions.
506 memset((caddr_t
)&ac
, 0, sizeof(acct_t
));
508 ac
.ac_version
= ACCT_VERSION
| ACCT_BYTEORDER
;
509 strlcpy(ac
.ac_comm
, current
->comm
, sizeof(ac
.ac_comm
));
511 /* calculate run_time in nsec*/
512 do_posix_clock_monotonic_gettime(&uptime
);
513 run_time
= (u64
)uptime
.tv_sec
*NSEC_PER_SEC
+ uptime
.tv_nsec
;
514 run_time
-= (u64
)current
->group_leader
->start_time
.tv_sec
* NSEC_PER_SEC
515 + current
->group_leader
->start_time
.tv_nsec
;
516 /* convert nsec -> AHZ */
517 elapsed
= nsec_to_AHZ(run_time
);
519 ac
.ac_etime
= encode_float(elapsed
);
521 ac
.ac_etime
= encode_comp_t(elapsed
< (unsigned long) -1l ?
522 (unsigned long) elapsed
: (unsigned long) -1l);
524 #if ACCT_VERSION==1 || ACCT_VERSION==2
526 /* new enlarged etime field */
527 comp2_t etime
= encode_comp2_t(elapsed
);
528 ac
.ac_etime_hi
= etime
>> 16;
529 ac
.ac_etime_lo
= (u16
) etime
;
532 do_div(elapsed
, AHZ
);
533 ac
.ac_btime
= get_seconds() - elapsed
;
534 /* we really need to bite the bullet and change layout */
535 current_uid_gid(&ac
.ac_uid
, &ac
.ac_gid
);
539 #if ACCT_VERSION==1 || ACCT_VERSION==2
540 /* backward-compatible 16 bit fields */
541 ac
.ac_uid16
= ac
.ac_uid
;
542 ac
.ac_gid16
= ac
.ac_gid
;
545 ac
.ac_pid
= task_tgid_nr_ns(current
, ns
);
547 ac
.ac_ppid
= task_tgid_nr_ns(rcu_dereference(current
->real_parent
), ns
);
551 spin_lock_irq(¤t
->sighand
->siglock
);
552 tty
= current
->signal
->tty
; /* Safe as we hold the siglock */
553 ac
.ac_tty
= tty
? old_encode_dev(tty_devnum(tty
)) : 0;
554 ac
.ac_utime
= encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct
->ac_utime
)));
555 ac
.ac_stime
= encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct
->ac_stime
)));
556 ac
.ac_flag
= pacct
->ac_flag
;
557 ac
.ac_mem
= encode_comp_t(pacct
->ac_mem
);
558 ac
.ac_minflt
= encode_comp_t(pacct
->ac_minflt
);
559 ac
.ac_majflt
= encode_comp_t(pacct
->ac_majflt
);
560 ac
.ac_exitcode
= pacct
->ac_exitcode
;
561 spin_unlock_irq(¤t
->sighand
->siglock
);
562 ac
.ac_io
= encode_comp_t(0 /* current->io_usage */); /* %% */
563 ac
.ac_rw
= encode_comp_t(ac
.ac_io
/ 1024);
564 ac
.ac_swaps
= encode_comp_t(0);
567 * Kernel segment override to datasegment and write it
568 * to the accounting file.
573 * Accounting records are not subject to resource limits.
575 flim
= current
->signal
->rlim
[RLIMIT_FSIZE
].rlim_cur
;
576 current
->signal
->rlim
[RLIMIT_FSIZE
].rlim_cur
= RLIM_INFINITY
;
577 file
->f_op
->write(file
, (char *)&ac
,
578 sizeof(acct_t
), &file
->f_pos
);
579 current
->signal
->rlim
[RLIMIT_FSIZE
].rlim_cur
= flim
;
584 * acct_init_pacct - initialize a new pacct_struct
585 * @pacct: per-process accounting info struct to initialize
587 void acct_init_pacct(struct pacct_struct
*pacct
)
589 memset(pacct
, 0, sizeof(struct pacct_struct
));
590 pacct
->ac_utime
= pacct
->ac_stime
= cputime_zero
;
594 * acct_collect - collect accounting information into pacct_struct
595 * @exitcode: task exit code
596 * @group_dead: not 0, if this thread is the last one in the process.
598 void acct_collect(long exitcode
, int group_dead
)
600 struct pacct_struct
*pacct
= ¤t
->signal
->pacct
;
601 unsigned long vsize
= 0;
603 if (group_dead
&& current
->mm
) {
604 struct vm_area_struct
*vma
;
605 down_read(¤t
->mm
->mmap_sem
);
606 vma
= current
->mm
->mmap
;
608 vsize
+= vma
->vm_end
- vma
->vm_start
;
611 up_read(¤t
->mm
->mmap_sem
);
614 spin_lock_irq(¤t
->sighand
->siglock
);
616 pacct
->ac_mem
= vsize
/ 1024;
617 if (thread_group_leader(current
)) {
618 pacct
->ac_exitcode
= exitcode
;
619 if (current
->flags
& PF_FORKNOEXEC
)
620 pacct
->ac_flag
|= AFORK
;
622 if (current
->flags
& PF_SUPERPRIV
)
623 pacct
->ac_flag
|= ASU
;
624 if (current
->flags
& PF_DUMPCORE
)
625 pacct
->ac_flag
|= ACORE
;
626 if (current
->flags
& PF_SIGNALED
)
627 pacct
->ac_flag
|= AXSIG
;
628 pacct
->ac_utime
= cputime_add(pacct
->ac_utime
, current
->utime
);
629 pacct
->ac_stime
= cputime_add(pacct
->ac_stime
, current
->stime
);
630 pacct
->ac_minflt
+= current
->min_flt
;
631 pacct
->ac_majflt
+= current
->maj_flt
;
632 spin_unlock_irq(¤t
->sighand
->siglock
);
635 static void acct_process_in_ns(struct pid_namespace
*ns
)
637 struct file
*file
= NULL
;
638 struct bsd_acct_struct
*acct
;
642 * accelerate the common fastpath:
644 if (!acct
|| !acct
->file
)
647 spin_lock(&acct_lock
);
649 if (unlikely(!file
)) {
650 spin_unlock(&acct_lock
);
654 spin_unlock(&acct_lock
);
656 do_acct_process(acct
, ns
, file
);
661 * acct_process - now just a wrapper around acct_process_in_ns,
662 * which in turn is a wrapper around do_acct_process.
664 * handles process accounting for an exiting task
666 void acct_process(void)
668 struct pid_namespace
*ns
;
671 * This loop is safe lockless, since current is still
672 * alive and holds its namespace, which in turn holds
675 for (ns
= task_active_pid_ns(current
); ns
!= NULL
; ns
= ns
->parent
)
676 acct_process_in_ns(ns
);