1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * linux/kernel/acct.c |
4 | * |
5 | * BSD Process Accounting for Linux |
6 | * |
7 | * Author: Marco van Wieringen <mvw@planets.elm.net> |
8 | * |
9 | * Some code based on ideas and code from: |
10 | * Thomas K. Dyas <tdyas@eden.rutgers.edu> |
11 | * |
12 | * This file implements BSD-style process accounting. Whenever any |
13 | * process exits, an accounting record of type "struct acct" is |
14 | * written to the file specified with the acct() system call. It is |
15 | * up to user-level programs to do useful things with the accounting |
16 | * log. The kernel just provides the raw accounting information. |
17 | * |
18 | * (C) Copyright 1995 - 1997 Marco van Wieringen - ELM Consultancy B.V. |
19 | * |
20 | * Plugged two leaks. 1) It didn't return acct_file into the free_filps if |
21 | * the file happened to be read-only. 2) If the accounting was suspended |
22 | * due to the lack of space it happily allowed to reopen it and completely |
23 | * lost the old acct_file. 3/10/98, Al Viro. |
24 | * |
25 | * Now we silently close acct_file on attempt to reopen. Cleaned sys_acct(). |
26 | * XTerms and EMACS are manifestations of pure evil. 21/10/98, AV. |
27 | * |
28 | * Fixed a nasty interaction with sys_umount(). If the accounting |
29 | * was suspeneded we failed to stop it on umount(). Messy. |
30 | * Another one: remount to readonly didn't stop accounting. |
31 | * Question: what should we do if we have CAP_SYS_ADMIN but not |
32 | * CAP_SYS_PACCT? Current code does the following: umount returns -EBUSY |
33 | * unless we are messing with the root. In that case we are getting a |
34 | * real mess with do_remount_sb(). 9/11/98, AV. |
35 | * |
36 | * Fixed a bunch of races (and pair of leaks). Probably not the best way, |
37 | * but this one obviously doesn't introduce deadlocks. Later. BTW, found |
38 | * one race (and leak) in BSD implementation. |
39 | * OK, that's better. ANOTHER race and leak in BSD variant. There always |
40 | * is one more bug... 10/11/98, AV. |
41 | * |
42 | * Oh, fsck... Oopsable SMP race in do_process_acct() - we must hold |
43 | * ->mmap_lock to walk the vma list of current->mm. Nasty, since it leaks |
44 | * a struct file opened for write. Fixed. 2/6/2000, AV. |
45 | */ |
46 | |
47 | #include <linux/mm.h> |
48 | #include <linux/slab.h> |
49 | #include <linux/acct.h> |
50 | #include <linux/capability.h> |
51 | #include <linux/file.h> |
52 | #include <linux/tty.h> |
53 | #include <linux/security.h> |
54 | #include <linux/vfs.h> |
55 | #include <linux/jiffies.h> |
56 | #include <linux/times.h> |
57 | #include <linux/syscalls.h> |
58 | #include <linux/mount.h> |
59 | #include <linux/uaccess.h> |
60 | #include <linux/sched/cputime.h> |
61 | |
62 | #include <asm/div64.h> |
63 | #include <linux/pid_namespace.h> |
64 | #include <linux/fs_pin.h> |
65 | |
66 | /* |
67 | * These constants control the amount of freespace that suspend and |
68 | * resume the process accounting system, and the time delay between |
69 | * each check. |
70 | * Turned into sysctl-controllable parameters. AV, 12/11/98 |
71 | */ |
72 | |
73 | static int acct_parm[3] = {4, 2, 30}; |
74 | #define RESUME (acct_parm[0]) /* >foo% free space - resume */ |
75 | #define SUSPEND (acct_parm[1]) /* <foo% free space - suspend */ |
76 | #define ACCT_TIMEOUT (acct_parm[2]) /* foo second timeout between checks */ |
77 | |
78 | #ifdef CONFIG_SYSCTL |
79 | static struct ctl_table kern_acct_table[] = { |
80 | { |
81 | .procname = "acct" , |
82 | .data = &acct_parm, |
83 | .maxlen = 3*sizeof(int), |
84 | .mode = 0644, |
85 | .proc_handler = proc_dointvec, |
86 | }, |
87 | { } |
88 | }; |
89 | |
90 | static __init int kernel_acct_sysctls_init(void) |
91 | { |
92 | register_sysctl_init("kernel" , kern_acct_table); |
93 | return 0; |
94 | } |
95 | late_initcall(kernel_acct_sysctls_init); |
96 | #endif /* CONFIG_SYSCTL */ |
97 | |
98 | /* |
99 | * External references and all of the globals. |
100 | */ |
101 | |
102 | struct bsd_acct_struct { |
103 | struct fs_pin pin; |
104 | atomic_long_t count; |
105 | struct rcu_head rcu; |
106 | struct mutex lock; |
107 | int active; |
108 | unsigned long needcheck; |
109 | struct file *file; |
110 | struct pid_namespace *ns; |
111 | struct work_struct work; |
112 | struct completion done; |
113 | }; |
114 | |
115 | static void do_acct_process(struct bsd_acct_struct *acct); |
116 | |
117 | /* |
118 | * Check the amount of free space and suspend/resume accordingly. |
119 | */ |
120 | static int check_free_space(struct bsd_acct_struct *acct) |
121 | { |
122 | struct kstatfs sbuf; |
123 | |
124 | if (time_is_after_jiffies(acct->needcheck)) |
125 | goto out; |
126 | |
127 | /* May block */ |
128 | if (vfs_statfs(&acct->file->f_path, &sbuf)) |
129 | goto out; |
130 | |
131 | if (acct->active) { |
132 | u64 suspend = sbuf.f_blocks * SUSPEND; |
133 | do_div(suspend, 100); |
134 | if (sbuf.f_bavail <= suspend) { |
135 | acct->active = 0; |
136 | pr_info("Process accounting paused\n" ); |
137 | } |
138 | } else { |
139 | u64 resume = sbuf.f_blocks * RESUME; |
140 | do_div(resume, 100); |
141 | if (sbuf.f_bavail >= resume) { |
142 | acct->active = 1; |
143 | pr_info("Process accounting resumed\n" ); |
144 | } |
145 | } |
146 | |
147 | acct->needcheck = jiffies + ACCT_TIMEOUT*HZ; |
148 | out: |
149 | return acct->active; |
150 | } |
151 | |
152 | static void acct_put(struct bsd_acct_struct *p) |
153 | { |
154 | if (atomic_long_dec_and_test(v: &p->count)) |
155 | kfree_rcu(p, rcu); |
156 | } |
157 | |
158 | static inline struct bsd_acct_struct *to_acct(struct fs_pin *p) |
159 | { |
160 | return p ? container_of(p, struct bsd_acct_struct, pin) : NULL; |
161 | } |
162 | |
163 | static struct bsd_acct_struct *acct_get(struct pid_namespace *ns) |
164 | { |
165 | struct bsd_acct_struct *res; |
166 | again: |
167 | smp_rmb(); |
168 | rcu_read_lock(); |
169 | res = to_acct(READ_ONCE(ns->bacct)); |
170 | if (!res) { |
171 | rcu_read_unlock(); |
172 | return NULL; |
173 | } |
174 | if (!atomic_long_inc_not_zero(v: &res->count)) { |
175 | rcu_read_unlock(); |
176 | cpu_relax(); |
177 | goto again; |
178 | } |
179 | rcu_read_unlock(); |
180 | mutex_lock(&res->lock); |
181 | if (res != to_acct(READ_ONCE(ns->bacct))) { |
182 | mutex_unlock(lock: &res->lock); |
183 | acct_put(p: res); |
184 | goto again; |
185 | } |
186 | return res; |
187 | } |
188 | |
189 | static void acct_pin_kill(struct fs_pin *pin) |
190 | { |
191 | struct bsd_acct_struct *acct = to_acct(p: pin); |
192 | mutex_lock(&acct->lock); |
193 | do_acct_process(acct); |
194 | schedule_work(work: &acct->work); |
195 | wait_for_completion(&acct->done); |
196 | cmpxchg(&acct->ns->bacct, pin, NULL); |
197 | mutex_unlock(lock: &acct->lock); |
198 | pin_remove(pin); |
199 | acct_put(p: acct); |
200 | } |
201 | |
202 | static void close_work(struct work_struct *work) |
203 | { |
204 | struct bsd_acct_struct *acct = container_of(work, struct bsd_acct_struct, work); |
205 | struct file *file = acct->file; |
206 | if (file->f_op->flush) |
207 | file->f_op->flush(file, NULL); |
208 | __fput_sync(file); |
209 | complete(&acct->done); |
210 | } |
211 | |
212 | static int acct_on(struct filename *pathname) |
213 | { |
214 | struct file *file; |
215 | struct vfsmount *mnt, *internal; |
216 | struct pid_namespace *ns = task_active_pid_ns(current); |
217 | struct bsd_acct_struct *acct; |
218 | struct fs_pin *old; |
219 | int err; |
220 | |
221 | acct = kzalloc(size: sizeof(struct bsd_acct_struct), GFP_KERNEL); |
222 | if (!acct) |
223 | return -ENOMEM; |
224 | |
225 | /* Difference from BSD - they don't do O_APPEND */ |
226 | file = file_open_name(pathname, O_WRONLY|O_APPEND|O_LARGEFILE, 0); |
227 | if (IS_ERR(ptr: file)) { |
228 | kfree(objp: acct); |
229 | return PTR_ERR(ptr: file); |
230 | } |
231 | |
232 | if (!S_ISREG(file_inode(file)->i_mode)) { |
233 | kfree(objp: acct); |
234 | filp_close(file, NULL); |
235 | return -EACCES; |
236 | } |
237 | |
238 | if (!(file->f_mode & FMODE_CAN_WRITE)) { |
239 | kfree(objp: acct); |
240 | filp_close(file, NULL); |
241 | return -EIO; |
242 | } |
243 | internal = mnt_clone_internal(path: &file->f_path); |
244 | if (IS_ERR(ptr: internal)) { |
245 | kfree(objp: acct); |
246 | filp_close(file, NULL); |
247 | return PTR_ERR(ptr: internal); |
248 | } |
249 | err = mnt_get_write_access(mnt: internal); |
250 | if (err) { |
251 | mntput(mnt: internal); |
252 | kfree(objp: acct); |
253 | filp_close(file, NULL); |
254 | return err; |
255 | } |
256 | mnt = file->f_path.mnt; |
257 | file->f_path.mnt = internal; |
258 | |
259 | atomic_long_set(v: &acct->count, i: 1); |
260 | init_fs_pin(p: &acct->pin, kill: acct_pin_kill); |
261 | acct->file = file; |
262 | acct->needcheck = jiffies; |
263 | acct->ns = ns; |
264 | mutex_init(&acct->lock); |
265 | INIT_WORK(&acct->work, close_work); |
266 | init_completion(x: &acct->done); |
267 | mutex_lock_nested(lock: &acct->lock, subclass: 1); /* nobody has seen it yet */ |
268 | pin_insert(&acct->pin, mnt); |
269 | |
270 | rcu_read_lock(); |
271 | old = xchg(&ns->bacct, &acct->pin); |
272 | mutex_unlock(lock: &acct->lock); |
273 | pin_kill(old); |
274 | mnt_put_write_access(mnt); |
275 | mntput(mnt); |
276 | return 0; |
277 | } |
278 | |
279 | static DEFINE_MUTEX(acct_on_mutex); |
280 | |
281 | /** |
282 | * sys_acct - enable/disable process accounting |
283 | * @name: file name for accounting records or NULL to shutdown accounting |
284 | * |
285 | * sys_acct() is the only system call needed to implement process |
286 | * accounting. It takes the name of the file where accounting records |
287 | * should be written. If the filename is NULL, accounting will be |
288 | * shutdown. |
289 | * |
290 | * Returns: 0 for success or negative errno values for failure. |
291 | */ |
292 | SYSCALL_DEFINE1(acct, const char __user *, name) |
293 | { |
294 | int error = 0; |
295 | |
296 | if (!capable(CAP_SYS_PACCT)) |
297 | return -EPERM; |
298 | |
299 | if (name) { |
300 | struct filename *tmp = getname(name); |
301 | |
302 | if (IS_ERR(ptr: tmp)) |
303 | return PTR_ERR(ptr: tmp); |
304 | mutex_lock(&acct_on_mutex); |
305 | error = acct_on(pathname: tmp); |
306 | mutex_unlock(lock: &acct_on_mutex); |
307 | putname(name: tmp); |
308 | } else { |
309 | rcu_read_lock(); |
310 | pin_kill(task_active_pid_ns(current)->bacct); |
311 | } |
312 | |
313 | return error; |
314 | } |
315 | |
316 | void acct_exit_ns(struct pid_namespace *ns) |
317 | { |
318 | rcu_read_lock(); |
319 | pin_kill(ns->bacct); |
320 | } |
321 | |
322 | /* |
323 | * encode an u64 into a comp_t |
324 | * |
325 | * This routine has been adopted from the encode_comp_t() function in |
326 | * the kern_acct.c file of the FreeBSD operating system. The encoding |
327 | * is a 13-bit fraction with a 3-bit (base 8) exponent. |
328 | */ |
329 | |
330 | #define MANTSIZE 13 /* 13 bit mantissa. */ |
331 | #define EXPSIZE 3 /* Base 8 (3 bit) exponent. */ |
332 | #define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */ |
333 | |
334 | static comp_t encode_comp_t(u64 value) |
335 | { |
336 | int exp, rnd; |
337 | |
338 | exp = rnd = 0; |
339 | while (value > MAXFRACT) { |
340 | rnd = value & (1 << (EXPSIZE - 1)); /* Round up? */ |
341 | value >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */ |
342 | exp++; |
343 | } |
344 | |
345 | /* |
346 | * If we need to round up, do it (and handle overflow correctly). |
347 | */ |
348 | if (rnd && (++value > MAXFRACT)) { |
349 | value >>= EXPSIZE; |
350 | exp++; |
351 | } |
352 | |
353 | if (exp > (((comp_t) ~0U) >> MANTSIZE)) |
354 | return (comp_t) ~0U; |
355 | /* |
356 | * Clean it up and polish it off. |
357 | */ |
358 | exp <<= MANTSIZE; /* Shift the exponent into place */ |
359 | exp += value; /* and add on the mantissa. */ |
360 | return exp; |
361 | } |
362 | |
363 | #if ACCT_VERSION == 1 || ACCT_VERSION == 2 |
364 | /* |
365 | * encode an u64 into a comp2_t (24 bits) |
366 | * |
367 | * Format: 5 bit base 2 exponent, 20 bits mantissa. |
368 | * The leading bit of the mantissa is not stored, but implied for |
369 | * non-zero exponents. |
370 | * Largest encodable value is 50 bits. |
371 | */ |
372 | |
373 | #define MANTSIZE2 20 /* 20 bit mantissa. */ |
374 | #define EXPSIZE2 5 /* 5 bit base 2 exponent. */ |
375 | #define MAXFRACT2 ((1ul << MANTSIZE2) - 1) /* Maximum fractional value. */ |
376 | #define MAXEXP2 ((1 << EXPSIZE2) - 1) /* Maximum exponent. */ |
377 | |
378 | static comp2_t encode_comp2_t(u64 value) |
379 | { |
380 | int exp, rnd; |
381 | |
382 | exp = (value > (MAXFRACT2>>1)); |
383 | rnd = 0; |
384 | while (value > MAXFRACT2) { |
385 | rnd = value & 1; |
386 | value >>= 1; |
387 | exp++; |
388 | } |
389 | |
390 | /* |
391 | * If we need to round up, do it (and handle overflow correctly). |
392 | */ |
393 | if (rnd && (++value > MAXFRACT2)) { |
394 | value >>= 1; |
395 | exp++; |
396 | } |
397 | |
398 | if (exp > MAXEXP2) { |
399 | /* Overflow. Return largest representable number instead. */ |
400 | return (1ul << (MANTSIZE2+EXPSIZE2-1)) - 1; |
401 | } else { |
402 | return (value & (MAXFRACT2>>1)) | (exp << (MANTSIZE2-1)); |
403 | } |
404 | } |
405 | #elif ACCT_VERSION == 3 |
406 | /* |
407 | * encode an u64 into a 32 bit IEEE float |
408 | */ |
409 | static u32 encode_float(u64 value) |
410 | { |
411 | unsigned exp = 190; |
412 | unsigned u; |
413 | |
414 | if (value == 0) |
415 | return 0; |
416 | while ((s64)value > 0) { |
417 | value <<= 1; |
418 | exp--; |
419 | } |
420 | u = (u32)(value >> 40) & 0x7fffffu; |
421 | return u | (exp << 23); |
422 | } |
423 | #endif |
424 | |
425 | /* |
426 | * Write an accounting entry for an exiting process |
427 | * |
428 | * The acct_process() call is the workhorse of the process |
429 | * accounting system. The struct acct is built here and then written |
430 | * into the accounting file. This function should only be called from |
431 | * do_exit() or when switching to a different output file. |
432 | */ |
433 | |
434 | static void fill_ac(acct_t *ac) |
435 | { |
436 | struct pacct_struct *pacct = ¤t->signal->pacct; |
437 | u64 elapsed, run_time; |
438 | time64_t btime; |
439 | struct tty_struct *tty; |
440 | |
441 | /* |
442 | * Fill the accounting struct with the needed info as recorded |
443 | * by the different kernel functions. |
444 | */ |
445 | memset(ac, 0, sizeof(acct_t)); |
446 | |
447 | ac->ac_version = ACCT_VERSION | ACCT_BYTEORDER; |
448 | strscpy(p: ac->ac_comm, current->comm, size: sizeof(ac->ac_comm)); |
449 | |
450 | /* calculate run_time in nsec*/ |
451 | run_time = ktime_get_ns(); |
452 | run_time -= current->group_leader->start_time; |
453 | /* convert nsec -> AHZ */ |
454 | elapsed = nsec_to_AHZ(x: run_time); |
455 | #if ACCT_VERSION == 3 |
456 | ac->ac_etime = encode_float(value: elapsed); |
457 | #else |
458 | ac->ac_etime = encode_comp_t(elapsed < (unsigned long) -1l ? |
459 | (unsigned long) elapsed : (unsigned long) -1l); |
460 | #endif |
461 | #if ACCT_VERSION == 1 || ACCT_VERSION == 2 |
462 | { |
463 | /* new enlarged etime field */ |
464 | comp2_t etime = encode_comp2_t(elapsed); |
465 | |
466 | ac->ac_etime_hi = etime >> 16; |
467 | ac->ac_etime_lo = (u16) etime; |
468 | } |
469 | #endif |
470 | do_div(elapsed, AHZ); |
471 | btime = ktime_get_real_seconds() - elapsed; |
472 | ac->ac_btime = clamp_t(time64_t, btime, 0, U32_MAX); |
473 | #if ACCT_VERSION == 2 |
474 | ac->ac_ahz = AHZ; |
475 | #endif |
476 | |
477 | spin_lock_irq(lock: ¤t->sighand->siglock); |
478 | tty = current->signal->tty; /* Safe as we hold the siglock */ |
479 | ac->ac_tty = tty ? old_encode_dev(dev: tty_devnum(tty)) : 0; |
480 | ac->ac_utime = encode_comp_t(value: nsec_to_AHZ(x: pacct->ac_utime)); |
481 | ac->ac_stime = encode_comp_t(value: nsec_to_AHZ(x: pacct->ac_stime)); |
482 | ac->ac_flag = pacct->ac_flag; |
483 | ac->ac_mem = encode_comp_t(value: pacct->ac_mem); |
484 | ac->ac_minflt = encode_comp_t(value: pacct->ac_minflt); |
485 | ac->ac_majflt = encode_comp_t(value: pacct->ac_majflt); |
486 | ac->ac_exitcode = pacct->ac_exitcode; |
487 | spin_unlock_irq(lock: ¤t->sighand->siglock); |
488 | } |
489 | /* |
490 | * do_acct_process does all actual work. Caller holds the reference to file. |
491 | */ |
492 | static void do_acct_process(struct bsd_acct_struct *acct) |
493 | { |
494 | acct_t ac; |
495 | unsigned long flim; |
496 | const struct cred *orig_cred; |
497 | struct file *file = acct->file; |
498 | |
499 | /* |
500 | * Accounting records are not subject to resource limits. |
501 | */ |
502 | flim = rlimit(RLIMIT_FSIZE); |
503 | current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY; |
504 | /* Perform file operations on behalf of whoever enabled accounting */ |
505 | orig_cred = override_creds(file->f_cred); |
506 | |
507 | /* |
508 | * First check to see if there is enough free_space to continue |
509 | * the process accounting system. |
510 | */ |
511 | if (!check_free_space(acct)) |
512 | goto out; |
513 | |
514 | fill_ac(ac: &ac); |
515 | /* we really need to bite the bullet and change layout */ |
516 | ac.ac_uid = from_kuid_munged(to: file->f_cred->user_ns, uid: orig_cred->uid); |
517 | ac.ac_gid = from_kgid_munged(to: file->f_cred->user_ns, gid: orig_cred->gid); |
518 | #if ACCT_VERSION == 1 || ACCT_VERSION == 2 |
519 | /* backward-compatible 16 bit fields */ |
520 | ac.ac_uid16 = ac.ac_uid; |
521 | ac.ac_gid16 = ac.ac_gid; |
522 | #elif ACCT_VERSION == 3 |
523 | { |
524 | struct pid_namespace *ns = acct->ns; |
525 | |
526 | ac.ac_pid = task_tgid_nr_ns(current, ns); |
527 | rcu_read_lock(); |
528 | ac.ac_ppid = task_tgid_nr_ns(rcu_dereference(current->real_parent), |
529 | ns); |
530 | rcu_read_unlock(); |
531 | } |
532 | #endif |
533 | /* |
534 | * Get freeze protection. If the fs is frozen, just skip the write |
535 | * as we could deadlock the system otherwise. |
536 | */ |
537 | if (file_start_write_trylock(file)) { |
538 | /* it's been opened O_APPEND, so position is irrelevant */ |
539 | loff_t pos = 0; |
540 | __kernel_write(file, &ac, sizeof(acct_t), &pos); |
541 | file_end_write(file); |
542 | } |
543 | out: |
544 | current->signal->rlim[RLIMIT_FSIZE].rlim_cur = flim; |
545 | revert_creds(orig_cred); |
546 | } |
547 | |
548 | /** |
549 | * acct_collect - collect accounting information into pacct_struct |
550 | * @exitcode: task exit code |
551 | * @group_dead: not 0, if this thread is the last one in the process. |
552 | */ |
553 | void acct_collect(long exitcode, int group_dead) |
554 | { |
555 | struct pacct_struct *pacct = ¤t->signal->pacct; |
556 | u64 utime, stime; |
557 | unsigned long vsize = 0; |
558 | |
559 | if (group_dead && current->mm) { |
560 | struct mm_struct *mm = current->mm; |
561 | VMA_ITERATOR(vmi, mm, 0); |
562 | struct vm_area_struct *vma; |
563 | |
564 | mmap_read_lock(mm); |
565 | for_each_vma(vmi, vma) |
566 | vsize += vma->vm_end - vma->vm_start; |
567 | mmap_read_unlock(mm); |
568 | } |
569 | |
570 | spin_lock_irq(lock: ¤t->sighand->siglock); |
571 | if (group_dead) |
572 | pacct->ac_mem = vsize / 1024; |
573 | if (thread_group_leader(current)) { |
574 | pacct->ac_exitcode = exitcode; |
575 | if (current->flags & PF_FORKNOEXEC) |
576 | pacct->ac_flag |= AFORK; |
577 | } |
578 | if (current->flags & PF_SUPERPRIV) |
579 | pacct->ac_flag |= ASU; |
580 | if (current->flags & PF_DUMPCORE) |
581 | pacct->ac_flag |= ACORE; |
582 | if (current->flags & PF_SIGNALED) |
583 | pacct->ac_flag |= AXSIG; |
584 | |
585 | task_cputime(current, utime: &utime, stime: &stime); |
586 | pacct->ac_utime += utime; |
587 | pacct->ac_stime += stime; |
588 | pacct->ac_minflt += current->min_flt; |
589 | pacct->ac_majflt += current->maj_flt; |
590 | spin_unlock_irq(lock: ¤t->sighand->siglock); |
591 | } |
592 | |
593 | static void slow_acct_process(struct pid_namespace *ns) |
594 | { |
595 | for ( ; ns; ns = ns->parent) { |
596 | struct bsd_acct_struct *acct = acct_get(ns); |
597 | if (acct) { |
598 | do_acct_process(acct); |
599 | mutex_unlock(lock: &acct->lock); |
600 | acct_put(p: acct); |
601 | } |
602 | } |
603 | } |
604 | |
605 | /** |
606 | * acct_process - handles process accounting for an exiting task |
607 | */ |
608 | void acct_process(void) |
609 | { |
610 | struct pid_namespace *ns; |
611 | |
612 | /* |
613 | * This loop is safe lockless, since current is still |
614 | * alive and holds its namespace, which in turn holds |
615 | * its parent. |
616 | */ |
617 | for (ns = task_active_pid_ns(current); ns != NULL; ns = ns->parent) { |
618 | if (ns->bacct) |
619 | break; |
620 | } |
621 | if (unlikely(ns)) |
622 | slow_acct_process(ns); |
623 | } |
624 | |