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