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.
46 #include <linux/config.h>
47 #include <linux/errno.h>
48 #include <linux/kernel.h>
50 #ifdef CONFIG_BSD_PROCESS_ACCT
52 #include <linux/slab.h>
53 #include <linux/acct.h>
54 #include <linux/smp_lock.h>
55 #include <linux/file.h>
56 #include <linux/tty.h>
58 #include <asm/uaccess.h>
61 * These constants control the amount of freespace that suspend and
62 * resume the process accounting system, and the time delay between
64 * Turned into sysctl-controllable parameters. AV, 12/11/98
67 int acct_parm[3] = {4, 2, 30};
68 #define RESUME (acct_parm[0]) /* >foo% free space - resume */
69 #define SUSPEND (acct_parm[1]) /* <foo% free space - suspend */
70 #define ACCT_TIMEOUT (acct_parm[2]) /* foo second timeout between checks */
73 * External references and all of the globals.
76 static volatile int acct_active;
77 static volatile int acct_needcheck;
78 static struct file *acct_file;
79 static struct timer_list acct_timer;
80 static void do_acct_process(long, struct file *);
83 * Called whenever the timer says to check the free space.
85 static void acct_timeout(unsigned long unused)
91 * Check the amount of free space and suspend/resume accordingly.
93 static int check_free_space(struct file *file)
101 if (!file || !acct_needcheck)
106 if (vfs_statfs(file->f_dentry->d_inode->i_sb, &sbuf))
109 if (sbuf.f_bavail <= SUSPEND * sbuf.f_blocks / 100)
111 else if (sbuf.f_bavail >= RESUME * sbuf.f_blocks / 100)
117 * If some joker switched acct_file under us we'ld better be
118 * silent and _not_ touch anything.
121 if (file != acct_file) {
130 printk(KERN_INFO "Process accounting paused\n");
135 printk(KERN_INFO "Process accounting resumed\n");
139 del_timer(&acct_timer);
141 acct_timer.expires = jiffies + ACCT_TIMEOUT*HZ;
142 add_timer(&acct_timer);
150 * sys_acct() is the only system call needed to implement process
151 * accounting. It takes the name of the file where accounting records
152 * should be written. If the filename is NULL, accounting will be
155 asmlinkage long sys_acct(const char *name)
157 struct file *file = NULL, *old_acct = NULL;
161 if (!capable(CAP_SYS_PACCT))
166 error = PTR_ERR(tmp);
169 /* Difference from BSD - they don't do O_APPEND */
170 file = filp_open(tmp, O_WRONLY|O_APPEND, 0);
173 error = PTR_ERR(file);
177 if (!S_ISREG(file->f_dentry->d_inode->i_mode))
181 if (!file->f_op->write)
188 old_acct = acct_file;
189 del_timer(&acct_timer);
198 /* It's been deleted if it was used before so this is safe */
199 init_timer(&acct_timer);
200 acct_timer.function = acct_timeout;
201 acct_timer.expires = jiffies + ACCT_TIMEOUT*HZ;
202 add_timer(&acct_timer);
206 do_acct_process(0,old_acct);
207 filp_close(old_acct, NULL);
212 filp_close(file, NULL);
216 void acct_auto_close(kdev_t dev)
219 if (acct_file && acct_file->f_dentry->d_inode->i_dev == dev)
225 * encode an unsigned long into a comp_t
227 * This routine has been adopted from the encode_comp_t() function in
228 * the kern_acct.c file of the FreeBSD operating system. The encoding
229 * is a 13-bit fraction with a 3-bit (base 8) exponent.
232 #define MANTSIZE 13 /* 13 bit mantissa. */
233 #define EXPSIZE 3 /* Base 8 (3 bit) exponent. */
234 #define MAXFRACT ((1 << MANTSIZE) - 1) /* Maximum fractional value. */
236 static comp_t encode_comp_t(unsigned long value)
241 while (value > MAXFRACT) {
242 rnd = value & (1 << (EXPSIZE - 1)); /* Round up? */
243 value >>= EXPSIZE; /* Base 8 exponent == 3 bit shift. */
248 * If we need to round up, do it (and handle overflow correctly).
250 if (rnd && (++value > MAXFRACT)) {
256 * Clean it up and polish it off.
258 exp <<= MANTSIZE; /* Shift the exponent into place */
259 exp += value; /* and add on the mantissa. */
264 * Write an accounting entry for an exiting process
266 * The acct_process() call is the workhorse of the process
267 * accounting system. The struct acct is built here and then written
268 * into the accounting file. This function should only be called from
273 * do_acct_process does all actual work. Caller holds the reference to file.
275 static void do_acct_process(long exitcode, struct file *file)
283 * First check to see if there is enough free_space to continue
284 * the process accounting system.
286 if (!check_free_space(file))
290 * Fill the accounting struct with the needed info as recorded
291 * by the different kernel functions.
293 memset((caddr_t)&ac, 0, sizeof(struct acct));
295 strncpy(ac.ac_comm, current->comm, ACCT_COMM);
296 ac.ac_comm[ACCT_COMM - 1] = '\0';
298 ac.ac_btime = CT_TO_SECS(current->start_time) + (xtime.tv_sec - (jiffies / HZ));
299 ac.ac_etime = encode_comp_t(jiffies - current->start_time);
300 ac.ac_utime = encode_comp_t(current->times.tms_utime);
301 ac.ac_stime = encode_comp_t(current->times.tms_stime);
302 ac.ac_uid = current->uid;
303 ac.ac_gid = current->gid;
304 ac.ac_tty = (current->tty) ? kdev_t_to_nr(current->tty->device) : 0;
307 if (current->flags & PF_FORKNOEXEC)
309 if (current->flags & PF_SUPERPRIV)
311 if (current->flags & PF_DUMPCORE)
313 if (current->flags & PF_SIGNALED)
318 struct vm_area_struct *vma;
319 down_read(¤t->mm->mmap_sem);
320 vma = current->mm->mmap;
322 vsize += vma->vm_end - vma->vm_start;
325 up_read(¤t->mm->mmap_sem);
327 vsize = vsize / 1024;
328 ac.ac_mem = encode_comp_t(vsize);
329 ac.ac_io = encode_comp_t(0 /* current->io_usage */); /* %% */
330 ac.ac_rw = encode_comp_t(ac.ac_io / 1024);
331 ac.ac_minflt = encode_comp_t(current->min_flt);
332 ac.ac_majflt = encode_comp_t(current->maj_flt);
333 ac.ac_swaps = encode_comp_t(current->nswap);
334 ac.ac_exitcode = exitcode;
337 * Kernel segment override to datasegment and write it
338 * to the accounting file.
343 * Accounting records are not subject to resource limits.
345 flim = current->rlim[RLIMIT_FSIZE].rlim_cur;
346 current->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
347 file->f_op->write(file, (char *)&ac,
348 sizeof(struct acct), &file->f_pos);
349 current->rlim[RLIMIT_FSIZE].rlim_cur = flim;
354 * acct_process - now just a wrapper around do_acct_process
356 int acct_process(long exitcode)
358 struct file *file = NULL;
364 do_acct_process(exitcode, file);
373 * Dummy system call when BSD process accounting is not configured
377 asmlinkage long sys_acct(const char * filename)