~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/kernel/time/itimer.c

Version: ~ [ linux-5.14-rc1 ] ~ [ linux-5.13.1 ] ~ [ linux-5.12.16 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.49 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.131 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.197 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.239 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.275 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.275 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /*
  2  * linux/kernel/itimer.c
  3  *
  4  * Copyright (C) 1992 Darren Senn
  5  */
  6 
  7 /* These are all the functions necessary to implement itimers */
  8 
  9 #include <linux/mm.h>
 10 #include <linux/interrupt.h>
 11 #include <linux/syscalls.h>
 12 #include <linux/time.h>
 13 #include <linux/posix-timers.h>
 14 #include <linux/hrtimer.h>
 15 #include <trace/events/timer.h>
 16 
 17 #include <asm/uaccess.h>
 18 
 19 /**
 20  * itimer_get_remtime - get remaining time for the timer
 21  *
 22  * @timer: the timer to read
 23  *
 24  * Returns the delta between the expiry time and now, which can be
 25  * less than zero or 1usec for an pending expired timer
 26  */
 27 static struct timeval itimer_get_remtime(struct hrtimer *timer)
 28 {
 29         ktime_t rem = __hrtimer_get_remaining(timer, true);
 30 
 31         /*
 32          * Racy but safe: if the itimer expires after the above
 33          * hrtimer_get_remtime() call but before this condition
 34          * then we return 0 - which is correct.
 35          */
 36         if (hrtimer_active(timer)) {
 37                 if (rem.tv64 <= 0)
 38                         rem.tv64 = NSEC_PER_USEC;
 39         } else
 40                 rem.tv64 = 0;
 41 
 42         return ktime_to_timeval(rem);
 43 }
 44 
 45 static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
 46                            struct itimerval *const value)
 47 {
 48         cputime_t cval, cinterval;
 49         struct cpu_itimer *it = &tsk->signal->it[clock_id];
 50 
 51         spin_lock_irq(&tsk->sighand->siglock);
 52 
 53         cval = it->expires;
 54         cinterval = it->incr;
 55         if (cval) {
 56                 struct task_cputime cputime;
 57                 cputime_t t;
 58 
 59                 thread_group_cputimer(tsk, &cputime);
 60                 if (clock_id == CPUCLOCK_PROF)
 61                         t = cputime.utime + cputime.stime;
 62                 else
 63                         /* CPUCLOCK_VIRT */
 64                         t = cputime.utime;
 65 
 66                 if (cval < t)
 67                         /* about to fire */
 68                         cval = cputime_one_jiffy;
 69                 else
 70                         cval = cval - t;
 71         }
 72 
 73         spin_unlock_irq(&tsk->sighand->siglock);
 74 
 75         cputime_to_timeval(cval, &value->it_value);
 76         cputime_to_timeval(cinterval, &value->it_interval);
 77 }
 78 
 79 int do_getitimer(int which, struct itimerval *value)
 80 {
 81         struct task_struct *tsk = current;
 82 
 83         switch (which) {
 84         case ITIMER_REAL:
 85                 spin_lock_irq(&tsk->sighand->siglock);
 86                 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
 87                 value->it_interval =
 88                         ktime_to_timeval(tsk->signal->it_real_incr);
 89                 spin_unlock_irq(&tsk->sighand->siglock);
 90                 break;
 91         case ITIMER_VIRTUAL:
 92                 get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
 93                 break;
 94         case ITIMER_PROF:
 95                 get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
 96                 break;
 97         default:
 98                 return(-EINVAL);
 99         }
100         return 0;
101 }
102 
103 SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
104 {
105         int error = -EFAULT;
106         struct itimerval get_buffer;
107 
108         if (value) {
109                 error = do_getitimer(which, &get_buffer);
110                 if (!error &&
111                     copy_to_user(value, &get_buffer, sizeof(get_buffer)))
112                         error = -EFAULT;
113         }
114         return error;
115 }
116 
117 
118 /*
119  * The timer is automagically restarted, when interval != 0
120  */
121 enum hrtimer_restart it_real_fn(struct hrtimer *timer)
122 {
123         struct signal_struct *sig =
124                 container_of(timer, struct signal_struct, real_timer);
125 
126         trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0);
127         kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
128 
129         return HRTIMER_NORESTART;
130 }
131 
132 static inline u32 cputime_sub_ns(cputime_t ct, s64 real_ns)
133 {
134         struct timespec ts;
135         s64 cpu_ns;
136 
137         cputime_to_timespec(ct, &ts);
138         cpu_ns = timespec_to_ns(&ts);
139 
140         return (cpu_ns <= real_ns) ? 0 : cpu_ns - real_ns;
141 }
142 
143 static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
144                            const struct itimerval *const value,
145                            struct itimerval *const ovalue)
146 {
147         cputime_t cval, nval, cinterval, ninterval;
148         s64 ns_ninterval, ns_nval;
149         u32 error, incr_error;
150         struct cpu_itimer *it = &tsk->signal->it[clock_id];
151 
152         nval = timeval_to_cputime(&value->it_value);
153         ns_nval = timeval_to_ns(&value->it_value);
154         ninterval = timeval_to_cputime(&value->it_interval);
155         ns_ninterval = timeval_to_ns(&value->it_interval);
156 
157         error = cputime_sub_ns(nval, ns_nval);
158         incr_error = cputime_sub_ns(ninterval, ns_ninterval);
159 
160         spin_lock_irq(&tsk->sighand->siglock);
161 
162         cval = it->expires;
163         cinterval = it->incr;
164         if (cval || nval) {
165                 if (nval > 0)
166                         nval += cputime_one_jiffy;
167                 set_process_cpu_timer(tsk, clock_id, &nval, &cval);
168         }
169         it->expires = nval;
170         it->incr = ninterval;
171         it->error = error;
172         it->incr_error = incr_error;
173         trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
174                            ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
175 
176         spin_unlock_irq(&tsk->sighand->siglock);
177 
178         if (ovalue) {
179                 cputime_to_timeval(cval, &ovalue->it_value);
180                 cputime_to_timeval(cinterval, &ovalue->it_interval);
181         }
182 }
183 
184 /*
185  * Returns true if the timeval is in canonical form
186  */
187 #define timeval_valid(t) \
188         (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
189 
190 int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
191 {
192         struct task_struct *tsk = current;
193         struct hrtimer *timer;
194         ktime_t expires;
195 
196         /*
197          * Validate the timevals in value.
198          */
199         if (!timeval_valid(&value->it_value) ||
200             !timeval_valid(&value->it_interval))
201                 return -EINVAL;
202 
203         switch (which) {
204         case ITIMER_REAL:
205 again:
206                 spin_lock_irq(&tsk->sighand->siglock);
207                 timer = &tsk->signal->real_timer;
208                 if (ovalue) {
209                         ovalue->it_value = itimer_get_remtime(timer);
210                         ovalue->it_interval
211                                 = ktime_to_timeval(tsk->signal->it_real_incr);
212                 }
213                 /* We are sharing ->siglock with it_real_fn() */
214                 if (hrtimer_try_to_cancel(timer) < 0) {
215                         spin_unlock_irq(&tsk->sighand->siglock);
216                         goto again;
217                 }
218                 expires = timeval_to_ktime(value->it_value);
219                 if (expires.tv64 != 0) {
220                         tsk->signal->it_real_incr =
221                                 timeval_to_ktime(value->it_interval);
222                         hrtimer_start(timer, expires, HRTIMER_MODE_REL);
223                 } else
224                         tsk->signal->it_real_incr.tv64 = 0;
225 
226                 trace_itimer_state(ITIMER_REAL, value, 0);
227                 spin_unlock_irq(&tsk->sighand->siglock);
228                 break;
229         case ITIMER_VIRTUAL:
230                 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
231                 break;
232         case ITIMER_PROF:
233                 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
234                 break;
235         default:
236                 return -EINVAL;
237         }
238         return 0;
239 }
240 
241 /**
242  * alarm_setitimer - set alarm in seconds
243  *
244  * @seconds:    number of seconds until alarm
245  *              0 disables the alarm
246  *
247  * Returns the remaining time in seconds of a pending timer or 0 when
248  * the timer is not active.
249  *
250  * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
251  * negative timeval settings which would cause immediate expiry.
252  */
253 unsigned int alarm_setitimer(unsigned int seconds)
254 {
255         struct itimerval it_new, it_old;
256 
257 #if BITS_PER_LONG < 64
258         if (seconds > INT_MAX)
259                 seconds = INT_MAX;
260 #endif
261         it_new.it_value.tv_sec = seconds;
262         it_new.it_value.tv_usec = 0;
263         it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
264 
265         do_setitimer(ITIMER_REAL, &it_new, &it_old);
266 
267         /*
268          * We can't return 0 if we have an alarm pending ...  And we'd
269          * better return too much than too little anyway
270          */
271         if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
272               it_old.it_value.tv_usec >= 500000)
273                 it_old.it_value.tv_sec++;
274 
275         return it_old.it_value.tv_sec;
276 }
277 
278 SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
279                 struct itimerval __user *, ovalue)
280 {
281         struct itimerval set_buffer, get_buffer;
282         int error;
283 
284         if (value) {
285                 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
286                         return -EFAULT;
287         } else {
288                 memset(&set_buffer, 0, sizeof(set_buffer));
289                 printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
290                             " Misfeature support will be removed\n",
291                             current->comm);
292         }
293 
294         error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
295         if (error || !ovalue)
296                 return error;
297 
298         if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
299                 return -EFAULT;
300         return 0;
301 }
302 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp