/* * linux/kernel/posix_timers.c * * * 2002-10-15 Posix Clocks & timers * by George Anzinger george@mvista.com * * Copyright (C) 2002 2003 by MontaVista Software. * * 2004-06-01 Fix CLOCK_REALTIME clock/timer TIMER_ABSTIME bug. * Copyright (C) 2004 Boris Hu * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or (at * your option) any later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * * MontaVista Software | 1237 East Arques Avenue | Sunnyvale | CA 94085 | USA */ /* These are all the functions necessary to implement * POSIX clocks & timers */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifndef div_long_long_rem #include #define div_long_long_rem(dividend,divisor,remainder) ({ \ u64 result = dividend; \ *remainder = do_div(result,divisor); \ result; }) #endif #define CLOCK_REALTIME_RES TICK_NSEC /* In nano seconds. */ static inline u64 mpy_l_X_l_ll(unsigned long mpy1,unsigned long mpy2) { return (u64)mpy1 * mpy2; } /* * Management arrays for POSIX timers. Timers are kept in slab memory * Timer ids are allocated by an external routine that keeps track of the * id and the timer. The external interface is: * * void *idr_find(struct idr *idp, int id); to find timer_id * int idr_get_new(struct idr *idp, void *ptr); to get a new id and * related it to * void idr_remove(struct idr *idp, int id); to release * void idr_init(struct idr *idp); to initialize * which we supply. * The idr_get_new *may* call slab for more memory so it must not be * called under a spin lock. Likewise idr_remore may release memory * (but it may be ok to do this under a lock...). * idr_find is just a memory look up and is quite fast. A -1 return * indicates that the requested id does not exist. */ /* * Lets keep our timers in a slab cache :-) */ static kmem_cache_t *posix_timers_cache; static struct idr posix_timers_id; static DEFINE_SPINLOCK(idr_lock); /* * we assume that the new SIGEV_THREAD_ID shares no bits with the other * SIGEV values. Here we put out an error if this assumption fails. */ #if SIGEV_THREAD_ID != (SIGEV_THREAD_ID & \ ~(SIGEV_SIGNAL | SIGEV_NONE | SIGEV_THREAD)) #error "SIGEV_THREAD_ID must not share bit with other SIGEV values!" #endif /* * The timer ID is turned into a timer address by idr_find(). * Verifying a valid ID consists of: * * a) checking that idr_find() returns other than -1. * b) checking that the timer id matches the one in the timer itself. * c) that the timer owner is in the callers thread group. */ /* * CLOCKs: The POSIX standard calls for a couple of clocks and allows us * to implement others. This structure defines the various * clocks and allows the possibility of adding others. We * provide an interface to add clocks to the table and expect * the "arch" code to add at least one clock that is high * resolution. Here we define the standard CLOCK_REALTIME as a * 1/HZ resolution clock. * * RESOLUTION: Clock resolution is used to round up timer and interval * times, NOT to report clock times, which are reported with as * much resolution as the system can muster. In some cases this * resolution may depend on the underlying clock hardware and * may not be quantifiable until run time, and only then is the * necessary code is written. The standard says we should say * something about this issue in the documentation... * * FUNCTIONS: The CLOCKs structure defines possible functions to handle * various clock functions. For clocks that use the standard * system timer code these entries should be NULL. This will * allow dispatch without the overhead of indirect function * calls. CLOCKS that depend on other sources (e.g. WWV or GPS) * must supply functions here, even if the function just returns * ENOSYS. The standard POSIX timer management code assumes the * following: 1.) The k_itimer struct (sched.h) is used for the * timer. 2.) The list, it_lock, it_clock, it_id and it_process * fields are not modified by timer code. * * At this time all functions EXCEPT clock_nanosleep can be * redirected by the CLOCKS structure. Clock_nanosleep is in * there, but the code ignores it. * * Permissions: It is assumed that the clock_settime() function defined * for each clock will take care of permission checks. Some * clocks may be set able by any user (i.e. local process * clocks) others not. Currently the only set able clock we * have is CLOCK_REALTIME and its high res counter part, both of * which we beg off on and pass to do_sys_settimeofday(). */ static struct k_clock posix_clocks[MAX_CLOCKS]; /* * We only have one real clock that can be set so we need only one abs list, * even if we should want to have several clocks with differing resolutions. */ static struct k_clock_abs abs_list = {.list = LIST_HEAD_INIT(abs_list.list), .lock = SPIN_LOCK_UNLOCKED}; static void posix_timer_fn(unsigned long); static u64 do_posix_clock_monotonic_gettime_parts( struct timespec *tp, struct timespec *mo); int do_posix_clock_monotonic_gettime(struct timespec *tp); static int do_posix_clock_monotonic_get(clockid_t, struct timespec *tp); static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags); static inline void unlock_timer(struct k_itimer *timr, unsigned long flags) { spin_unlock_irqrestore(&timr->it_lock, flags); } /* * Call the k_clock hook function if non-null, or the default function. */ #define CLOCK_DISPATCH(clock, call, arglist) \ ((clock) < 0 ? posix_cpu_##call arglist : \ (posix_clocks[clock].call != NULL \ ? (*posix_clocks[clock].call) arglist : common_##call arglist)) /* * Default clock hook functions when the struct k_clock passed * to register_posix_clock leaves a function pointer null. * * The function common_CALL is the default implementation for * the function pointer CALL in struct k_clock. */ static inline int common_clock_getres(clockid_t which_clock, struct timespec *tp) { tp->tv_sec = 0; tp->tv_nsec = posix_clocks[which_clock].res; return 0; } static inline int common_clock_get(clockid_t which_clock, struct timespec *tp) { getnstimeofday(tp); return 0; } static inline int common_clock_set(clockid_t which_clock, struct timespec *tp) { return do_sys_settimeofday(tp, NULL); } static inline int common_timer_create(struct k_itimer *new_timer) { INIT_LIST_HEAD(&new_timer->it.real.abs_timer_entry); init_timer(&new_timer->it.real.timer); new_timer->it.real.timer.data = (unsigned long) new_timer; new_timer->it.real.timer.function = posix_timer_fn; return 0; } /* * These ones are defined below. */ static int common_nsleep(clockid_t, int flags, struct timespec *t); static void common_timer_get(struct k_itimer *, struct itimerspec *); static int common_timer_set(struct k_itimer *, int, struct itimerspec *, struct itimerspec *); static int common_timer_del(struct k_itimer *timer); /* * Return nonzero iff we know a priori this clockid_t value is bogus. */ static inline int invalid_clockid(clockid_t which_clock) { if (which_clock < 0) /* CPU clock, posix_cpu_* will check it */ return 0; if ((unsigned) which_clock >= MAX_CLOCKS) return 1; if (posix_clocks[which_clock].clock_getres != NULL) return 0; #ifndef CLOCK_DISPATCH_DIRECT if (posix_clocks[which_clock].res != 0) return 0; #endif return 1; } /* * Initialize everything, well, just everything in Posix clocks/timers ;) */ static __init int init_posix_timers(void) { struct k_clock clock_realtime = {.res = CLOCK_REALTIME_RES, .abs_struct = &abs_list }; struct k_clock clock_monotonic = {.res = CLOCK_REALTIME_RES, .abs_struct = NULL, .clock_get = do_posix_clock_monotonic_get, .clock_set = do_posix_clock_nosettime }; register_posix_clock(CLOCK_REALTIME, &clock_realtime); register_posix_clock(CLOCK_MONOTONIC, &clock_monotonic); posix_timers_cache = kmem_cache_create("posix_timers_cache", sizeof (struct k_itimer), 0, 0, NULL, NULL); idr_init(&posix_timers_id); return 0; } __initcall(init_posix_timers); static void tstojiffie(struct timespec *tp, int res, u64 *jiff) { long sec = tp->tv_sec; long nsec = tp->tv_nsec + res - 1; if (nsec > NSEC_PER_SEC) { sec++; nsec -= NSEC_PER_SEC; } /* * The scaling constants are defined in * The difference between there and here is that we do the * res rounding and compute a 64-bit result (well so does that * but it then throws away the high bits). */ *jiff = (mpy_l_X_l_ll(sec, SEC_CONVERSION) + (mpy_l_X_l_ll(nsec, NSEC_CONVERSION) >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC; } /* * This function adjusts the timer as needed as a result of the clock * being set. It should only be called for absolute timers, and then * under the abs_list lock. It computes the time difference and sets * the new jiffies value in the timer. It also updates the timers * reference wall_to_monotonic value. It is complicated by the fact * that tstojiffies() only handles positive times and it needs to work * with both positive and negative times. Also, for negative offsets, * we need to defeat the res round up. * * Return is true if there is a new time, else false. */ static long add_clockset_delta(struct k_itimer *timr, struct timespec *new_wall_to) { struct timespec delta; int sign = 0; u64 exp; set_normalized_timespec(&delta, new_wall_to->tv_sec - timr->it.real.wall_to_prev.tv_sec, new_wall_to->tv_nsec - timr->it.real.wall_to_prev.tv_nsec); if (likely(!(delta.tv_sec | delta.tv_nsec))) return 0; if (delta.tv_sec < 0) { set_normalized_timespec(&delta, -delta.tv_sec, 1 - delta.tv_nsec - posix_clocks[timr->it_clock].res); sign++; } tstojiffie(&delta, posix_clocks[timr->it_clock].res, &exp); timr->it.real.wall_to_prev = *new_wall_to; timr->it.real.timer.expires += (sign ? -exp : exp); return 1; } static void remove_from_abslist(struct k_itimer *timr) { if (!list_empty(&timr->it.real.abs_timer_entry)) { spin_lock(&abs_list.lock); list_del_init(&timr->it.real.abs_timer_entry); spin_unlock(&abs_list.lock); } } static void schedule_next_timer(struct k_itimer *timr) { struct timespec new_wall_to; struct now_struct now; unsigned long seq; /* * Set up the timer for the next interval (if there is one). * Note: this code uses the abs_timer_lock to protect * it.real.wall_to_prev and must hold it until exp is set, not exactly * obvious... * This function is used for CLOCK_REALTIME* and * CLOCK_MONOTONIC* timers. If we ever want to handle other * CLOCKs, the calling code (do_schedule_next_timer) would need * to pull the "clock" info from the timer and dispatch the * "other" CLOCKs "next timer" code (which, I suppose should * also be added to the k_clock structure). */ if (!timr->it.real.incr) return; do { seq = read_seqbegin(&xtime_lock); new_wall_to = wall_to_monotonic; posix_get_now(&now); } while (read_seqretry(&xtime_lock, seq)); if (!list_empty(&timr->it.real.abs_timer_entry)) { spin_lock(&abs_list.lock); add_clockset_delta(timr, &new_wall_to); posix_bump_timer(timr, now); spin_unlock(&abs_list.lock); } else { posix_bump_timer(timr, now); } timr->it_overrun_last = timr->it_overrun; timr->it_overrun = -1; ++timr->it_requeue_pending; add_timer(&timr->it.real.timer); } /* * This function is exported for use by the signal deliver code. It is * called just prior to the info block being released and passes that * block to us. It's function is to update the overrun entry AND to * restart the timer. It should only be called if the timer is to be * restarted (i.e. we have flagged this in the sys_private entry of the * info block). * * To protect aginst the timer going away while the interrupt is queued, * we require that the it_requeue_pending flag be set. */ void do_schedule_next_timer(struct siginfo *info) { struct k_itimer *timr; unsigned long flags; timr = lock_timer(info->si_tid, &flags); if (!timr || timr->it_requeue_pending != info->si_sys_private) goto exit; if (timr->it_clock < 0) /* CPU clock */ posix_cpu_timer_schedule(timr); else schedule_next_timer(timr); info->si_overrun = timr->it_overrun_last; exit: if (timr) unlock_timer(timr, flags); } int posix_timer_event(struct k_itimer *timr,int si_private) { memset(&timr->sigq->info, 0, sizeof(siginfo_t)); timr->sigq->info.si_sys_private = si_private; /* * Send signal to the process that owns this timer. * This code assumes that all the possible abs_lists share the * same lock (there is only one list at this time). If this is * not the case, the CLOCK info would need to be used to find * the proper abs list lock. */ timr->sigq->info.si_signo = timr->it_sigev_signo; timr->sigq->info.si_errno = 0; timr->sigq->info.si_code = SI_TIMER; timr->sigq->info.si_tid = timr->it_id; timr->sigq->info.si_value = timr->it_sigev_value; if (timr->it_sigev_notify & SIGEV_THREAD_ID) { if (unlikely(timr->it_process->flags & PF_EXITING)) { timr->it_sigev_notify = SIGEV_SIGNAL; put_task_struct(timr->it_process); timr->it_process = timr->it_process->group_leader; goto group; } return send_sigqueue(timr->it_sigev_signo, timr->sigq, timr->it_process); } else { group: return send_group_sigqueue(timr->it_sigev_signo, timr->sigq, timr->it_process); } } EXPORT_SYMBOL_GPL(posix_timer_event); /* * This function gets called when a POSIX.1b interval timer expires. It * is used as a callback from the kernel internal timer. The * run_timer_list code ALWAYS calls with interrupts on. * This code is for CLOCK_REALTIME* and CLOCK_MONOTONIC* timers. */ static void posix_timer_fn(unsigned long __data) { struct k_itimer *timr = (struct k_itimer *) __data; unsigned long flags; unsigned long seq; struct timespec delta, new_wall_to; u64 exp = 0; int do_notify = 1; spin_lock_irqsave(&timr->it_lock, flags); if (!list_empty(&timr->it.real.abs_timer_entry)) { spin_lock(&abs_list.lock); do { seq = read_seqbegin(&xtime_lock); new_wall_to = wall_to_monotonic; } while (read_seqretry(&xtime_lock, seq)); set_normalized_timespec(&delta, new_wall_to.tv_sec - timr->it.real.wall_to_prev.tv_sec, new_wall_to.tv_nsec - timr->it.real.wall_to_prev.tv_nsec); if (likely((delta.tv_sec | delta.tv_nsec ) == 0)) { /* do nothing, timer is on time */ } else if (delta.tv_sec < 0) { /* do nothing, timer is already late */ } else { /* timer is early due to a clock set */ tstojiffie(&delta, posix_clocks[timr->it_clock].res, &exp); timr->it.real.wall_to_prev = new_wall_to; timr->it.real.timer.expires += exp; add_timer(&timr->it.real.timer); do_notify = 0; } spin_unlock(&abs_list.lock); } if (do_notify) { int si_private=0; if (timr->it.real.incr) si_private = ++timr->it_requeue_pending; else { remove_from_abslist(timr); } if (posix_timer_event(timr, si_private)) /* * signal was not sent because of sig_ignor * we will not get a call back to restart it AND * it should be restarted. */ schedule_next_timer(timr); } unlock_timer(timr, flags); /* hold thru abs lock to keep irq off */ } static inline struct task_struct * good_sigevent(sigevent_t * event) { struct task_struct *rtn = current->group_leader; if ((event->sigev_notify & SIGEV_THREAD_ID ) && (!(rtn = find_task_by_pid(event->sigev_notify_thread_id)) || rtn->tgid != current->tgid || (event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_SIGNAL)) return NULL; if (((event->sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE) && ((event->sigev_signo <= 0) || (event->sigev_signo > SIGRTMAX))) return NULL; return rtn; } void register_posix_clock(clockid_t clock_id, struct k_clock *new_clock) { if ((unsigned) clock_id >= MAX_CLOCKS) { printk("POSIX clock register failed for clock_id %d\n", clock_id); return; } posix_clocks[clock_id] = *new_clock; } EXPORT_SYMBOL_GPL(register_posix_clock); static struct k_itimer * alloc_posix_timer(void) { struct k_itimer *tmr; tmr = kmem_cache_alloc(posix_timers_cache, GFP_KERNEL); if (!tmr) return tmr; memset(tmr, 0, sizeof (struct k_itimer)); if (unlikely(!(tmr->sigq = sigqueue_alloc()))) { kmem_cache_free(posix_timers_cache, tmr); tmr = NULL; } return tmr; } #define IT_ID_SET 1 #define IT_ID_NOT_SET 0 static void release_posix_timer(struct k_itimer *tmr, int it_id_set) { if (it_id_set) { unsigned long flags; spin_lock_irqsave(&idr_lock, flags); idr_remove(&posix_timers_id, tmr->it_id); spin_unlock_irqrestore(&idr_lock, flags); } sigqueue_free(tmr->sigq); if (unlikely(tmr->it_process) && tmr->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID)) put_task_struct(tmr->it_process); kmem_cache_free(posix_timers_cache, tmr); } /* Create a POSIX.1b interval timer. */ asmlinkage long sys_timer_create(clockid_t which_clock, struct sigevent __user *timer_event_spec, timer_t __user * created_timer_id) { int error = 0; struct k_itimer *new_timer = NULL; int new_timer_id; struct task_struct *process = NULL; unsigned long flags; sigevent_t event; int it_id_set = IT_ID_NOT_SET; if (invalid_clockid(which_clock)) return -EINVAL; new_timer = alloc_posix_timer(); if (unlikely(!new_timer)) return -EAGAIN; spin_lock_init(&new_timer->it_lock); retry: if (unlikely(!idr_pre_get(&posix_timers_id, GFP_KERNEL))) { error = -EAGAIN; goto out; } spin_lock_irq(&idr_lock); error = idr_get_new(&posix_timers_id, (void *) new_timer, &new_timer_id); spin_unlock_irq(&idr_lock); if (error == -EAGAIN) goto retry; else if (error) { /* * Wierd looking, but we return EAGAIN if the IDR is * full (proper POSIX return value for this) */ error = -EAGAIN; goto out; } it_id_set = IT_ID_SET; new_timer->it_id = (timer_t) new_timer_id; new_timer->it_clock = which_clock; new_timer->it_overrun = -1; error = CLOCK_DISPATCH(which_clock, timer_create, (new_timer)); if (error) goto out; /* * return the timer_id now. The next step is hard to * back out if there is an error. */ if (copy_to_user(created_timer_id, &new_timer_id, sizeof (new_timer_id))) { error = -EFAULT; goto out; } if (timer_event_spec) { if (copy_from_user(&event, timer_event_spec, sizeof (event))) { error = -EFAULT; goto out; } new_timer->it_sigev_notify = event.sigev_notify; new_timer->it_sigev_signo = event.sigev_signo; new_timer->it_sigev_value = event.sigev_value; read_lock(&tasklist_lock); if ((process = good_sigevent(&event))) { /* * We may be setting up this process for another * thread. It may be exiting. To catch this * case the we check the PF_EXITING flag. If * the flag is not set, the siglock will catch * him before it is too late (in exit_itimers). * * The exec case is a bit more invloved but easy * to code. If the process is in our thread * group (and it must be or we would not allow * it here) and is doing an exec, it will cause * us to be killed. In this case it will wait * for us to die which means we can finish this * linkage with our last gasp. I.e. no code :) */ spin_lock_irqsave(&process->sighand->siglock, flags); if (!(process->flags & PF_EXITING)) { new_timer->it_process = process; list_add(&new_timer->list, &process->signal->posix_timers); spin_unlock_irqrestore(&process->sighand->siglock, flags); if (new_timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID)) get_task_struct(process); } else { spin_unlock_irqrestore(&process->sighand->siglock, flags); process = NULL; } } read_unlock(&tasklist_lock); if (!process) { error = -EINVAL; goto out; } } else { new_timer->it_sigev_notify = SIGEV_SIGNAL; new_timer->it_sigev_signo = SIGALRM; new_timer->it_sigev_value.sival_int = new_timer->it_id; process = current->group_leader; spin_lock_irqsave(&process->sighand->siglock, flags); new_timer->it_process = process; list_add(&new_timer->list, &process->signal->posix_timers); spin_unlock_irqrestore(&process->sighand->siglock, flags); } /* * In the case of the timer belonging to another task, after * the task is unlocked, the timer is owned by the other task * and may cease to exist at any time. Don't use or modify * new_timer after the unlock call. */ out: if (error) release_posix_timer(new_timer, it_id_set); return error; } /* * good_timespec * * This function checks the elements of a timespec structure. * * Arguments: * ts : Pointer to the timespec structure to check * * Return value: * If a NULL pointer was passed in, or the tv_nsec field was less than 0 * or greater than NSEC_PER_SEC, or the tv_sec field was less than 0, * this function returns 0. Otherwise it returns 1. */ static int good_timespec(const struct timespec *ts) { if ((!ts) || (ts->tv_sec < 0) || ((unsigned) ts->tv_nsec >= NSEC_PER_SEC)) return 0; return 1; } /* * Locking issues: We need to protect the result of the id look up until * we get the timer locked down so it is not deleted under us. The * removal is done under the idr spinlock so we use that here to bridge * the find to the timer lock. To avoid a dead lock, the timer id MUST * be release with out holding the timer lock. */ static struct k_itimer * lock_timer(timer_t timer_id, unsigned long *flags) { struct k_itimer *timr; /* * Watch out here. We do a irqsave on the idr_lock and pass the * flags part over to the timer lock. Must not let interrupts in * while we are moving the lock. */ spin_lock_irqsave(&idr_lock, *flags); timr = (struct k_itimer *) idr_find(&posix_timers_id, (int) timer_id); if (timr) { spin_lock(&timr->it_lock); spin_unlock(&idr_lock); if ((timr->it_id != timer_id) || !(timr->it_process) || timr->it_process->tgid != current->tgid) { unlock_timer(timr, *flags); timr = NULL; } } else spin_unlock_irqrestore(&idr_lock, *flags); return timr; } /* * Get the time remaining on a POSIX.1b interval timer. This function * is ALWAYS called with spin_lock_irq on the timer, thus it must not * mess with irq. * * We have a couple of messes to clean up here. First there is the case * of a timer that has a requeue pending. These timers should appear to * be in the timer list with an expiry as if we were to requeue them * now. * * The second issue is the SIGEV_NONE timer which may be active but is * not really ever put in the timer list (to save system resources). * This timer may be expired, and if so, we will do it here. Otherwise * it is the same as a requeue pending timer WRT to what we should * report. */ static void common_timer_get(struct k_itimer *timr, struct itimerspec *cur_setting) { unsigned long expires; struct now_struct now; do expires = timr->it.real.timer.expires; while ((volatile long) (timr->it.real.timer.expires) != expires); posix_get_now(&now); if (expires && ((timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) && !timr->it.real.incr && posix_time_before(&timr->it.real.timer, &now)) timr->it.real.timer.expires = expires = 0; if (expires) { if (timr->it_requeue_pending & REQUEUE_PENDING || (timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) { posix_bump_timer(timr, now); expires = timr->it.real.timer.expires; } else if (!timer_pending(&timr->it.real.timer)) expires = 0; if (expires) expires -= now.jiffies; } jiffies_to_timespec(expires, &cur_setting->it_value); jiffies_to_timespec(timr->it.real.incr, &cur_setting->it_interval); if (cur_setting->it_value.tv_sec < 0) { cur_setting->it_value.tv_nsec = 1; cur_setting->it_value.tv_sec = 0; } } /* Get the time remaining on a POSIX.1b interval timer. */ asmlinkage long sys_timer_gettime(timer_t timer_id, struct itimerspec __user *setting) { struct k_itimer *timr; struct itimerspec cur_setting; unsigned long flags; timr = lock_timer(timer_id, &flags); if (!timr) return -EINVAL; CLOCK_DISPATCH(timr->it_clock, timer_get, (timr, &cur_setting)); unlock_timer(timr, flags); if (copy_to_user(setting, &cur_setting, sizeof (cur_setting))) return -EFAULT; return 0; } /* * Get the number of overruns of a POSIX.1b interval timer. This is to * be the overrun of the timer last delivered. At the same time we are * accumulating overruns on the next timer. The overrun is frozen when * the signal is delivered, either at the notify time (if the info block * is not queued) or at the actual delivery time (as we are informed by * the call back to do_schedule_next_timer(). So all we need to do is * to pick up the frozen overrun. */ asmlinkage long sys_timer_getoverrun(timer_t timer_id) { struct k_itimer *timr; int overrun; long flags; timr = lock_timer(timer_id, &flags); if (!timr) return -EINVAL; overrun = timr->it_overrun_last; unlock_timer(timr, flags); return overrun; } /* * Adjust for absolute time * * If absolute time is given and it is not CLOCK_MONOTONIC, we need to * adjust for the offset between the timer clock (CLOCK_MONOTONIC) and * what ever clock he is using. * * If it is relative time, we need to add the current (CLOCK_MONOTONIC) * time to it to get the proper time for the timer. */ static int adjust_abs_time(struct k_clock *clock, struct timespec *tp, int abs, u64 *exp, struct timespec *wall_to) { struct timespec now; struct timespec oc = *tp; u64 jiffies_64_f; int rtn =0; if (abs) { /* * The mask pick up the 4 basic clocks */ if (!((clock - &posix_clocks[0]) & ~CLOCKS_MASK)) { jiffies_64_f = do_posix_clock_monotonic_gettime_parts( &now, wall_to); /* * If we are doing a MONOTONIC clock */ if((clock - &posix_clocks[0]) & CLOCKS_MONO){ now.tv_sec += wall_to->tv_sec; now.tv_nsec += wall_to->tv_nsec; } } else { /* * Not one of the basic clocks */ clock->clock_get(clock - posix_clocks, &now); jiffies_64_f = get_jiffies_64(); } /* * Take away now to get delta and normalize */ set_normalized_timespec(&oc, oc.tv_sec - now.tv_sec, oc.tv_nsec - now.tv_nsec); }else{ jiffies_64_f = get_jiffies_64(); } /* * Check if the requested time is prior to now (if so set now) */ if (oc.tv_sec < 0) oc.tv_sec = oc.tv_nsec = 0; if (oc.tv_sec | oc.tv_nsec) set_normalized_timespec(&oc, oc.tv_sec, oc.tv_nsec + clock->res); tstojiffie(&oc, clock->res, exp); /* * Check if the requested time is more than the timer code * can handle (if so we error out but return the value too). */ if (*exp > ((u64)MAX_JIFFY_OFFSET)) /* * This is a considered response, not exactly in * line with the standard (in fact it is silent on * possible overflows). We assume such a large * value is ALMOST always a programming error and * try not to compound it by setting a really dumb * value. */ rtn = -EINVAL; /* * return the actual jiffies expire time, full 64 bits */ *exp += jiffies_64_f; return rtn; } /* Set a POSIX.1b interval timer. */ /* timr->it_lock is taken. */ static inline int common_timer_set(struct k_itimer *timr, int flags, struct itimerspec *new_setting, struct itimerspec *old_setting) { struct k_clock *clock = &posix_clocks[timr->it_clock]; u64 expire_64; if (old_setting) common_timer_get(timr, old_setting); /* disable the timer */ timr->it.real.incr = 0; /* * careful here. If smp we could be in the "fire" routine which will * be spinning as we hold the lock. But this is ONLY an SMP issue. */ if (try_to_del_timer_sync(&timr->it.real.timer) < 0) { #ifdef CONFIG_SMP /* * It can only be active if on an other cpu. Since * we have cleared the interval stuff above, it should * clear once we release the spin lock. Of course once * we do that anything could happen, including the * complete melt down of the timer. So return with * a "retry" exit status. */ return TIMER_RETRY; #endif } remove_from_abslist(timr); timr->it_requeue_pending = (timr->it_requeue_pending + 2) & ~REQUEUE_PENDING; timr->it_overrun_last = 0; timr->it_overrun = -1; /* *switch off the timer when it_value is zero */ if (!new_setting->it_value.tv_sec && !new_setting->it_value.tv_nsec) { timr->it.real.timer.expires = 0; return 0; } if (adjust_abs_time(clock, &new_setting->it_value, flags & TIMER_ABSTIME, &expire_64, &(timr->it.real.wall_to_prev))) { return -EINVAL; } timr->it.real.timer.expires = (unsigned long)expire_64; tstojiffie(&new_setting->it_interval, clock->res, &expire_64); timr->it.real.incr = (unsigned long)expire_64; /* * We do not even queue SIGEV_NONE timers! But we do put them * in the abs list so we can do that right. */ if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE)) add_timer(&timr->it.real.timer); if (flags & TIMER_ABSTIME && clock->abs_struct) { spin_lock(&clock->abs_struct->lock); list_add_tail(&(timr->it.real.abs_timer_entry), &(clock->abs_struct->list)); spin_unlock(&clock->abs_struct->lock); } return 0; } /* Set a POSIX.1b interval timer */ asmlinkage long sys_timer_settime(timer_t timer_id, int flags, const struct itimerspec __user *new_setting, struct itimerspec __user *old_setting) { struct k_itimer *timr; struct itimerspec new_spec, old_spec; int error = 0; long flag; struct itimerspec *rtn = old_setting ? &old_spec : NULL; if (!new_setting) return -EINVAL; if (copy_from_user(&new_spec, new_setting, sizeof (new_spec))) return -EFAULT; if ((!good_timespec(&new_spec.it_interval)) || (!good_timespec(&new_spec.it_value))) return -EINVAL; retry: timr = lock_timer(timer_id, &flag); if (!timr) return -EINVAL; error = CLOCK_DISPATCH(timr->it_clock, timer_set, (timr, flags, &new_spec, rtn)); unlock_timer(timr, flag); if (error == TIMER_RETRY) { rtn = NULL; // We already got the old time... goto retry; } if (old_setting && !error && copy_to_user(old_setting, &old_spec, sizeof (old_spec))) error = -EFAULT; return error; } static inline int common_timer_del(struct k_itimer *timer) { timer->it.real.incr = 0; if (try_to_del_timer_sync(&timer->it.real.timer) < 0) { #ifdef CONFIG_SMP /* * It can only be active if on an other cpu. Since * we have cleared the interval stuff above, it should * clear once we release the spin lock. Of course once * we do that anything could happen, including the * complete melt down of the timer. So return with * a "retry" exit status. */ return TIMER_RETRY; #endif } remove_from_abslist(timer); return 0; } static inline int timer_delete_hook(struct k_itimer *timer) { return CLOCK_DISPATCH(timer->it_clock, timer_del, (timer)); } /* Delete a POSIX.1b interval timer. */ asmlinkage long sys_timer_delete(timer_t timer_id) { struct k_itimer *timer; long flags; #ifdef CONFIG_SMP int error; retry_delete: #endif timer = lock_timer(timer_id, &flags); if (!timer) return -EINVAL; #ifdef CONFIG_SMP error = timer_delete_hook(timer); if (error == TIMER_RETRY) { unlock_timer(timer, flags); goto retry_delete; } #else timer_delete_hook(timer); #endif spin_lock(¤t->sighand->siglock); list_del(&timer->list); spin_unlock(¤t->sighand->siglock); /* * This keeps any tasks waiting on the spin lock from thinking * they got something (see the lock code above). */ if (timer->it_process) { if (timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID)) put_task_struct(timer->it_process); timer->it_process = NULL; } unlock_timer(timer, flags); release_posix_timer(timer, IT_ID_SET); return 0; } /* * return timer owned by the process, used by exit_itimers */ static inline void itimer_delete(struct k_itimer *timer) { unsigned long flags; #ifdef CONFIG_SMP int error; retry_delete: #endif spin_lock_irqsave(&timer->it_lock, flags); #ifdef CONFIG_SMP error = timer_delete_hook(timer); if (error == TIMER_RETRY) { unlock_timer(timer, flags); goto retry_delete; } #else timer_delete_hook(timer); #endif list_del(&timer->list); /* * This keeps any tasks waiting on the spin lock from thinking * they got something (see the lock code above). */ if (timer->it_process) { if (timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID)) put_task_struct(timer->it_process); timer->it_process = NULL; } unlock_timer(timer, flags); release_posix_timer(timer, IT_ID_SET); } /* * This is called by __exit_signal, only when there are no more * references to the shared signal_struct. */ void exit_itimers(struct signal_struct *sig) { struct k_itimer *tmr; while (!list_empty(&sig->posix_timers)) { tmr = list_entry(sig->posix_timers.next, struct k_itimer, list); itimer_delete(tmr); } } /* * And now for the "clock" calls * * These functions are called both from timer functions (with the timer * spin_lock_irq() held and from clock calls with no locking. They must * use the save flags versions of locks. */ /* * We do ticks here to avoid the irq lock ( they take sooo long). * The seqlock is great here. Since we a reader, we don't really care * if we are interrupted since we don't take lock that will stall us or * any other cpu. Voila, no irq lock is needed. * */ static u64 do_posix_clock_monotonic_gettime_parts( struct timespec *tp, struct timespec *mo) { u64 jiff; unsigned int seq; do { seq = read_seqbegin(&xtime_lock); getnstimeofday(tp); *mo = wall_to_monotonic; jiff = jiffies_64; } while(read_seqretry(&xtime_lock, seq)); return jiff; } static int do_posix_clock_monotonic_get(clockid_t clock, struct timespec *tp) { struct timespec wall_to_mono; do_posix_clock_monotonic_gettime_parts(tp, &wall_to_mono); tp->tv_sec += wall_to_mono.tv_sec; tp->tv_nsec += wall_to_mono.tv_nsec; if ((tp->tv_nsec - NSEC_PER_SEC) > 0) { tp->tv_nsec -= NSEC_PER_SEC; tp->tv_sec++; } return 0; } int do_posix_clock_monotonic_gettime(struct timespec *tp) { return do_posix_clock_monotonic_get(CLOCK_MONOTONIC, tp); } int do_posix_clock_nosettime(clockid_t clockid, struct timespec *tp) { return -EINVAL; } EXPORT_SYMBOL_GPL(do_posix_clock_nosettime); int do_posix_clock_notimer_create(struct k_itimer *timer) { return -EINVAL; } EXPORT_SYMBOL_GPL(do_posix_clock_notimer_create); int do_posix_clock_nonanosleep(clockid_t clock, int flags, struct timespec *t) { #ifndef ENOTSUP return -EOPNOTSUPP; /* aka ENOTSUP in userland for POSIX */ #else /* parisc does define it separately. */ return -ENOTSUP; #endif } EXPORT_SYMBOL_GPL(do_posix_clock_nonanosleep); asmlinkage long sys_clock_settime(clockid_t which_clock, const struct timespec __user *tp) { struct timespec new_tp; if (invalid_clockid(which_clock)) return -EINVAL; if (copy_from_user(&new_tp, tp, sizeof (*tp))) return -EFAULT; return CLOCK_DISPATCH(which_clock, clock_set, (which_clock, &new_tp)); } asmlinkage long sys_clock_gettime(clockid_t which_clock, struct timespec __user *tp) { struct timespec kernel_tp; int error; if (invalid_clockid(which_clock)) return -EINVAL; error = CLOCK_DISPATCH(which_clock, clock_get, (which_clock, &kernel_tp)); if (!error && copy_to_user(tp, &kernel_tp, sizeof (kernel_tp))) error = -EFAULT; return error; } asmlinkage long sys_clock_getres(clockid_t which_clock, struct timespec __user *tp) { struct timespec rtn_tp; int error; if (invalid_clockid(which_clock)) return -EINVAL; error = CLOCK_DISPATCH(which_clock, clock_getres, (which_clock, &rtn_tp)); if (!error && tp && copy_to_user(tp, &rtn_tp, sizeof (rtn_tp))) { error = -EFAULT; } return error; } static void nanosleep_wake_up(unsigned long __data) { struct task_struct *p = (struct task_struct *) __data; wake_up_process(p); } /* * The standard says that an absolute nanosleep call MUST wake up at * the requested time in spite of clock settings. Here is what we do: * For each nanosleep call that needs it (only absolute and not on * CLOCK_MONOTONIC* (as it can not be set)) we thread a little structure * into the "nanosleep_abs_list". All we need is the task_struct pointer. * When ever the clock is set we just wake up all those tasks. The rest * is done by the while loop in clock_nanosleep(). * * On locking, clock_was_set() is called from update_wall_clock which * holds (or has held for it) a write_lock_irq( xtime_lock) and is * called from the timer bh code. Thus we need the irq save locks. * * Also, on the call from update_wall_clock, that is done as part of a * softirq thing. We don't want to delay the system that much (possibly * long list of timers to fix), so we defer that work to keventd. */ static DECLARE_WAIT_QUEUE_HEAD(nanosleep_abs_wqueue); static DECLARE_WORK(clock_was_set_work, (void(*)(void*))clock_was_set, NULL); static DECLARE_MUTEX(clock_was_set_lock); void clock_was_set(void) { struct k_itimer *timr; struct timespec new_wall_to; LIST_HEAD(cws_list); unsigned long seq; if (unlikely(in_interrupt())) { schedule_work(&clock_was_set_work); return; } wake_up_all(&nanosleep_abs_wqueue); /* * Check if there exist TIMER_ABSTIME timers to correct. * * Notes on locking: This code is run in task context with irq * on. We CAN be interrupted! All other usage of the abs list * lock is under the timer lock which holds the irq lock as * well. We REALLY don't want to scan the whole list with the * interrupt system off, AND we would like a sequence lock on * this code as well. Since we assume that the clock will not * be set often, it seems ok to take and release the irq lock * for each timer. In fact add_timer will do this, so this is * not an issue. So we know when we are done, we will move the * whole list to a new location. Then as we process each entry, * we will move it to the actual list again. This way, when our * copy is empty, we are done. We are not all that concerned * about preemption so we will use a semaphore lock to protect * aginst reentry. This way we will not stall another * processor. It is possible that this may delay some timers * that should have expired, given the new clock, but even this * will be minimal as we will always update to the current time, * even if it was set by a task that is waiting for entry to * this code. Timers that expire too early will be caught by * the expire code and restarted. * Absolute timers that repeat are left in the abs list while * waiting for the task to pick up the signal. This means we * may find timers that are not in the "add_timer" list, but are * in the abs list. We do the same thing for these, save * putting them back in the "add_timer" list. (Note, these are * left in the abs list mainly to indicate that they are * ABSOLUTE timers, a fact that is used by the re-arm code, and * for which we have no other flag.) */ down(&clock_was_set_lock); spin_lock_irq(&abs_list.lock); list_splice_init(&abs_list.list, &cws_list); spin_unlock_irq(&abs_list.lock); do { do { seq = read_seqbegin(&xtime_lock); new_wall_to = wall_to_monotonic; } while (read_seqretry(&xtime_lock, seq)); spin_lock_irq(&abs_list.lock); if (list_empty(&cws_list)) { spin_unlock_irq(&abs_list.lock); break; } timr = list_entry(cws_list.next, struct k_itimer, it.real.abs_timer_entry); list_del_init(&timr->it.real.abs_timer_entry); if (add_clockset_delta(timr, &new_wall_to) && del_timer(&timr->it.real.timer)) /* timer run yet? */ add_timer(&timr->it.real.timer); list_add(&timr->it.real.abs_timer_entry, &abs_list.list); spin_unlock_irq(&abs_list.lock); } while (1); up(&clock_was_set_lock); } long clock_nanosleep_restart(struct restart_block *restart_block); asmlinkage long sys_clock_nanosleep(clockid_t which_clock, int flags, const struct timespec __user *rqtp, struct timespec __user *rmtp) { struct timespec t; struct restart_block *restart_block = &(current_thread_info()->restart_block); int ret; if (invalid_clockid(which_clock)) return -EINVAL; if (copy_from_user(&t, rqtp, sizeof (struct timespec))) return -EFAULT; if ((unsigned) t.tv_nsec >= NSEC_PER_SEC || t.tv_sec < 0) return -EINVAL; /* * Do this here as nsleep function does not have the real address. */ restart_block->arg1 = (unsigned long)rmtp; ret = CLOCK_DISPATCH(which_clock, nsleep, (which_clock, flags, &t)); if ((ret == -ERESTART_RESTARTBLOCK) && rmtp && copy_to_user(rmtp, &t, sizeof (t))) return -EFAULT; return ret; } static int common_nsleep(clockid_t which_clock, int flags, struct timespec *tsave) { struct timespec t, dum; struct timer_list new_timer; DECLARE_WAITQUEUE(abs_wqueue, current); u64 rq_time = (u64)0; s64 left; int abs; struct restart_block *restart_block = ¤t_thread_info()->restart_block; abs_wqueue.flags = 0; init_timer(&new_timer); new_timer.expires = 0; new_timer.data = (unsigned long) current; new_timer.function = nanosleep_wake_up; abs = flags & TIMER_ABSTIME; if (restart_block->fn == clock_nanosleep_restart) { /* * Interrupted by a non-delivered signal, pick up remaining * time and continue. Remaining time is in arg2 & 3. */ restart_block->fn = do_no_restart_syscall; rq_time = restart_block->arg3; rq_time = (rq_time << 32) + restart_block->arg2; if (!rq_time) return -EINTR; left = rq_time - get_jiffies_64(); if (left <= (s64)0) return 0; /* Already passed */ } if (abs && (posix_clocks[which_clock].clock_get != posix_clocks[CLOCK_MONOTONIC].clock_get)) add_wait_queue(&nanosleep_abs_wqueue, &abs_wqueue); do { t = *tsave; if (abs || !rq_time) { adjust_abs_time(&posix_clocks[which_clock], &t, abs, &rq_time, &dum); } left = rq_time - get_jiffies_64(); if (left >= (s64)MAX_JIFFY_OFFSET) left = (s64)MAX_JIFFY_OFFSET; if (left < (s64)0) break; new_timer.expires = jiffies + left; __set_current_state(TASK_INTERRUPTIBLE); add_timer(&new_timer); schedule(); del_timer_sync(&new_timer); left = rq_time - get_jiffies_64(); } while (left > (s64)0 && !test_thread_flag(TIF_SIGPENDING)); if (abs_wqueue.task_list.next) finish_wait(&nanosleep_abs_wqueue, &abs_wqueue); if (left > (s64)0) { /* * Always restart abs calls from scratch to pick up any * clock shifting that happened while we are away. */ if (abs) return -ERESTARTNOHAND; left *= TICK_NSEC; tsave->tv_sec = div_long_long_rem(left, NSEC_PER_SEC, &tsave->tv_nsec); /* * Restart works by saving the time remaing in * arg2 & 3 (it is 64-bits of jiffies). The other * info we need is the clock_id (saved in arg0). * The sys_call interface needs the users * timespec return address which _it_ saves in arg1. * Since we have cast the nanosleep call to a clock_nanosleep * both can be restarted with the same code. */ restart_block->fn = clock_nanosleep_restart; restart_block->arg0 = which_clock; /* * Caller sets arg1 */ restart_block->arg2 = rq_time & 0xffffffffLL; restart_block->arg3 = rq_time >> 32; return -ERESTART_RESTARTBLOCK; } return 0; } /* * This will restart clock_nanosleep. */ long clock_nanosleep_restart(struct restart_block *restart_block) { struct timespec t; int ret = common_nsleep(restart_block->arg0, 0, &t); if ((ret == -ERESTART_RESTARTBLOCK) && restart_block->arg1 && copy_to_user((struct timespec __user *)(restart_block->arg1), &t, sizeof (t))) return -EFAULT; return ret; }