*
* 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
#include <linux/idr.h>
#include <linux/posix-timers.h>
#include <linux/wait.h>
+#include <linux/workqueue.h>
#ifndef div_long_long_rem
#include <asm/div64.h>
*/
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};
#define if_clock_do(clock_fun,alt_fun,parms) \
(!clock_fun) ? alt_fun parms : clock_fun parms
*/
static __init int init_posix_timers(void)
{
- struct k_clock clock_realtime = {.res = CLOCK_REALTIME_RES };
+ 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_gettime,
.clock_set = do_posix_clock_monotonic_settime
};
register_posix_clock(CLOCK_MONOTONIC, &clock_monotonic);
posix_timers_cache = kmem_cache_create("posix_timers_cache",
- sizeof (struct k_itimer), 0, 0, 0, 0);
+ sizeof (struct k_itimer), 0, 0, NULL, NULL);
idr_init(&posix_timers_id);
-
return 0;
}
(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->wall_to_prev.tv_sec,
+ new_wall_to->tv_nsec -
+ timr->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->wall_to_prev = *new_wall_to;
+ timr->it_timer.expires += (sign ? -exp : exp);
+ return 1;
+}
+
+static void remove_from_abslist(struct k_itimer *timr)
+{
+ if (!list_empty(&timr->abs_timer_entry)) {
+ spin_lock(&abs_list.lock);
+ list_del_init(&timr->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) */
+ /*
+ * Set up the timer for the next interval (if there is one).
+ * Note: this code uses the abs_timer_lock to protect
+ * 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_incr)
return;
- posix_get_now(&now);
do {
- posix_bump_timer(timr);
- }while (posix_time_before(&timr->it_timer, &now));
+ 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->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;
memset(&timr->sigq->info, 0, sizeof(siginfo_t));
- /* Send signal to the process that owns this timer. */
+ /*
+ * 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_value = timr->it_sigev_value;
if (timr->it_incr)
timr->sigq->info.si_sys_private = ++timr->it_requeue_pending;
+ else {
+ remove_from_abslist(timr);
+ }
if (timr->it_sigev_notify & SIGEV_THREAD_ID) {
if (unlikely(timr->it_process->flags & PF_EXITING)) {
* 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 interrutps 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);
set_timer_inactive(timr);
- timer_notify_task(timr);
- unlock_timer(timr, flags);
+ if (!list_empty(&timr->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->wall_to_prev.tv_sec,
+ new_wall_to.tv_nsec -
+ timr->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->wall_to_prev = new_wall_to;
+ timr->it_timer.expires += exp;
+ add_timer(&timr->it_timer);
+ do_notify = 0;
+ }
+ spin_unlock(&abs_list.lock);
+
+ }
+ if (do_notify)
+ timer_notify_task(timr);
+ unlock_timer(timr, flags); /* hold thru abs lock to keep irq off */
}
if (!tmr)
return tmr;
memset(tmr, 0, sizeof (struct k_itimer));
- tmr->it_id = (timer_t)-1;
+ INIT_LIST_HEAD(&tmr->abs_timer_entry);
if (unlikely(!(tmr->sigq = sigqueue_alloc()))) {
kmem_cache_free(posix_timers_cache, tmr);
- tmr = 0;
+ tmr = NULL;
}
return tmr;
}
-static void release_posix_timer(struct k_itimer *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 (tmr->it_id != -1) {
+ if (it_id_set) {
unsigned long flags;
spin_lock_irqsave(&idr_lock, flags);
idr_remove(&posix_timers_id, tmr->it_id);
{
int error = 0;
struct k_itimer *new_timer = NULL;
- timer_t new_timer_id;
- struct task_struct *process = 0;
+ int new_timer_id;
+ struct task_struct *process = NULL;
unsigned long flags;
sigevent_t event;
+ int it_id_set = IT_ID_NOT_SET;
if ((unsigned) which_clock >= MAX_CLOCKS ||
!posix_clocks[which_clock].res)
return -EAGAIN;
spin_lock_init(&new_timer->it_lock);
- do {
- if (unlikely(!idr_pre_get(&posix_timers_id, GFP_KERNEL))) {
- error = -EAGAIN;
- new_timer->it_id = (timer_t)-1;
- goto out;
- }
- spin_lock_irq(&idr_lock);
- new_timer_id = (timer_t) idr_get_new(&posix_timers_id,
- (void *) new_timer);
- spin_unlock_irq(&idr_lock);
- } while (unlikely(new_timer_id == -1));
+ 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_incr = 0;
+ new_timer->it_overrun = -1;
+ init_timer(&new_timer->it_timer);
+ new_timer->it_timer.expires = 0;
+ new_timer->it_timer.data = (unsigned long) new_timer;
+ new_timer->it_timer.function = posix_timer_fn;
+ set_timer_inactive(new_timer);
- new_timer->it_id = new_timer_id;
/*
* return the timer_id now. The next step is hard to
* back out if there is an error.
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))) {
/*
*/
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);
get_task_struct(process);
} else {
spin_unlock_irqrestore(&process->sighand->siglock, flags);
- process = 0;
+ process = NULL;
}
}
read_unlock(&tasklist_lock);
error = -EINVAL;
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;
} 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);
}
- new_timer->it_clock = which_clock;
- new_timer->it_incr = 0;
- new_timer->it_overrun = -1;
- init_timer(&new_timer->it_timer);
- new_timer->it_timer.expires = 0;
- new_timer->it_timer.data = (unsigned long) new_timer;
- new_timer->it_timer.function = posix_timer_fn;
- set_timer_inactive(new_timer);
-
- /*
- * Once we set the process, it can be found so do it last...
+ /*
+ * 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.
*/
- new_timer->it_process = process;
+
out:
if (error)
- release_posix_timer(new_timer);
+ release_posix_timer(new_timer, it_id_set);
return error;
}
if (expires) {
if (timr->it_requeue_pending & REQUEUE_PENDING ||
(timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
- while (posix_time_before(&timr->it_timer, &now))
- posix_bump_timer(timr);
+ posix_bump_timer(timr, now);
expires = timr->it_timer.expires;
}
else
* 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)
+ int abs, u64 *exp, struct timespec *wall_to)
{
struct timespec now;
struct timespec oc = *tp;
- struct timespec wall_to_mono;
u64 jiffies_64_f;
int rtn =0;
/*
* The mask pick up the 4 basic clocks
*/
- if (!(clock - &posix_clocks[0]) & ~CLOCKS_MASK) {
+ if (!((clock - &posix_clocks[0]) & ~CLOCKS_MASK)) {
jiffies_64_f = do_posix_clock_monotonic_gettime_parts(
- &now, &wall_to_mono);
+ &now, wall_to);
/*
* If we are doing a MONOTONIC clock
*/
if((clock - &posix_clocks[0]) & CLOCKS_MONO){
- now.tv_sec += wall_to_mono.tv_sec;
- now.tv_nsec += wall_to_mono.tv_nsec;
+ now.tv_sec += wall_to->tv_sec;
+ now.tv_nsec += wall_to->tv_nsec;
}
} else {
/*
#else
del_timer(&timr->it_timer);
#endif
+ remove_from_abslist(timr);
+
timr->it_requeue_pending = (timr->it_requeue_pending + 2) &
~REQUEUE_PENDING;
timr->it_overrun_last = 0;
if (adjust_abs_time(clock,
&new_setting->it_value, flags & TIMER_ABSTIME,
- &expire_64)) {
+ &expire_64, &(timr->wall_to_prev))) {
return -EINVAL;
}
timr->it_timer.expires = (unsigned long)expire_64;
tstojiffie(&new_setting->it_interval, clock->res, &expire_64);
timr->it_incr = (unsigned long)expire_64;
-
/*
- * For some reason the timer does not fire immediately if expires is
- * equal to jiffies, so the timer notify function is called directly.
- * We do not even queue SIGEV_NONE timers!
+ * 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)) {
- if (timr->it_timer.expires == jiffies)
- timer_notify_task(timr);
- else
- add_timer(&timr->it_timer);
+ if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) != SIGEV_NONE))
+ add_timer(&timr->it_timer);
+
+ if (flags & TIMER_ABSTIME && clock->abs_struct) {
+ spin_lock(&clock->abs_struct->lock);
+ list_add_tail(&(timr->abs_timer_entry),
+ &(clock->abs_struct->list));
+ spin_unlock(&clock->abs_struct->lock);
}
return 0;
}
if (!posix_clocks[timr->it_clock].timer_set)
error = do_timer_settime(timr, flags, &new_spec, rtn);
else
- error = posix_clocks[timr->it_clock].timer_set(timr,
+ error = posix_clocks[timr->it_clock].timer_set(timr,
flags,
&new_spec, rtn);
unlock_timer(timr, flag);
#else
del_timer(&timer->it_timer);
#endif
+ remove_from_abslist(timer);
+
return 0;
}
timer->it_process = NULL;
}
unlock_timer(timer, flags);
- release_posix_timer(timer);
+ release_posix_timer(timer, IT_ID_SET);
return 0;
}
/*
timer->it_process = NULL;
}
unlock_timer(timer, flags);
- release_posix_timer(timer);
+ release_posix_timer(timer, IT_ID_SET);
}
/*
* 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,
+ abs_timer_entry);
+
+ list_del_init(&timr->abs_timer_entry);
+ if (add_clockset_delta(timr, &new_wall_to) &&
+ del_timer(&timr->it_timer)) /* timer run yet? */
+ add_timer(&timr->it_timer);
+ list_add(&timr->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);
long
do_clock_nanosleep(clockid_t which_clock, int flags, struct timespec *tsave)
{
- struct timespec t;
+ struct timespec t, dum;
struct timer_list new_timer;
DECLARE_WAITQUEUE(abs_wqueue, current);
u64 rq_time = (u64)0;
t = *tsave;
if (abs || !rq_time) {
adjust_abs_time(&posix_clocks[which_clock], &t, abs,
- &rq_time);
+ &rq_time, &dum);
rq_time += (t.tv_sec || t.tv_nsec);
}
git://git.onelab.eu / linux-2.6.git / blobdiff