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linux/kernel/posix-timers.c

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/*
* 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 <linux/mm.h>
#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <asm/uaccess.h>
#include <asm/semaphore.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/compiler.h>
#include <linux/idr.h>
#include <linux/posix-timers.h>
#include <linux/syscalls.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
#include <linux/module.h>
#ifndef div_long_long_rem
#include <asm/div64.h>
#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 <id>
* int idr_get_new(struct idr *idp, void *ptr); to get a new id and
* related it to <ptr>
* void idr_remove(struct idr *idp, int id); to release <id>
* void idr_init(struct idr *idp); to initialize <idp>
* 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 <linux/time.h>
* 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) {
struct task_struct *leader;
int ret = send_sigqueue(timr->it_sigev_signo, timr->sigq,
timr->it_process);
if (likely(ret >= 0))
return ret;
timr->it_sigev_notify = SIGEV_SIGNAL;
leader = timr->it_process->group_leader;
put_task_struct(timr->it_process);
timr->it_process = leader;
}
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(&current->sighand->siglock);
list_del(&timer->list);
spin_unlock(&current->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 do_exit or de_thread, 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);
set_normalized_timespec(tp, tp->tv_sec + wall_to_mono.tv_sec,
tp->tv_nsec + wall_to_mono.tv_nsec);
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;
}
/*
* 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;
DECLARE_WAITQUEUE(abs_wqueue, current);
u64 rq_time = (u64)0;
s64 left;
int abs;
struct restart_block *restart_block =
&current_thread_info()->restart_block;
abs_wqueue.flags = 0;
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;
schedule_timeout_interruptible(left);
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;
}
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