/*
* 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/interrupt.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/mutex.h>
#include <asm/uaccess.h>
#include <linux/list.h>
#include <linux/init.h>
#include <linux/compiler.h>
#include <linux/hash.h>
#include <linux/posix-clock.h>
#include <linux/posix-timers.h>
#include <linux/syscalls.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
#include <linux/export.h>
#include <linux/hashtable.h>
#include "timekeeping.h"
/*
* Management arrays for POSIX timers. Timers are now kept in static hash table
* with 512 entries.
* Timer ids are allocated by local routine, which selects proper hash head by
* key, constructed from current->signal address and per signal struct counter.
* This keeps timer ids unique per process, but now they can intersect between
* processes.
*/
/*
* Lets keep our timers in a slab cache :-)
*/
static struct kmem_cache *posix_timers_cache;
static DEFINE_HASHTABLE(posix_timers_hashtable, 9);
static DEFINE_SPINLOCK(hash_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
/*
* parisc wants ENOTSUP instead of EOPNOTSUPP
*/
#ifndef ENOTSUP
# define ENANOSLEEP_NOTSUP EOPNOTSUPP
#else
# define ENANOSLEEP_NOTSUP ENOTSUP
#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.
*
* 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.
*
* 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_pid fields are not modified by timer code.
*
* 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];
/*
* These ones are defined below.
*/
static int common_nsleep(const clockid_t, int flags, struct timespec *t,
struct timespec __user *rmtp);
static int common_timer_create(struct k_itimer *new_timer);
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);
static enum hrtimer_restart posix_timer_fn(struct hrtimer *data);
static struct k_itimer *__lock_timer(timer_t timer_id, unsigned long *flags);
#define lock_timer(tid, flags) \
({ struct k_itimer *__timr; \
__cond_lock(&__timr->it_lock, __timr = __lock_timer(tid, flags)); \
__timr; \
})
static int hash(struct signal_struct *sig, unsigned int nr)
{
return hash_32(hash32_ptr(sig) ^ nr, HASH_BITS(posix_timers_hashtable));
}
static struct k_itimer *__posix_timers_find(struct hlist_head *head,
struct signal_struct *sig,
timer_t id)
{
struct k_itimer *timer;
hlist_for_each_entry_rcu(timer, head, t_hash) {
if ((timer->it_signal == sig) && (timer->it_id == id))
return timer;
}
return NULL;
}
static struct k_itimer *posix_timer_by_id(timer_t id)
{
struct signal_struct *sig = current->signal;
struct hlist_head *head = &posix_timers_hashtable[hash(sig, id)];
return __posix_timers_find(head, sig, id);