forked from luck/tmp_suning_uos_patched
aa5e97ce4b
The unit of the cputime accouting values that are stored per process is currently a microsecond. The CPU timer has a maximum granularity of 2**-12 microseconds. There is no benefit in storing the per process values in the lesser precision and there is the disadvantage that the backend has to do the rounding to microseconds. The better solution is to use the maximum granularity of the CPU timer as cputime unit. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
506 lines
13 KiB
C
506 lines
13 KiB
C
/*
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* arch/s390/kernel/vtime.c
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* Virtual cpu timer based timer functions.
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*
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* S390 version
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* Copyright (C) 2004 IBM Deutschland Entwicklung GmbH, IBM Corporation
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* Author(s): Jan Glauber <jan.glauber@de.ibm.com>
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/time.h>
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#include <linux/delay.h>
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#include <linux/init.h>
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#include <linux/smp.h>
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#include <linux/types.h>
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#include <linux/timex.h>
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#include <linux/notifier.h>
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#include <linux/kernel_stat.h>
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#include <linux/rcupdate.h>
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#include <linux/posix-timers.h>
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#include <asm/s390_ext.h>
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#include <asm/timer.h>
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#include <asm/irq_regs.h>
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static ext_int_info_t ext_int_info_timer;
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static DEFINE_PER_CPU(struct vtimer_queue, virt_cpu_timer);
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/*
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* Update process times based on virtual cpu times stored by entry.S
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* to the lowcore fields user_timer, system_timer & steal_clock.
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*/
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static void do_account_vtime(struct task_struct *tsk, int hardirq_offset)
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{
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struct thread_info *ti = task_thread_info(tsk);
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__u64 timer, clock, user, system, steal;
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timer = S390_lowcore.last_update_timer;
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clock = S390_lowcore.last_update_clock;
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asm volatile (" STPT %0\n" /* Store current cpu timer value */
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" STCK %1" /* Store current tod clock value */
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: "=m" (S390_lowcore.last_update_timer),
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"=m" (S390_lowcore.last_update_clock) );
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S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
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S390_lowcore.steal_timer += S390_lowcore.last_update_clock - clock;
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user = S390_lowcore.user_timer - ti->user_timer;
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S390_lowcore.steal_timer -= user;
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ti->user_timer = S390_lowcore.user_timer;
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account_user_time(tsk, user, user);
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system = S390_lowcore.system_timer - ti->system_timer;
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S390_lowcore.steal_timer -= system;
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ti->system_timer = S390_lowcore.system_timer;
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if (idle_task(smp_processor_id()) != current)
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account_system_time(tsk, hardirq_offset, system, system);
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else
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account_idle_time(system);
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steal = S390_lowcore.steal_timer;
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if ((s64) steal > 0) {
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S390_lowcore.steal_timer = 0;
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if (idle_task(smp_processor_id()) != current)
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account_steal_time(steal);
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else
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account_idle_time(steal);
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}
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}
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void account_vtime(struct task_struct *prev, struct task_struct *next)
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{
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struct thread_info *ti;
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do_account_vtime(prev, 0);
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ti = task_thread_info(prev);
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ti->user_timer = S390_lowcore.user_timer;
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ti->system_timer = S390_lowcore.system_timer;
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ti = task_thread_info(next);
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S390_lowcore.user_timer = ti->user_timer;
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S390_lowcore.system_timer = ti->system_timer;
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}
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void account_process_tick(struct task_struct *tsk, int user_tick)
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{
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do_account_vtime(tsk, HARDIRQ_OFFSET);
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}
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/*
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* Update process times based on virtual cpu times stored by entry.S
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* to the lowcore fields user_timer, system_timer & steal_clock.
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*/
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void account_system_vtime(struct task_struct *tsk)
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{
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struct thread_info *ti = task_thread_info(tsk);
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__u64 timer, system;
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timer = S390_lowcore.last_update_timer;
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asm volatile (" STPT %0" /* Store current cpu timer value */
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: "=m" (S390_lowcore.last_update_timer) );
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S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
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system = S390_lowcore.system_timer - ti->system_timer;
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S390_lowcore.steal_timer -= system;
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ti->system_timer = S390_lowcore.system_timer;
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if (in_irq() || idle_task(smp_processor_id()) != current)
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account_system_time(tsk, 0, system, system);
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else
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account_idle_time(system);
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}
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EXPORT_SYMBOL_GPL(account_system_vtime);
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static inline void set_vtimer(__u64 expires)
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{
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__u64 timer;
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asm volatile (" STPT %0\n" /* Store current cpu timer value */
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" SPT %1" /* Set new value immediatly afterwards */
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: "=m" (timer) : "m" (expires) );
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S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
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S390_lowcore.last_update_timer = expires;
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/* store expire time for this CPU timer */
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__get_cpu_var(virt_cpu_timer).to_expire = expires;
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}
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void vtime_start_cpu_timer(void)
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{
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struct vtimer_queue *vt_list;
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vt_list = &__get_cpu_var(virt_cpu_timer);
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/* CPU timer interrupt is pending, don't reprogramm it */
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if (vt_list->idle & 1LL<<63)
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return;
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if (!list_empty(&vt_list->list))
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set_vtimer(vt_list->idle);
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}
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void vtime_stop_cpu_timer(void)
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{
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struct vtimer_queue *vt_list;
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vt_list = &__get_cpu_var(virt_cpu_timer);
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/* nothing to do */
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if (list_empty(&vt_list->list)) {
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vt_list->idle = VTIMER_MAX_SLICE;
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goto fire;
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}
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/* store the actual expire value */
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asm volatile ("STPT %0" : "=m" (vt_list->idle));
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/*
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* If the CPU timer is negative we don't reprogramm
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* it because we will get instantly an interrupt.
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*/
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if (vt_list->idle & 1LL<<63)
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return;
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vt_list->offset += vt_list->to_expire - vt_list->idle;
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/*
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* We cannot halt the CPU timer, we just write a value that
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* nearly never expires (only after 71 years) and re-write
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* the stored expire value if we continue the timer
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*/
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fire:
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set_vtimer(VTIMER_MAX_SLICE);
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}
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/*
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* Sorted add to a list. List is linear searched until first bigger
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* element is found.
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*/
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static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
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{
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struct vtimer_list *event;
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list_for_each_entry(event, head, entry) {
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if (event->expires > timer->expires) {
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list_add_tail(&timer->entry, &event->entry);
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return;
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}
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}
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list_add_tail(&timer->entry, head);
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}
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/*
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* Do the callback functions of expired vtimer events.
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* Called from within the interrupt handler.
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*/
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static void do_callbacks(struct list_head *cb_list)
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{
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struct vtimer_queue *vt_list;
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struct vtimer_list *event, *tmp;
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void (*fn)(unsigned long);
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unsigned long data;
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if (list_empty(cb_list))
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return;
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vt_list = &__get_cpu_var(virt_cpu_timer);
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list_for_each_entry_safe(event, tmp, cb_list, entry) {
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fn = event->function;
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data = event->data;
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fn(data);
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if (!event->interval)
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/* delete one shot timer */
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list_del_init(&event->entry);
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else {
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/* move interval timer back to list */
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spin_lock(&vt_list->lock);
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list_del_init(&event->entry);
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list_add_sorted(event, &vt_list->list);
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spin_unlock(&vt_list->lock);
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}
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}
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}
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/*
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* Handler for the virtual CPU timer.
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*/
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static void do_cpu_timer_interrupt(__u16 error_code)
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{
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__u64 next, delta;
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struct vtimer_queue *vt_list;
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struct vtimer_list *event, *tmp;
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struct list_head *ptr;
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/* the callback queue */
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struct list_head cb_list;
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INIT_LIST_HEAD(&cb_list);
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vt_list = &__get_cpu_var(virt_cpu_timer);
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/* walk timer list, fire all expired events */
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spin_lock(&vt_list->lock);
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if (vt_list->to_expire < VTIMER_MAX_SLICE)
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vt_list->offset += vt_list->to_expire;
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list_for_each_entry_safe(event, tmp, &vt_list->list, entry) {
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if (event->expires > vt_list->offset)
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/* found first unexpired event, leave */
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break;
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/* re-charge interval timer, we have to add the offset */
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if (event->interval)
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event->expires = event->interval + vt_list->offset;
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/* move expired timer to the callback queue */
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list_move_tail(&event->entry, &cb_list);
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}
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spin_unlock(&vt_list->lock);
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do_callbacks(&cb_list);
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/* next event is first in list */
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spin_lock(&vt_list->lock);
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if (!list_empty(&vt_list->list)) {
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ptr = vt_list->list.next;
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event = list_entry(ptr, struct vtimer_list, entry);
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next = event->expires - vt_list->offset;
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/* add the expired time from this interrupt handler
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* and the callback functions
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*/
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asm volatile ("STPT %0" : "=m" (delta));
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delta = 0xffffffffffffffffLL - delta + 1;
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vt_list->offset += delta;
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next -= delta;
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} else {
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vt_list->offset = 0;
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next = VTIMER_MAX_SLICE;
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}
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spin_unlock(&vt_list->lock);
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set_vtimer(next);
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}
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void init_virt_timer(struct vtimer_list *timer)
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{
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timer->function = NULL;
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INIT_LIST_HEAD(&timer->entry);
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spin_lock_init(&timer->lock);
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}
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EXPORT_SYMBOL(init_virt_timer);
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static inline int vtimer_pending(struct vtimer_list *timer)
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{
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return (!list_empty(&timer->entry));
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}
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/*
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* this function should only run on the specified CPU
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*/
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static void internal_add_vtimer(struct vtimer_list *timer)
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{
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unsigned long flags;
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__u64 done;
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struct vtimer_list *event;
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struct vtimer_queue *vt_list;
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vt_list = &per_cpu(virt_cpu_timer, timer->cpu);
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spin_lock_irqsave(&vt_list->lock, flags);
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BUG_ON(timer->cpu != smp_processor_id());
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/* if list is empty we only have to set the timer */
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if (list_empty(&vt_list->list)) {
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/* reset the offset, this may happen if the last timer was
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* just deleted by mod_virt_timer and the interrupt
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* didn't happen until here
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*/
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vt_list->offset = 0;
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goto fire;
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}
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/* save progress */
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asm volatile ("STPT %0" : "=m" (done));
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/* calculate completed work */
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done = vt_list->to_expire - done + vt_list->offset;
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vt_list->offset = 0;
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list_for_each_entry(event, &vt_list->list, entry)
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event->expires -= done;
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fire:
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list_add_sorted(timer, &vt_list->list);
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/* get first element, which is the next vtimer slice */
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event = list_entry(vt_list->list.next, struct vtimer_list, entry);
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set_vtimer(event->expires);
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spin_unlock_irqrestore(&vt_list->lock, flags);
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/* release CPU acquired in prepare_vtimer or mod_virt_timer() */
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put_cpu();
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}
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static inline void prepare_vtimer(struct vtimer_list *timer)
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{
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BUG_ON(!timer->function);
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BUG_ON(!timer->expires || timer->expires > VTIMER_MAX_SLICE);
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BUG_ON(vtimer_pending(timer));
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timer->cpu = get_cpu();
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}
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/*
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* add_virt_timer - add an oneshot virtual CPU timer
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*/
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void add_virt_timer(void *new)
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{
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struct vtimer_list *timer;
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timer = (struct vtimer_list *)new;
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prepare_vtimer(timer);
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timer->interval = 0;
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internal_add_vtimer(timer);
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}
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EXPORT_SYMBOL(add_virt_timer);
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/*
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* add_virt_timer_int - add an interval virtual CPU timer
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*/
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void add_virt_timer_periodic(void *new)
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{
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struct vtimer_list *timer;
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timer = (struct vtimer_list *)new;
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prepare_vtimer(timer);
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timer->interval = timer->expires;
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internal_add_vtimer(timer);
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}
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EXPORT_SYMBOL(add_virt_timer_periodic);
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/*
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* If we change a pending timer the function must be called on the CPU
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* where the timer is running on, e.g. by smp_call_function_single()
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*
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* The original mod_timer adds the timer if it is not pending. For compatibility
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* we do the same. The timer will be added on the current CPU as a oneshot timer.
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*
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* returns whether it has modified a pending timer (1) or not (0)
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*/
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int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
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{
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struct vtimer_queue *vt_list;
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unsigned long flags;
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int cpu;
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BUG_ON(!timer->function);
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BUG_ON(!expires || expires > VTIMER_MAX_SLICE);
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/*
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* This is a common optimization triggered by the
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* networking code - if the timer is re-modified
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* to be the same thing then just return:
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*/
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if (timer->expires == expires && vtimer_pending(timer))
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return 1;
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cpu = get_cpu();
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vt_list = &per_cpu(virt_cpu_timer, cpu);
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/* check if we run on the right CPU */
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BUG_ON(timer->cpu != cpu);
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/* disable interrupts before test if timer is pending */
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spin_lock_irqsave(&vt_list->lock, flags);
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/* if timer isn't pending add it on the current CPU */
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if (!vtimer_pending(timer)) {
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spin_unlock_irqrestore(&vt_list->lock, flags);
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/* we do not activate an interval timer with mod_virt_timer */
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timer->interval = 0;
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timer->expires = expires;
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timer->cpu = cpu;
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internal_add_vtimer(timer);
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return 0;
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}
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list_del_init(&timer->entry);
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timer->expires = expires;
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/* also change the interval if we have an interval timer */
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if (timer->interval)
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timer->interval = expires;
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/* the timer can't expire anymore so we can release the lock */
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spin_unlock_irqrestore(&vt_list->lock, flags);
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internal_add_vtimer(timer);
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return 1;
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}
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EXPORT_SYMBOL(mod_virt_timer);
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/*
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* delete a virtual timer
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*
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* returns whether the deleted timer was pending (1) or not (0)
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*/
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int del_virt_timer(struct vtimer_list *timer)
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{
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unsigned long flags;
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struct vtimer_queue *vt_list;
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/* check if timer is pending */
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if (!vtimer_pending(timer))
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return 0;
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vt_list = &per_cpu(virt_cpu_timer, timer->cpu);
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spin_lock_irqsave(&vt_list->lock, flags);
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/* we don't interrupt a running timer, just let it expire! */
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list_del_init(&timer->entry);
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/* last timer removed */
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if (list_empty(&vt_list->list)) {
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vt_list->to_expire = 0;
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vt_list->offset = 0;
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}
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spin_unlock_irqrestore(&vt_list->lock, flags);
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return 1;
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}
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EXPORT_SYMBOL(del_virt_timer);
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/*
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* Start the virtual CPU timer on the current CPU.
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*/
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void init_cpu_vtimer(void)
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{
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struct vtimer_queue *vt_list;
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/* kick the virtual timer */
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S390_lowcore.exit_timer = VTIMER_MAX_SLICE;
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S390_lowcore.last_update_timer = VTIMER_MAX_SLICE;
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asm volatile ("STCK %0" : "=m" (S390_lowcore.last_update_clock));
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asm volatile ("SPT %0" : : "m" (S390_lowcore.last_update_timer));
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/* enable cpu timer interrupts */
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__ctl_set_bit(0,10);
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vt_list = &__get_cpu_var(virt_cpu_timer);
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INIT_LIST_HEAD(&vt_list->list);
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spin_lock_init(&vt_list->lock);
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vt_list->to_expire = 0;
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vt_list->offset = 0;
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vt_list->idle = 0;
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}
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void __init vtime_init(void)
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{
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/* request the cpu timer external interrupt */
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if (register_early_external_interrupt(0x1005, do_cpu_timer_interrupt,
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&ext_int_info_timer) != 0)
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panic("Couldn't request external interrupt 0x1005");
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/* Enable cpu timer interrupts on the boot cpu. */
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init_cpu_vtimer();
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}
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