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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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2456e85535
ktime is a union because the initial implementation stored the time in scalar nanoseconds on 64 bit machine and in a endianess optimized timespec variant for 32bit machines. The Y2038 cleanup removed the timespec variant and switched everything to scalar nanoseconds. The union remained, but become completely pointless. Get rid of the union and just keep ktime_t as simple typedef of type s64. The conversion was done with coccinelle and some manual mopping up. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org>
111 lines
3 KiB
C
111 lines
3 KiB
C
/*
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* linux/kernel/time/tick-broadcast-hrtimer.c
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* This file emulates a local clock event device
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* via a pseudo clock device.
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*/
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#include <linux/cpu.h>
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#include <linux/err.h>
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#include <linux/hrtimer.h>
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#include <linux/interrupt.h>
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#include <linux/percpu.h>
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#include <linux/profile.h>
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#include <linux/clockchips.h>
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#include <linux/sched.h>
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#include <linux/smp.h>
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#include <linux/module.h>
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#include "tick-internal.h"
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static struct hrtimer bctimer;
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static int bc_shutdown(struct clock_event_device *evt)
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{
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/*
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* Note, we cannot cancel the timer here as we might
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* run into the following live lock scenario:
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*
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* cpu 0 cpu1
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* lock(broadcast_lock);
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* hrtimer_interrupt()
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* bc_handler()
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* tick_handle_oneshot_broadcast();
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* lock(broadcast_lock);
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* hrtimer_cancel()
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* wait_for_callback()
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*/
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hrtimer_try_to_cancel(&bctimer);
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return 0;
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}
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/*
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* This is called from the guts of the broadcast code when the cpu
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* which is about to enter idle has the earliest broadcast timer event.
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*/
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static int bc_set_next(ktime_t expires, struct clock_event_device *bc)
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{
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int bc_moved;
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/*
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* We try to cancel the timer first. If the callback is on
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* flight on some other cpu then we let it handle it. If we
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* were able to cancel the timer nothing can rearm it as we
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* own broadcast_lock.
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*
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* However we can also be called from the event handler of
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* ce_broadcast_hrtimer itself when it expires. We cannot
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* restart the timer because we are in the callback, but we
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* can set the expiry time and let the callback return
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* HRTIMER_RESTART.
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*
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* Since we are in the idle loop at this point and because
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* hrtimer_{start/cancel} functions call into tracing,
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* calls to these functions must be bound within RCU_NONIDLE.
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*/
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RCU_NONIDLE({
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bc_moved = hrtimer_try_to_cancel(&bctimer) >= 0;
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if (bc_moved)
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hrtimer_start(&bctimer, expires,
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HRTIMER_MODE_ABS_PINNED);});
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if (bc_moved) {
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/* Bind the "device" to the cpu */
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bc->bound_on = smp_processor_id();
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} else if (bc->bound_on == smp_processor_id()) {
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hrtimer_set_expires(&bctimer, expires);
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}
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return 0;
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}
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static struct clock_event_device ce_broadcast_hrtimer = {
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.name = "bc_hrtimer",
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.set_state_shutdown = bc_shutdown,
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.set_next_ktime = bc_set_next,
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.features = CLOCK_EVT_FEAT_ONESHOT |
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CLOCK_EVT_FEAT_KTIME |
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CLOCK_EVT_FEAT_HRTIMER,
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.rating = 0,
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.bound_on = -1,
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.min_delta_ns = 1,
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.max_delta_ns = KTIME_MAX,
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.min_delta_ticks = 1,
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.max_delta_ticks = ULONG_MAX,
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.mult = 1,
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.shift = 0,
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.cpumask = cpu_all_mask,
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};
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static enum hrtimer_restart bc_handler(struct hrtimer *t)
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{
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ce_broadcast_hrtimer.event_handler(&ce_broadcast_hrtimer);
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if (clockevent_state_oneshot(&ce_broadcast_hrtimer))
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if (ce_broadcast_hrtimer.next_event != KTIME_MAX)
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return HRTIMER_RESTART;
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return HRTIMER_NORESTART;
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}
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void tick_setup_hrtimer_broadcast(void)
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{
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hrtimer_init(&bctimer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
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bctimer.function = bc_handler;
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clockevents_register_device(&ce_broadcast_hrtimer);
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}
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