![Tejun Heo](/assets/img/avatar_default.png)
Regardless of the previous CPU a timer was on, add_timer_on() currently simply sets timer->flags to the new CPU. As the caller must be seeing the timer as idle, this is locally fine, but the timer leaving the old base while unlocked can lead to race conditions as follows. Let's say timer was on cpu 0. cpu 0 cpu 1 ----------------------------------------------------------------------------- del_timer(timer) succeeds del_timer(timer) lock_timer_base(timer) locks cpu_0_base add_timer_on(timer, 1) spin_lock(&cpu_1_base->lock) timer->flags set to cpu_1_base operates on @timer operates on @timer This triggered with mod_delayed_work_on() which contains "if (del_timer()) add_timer_on()" sequence eventually leading to the following oops. BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<ffffffff810ca6e9>] detach_if_pending+0x69/0x1a0 ... Workqueue: wqthrash wqthrash_workfunc [wqthrash] task: ffff8800172ca680 ti: ffff8800172d0000 task.ti: ffff8800172d0000 RIP: 0010:[<ffffffff810ca6e9>] [<ffffffff810ca6e9>] detach_if_pending+0x69/0x1a0 ... Call Trace: [<ffffffff810cb0b4>] del_timer+0x44/0x60 [<ffffffff8106e836>] try_to_grab_pending+0xb6/0x160 [<ffffffff8106e913>] mod_delayed_work_on+0x33/0x80 [<ffffffffa0000081>] wqthrash_workfunc+0x61/0x90 [wqthrash] [<ffffffff8106dba8>] process_one_work+0x1e8/0x650 [<ffffffff8106e05e>] worker_thread+0x4e/0x450 [<ffffffff810746af>] kthread+0xef/0x110 [<ffffffff8185980f>] ret_from_fork+0x3f/0x70 Fix it by updating add_timer_on() to perform proper migration as __mod_timer() does. Reported-and-tested-by: Jeff Layton <jlayton@poochiereds.net> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Chris Worley <chris.worley@primarydata.com> Cc: bfields@fieldses.org Cc: Michael Skralivetsky <michael.skralivetsky@primarydata.com> Cc: Trond Myklebust <trond.myklebust@primarydata.com> Cc: Shaohua Li <shli@fb.com> Cc: Jeff Layton <jlayton@poochiereds.net> Cc: kernel-team@fb.com Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20151029103113.2f893924@tlielax.poochiereds.net Link: http://lkml.kernel.org/r/20151104171533.GI5749@mtj.duckdns.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
1719 lines
46 KiB
C
1719 lines
46 KiB
C
/*
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* linux/kernel/timer.c
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*
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* Kernel internal timers
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* 1997-01-28 Modified by Finn Arne Gangstad to make timers scale better.
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*
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* 1997-09-10 Updated NTP code according to technical memorandum Jan '96
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* "A Kernel Model for Precision Timekeeping" by Dave Mills
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* 1998-12-24 Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
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* serialize accesses to xtime/lost_ticks).
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* Copyright (C) 1998 Andrea Arcangeli
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* 1999-03-10 Improved NTP compatibility by Ulrich Windl
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* 2002-05-31 Move sys_sysinfo here and make its locking sane, Robert Love
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* 2000-10-05 Implemented scalable SMP per-CPU timer handling.
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* Copyright (C) 2000, 2001, 2002 Ingo Molnar
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* Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar
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*/
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#include <linux/kernel_stat.h>
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#include <linux/export.h>
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#include <linux/interrupt.h>
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#include <linux/percpu.h>
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/pid_namespace.h>
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#include <linux/notifier.h>
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#include <linux/thread_info.h>
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#include <linux/time.h>
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#include <linux/jiffies.h>
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#include <linux/posix-timers.h>
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#include <linux/cpu.h>
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#include <linux/syscalls.h>
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#include <linux/delay.h>
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#include <linux/tick.h>
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#include <linux/kallsyms.h>
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#include <linux/irq_work.h>
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#include <linux/sched.h>
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#include <linux/sched/sysctl.h>
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#include <linux/slab.h>
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#include <linux/compat.h>
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#include <asm/uaccess.h>
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#include <asm/unistd.h>
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#include <asm/div64.h>
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#include <asm/timex.h>
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#include <asm/io.h>
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#include "tick-internal.h"
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#define CREATE_TRACE_POINTS
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#include <trace/events/timer.h>
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__visible u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
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EXPORT_SYMBOL(jiffies_64);
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/*
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* per-CPU timer vector definitions:
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*/
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#define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6)
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#define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8)
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#define TVN_SIZE (1 << TVN_BITS)
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#define TVR_SIZE (1 << TVR_BITS)
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#define TVN_MASK (TVN_SIZE - 1)
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#define TVR_MASK (TVR_SIZE - 1)
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#define MAX_TVAL ((unsigned long)((1ULL << (TVR_BITS + 4*TVN_BITS)) - 1))
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struct tvec {
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struct hlist_head vec[TVN_SIZE];
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};
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struct tvec_root {
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struct hlist_head vec[TVR_SIZE];
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};
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struct tvec_base {
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spinlock_t lock;
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struct timer_list *running_timer;
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unsigned long timer_jiffies;
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unsigned long next_timer;
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unsigned long active_timers;
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unsigned long all_timers;
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int cpu;
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bool migration_enabled;
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bool nohz_active;
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struct tvec_root tv1;
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struct tvec tv2;
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struct tvec tv3;
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struct tvec tv4;
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struct tvec tv5;
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} ____cacheline_aligned;
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static DEFINE_PER_CPU(struct tvec_base, tvec_bases);
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#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
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unsigned int sysctl_timer_migration = 1;
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void timers_update_migration(bool update_nohz)
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{
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bool on = sysctl_timer_migration && tick_nohz_active;
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unsigned int cpu;
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/* Avoid the loop, if nothing to update */
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if (this_cpu_read(tvec_bases.migration_enabled) == on)
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return;
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for_each_possible_cpu(cpu) {
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per_cpu(tvec_bases.migration_enabled, cpu) = on;
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per_cpu(hrtimer_bases.migration_enabled, cpu) = on;
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if (!update_nohz)
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continue;
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per_cpu(tvec_bases.nohz_active, cpu) = true;
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per_cpu(hrtimer_bases.nohz_active, cpu) = true;
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}
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}
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int timer_migration_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp,
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loff_t *ppos)
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{
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static DEFINE_MUTEX(mutex);
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int ret;
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mutex_lock(&mutex);
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ret = proc_dointvec(table, write, buffer, lenp, ppos);
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if (!ret && write)
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timers_update_migration(false);
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mutex_unlock(&mutex);
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return ret;
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}
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static inline struct tvec_base *get_target_base(struct tvec_base *base,
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int pinned)
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{
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if (pinned || !base->migration_enabled)
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return this_cpu_ptr(&tvec_bases);
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return per_cpu_ptr(&tvec_bases, get_nohz_timer_target());
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}
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#else
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static inline struct tvec_base *get_target_base(struct tvec_base *base,
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int pinned)
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{
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return this_cpu_ptr(&tvec_bases);
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}
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#endif
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static unsigned long round_jiffies_common(unsigned long j, int cpu,
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bool force_up)
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{
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int rem;
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unsigned long original = j;
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/*
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* We don't want all cpus firing their timers at once hitting the
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* same lock or cachelines, so we skew each extra cpu with an extra
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* 3 jiffies. This 3 jiffies came originally from the mm/ code which
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* already did this.
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* The skew is done by adding 3*cpunr, then round, then subtract this
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* extra offset again.
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*/
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j += cpu * 3;
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rem = j % HZ;
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/*
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* If the target jiffie is just after a whole second (which can happen
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* due to delays of the timer irq, long irq off times etc etc) then
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* we should round down to the whole second, not up. Use 1/4th second
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* as cutoff for this rounding as an extreme upper bound for this.
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* But never round down if @force_up is set.
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*/
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if (rem < HZ/4 && !force_up) /* round down */
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j = j - rem;
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else /* round up */
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j = j - rem + HZ;
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/* now that we have rounded, subtract the extra skew again */
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j -= cpu * 3;
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/*
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* Make sure j is still in the future. Otherwise return the
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* unmodified value.
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*/
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return time_is_after_jiffies(j) ? j : original;
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}
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/**
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* __round_jiffies - function to round jiffies to a full second
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* @j: the time in (absolute) jiffies that should be rounded
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* @cpu: the processor number on which the timeout will happen
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*
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* __round_jiffies() rounds an absolute time in the future (in jiffies)
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* up or down to (approximately) full seconds. This is useful for timers
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* for which the exact time they fire does not matter too much, as long as
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* they fire approximately every X seconds.
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*
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* By rounding these timers to whole seconds, all such timers will fire
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* at the same time, rather than at various times spread out. The goal
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* of this is to have the CPU wake up less, which saves power.
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*
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* The exact rounding is skewed for each processor to avoid all
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* processors firing at the exact same time, which could lead
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* to lock contention or spurious cache line bouncing.
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*
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* The return value is the rounded version of the @j parameter.
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*/
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unsigned long __round_jiffies(unsigned long j, int cpu)
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{
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return round_jiffies_common(j, cpu, false);
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}
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EXPORT_SYMBOL_GPL(__round_jiffies);
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/**
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* __round_jiffies_relative - function to round jiffies to a full second
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* @j: the time in (relative) jiffies that should be rounded
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* @cpu: the processor number on which the timeout will happen
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*
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* __round_jiffies_relative() rounds a time delta in the future (in jiffies)
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* up or down to (approximately) full seconds. This is useful for timers
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* for which the exact time they fire does not matter too much, as long as
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* they fire approximately every X seconds.
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*
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* By rounding these timers to whole seconds, all such timers will fire
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* at the same time, rather than at various times spread out. The goal
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* of this is to have the CPU wake up less, which saves power.
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*
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* The exact rounding is skewed for each processor to avoid all
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* processors firing at the exact same time, which could lead
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* to lock contention or spurious cache line bouncing.
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*
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* The return value is the rounded version of the @j parameter.
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*/
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unsigned long __round_jiffies_relative(unsigned long j, int cpu)
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{
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unsigned long j0 = jiffies;
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/* Use j0 because jiffies might change while we run */
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return round_jiffies_common(j + j0, cpu, false) - j0;
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}
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EXPORT_SYMBOL_GPL(__round_jiffies_relative);
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/**
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* round_jiffies - function to round jiffies to a full second
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* @j: the time in (absolute) jiffies that should be rounded
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*
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* round_jiffies() rounds an absolute time in the future (in jiffies)
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* up or down to (approximately) full seconds. This is useful for timers
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* for which the exact time they fire does not matter too much, as long as
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* they fire approximately every X seconds.
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*
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* By rounding these timers to whole seconds, all such timers will fire
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* at the same time, rather than at various times spread out. The goal
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* of this is to have the CPU wake up less, which saves power.
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*
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* The return value is the rounded version of the @j parameter.
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*/
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unsigned long round_jiffies(unsigned long j)
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{
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return round_jiffies_common(j, raw_smp_processor_id(), false);
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}
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EXPORT_SYMBOL_GPL(round_jiffies);
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/**
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* round_jiffies_relative - function to round jiffies to a full second
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* @j: the time in (relative) jiffies that should be rounded
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*
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* round_jiffies_relative() rounds a time delta in the future (in jiffies)
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* up or down to (approximately) full seconds. This is useful for timers
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* for which the exact time they fire does not matter too much, as long as
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* they fire approximately every X seconds.
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*
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* By rounding these timers to whole seconds, all such timers will fire
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* at the same time, rather than at various times spread out. The goal
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* of this is to have the CPU wake up less, which saves power.
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*
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* The return value is the rounded version of the @j parameter.
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*/
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unsigned long round_jiffies_relative(unsigned long j)
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{
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return __round_jiffies_relative(j, raw_smp_processor_id());
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}
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EXPORT_SYMBOL_GPL(round_jiffies_relative);
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/**
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* __round_jiffies_up - function to round jiffies up to a full second
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* @j: the time in (absolute) jiffies that should be rounded
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* @cpu: the processor number on which the timeout will happen
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*
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* This is the same as __round_jiffies() except that it will never
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* round down. This is useful for timeouts for which the exact time
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* of firing does not matter too much, as long as they don't fire too
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* early.
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*/
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unsigned long __round_jiffies_up(unsigned long j, int cpu)
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{
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return round_jiffies_common(j, cpu, true);
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}
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EXPORT_SYMBOL_GPL(__round_jiffies_up);
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/**
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* __round_jiffies_up_relative - function to round jiffies up to a full second
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* @j: the time in (relative) jiffies that should be rounded
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* @cpu: the processor number on which the timeout will happen
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*
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* This is the same as __round_jiffies_relative() except that it will never
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* round down. This is useful for timeouts for which the exact time
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* of firing does not matter too much, as long as they don't fire too
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* early.
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*/
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unsigned long __round_jiffies_up_relative(unsigned long j, int cpu)
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{
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unsigned long j0 = jiffies;
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/* Use j0 because jiffies might change while we run */
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return round_jiffies_common(j + j0, cpu, true) - j0;
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}
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EXPORT_SYMBOL_GPL(__round_jiffies_up_relative);
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/**
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* round_jiffies_up - function to round jiffies up to a full second
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* @j: the time in (absolute) jiffies that should be rounded
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*
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* This is the same as round_jiffies() except that it will never
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* round down. This is useful for timeouts for which the exact time
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* of firing does not matter too much, as long as they don't fire too
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* early.
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*/
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unsigned long round_jiffies_up(unsigned long j)
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{
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return round_jiffies_common(j, raw_smp_processor_id(), true);
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}
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EXPORT_SYMBOL_GPL(round_jiffies_up);
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/**
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* round_jiffies_up_relative - function to round jiffies up to a full second
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* @j: the time in (relative) jiffies that should be rounded
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*
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* This is the same as round_jiffies_relative() except that it will never
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* round down. This is useful for timeouts for which the exact time
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* of firing does not matter too much, as long as they don't fire too
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* early.
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*/
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unsigned long round_jiffies_up_relative(unsigned long j)
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{
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return __round_jiffies_up_relative(j, raw_smp_processor_id());
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}
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EXPORT_SYMBOL_GPL(round_jiffies_up_relative);
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/**
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* set_timer_slack - set the allowed slack for a timer
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* @timer: the timer to be modified
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* @slack_hz: the amount of time (in jiffies) allowed for rounding
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*
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* Set the amount of time, in jiffies, that a certain timer has
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* in terms of slack. By setting this value, the timer subsystem
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* will schedule the actual timer somewhere between
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* the time mod_timer() asks for, and that time plus the slack.
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*
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* By setting the slack to -1, a percentage of the delay is used
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* instead.
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*/
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void set_timer_slack(struct timer_list *timer, int slack_hz)
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{
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timer->slack = slack_hz;
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}
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EXPORT_SYMBOL_GPL(set_timer_slack);
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static void
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__internal_add_timer(struct tvec_base *base, struct timer_list *timer)
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{
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unsigned long expires = timer->expires;
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unsigned long idx = expires - base->timer_jiffies;
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struct hlist_head *vec;
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if (idx < TVR_SIZE) {
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int i = expires & TVR_MASK;
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vec = base->tv1.vec + i;
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} else if (idx < 1 << (TVR_BITS + TVN_BITS)) {
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int i = (expires >> TVR_BITS) & TVN_MASK;
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vec = base->tv2.vec + i;
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} else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) {
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int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
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vec = base->tv3.vec + i;
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} else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) {
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int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK;
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vec = base->tv4.vec + i;
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} else if ((signed long) idx < 0) {
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/*
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* Can happen if you add a timer with expires == jiffies,
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* or you set a timer to go off in the past
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*/
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vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK);
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} else {
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int i;
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/* If the timeout is larger than MAX_TVAL (on 64-bit
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* architectures or with CONFIG_BASE_SMALL=1) then we
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* use the maximum timeout.
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*/
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if (idx > MAX_TVAL) {
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idx = MAX_TVAL;
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expires = idx + base->timer_jiffies;
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}
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i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
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vec = base->tv5.vec + i;
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}
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hlist_add_head(&timer->entry, vec);
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}
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static void internal_add_timer(struct tvec_base *base, struct timer_list *timer)
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{
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/* Advance base->jiffies, if the base is empty */
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if (!base->all_timers++)
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base->timer_jiffies = jiffies;
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__internal_add_timer(base, timer);
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/*
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* Update base->active_timers and base->next_timer
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*/
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if (!(timer->flags & TIMER_DEFERRABLE)) {
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if (!base->active_timers++ ||
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time_before(timer->expires, base->next_timer))
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base->next_timer = timer->expires;
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}
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/*
|
|
* Check whether the other CPU is in dynticks mode and needs
|
|
* to be triggered to reevaluate the timer wheel.
|
|
* We are protected against the other CPU fiddling
|
|
* with the timer by holding the timer base lock. This also
|
|
* makes sure that a CPU on the way to stop its tick can not
|
|
* evaluate the timer wheel.
|
|
*
|
|
* Spare the IPI for deferrable timers on idle targets though.
|
|
* The next busy ticks will take care of it. Except full dynticks
|
|
* require special care against races with idle_cpu(), lets deal
|
|
* with that later.
|
|
*/
|
|
if (base->nohz_active) {
|
|
if (!(timer->flags & TIMER_DEFERRABLE) ||
|
|
tick_nohz_full_cpu(base->cpu))
|
|
wake_up_nohz_cpu(base->cpu);
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_TIMER_STATS
|
|
void __timer_stats_timer_set_start_info(struct timer_list *timer, void *addr)
|
|
{
|
|
if (timer->start_site)
|
|
return;
|
|
|
|
timer->start_site = addr;
|
|
memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
|
|
timer->start_pid = current->pid;
|
|
}
|
|
|
|
static void timer_stats_account_timer(struct timer_list *timer)
|
|
{
|
|
void *site;
|
|
|
|
/*
|
|
* start_site can be concurrently reset by
|
|
* timer_stats_timer_clear_start_info()
|
|
*/
|
|
site = READ_ONCE(timer->start_site);
|
|
if (likely(!site))
|
|
return;
|
|
|
|
timer_stats_update_stats(timer, timer->start_pid, site,
|
|
timer->function, timer->start_comm,
|
|
timer->flags);
|
|
}
|
|
|
|
#else
|
|
static void timer_stats_account_timer(struct timer_list *timer) {}
|
|
#endif
|
|
|
|
#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
|
|
|
|
static struct debug_obj_descr timer_debug_descr;
|
|
|
|
static void *timer_debug_hint(void *addr)
|
|
{
|
|
return ((struct timer_list *) addr)->function;
|
|
}
|
|
|
|
/*
|
|
* fixup_init is called when:
|
|
* - an active object is initialized
|
|
*/
|
|
static int timer_fixup_init(void *addr, enum debug_obj_state state)
|
|
{
|
|
struct timer_list *timer = addr;
|
|
|
|
switch (state) {
|
|
case ODEBUG_STATE_ACTIVE:
|
|
del_timer_sync(timer);
|
|
debug_object_init(timer, &timer_debug_descr);
|
|
return 1;
|
|
default:
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/* Stub timer callback for improperly used timers. */
|
|
static void stub_timer(unsigned long data)
|
|
{
|
|
WARN_ON(1);
|
|
}
|
|
|
|
/*
|
|
* fixup_activate is called when:
|
|
* - an active object is activated
|
|
* - an unknown object is activated (might be a statically initialized object)
|
|
*/
|
|
static int timer_fixup_activate(void *addr, enum debug_obj_state state)
|
|
{
|
|
struct timer_list *timer = addr;
|
|
|
|
switch (state) {
|
|
|
|
case ODEBUG_STATE_NOTAVAILABLE:
|
|
/*
|
|
* This is not really a fixup. The timer was
|
|
* statically initialized. We just make sure that it
|
|
* is tracked in the object tracker.
|
|
*/
|
|
if (timer->entry.pprev == NULL &&
|
|
timer->entry.next == TIMER_ENTRY_STATIC) {
|
|
debug_object_init(timer, &timer_debug_descr);
|
|
debug_object_activate(timer, &timer_debug_descr);
|
|
return 0;
|
|
} else {
|
|
setup_timer(timer, stub_timer, 0);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
|
|
case ODEBUG_STATE_ACTIVE:
|
|
WARN_ON(1);
|
|
|
|
default:
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* fixup_free is called when:
|
|
* - an active object is freed
|
|
*/
|
|
static int timer_fixup_free(void *addr, enum debug_obj_state state)
|
|
{
|
|
struct timer_list *timer = addr;
|
|
|
|
switch (state) {
|
|
case ODEBUG_STATE_ACTIVE:
|
|
del_timer_sync(timer);
|
|
debug_object_free(timer, &timer_debug_descr);
|
|
return 1;
|
|
default:
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* fixup_assert_init is called when:
|
|
* - an untracked/uninit-ed object is found
|
|
*/
|
|
static int timer_fixup_assert_init(void *addr, enum debug_obj_state state)
|
|
{
|
|
struct timer_list *timer = addr;
|
|
|
|
switch (state) {
|
|
case ODEBUG_STATE_NOTAVAILABLE:
|
|
if (timer->entry.next == TIMER_ENTRY_STATIC) {
|
|
/*
|
|
* This is not really a fixup. The timer was
|
|
* statically initialized. We just make sure that it
|
|
* is tracked in the object tracker.
|
|
*/
|
|
debug_object_init(timer, &timer_debug_descr);
|
|
return 0;
|
|
} else {
|
|
setup_timer(timer, stub_timer, 0);
|
|
return 1;
|
|
}
|
|
default:
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
static struct debug_obj_descr timer_debug_descr = {
|
|
.name = "timer_list",
|
|
.debug_hint = timer_debug_hint,
|
|
.fixup_init = timer_fixup_init,
|
|
.fixup_activate = timer_fixup_activate,
|
|
.fixup_free = timer_fixup_free,
|
|
.fixup_assert_init = timer_fixup_assert_init,
|
|
};
|
|
|
|
static inline void debug_timer_init(struct timer_list *timer)
|
|
{
|
|
debug_object_init(timer, &timer_debug_descr);
|
|
}
|
|
|
|
static inline void debug_timer_activate(struct timer_list *timer)
|
|
{
|
|
debug_object_activate(timer, &timer_debug_descr);
|
|
}
|
|
|
|
static inline void debug_timer_deactivate(struct timer_list *timer)
|
|
{
|
|
debug_object_deactivate(timer, &timer_debug_descr);
|
|
}
|
|
|
|
static inline void debug_timer_free(struct timer_list *timer)
|
|
{
|
|
debug_object_free(timer, &timer_debug_descr);
|
|
}
|
|
|
|
static inline void debug_timer_assert_init(struct timer_list *timer)
|
|
{
|
|
debug_object_assert_init(timer, &timer_debug_descr);
|
|
}
|
|
|
|
static void do_init_timer(struct timer_list *timer, unsigned int flags,
|
|
const char *name, struct lock_class_key *key);
|
|
|
|
void init_timer_on_stack_key(struct timer_list *timer, unsigned int flags,
|
|
const char *name, struct lock_class_key *key)
|
|
{
|
|
debug_object_init_on_stack(timer, &timer_debug_descr);
|
|
do_init_timer(timer, flags, name, key);
|
|
}
|
|
EXPORT_SYMBOL_GPL(init_timer_on_stack_key);
|
|
|
|
void destroy_timer_on_stack(struct timer_list *timer)
|
|
{
|
|
debug_object_free(timer, &timer_debug_descr);
|
|
}
|
|
EXPORT_SYMBOL_GPL(destroy_timer_on_stack);
|
|
|
|
#else
|
|
static inline void debug_timer_init(struct timer_list *timer) { }
|
|
static inline void debug_timer_activate(struct timer_list *timer) { }
|
|
static inline void debug_timer_deactivate(struct timer_list *timer) { }
|
|
static inline void debug_timer_assert_init(struct timer_list *timer) { }
|
|
#endif
|
|
|
|
static inline void debug_init(struct timer_list *timer)
|
|
{
|
|
debug_timer_init(timer);
|
|
trace_timer_init(timer);
|
|
}
|
|
|
|
static inline void
|
|
debug_activate(struct timer_list *timer, unsigned long expires)
|
|
{
|
|
debug_timer_activate(timer);
|
|
trace_timer_start(timer, expires, timer->flags);
|
|
}
|
|
|
|
static inline void debug_deactivate(struct timer_list *timer)
|
|
{
|
|
debug_timer_deactivate(timer);
|
|
trace_timer_cancel(timer);
|
|
}
|
|
|
|
static inline void debug_assert_init(struct timer_list *timer)
|
|
{
|
|
debug_timer_assert_init(timer);
|
|
}
|
|
|
|
static void do_init_timer(struct timer_list *timer, unsigned int flags,
|
|
const char *name, struct lock_class_key *key)
|
|
{
|
|
timer->entry.pprev = NULL;
|
|
timer->flags = flags | raw_smp_processor_id();
|
|
timer->slack = -1;
|
|
#ifdef CONFIG_TIMER_STATS
|
|
timer->start_site = NULL;
|
|
timer->start_pid = -1;
|
|
memset(timer->start_comm, 0, TASK_COMM_LEN);
|
|
#endif
|
|
lockdep_init_map(&timer->lockdep_map, name, key, 0);
|
|
}
|
|
|
|
/**
|
|
* init_timer_key - initialize a timer
|
|
* @timer: the timer to be initialized
|
|
* @flags: timer flags
|
|
* @name: name of the timer
|
|
* @key: lockdep class key of the fake lock used for tracking timer
|
|
* sync lock dependencies
|
|
*
|
|
* init_timer_key() must be done to a timer prior calling *any* of the
|
|
* other timer functions.
|
|
*/
|
|
void init_timer_key(struct timer_list *timer, unsigned int flags,
|
|
const char *name, struct lock_class_key *key)
|
|
{
|
|
debug_init(timer);
|
|
do_init_timer(timer, flags, name, key);
|
|
}
|
|
EXPORT_SYMBOL(init_timer_key);
|
|
|
|
static inline void detach_timer(struct timer_list *timer, bool clear_pending)
|
|
{
|
|
struct hlist_node *entry = &timer->entry;
|
|
|
|
debug_deactivate(timer);
|
|
|
|
__hlist_del(entry);
|
|
if (clear_pending)
|
|
entry->pprev = NULL;
|
|
entry->next = LIST_POISON2;
|
|
}
|
|
|
|
static inline void
|
|
detach_expired_timer(struct timer_list *timer, struct tvec_base *base)
|
|
{
|
|
detach_timer(timer, true);
|
|
if (!(timer->flags & TIMER_DEFERRABLE))
|
|
base->active_timers--;
|
|
base->all_timers--;
|
|
}
|
|
|
|
static int detach_if_pending(struct timer_list *timer, struct tvec_base *base,
|
|
bool clear_pending)
|
|
{
|
|
if (!timer_pending(timer))
|
|
return 0;
|
|
|
|
detach_timer(timer, clear_pending);
|
|
if (!(timer->flags & TIMER_DEFERRABLE)) {
|
|
base->active_timers--;
|
|
if (timer->expires == base->next_timer)
|
|
base->next_timer = base->timer_jiffies;
|
|
}
|
|
/* If this was the last timer, advance base->jiffies */
|
|
if (!--base->all_timers)
|
|
base->timer_jiffies = jiffies;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* We are using hashed locking: holding per_cpu(tvec_bases).lock
|
|
* means that all timers which are tied to this base via timer->base are
|
|
* locked, and the base itself is locked too.
|
|
*
|
|
* So __run_timers/migrate_timers can safely modify all timers which could
|
|
* be found on ->tvX lists.
|
|
*
|
|
* When the timer's base is locked and removed from the list, the
|
|
* TIMER_MIGRATING flag is set, FIXME
|
|
*/
|
|
static struct tvec_base *lock_timer_base(struct timer_list *timer,
|
|
unsigned long *flags)
|
|
__acquires(timer->base->lock)
|
|
{
|
|
for (;;) {
|
|
u32 tf = timer->flags;
|
|
struct tvec_base *base;
|
|
|
|
if (!(tf & TIMER_MIGRATING)) {
|
|
base = per_cpu_ptr(&tvec_bases, tf & TIMER_CPUMASK);
|
|
spin_lock_irqsave(&base->lock, *flags);
|
|
if (timer->flags == tf)
|
|
return base;
|
|
spin_unlock_irqrestore(&base->lock, *flags);
|
|
}
|
|
cpu_relax();
|
|
}
|
|
}
|
|
|
|
static inline int
|
|
__mod_timer(struct timer_list *timer, unsigned long expires,
|
|
bool pending_only, int pinned)
|
|
{
|
|
struct tvec_base *base, *new_base;
|
|
unsigned long flags;
|
|
int ret = 0;
|
|
|
|
timer_stats_timer_set_start_info(timer);
|
|
BUG_ON(!timer->function);
|
|
|
|
base = lock_timer_base(timer, &flags);
|
|
|
|
ret = detach_if_pending(timer, base, false);
|
|
if (!ret && pending_only)
|
|
goto out_unlock;
|
|
|
|
debug_activate(timer, expires);
|
|
|
|
new_base = get_target_base(base, pinned);
|
|
|
|
if (base != new_base) {
|
|
/*
|
|
* We are trying to schedule the timer on the local CPU.
|
|
* However we can't change timer's base while it is running,
|
|
* otherwise del_timer_sync() can't detect that the timer's
|
|
* handler yet has not finished. This also guarantees that
|
|
* the timer is serialized wrt itself.
|
|
*/
|
|
if (likely(base->running_timer != timer)) {
|
|
/* See the comment in lock_timer_base() */
|
|
timer->flags |= TIMER_MIGRATING;
|
|
|
|
spin_unlock(&base->lock);
|
|
base = new_base;
|
|
spin_lock(&base->lock);
|
|
WRITE_ONCE(timer->flags,
|
|
(timer->flags & ~TIMER_BASEMASK) | base->cpu);
|
|
}
|
|
}
|
|
|
|
timer->expires = expires;
|
|
internal_add_timer(base, timer);
|
|
|
|
out_unlock:
|
|
spin_unlock_irqrestore(&base->lock, flags);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* mod_timer_pending - modify a pending timer's timeout
|
|
* @timer: the pending timer to be modified
|
|
* @expires: new timeout in jiffies
|
|
*
|
|
* mod_timer_pending() is the same for pending timers as mod_timer(),
|
|
* but will not re-activate and modify already deleted timers.
|
|
*
|
|
* It is useful for unserialized use of timers.
|
|
*/
|
|
int mod_timer_pending(struct timer_list *timer, unsigned long expires)
|
|
{
|
|
return __mod_timer(timer, expires, true, TIMER_NOT_PINNED);
|
|
}
|
|
EXPORT_SYMBOL(mod_timer_pending);
|
|
|
|
/*
|
|
* Decide where to put the timer while taking the slack into account
|
|
*
|
|
* Algorithm:
|
|
* 1) calculate the maximum (absolute) time
|
|
* 2) calculate the highest bit where the expires and new max are different
|
|
* 3) use this bit to make a mask
|
|
* 4) use the bitmask to round down the maximum time, so that all last
|
|
* bits are zeros
|
|
*/
|
|
static inline
|
|
unsigned long apply_slack(struct timer_list *timer, unsigned long expires)
|
|
{
|
|
unsigned long expires_limit, mask;
|
|
int bit;
|
|
|
|
if (timer->slack >= 0) {
|
|
expires_limit = expires + timer->slack;
|
|
} else {
|
|
long delta = expires - jiffies;
|
|
|
|
if (delta < 256)
|
|
return expires;
|
|
|
|
expires_limit = expires + delta / 256;
|
|
}
|
|
mask = expires ^ expires_limit;
|
|
if (mask == 0)
|
|
return expires;
|
|
|
|
bit = __fls(mask);
|
|
|
|
mask = (1UL << bit) - 1;
|
|
|
|
expires_limit = expires_limit & ~(mask);
|
|
|
|
return expires_limit;
|
|
}
|
|
|
|
/**
|
|
* mod_timer - modify a timer's timeout
|
|
* @timer: the timer to be modified
|
|
* @expires: new timeout in jiffies
|
|
*
|
|
* mod_timer() is a more efficient way to update the expire field of an
|
|
* active timer (if the timer is inactive it will be activated)
|
|
*
|
|
* mod_timer(timer, expires) is equivalent to:
|
|
*
|
|
* del_timer(timer); timer->expires = expires; add_timer(timer);
|
|
*
|
|
* Note that if there are multiple unserialized concurrent users of the
|
|
* same timer, then mod_timer() is the only safe way to modify the timeout,
|
|
* since add_timer() cannot modify an already running timer.
|
|
*
|
|
* The function returns whether it has modified a pending timer or not.
|
|
* (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
|
|
* active timer returns 1.)
|
|
*/
|
|
int mod_timer(struct timer_list *timer, unsigned long expires)
|
|
{
|
|
expires = apply_slack(timer, expires);
|
|
|
|
/*
|
|
* This is a common optimization triggered by the
|
|
* networking code - if the timer is re-modified
|
|
* to be the same thing then just return:
|
|
*/
|
|
if (timer_pending(timer) && timer->expires == expires)
|
|
return 1;
|
|
|
|
return __mod_timer(timer, expires, false, TIMER_NOT_PINNED);
|
|
}
|
|
EXPORT_SYMBOL(mod_timer);
|
|
|
|
/**
|
|
* mod_timer_pinned - modify a timer's timeout
|
|
* @timer: the timer to be modified
|
|
* @expires: new timeout in jiffies
|
|
*
|
|
* mod_timer_pinned() is a way to update the expire field of an
|
|
* active timer (if the timer is inactive it will be activated)
|
|
* and to ensure that the timer is scheduled on the current CPU.
|
|
*
|
|
* Note that this does not prevent the timer from being migrated
|
|
* when the current CPU goes offline. If this is a problem for
|
|
* you, use CPU-hotplug notifiers to handle it correctly, for
|
|
* example, cancelling the timer when the corresponding CPU goes
|
|
* offline.
|
|
*
|
|
* mod_timer_pinned(timer, expires) is equivalent to:
|
|
*
|
|
* del_timer(timer); timer->expires = expires; add_timer(timer);
|
|
*/
|
|
int mod_timer_pinned(struct timer_list *timer, unsigned long expires)
|
|
{
|
|
if (timer->expires == expires && timer_pending(timer))
|
|
return 1;
|
|
|
|
return __mod_timer(timer, expires, false, TIMER_PINNED);
|
|
}
|
|
EXPORT_SYMBOL(mod_timer_pinned);
|
|
|
|
/**
|
|
* add_timer - start a timer
|
|
* @timer: the timer to be added
|
|
*
|
|
* The kernel will do a ->function(->data) callback from the
|
|
* timer interrupt at the ->expires point in the future. The
|
|
* current time is 'jiffies'.
|
|
*
|
|
* The timer's ->expires, ->function (and if the handler uses it, ->data)
|
|
* fields must be set prior calling this function.
|
|
*
|
|
* Timers with an ->expires field in the past will be executed in the next
|
|
* timer tick.
|
|
*/
|
|
void add_timer(struct timer_list *timer)
|
|
{
|
|
BUG_ON(timer_pending(timer));
|
|
mod_timer(timer, timer->expires);
|
|
}
|
|
EXPORT_SYMBOL(add_timer);
|
|
|
|
/**
|
|
* add_timer_on - start a timer on a particular CPU
|
|
* @timer: the timer to be added
|
|
* @cpu: the CPU to start it on
|
|
*
|
|
* This is not very scalable on SMP. Double adds are not possible.
|
|
*/
|
|
void add_timer_on(struct timer_list *timer, int cpu)
|
|
{
|
|
struct tvec_base *new_base = per_cpu_ptr(&tvec_bases, cpu);
|
|
struct tvec_base *base;
|
|
unsigned long flags;
|
|
|
|
timer_stats_timer_set_start_info(timer);
|
|
BUG_ON(timer_pending(timer) || !timer->function);
|
|
|
|
/*
|
|
* If @timer was on a different CPU, it should be migrated with the
|
|
* old base locked to prevent other operations proceeding with the
|
|
* wrong base locked. See lock_timer_base().
|
|
*/
|
|
base = lock_timer_base(timer, &flags);
|
|
if (base != new_base) {
|
|
timer->flags |= TIMER_MIGRATING;
|
|
|
|
spin_unlock(&base->lock);
|
|
base = new_base;
|
|
spin_lock(&base->lock);
|
|
WRITE_ONCE(timer->flags,
|
|
(timer->flags & ~TIMER_BASEMASK) | cpu);
|
|
}
|
|
|
|
debug_activate(timer, timer->expires);
|
|
internal_add_timer(base, timer);
|
|
spin_unlock_irqrestore(&base->lock, flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(add_timer_on);
|
|
|
|
/**
|
|
* del_timer - deactive a timer.
|
|
* @timer: the timer to be deactivated
|
|
*
|
|
* del_timer() deactivates a timer - this works on both active and inactive
|
|
* timers.
|
|
*
|
|
* The function returns whether it has deactivated a pending timer or not.
|
|
* (ie. del_timer() of an inactive timer returns 0, del_timer() of an
|
|
* active timer returns 1.)
|
|
*/
|
|
int del_timer(struct timer_list *timer)
|
|
{
|
|
struct tvec_base *base;
|
|
unsigned long flags;
|
|
int ret = 0;
|
|
|
|
debug_assert_init(timer);
|
|
|
|
timer_stats_timer_clear_start_info(timer);
|
|
if (timer_pending(timer)) {
|
|
base = lock_timer_base(timer, &flags);
|
|
ret = detach_if_pending(timer, base, true);
|
|
spin_unlock_irqrestore(&base->lock, flags);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(del_timer);
|
|
|
|
/**
|
|
* try_to_del_timer_sync - Try to deactivate a timer
|
|
* @timer: timer do del
|
|
*
|
|
* This function tries to deactivate a timer. Upon successful (ret >= 0)
|
|
* exit the timer is not queued and the handler is not running on any CPU.
|
|
*/
|
|
int try_to_del_timer_sync(struct timer_list *timer)
|
|
{
|
|
struct tvec_base *base;
|
|
unsigned long flags;
|
|
int ret = -1;
|
|
|
|
debug_assert_init(timer);
|
|
|
|
base = lock_timer_base(timer, &flags);
|
|
|
|
if (base->running_timer != timer) {
|
|
timer_stats_timer_clear_start_info(timer);
|
|
ret = detach_if_pending(timer, base, true);
|
|
}
|
|
spin_unlock_irqrestore(&base->lock, flags);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(try_to_del_timer_sync);
|
|
|
|
#ifdef CONFIG_SMP
|
|
/**
|
|
* del_timer_sync - deactivate a timer and wait for the handler to finish.
|
|
* @timer: the timer to be deactivated
|
|
*
|
|
* This function only differs from del_timer() on SMP: besides deactivating
|
|
* the timer it also makes sure the handler has finished executing on other
|
|
* CPUs.
|
|
*
|
|
* Synchronization rules: Callers must prevent restarting of the timer,
|
|
* otherwise this function is meaningless. It must not be called from
|
|
* interrupt contexts unless the timer is an irqsafe one. The caller must
|
|
* not hold locks which would prevent completion of the timer's
|
|
* handler. The timer's handler must not call add_timer_on(). Upon exit the
|
|
* timer is not queued and the handler is not running on any CPU.
|
|
*
|
|
* Note: For !irqsafe timers, you must not hold locks that are held in
|
|
* interrupt context while calling this function. Even if the lock has
|
|
* nothing to do with the timer in question. Here's why:
|
|
*
|
|
* CPU0 CPU1
|
|
* ---- ----
|
|
* <SOFTIRQ>
|
|
* call_timer_fn();
|
|
* base->running_timer = mytimer;
|
|
* spin_lock_irq(somelock);
|
|
* <IRQ>
|
|
* spin_lock(somelock);
|
|
* del_timer_sync(mytimer);
|
|
* while (base->running_timer == mytimer);
|
|
*
|
|
* Now del_timer_sync() will never return and never release somelock.
|
|
* The interrupt on the other CPU is waiting to grab somelock but
|
|
* it has interrupted the softirq that CPU0 is waiting to finish.
|
|
*
|
|
* The function returns whether it has deactivated a pending timer or not.
|
|
*/
|
|
int del_timer_sync(struct timer_list *timer)
|
|
{
|
|
#ifdef CONFIG_LOCKDEP
|
|
unsigned long flags;
|
|
|
|
/*
|
|
* If lockdep gives a backtrace here, please reference
|
|
* the synchronization rules above.
|
|
*/
|
|
local_irq_save(flags);
|
|
lock_map_acquire(&timer->lockdep_map);
|
|
lock_map_release(&timer->lockdep_map);
|
|
local_irq_restore(flags);
|
|
#endif
|
|
/*
|
|
* don't use it in hardirq context, because it
|
|
* could lead to deadlock.
|
|
*/
|
|
WARN_ON(in_irq() && !(timer->flags & TIMER_IRQSAFE));
|
|
for (;;) {
|
|
int ret = try_to_del_timer_sync(timer);
|
|
if (ret >= 0)
|
|
return ret;
|
|
cpu_relax();
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(del_timer_sync);
|
|
#endif
|
|
|
|
static int cascade(struct tvec_base *base, struct tvec *tv, int index)
|
|
{
|
|
/* cascade all the timers from tv up one level */
|
|
struct timer_list *timer;
|
|
struct hlist_node *tmp;
|
|
struct hlist_head tv_list;
|
|
|
|
hlist_move_list(tv->vec + index, &tv_list);
|
|
|
|
/*
|
|
* We are removing _all_ timers from the list, so we
|
|
* don't have to detach them individually.
|
|
*/
|
|
hlist_for_each_entry_safe(timer, tmp, &tv_list, entry) {
|
|
/* No accounting, while moving them */
|
|
__internal_add_timer(base, timer);
|
|
}
|
|
|
|
return index;
|
|
}
|
|
|
|
static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long),
|
|
unsigned long data)
|
|
{
|
|
int count = preempt_count();
|
|
|
|
#ifdef CONFIG_LOCKDEP
|
|
/*
|
|
* It is permissible to free the timer from inside the
|
|
* function that is called from it, this we need to take into
|
|
* account for lockdep too. To avoid bogus "held lock freed"
|
|
* warnings as well as problems when looking into
|
|
* timer->lockdep_map, make a copy and use that here.
|
|
*/
|
|
struct lockdep_map lockdep_map;
|
|
|
|
lockdep_copy_map(&lockdep_map, &timer->lockdep_map);
|
|
#endif
|
|
/*
|
|
* Couple the lock chain with the lock chain at
|
|
* del_timer_sync() by acquiring the lock_map around the fn()
|
|
* call here and in del_timer_sync().
|
|
*/
|
|
lock_map_acquire(&lockdep_map);
|
|
|
|
trace_timer_expire_entry(timer);
|
|
fn(data);
|
|
trace_timer_expire_exit(timer);
|
|
|
|
lock_map_release(&lockdep_map);
|
|
|
|
if (count != preempt_count()) {
|
|
WARN_ONCE(1, "timer: %pF preempt leak: %08x -> %08x\n",
|
|
fn, count, preempt_count());
|
|
/*
|
|
* Restore the preempt count. That gives us a decent
|
|
* chance to survive and extract information. If the
|
|
* callback kept a lock held, bad luck, but not worse
|
|
* than the BUG() we had.
|
|
*/
|
|
preempt_count_set(count);
|
|
}
|
|
}
|
|
|
|
#define INDEX(N) ((base->timer_jiffies >> (TVR_BITS + (N) * TVN_BITS)) & TVN_MASK)
|
|
|
|
/**
|
|
* __run_timers - run all expired timers (if any) on this CPU.
|
|
* @base: the timer vector to be processed.
|
|
*
|
|
* This function cascades all vectors and executes all expired timer
|
|
* vectors.
|
|
*/
|
|
static inline void __run_timers(struct tvec_base *base)
|
|
{
|
|
struct timer_list *timer;
|
|
|
|
spin_lock_irq(&base->lock);
|
|
|
|
while (time_after_eq(jiffies, base->timer_jiffies)) {
|
|
struct hlist_head work_list;
|
|
struct hlist_head *head = &work_list;
|
|
int index;
|
|
|
|
if (!base->all_timers) {
|
|
base->timer_jiffies = jiffies;
|
|
break;
|
|
}
|
|
|
|
index = base->timer_jiffies & TVR_MASK;
|
|
|
|
/*
|
|
* Cascade timers:
|
|
*/
|
|
if (!index &&
|
|
(!cascade(base, &base->tv2, INDEX(0))) &&
|
|
(!cascade(base, &base->tv3, INDEX(1))) &&
|
|
!cascade(base, &base->tv4, INDEX(2)))
|
|
cascade(base, &base->tv5, INDEX(3));
|
|
++base->timer_jiffies;
|
|
hlist_move_list(base->tv1.vec + index, head);
|
|
while (!hlist_empty(head)) {
|
|
void (*fn)(unsigned long);
|
|
unsigned long data;
|
|
bool irqsafe;
|
|
|
|
timer = hlist_entry(head->first, struct timer_list, entry);
|
|
fn = timer->function;
|
|
data = timer->data;
|
|
irqsafe = timer->flags & TIMER_IRQSAFE;
|
|
|
|
timer_stats_account_timer(timer);
|
|
|
|
base->running_timer = timer;
|
|
detach_expired_timer(timer, base);
|
|
|
|
if (irqsafe) {
|
|
spin_unlock(&base->lock);
|
|
call_timer_fn(timer, fn, data);
|
|
spin_lock(&base->lock);
|
|
} else {
|
|
spin_unlock_irq(&base->lock);
|
|
call_timer_fn(timer, fn, data);
|
|
spin_lock_irq(&base->lock);
|
|
}
|
|
}
|
|
}
|
|
base->running_timer = NULL;
|
|
spin_unlock_irq(&base->lock);
|
|
}
|
|
|
|
#ifdef CONFIG_NO_HZ_COMMON
|
|
/*
|
|
* Find out when the next timer event is due to happen. This
|
|
* is used on S/390 to stop all activity when a CPU is idle.
|
|
* This function needs to be called with interrupts disabled.
|
|
*/
|
|
static unsigned long __next_timer_interrupt(struct tvec_base *base)
|
|
{
|
|
unsigned long timer_jiffies = base->timer_jiffies;
|
|
unsigned long expires = timer_jiffies + NEXT_TIMER_MAX_DELTA;
|
|
int index, slot, array, found = 0;
|
|
struct timer_list *nte;
|
|
struct tvec *varray[4];
|
|
|
|
/* Look for timer events in tv1. */
|
|
index = slot = timer_jiffies & TVR_MASK;
|
|
do {
|
|
hlist_for_each_entry(nte, base->tv1.vec + slot, entry) {
|
|
if (nte->flags & TIMER_DEFERRABLE)
|
|
continue;
|
|
|
|
found = 1;
|
|
expires = nte->expires;
|
|
/* Look at the cascade bucket(s)? */
|
|
if (!index || slot < index)
|
|
goto cascade;
|
|
return expires;
|
|
}
|
|
slot = (slot + 1) & TVR_MASK;
|
|
} while (slot != index);
|
|
|
|
cascade:
|
|
/* Calculate the next cascade event */
|
|
if (index)
|
|
timer_jiffies += TVR_SIZE - index;
|
|
timer_jiffies >>= TVR_BITS;
|
|
|
|
/* Check tv2-tv5. */
|
|
varray[0] = &base->tv2;
|
|
varray[1] = &base->tv3;
|
|
varray[2] = &base->tv4;
|
|
varray[3] = &base->tv5;
|
|
|
|
for (array = 0; array < 4; array++) {
|
|
struct tvec *varp = varray[array];
|
|
|
|
index = slot = timer_jiffies & TVN_MASK;
|
|
do {
|
|
hlist_for_each_entry(nte, varp->vec + slot, entry) {
|
|
if (nte->flags & TIMER_DEFERRABLE)
|
|
continue;
|
|
|
|
found = 1;
|
|
if (time_before(nte->expires, expires))
|
|
expires = nte->expires;
|
|
}
|
|
/*
|
|
* Do we still search for the first timer or are
|
|
* we looking up the cascade buckets ?
|
|
*/
|
|
if (found) {
|
|
/* Look at the cascade bucket(s)? */
|
|
if (!index || slot < index)
|
|
break;
|
|
return expires;
|
|
}
|
|
slot = (slot + 1) & TVN_MASK;
|
|
} while (slot != index);
|
|
|
|
if (index)
|
|
timer_jiffies += TVN_SIZE - index;
|
|
timer_jiffies >>= TVN_BITS;
|
|
}
|
|
return expires;
|
|
}
|
|
|
|
/*
|
|
* Check, if the next hrtimer event is before the next timer wheel
|
|
* event:
|
|
*/
|
|
static u64 cmp_next_hrtimer_event(u64 basem, u64 expires)
|
|
{
|
|
u64 nextevt = hrtimer_get_next_event();
|
|
|
|
/*
|
|
* If high resolution timers are enabled
|
|
* hrtimer_get_next_event() returns KTIME_MAX.
|
|
*/
|
|
if (expires <= nextevt)
|
|
return expires;
|
|
|
|
/*
|
|
* If the next timer is already expired, return the tick base
|
|
* time so the tick is fired immediately.
|
|
*/
|
|
if (nextevt <= basem)
|
|
return basem;
|
|
|
|
/*
|
|
* Round up to the next jiffie. High resolution timers are
|
|
* off, so the hrtimers are expired in the tick and we need to
|
|
* make sure that this tick really expires the timer to avoid
|
|
* a ping pong of the nohz stop code.
|
|
*
|
|
* Use DIV_ROUND_UP_ULL to prevent gcc calling __divdi3
|
|
*/
|
|
return DIV_ROUND_UP_ULL(nextevt, TICK_NSEC) * TICK_NSEC;
|
|
}
|
|
|
|
/**
|
|
* get_next_timer_interrupt - return the time (clock mono) of the next timer
|
|
* @basej: base time jiffies
|
|
* @basem: base time clock monotonic
|
|
*
|
|
* Returns the tick aligned clock monotonic time of the next pending
|
|
* timer or KTIME_MAX if no timer is pending.
|
|
*/
|
|
u64 get_next_timer_interrupt(unsigned long basej, u64 basem)
|
|
{
|
|
struct tvec_base *base = this_cpu_ptr(&tvec_bases);
|
|
u64 expires = KTIME_MAX;
|
|
unsigned long nextevt;
|
|
|
|
/*
|
|
* Pretend that there is no timer pending if the cpu is offline.
|
|
* Possible pending timers will be migrated later to an active cpu.
|
|
*/
|
|
if (cpu_is_offline(smp_processor_id()))
|
|
return expires;
|
|
|
|
spin_lock(&base->lock);
|
|
if (base->active_timers) {
|
|
if (time_before_eq(base->next_timer, base->timer_jiffies))
|
|
base->next_timer = __next_timer_interrupt(base);
|
|
nextevt = base->next_timer;
|
|
if (time_before_eq(nextevt, basej))
|
|
expires = basem;
|
|
else
|
|
expires = basem + (nextevt - basej) * TICK_NSEC;
|
|
}
|
|
spin_unlock(&base->lock);
|
|
|
|
return cmp_next_hrtimer_event(basem, expires);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Called from the timer interrupt handler to charge one tick to the current
|
|
* process. user_tick is 1 if the tick is user time, 0 for system.
|
|
*/
|
|
void update_process_times(int user_tick)
|
|
{
|
|
struct task_struct *p = current;
|
|
|
|
/* Note: this timer irq context must be accounted for as well. */
|
|
account_process_tick(p, user_tick);
|
|
run_local_timers();
|
|
rcu_check_callbacks(user_tick);
|
|
#ifdef CONFIG_IRQ_WORK
|
|
if (in_irq())
|
|
irq_work_tick();
|
|
#endif
|
|
scheduler_tick();
|
|
run_posix_cpu_timers(p);
|
|
}
|
|
|
|
/*
|
|
* This function runs timers and the timer-tq in bottom half context.
|
|
*/
|
|
static void run_timer_softirq(struct softirq_action *h)
|
|
{
|
|
struct tvec_base *base = this_cpu_ptr(&tvec_bases);
|
|
|
|
if (time_after_eq(jiffies, base->timer_jiffies))
|
|
__run_timers(base);
|
|
}
|
|
|
|
/*
|
|
* Called by the local, per-CPU timer interrupt on SMP.
|
|
*/
|
|
void run_local_timers(void)
|
|
{
|
|
hrtimer_run_queues();
|
|
raise_softirq(TIMER_SOFTIRQ);
|
|
}
|
|
|
|
#ifdef __ARCH_WANT_SYS_ALARM
|
|
|
|
/*
|
|
* For backwards compatibility? This can be done in libc so Alpha
|
|
* and all newer ports shouldn't need it.
|
|
*/
|
|
SYSCALL_DEFINE1(alarm, unsigned int, seconds)
|
|
{
|
|
return alarm_setitimer(seconds);
|
|
}
|
|
|
|
#endif
|
|
|
|
static void process_timeout(unsigned long __data)
|
|
{
|
|
wake_up_process((struct task_struct *)__data);
|
|
}
|
|
|
|
/**
|
|
* schedule_timeout - sleep until timeout
|
|
* @timeout: timeout value in jiffies
|
|
*
|
|
* Make the current task sleep until @timeout jiffies have
|
|
* elapsed. The routine will return immediately unless
|
|
* the current task state has been set (see set_current_state()).
|
|
*
|
|
* You can set the task state as follows -
|
|
*
|
|
* %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
|
|
* pass before the routine returns. The routine will return 0
|
|
*
|
|
* %TASK_INTERRUPTIBLE - the routine may return early if a signal is
|
|
* delivered to the current task. In this case the remaining time
|
|
* in jiffies will be returned, or 0 if the timer expired in time
|
|
*
|
|
* The current task state is guaranteed to be TASK_RUNNING when this
|
|
* routine returns.
|
|
*
|
|
* Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
|
|
* the CPU away without a bound on the timeout. In this case the return
|
|
* value will be %MAX_SCHEDULE_TIMEOUT.
|
|
*
|
|
* In all cases the return value is guaranteed to be non-negative.
|
|
*/
|
|
signed long __sched schedule_timeout(signed long timeout)
|
|
{
|
|
struct timer_list timer;
|
|
unsigned long expire;
|
|
|
|
switch (timeout)
|
|
{
|
|
case MAX_SCHEDULE_TIMEOUT:
|
|
/*
|
|
* These two special cases are useful to be comfortable
|
|
* in the caller. Nothing more. We could take
|
|
* MAX_SCHEDULE_TIMEOUT from one of the negative value
|
|
* but I' d like to return a valid offset (>=0) to allow
|
|
* the caller to do everything it want with the retval.
|
|
*/
|
|
schedule();
|
|
goto out;
|
|
default:
|
|
/*
|
|
* Another bit of PARANOID. Note that the retval will be
|
|
* 0 since no piece of kernel is supposed to do a check
|
|
* for a negative retval of schedule_timeout() (since it
|
|
* should never happens anyway). You just have the printk()
|
|
* that will tell you if something is gone wrong and where.
|
|
*/
|
|
if (timeout < 0) {
|
|
printk(KERN_ERR "schedule_timeout: wrong timeout "
|
|
"value %lx\n", timeout);
|
|
dump_stack();
|
|
current->state = TASK_RUNNING;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
expire = timeout + jiffies;
|
|
|
|
setup_timer_on_stack(&timer, process_timeout, (unsigned long)current);
|
|
__mod_timer(&timer, expire, false, TIMER_NOT_PINNED);
|
|
schedule();
|
|
del_singleshot_timer_sync(&timer);
|
|
|
|
/* Remove the timer from the object tracker */
|
|
destroy_timer_on_stack(&timer);
|
|
|
|
timeout = expire - jiffies;
|
|
|
|
out:
|
|
return timeout < 0 ? 0 : timeout;
|
|
}
|
|
EXPORT_SYMBOL(schedule_timeout);
|
|
|
|
/*
|
|
* We can use __set_current_state() here because schedule_timeout() calls
|
|
* schedule() unconditionally.
|
|
*/
|
|
signed long __sched schedule_timeout_interruptible(signed long timeout)
|
|
{
|
|
__set_current_state(TASK_INTERRUPTIBLE);
|
|
return schedule_timeout(timeout);
|
|
}
|
|
EXPORT_SYMBOL(schedule_timeout_interruptible);
|
|
|
|
signed long __sched schedule_timeout_killable(signed long timeout)
|
|
{
|
|
__set_current_state(TASK_KILLABLE);
|
|
return schedule_timeout(timeout);
|
|
}
|
|
EXPORT_SYMBOL(schedule_timeout_killable);
|
|
|
|
signed long __sched schedule_timeout_uninterruptible(signed long timeout)
|
|
{
|
|
__set_current_state(TASK_UNINTERRUPTIBLE);
|
|
return schedule_timeout(timeout);
|
|
}
|
|
EXPORT_SYMBOL(schedule_timeout_uninterruptible);
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
static void migrate_timer_list(struct tvec_base *new_base, struct hlist_head *head)
|
|
{
|
|
struct timer_list *timer;
|
|
int cpu = new_base->cpu;
|
|
|
|
while (!hlist_empty(head)) {
|
|
timer = hlist_entry(head->first, struct timer_list, entry);
|
|
/* We ignore the accounting on the dying cpu */
|
|
detach_timer(timer, false);
|
|
timer->flags = (timer->flags & ~TIMER_BASEMASK) | cpu;
|
|
internal_add_timer(new_base, timer);
|
|
}
|
|
}
|
|
|
|
static void migrate_timers(int cpu)
|
|
{
|
|
struct tvec_base *old_base;
|
|
struct tvec_base *new_base;
|
|
int i;
|
|
|
|
BUG_ON(cpu_online(cpu));
|
|
old_base = per_cpu_ptr(&tvec_bases, cpu);
|
|
new_base = get_cpu_ptr(&tvec_bases);
|
|
/*
|
|
* The caller is globally serialized and nobody else
|
|
* takes two locks at once, deadlock is not possible.
|
|
*/
|
|
spin_lock_irq(&new_base->lock);
|
|
spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
|
|
|
|
BUG_ON(old_base->running_timer);
|
|
|
|
for (i = 0; i < TVR_SIZE; i++)
|
|
migrate_timer_list(new_base, old_base->tv1.vec + i);
|
|
for (i = 0; i < TVN_SIZE; i++) {
|
|
migrate_timer_list(new_base, old_base->tv2.vec + i);
|
|
migrate_timer_list(new_base, old_base->tv3.vec + i);
|
|
migrate_timer_list(new_base, old_base->tv4.vec + i);
|
|
migrate_timer_list(new_base, old_base->tv5.vec + i);
|
|
}
|
|
|
|
old_base->active_timers = 0;
|
|
old_base->all_timers = 0;
|
|
|
|
spin_unlock(&old_base->lock);
|
|
spin_unlock_irq(&new_base->lock);
|
|
put_cpu_ptr(&tvec_bases);
|
|
}
|
|
|
|
static int timer_cpu_notify(struct notifier_block *self,
|
|
unsigned long action, void *hcpu)
|
|
{
|
|
switch (action) {
|
|
case CPU_DEAD:
|
|
case CPU_DEAD_FROZEN:
|
|
migrate_timers((long)hcpu);
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
return NOTIFY_OK;
|
|
}
|
|
|
|
static inline void timer_register_cpu_notifier(void)
|
|
{
|
|
cpu_notifier(timer_cpu_notify, 0);
|
|
}
|
|
#else
|
|
static inline void timer_register_cpu_notifier(void) { }
|
|
#endif /* CONFIG_HOTPLUG_CPU */
|
|
|
|
static void __init init_timer_cpu(int cpu)
|
|
{
|
|
struct tvec_base *base = per_cpu_ptr(&tvec_bases, cpu);
|
|
|
|
base->cpu = cpu;
|
|
spin_lock_init(&base->lock);
|
|
|
|
base->timer_jiffies = jiffies;
|
|
base->next_timer = base->timer_jiffies;
|
|
}
|
|
|
|
static void __init init_timer_cpus(void)
|
|
{
|
|
int cpu;
|
|
|
|
for_each_possible_cpu(cpu)
|
|
init_timer_cpu(cpu);
|
|
}
|
|
|
|
void __init init_timers(void)
|
|
{
|
|
init_timer_cpus();
|
|
init_timer_stats();
|
|
timer_register_cpu_notifier();
|
|
open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
|
|
}
|
|
|
|
/**
|
|
* msleep - sleep safely even with waitqueue interruptions
|
|
* @msecs: Time in milliseconds to sleep for
|
|
*/
|
|
void msleep(unsigned int msecs)
|
|
{
|
|
unsigned long timeout = msecs_to_jiffies(msecs) + 1;
|
|
|
|
while (timeout)
|
|
timeout = schedule_timeout_uninterruptible(timeout);
|
|
}
|
|
|
|
EXPORT_SYMBOL(msleep);
|
|
|
|
/**
|
|
* msleep_interruptible - sleep waiting for signals
|
|
* @msecs: Time in milliseconds to sleep for
|
|
*/
|
|
unsigned long msleep_interruptible(unsigned int msecs)
|
|
{
|
|
unsigned long timeout = msecs_to_jiffies(msecs) + 1;
|
|
|
|
while (timeout && !signal_pending(current))
|
|
timeout = schedule_timeout_interruptible(timeout);
|
|
return jiffies_to_msecs(timeout);
|
|
}
|
|
|
|
EXPORT_SYMBOL(msleep_interruptible);
|
|
|
|
static void __sched do_usleep_range(unsigned long min, unsigned long max)
|
|
{
|
|
ktime_t kmin;
|
|
unsigned long delta;
|
|
|
|
kmin = ktime_set(0, min * NSEC_PER_USEC);
|
|
delta = (max - min) * NSEC_PER_USEC;
|
|
schedule_hrtimeout_range(&kmin, delta, HRTIMER_MODE_REL);
|
|
}
|
|
|
|
/**
|
|
* usleep_range - Drop in replacement for udelay where wakeup is flexible
|
|
* @min: Minimum time in usecs to sleep
|
|
* @max: Maximum time in usecs to sleep
|
|
*/
|
|
void __sched usleep_range(unsigned long min, unsigned long max)
|
|
{
|
|
__set_current_state(TASK_UNINTERRUPTIBLE);
|
|
do_usleep_range(min, max);
|
|
}
|
|
EXPORT_SYMBOL(usleep_range);
|