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2089 lines
60 KiB
2089 lines
60 KiB
// SPDX-License-Identifier: GPL-2.0 |
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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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|
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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/signal.h> |
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#include <linux/sched/sysctl.h> |
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#include <linux/sched/nohz.h> |
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#include <linux/sched/debug.h> |
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#include <linux/slab.h> |
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#include <linux/compat.h> |
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#include <linux/random.h> |
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#include <linux/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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* The timer wheel has LVL_DEPTH array levels. Each level provides an array of |
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* LVL_SIZE buckets. Each level is driven by its own clock and therefor each |
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* level has a different granularity. |
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* |
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* The level granularity is: LVL_CLK_DIV ^ lvl |
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* The level clock frequency is: HZ / (LVL_CLK_DIV ^ level) |
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* |
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* The array level of a newly armed timer depends on the relative expiry |
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* time. The farther the expiry time is away the higher the array level and |
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* therefor the granularity becomes. |
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* |
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* Contrary to the original timer wheel implementation, which aims for 'exact' |
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* expiry of the timers, this implementation removes the need for recascading |
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* the timers into the lower array levels. The previous 'classic' timer wheel |
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* implementation of the kernel already violated the 'exact' expiry by adding |
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* slack to the expiry time to provide batched expiration. The granularity |
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* levels provide implicit batching. |
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* |
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* This is an optimization of the original timer wheel implementation for the |
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* majority of the timer wheel use cases: timeouts. The vast majority of |
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* timeout timers (networking, disk I/O ...) are canceled before expiry. If |
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* the timeout expires it indicates that normal operation is disturbed, so it |
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* does not matter much whether the timeout comes with a slight delay. |
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* |
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* The only exception to this are networking timers with a small expiry |
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* time. They rely on the granularity. Those fit into the first wheel level, |
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* which has HZ granularity. |
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* |
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* We don't have cascading anymore. timers with a expiry time above the |
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* capacity of the last wheel level are force expired at the maximum timeout |
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* value of the last wheel level. From data sampling we know that the maximum |
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* value observed is 5 days (network connection tracking), so this should not |
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* be an issue. |
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* |
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* The currently chosen array constants values are a good compromise between |
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* array size and granularity. |
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* |
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* This results in the following granularity and range levels: |
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* |
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* HZ 1000 steps |
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* Level Offset Granularity Range |
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* 0 0 1 ms 0 ms - 63 ms |
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* 1 64 8 ms 64 ms - 511 ms |
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* 2 128 64 ms 512 ms - 4095 ms (512ms - ~4s) |
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* 3 192 512 ms 4096 ms - 32767 ms (~4s - ~32s) |
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* 4 256 4096 ms (~4s) 32768 ms - 262143 ms (~32s - ~4m) |
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* 5 320 32768 ms (~32s) 262144 ms - 2097151 ms (~4m - ~34m) |
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* 6 384 262144 ms (~4m) 2097152 ms - 16777215 ms (~34m - ~4h) |
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* 7 448 2097152 ms (~34m) 16777216 ms - 134217727 ms (~4h - ~1d) |
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* 8 512 16777216 ms (~4h) 134217728 ms - 1073741822 ms (~1d - ~12d) |
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* |
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* HZ 300 |
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* Level Offset Granularity Range |
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* 0 0 3 ms 0 ms - 210 ms |
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* 1 64 26 ms 213 ms - 1703 ms (213ms - ~1s) |
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* 2 128 213 ms 1706 ms - 13650 ms (~1s - ~13s) |
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* 3 192 1706 ms (~1s) 13653 ms - 109223 ms (~13s - ~1m) |
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* 4 256 13653 ms (~13s) 109226 ms - 873810 ms (~1m - ~14m) |
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* 5 320 109226 ms (~1m) 873813 ms - 6990503 ms (~14m - ~1h) |
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* 6 384 873813 ms (~14m) 6990506 ms - 55924050 ms (~1h - ~15h) |
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* 7 448 6990506 ms (~1h) 55924053 ms - 447392423 ms (~15h - ~5d) |
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* 8 512 55924053 ms (~15h) 447392426 ms - 3579139406 ms (~5d - ~41d) |
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* |
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* HZ 250 |
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* Level Offset Granularity Range |
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* 0 0 4 ms 0 ms - 255 ms |
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* 1 64 32 ms 256 ms - 2047 ms (256ms - ~2s) |
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* 2 128 256 ms 2048 ms - 16383 ms (~2s - ~16s) |
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* 3 192 2048 ms (~2s) 16384 ms - 131071 ms (~16s - ~2m) |
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* 4 256 16384 ms (~16s) 131072 ms - 1048575 ms (~2m - ~17m) |
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* 5 320 131072 ms (~2m) 1048576 ms - 8388607 ms (~17m - ~2h) |
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* 6 384 1048576 ms (~17m) 8388608 ms - 67108863 ms (~2h - ~18h) |
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* 7 448 8388608 ms (~2h) 67108864 ms - 536870911 ms (~18h - ~6d) |
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* 8 512 67108864 ms (~18h) 536870912 ms - 4294967288 ms (~6d - ~49d) |
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* |
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* HZ 100 |
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* Level Offset Granularity Range |
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* 0 0 10 ms 0 ms - 630 ms |
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* 1 64 80 ms 640 ms - 5110 ms (640ms - ~5s) |
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* 2 128 640 ms 5120 ms - 40950 ms (~5s - ~40s) |
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* 3 192 5120 ms (~5s) 40960 ms - 327670 ms (~40s - ~5m) |
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* 4 256 40960 ms (~40s) 327680 ms - 2621430 ms (~5m - ~43m) |
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* 5 320 327680 ms (~5m) 2621440 ms - 20971510 ms (~43m - ~5h) |
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* 6 384 2621440 ms (~43m) 20971520 ms - 167772150 ms (~5h - ~1d) |
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* 7 448 20971520 ms (~5h) 167772160 ms - 1342177270 ms (~1d - ~15d) |
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*/ |
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/* Clock divisor for the next level */ |
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#define LVL_CLK_SHIFT 3 |
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#define LVL_CLK_DIV (1UL << LVL_CLK_SHIFT) |
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#define LVL_CLK_MASK (LVL_CLK_DIV - 1) |
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#define LVL_SHIFT(n) ((n) * LVL_CLK_SHIFT) |
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#define LVL_GRAN(n) (1UL << LVL_SHIFT(n)) |
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/* |
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* The time start value for each level to select the bucket at enqueue |
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* time. We start from the last possible delta of the previous level |
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* so that we can later add an extra LVL_GRAN(n) to n (see calc_index()). |
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*/ |
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#define LVL_START(n) ((LVL_SIZE - 1) << (((n) - 1) * LVL_CLK_SHIFT)) |
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/* Size of each clock level */ |
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#define LVL_BITS 6 |
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#define LVL_SIZE (1UL << LVL_BITS) |
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#define LVL_MASK (LVL_SIZE - 1) |
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#define LVL_OFFS(n) ((n) * LVL_SIZE) |
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/* Level depth */ |
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#if HZ > 100 |
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# define LVL_DEPTH 9 |
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# else |
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# define LVL_DEPTH 8 |
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#endif |
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/* The cutoff (max. capacity of the wheel) */ |
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#define WHEEL_TIMEOUT_CUTOFF (LVL_START(LVL_DEPTH)) |
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#define WHEEL_TIMEOUT_MAX (WHEEL_TIMEOUT_CUTOFF - LVL_GRAN(LVL_DEPTH - 1)) |
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/* |
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* The resulting wheel size. If NOHZ is configured we allocate two |
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* wheels so we have a separate storage for the deferrable timers. |
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*/ |
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#define WHEEL_SIZE (LVL_SIZE * LVL_DEPTH) |
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#ifdef CONFIG_NO_HZ_COMMON |
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# define NR_BASES 2 |
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# define BASE_STD 0 |
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# define BASE_DEF 1 |
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#else |
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# define NR_BASES 1 |
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# define BASE_STD 0 |
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# define BASE_DEF 0 |
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#endif |
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struct timer_base { |
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raw_spinlock_t lock; |
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struct timer_list *running_timer; |
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#ifdef CONFIG_PREEMPT_RT |
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spinlock_t expiry_lock; |
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atomic_t timer_waiters; |
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#endif |
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unsigned long clk; |
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unsigned long next_expiry; |
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unsigned int cpu; |
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bool next_expiry_recalc; |
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bool is_idle; |
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DECLARE_BITMAP(pending_map, WHEEL_SIZE); |
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struct hlist_head vectors[WHEEL_SIZE]; |
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} ____cacheline_aligned; |
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static DEFINE_PER_CPU(struct timer_base, timer_bases[NR_BASES]); |
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#ifdef CONFIG_NO_HZ_COMMON |
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static DEFINE_STATIC_KEY_FALSE(timers_nohz_active); |
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static DEFINE_MUTEX(timer_keys_mutex); |
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static void timer_update_keys(struct work_struct *work); |
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static DECLARE_WORK(timer_update_work, timer_update_keys); |
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#ifdef CONFIG_SMP |
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unsigned int sysctl_timer_migration = 1; |
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DEFINE_STATIC_KEY_FALSE(timers_migration_enabled); |
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static void timers_update_migration(void) |
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{ |
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if (sysctl_timer_migration && tick_nohz_active) |
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static_branch_enable(&timers_migration_enabled); |
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else |
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static_branch_disable(&timers_migration_enabled); |
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} |
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#else |
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static inline void timers_update_migration(void) { } |
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#endif /* !CONFIG_SMP */ |
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static void timer_update_keys(struct work_struct *work) |
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{ |
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mutex_lock(&timer_keys_mutex); |
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timers_update_migration(); |
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static_branch_enable(&timers_nohz_active); |
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mutex_unlock(&timer_keys_mutex); |
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} |
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void timers_update_nohz(void) |
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{ |
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schedule_work(&timer_update_work); |
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} |
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int timer_migration_handler(struct ctl_table *table, int write, |
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void *buffer, size_t *lenp, loff_t *ppos) |
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{ |
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int ret; |
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mutex_lock(&timer_keys_mutex); |
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ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
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if (!ret && write) |
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timers_update_migration(); |
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mutex_unlock(&timer_keys_mutex); |
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return ret; |
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} |
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static inline bool is_timers_nohz_active(void) |
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{ |
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return static_branch_unlikely(&timers_nohz_active); |
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} |
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#else |
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static inline bool is_timers_nohz_active(void) { return false; } |
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#endif /* NO_HZ_COMMON */ |
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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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/** |
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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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/** |
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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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/** |
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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 |
|
* 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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/** |
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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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/** |
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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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|
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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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/** |
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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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/** |
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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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static inline unsigned int timer_get_idx(struct timer_list *timer) |
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{ |
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return (timer->flags & TIMER_ARRAYMASK) >> TIMER_ARRAYSHIFT; |
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} |
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|
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static inline void timer_set_idx(struct timer_list *timer, unsigned int idx) |
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{ |
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timer->flags = (timer->flags & ~TIMER_ARRAYMASK) | |
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idx << TIMER_ARRAYSHIFT; |
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} |
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|
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/* |
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* Helper function to calculate the array index for a given expiry |
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* time. |
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*/ |
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static inline unsigned calc_index(unsigned long expires, unsigned lvl, |
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unsigned long *bucket_expiry) |
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{ |
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|
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/* |
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* The timer wheel has to guarantee that a timer does not fire |
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* early. Early expiry can happen due to: |
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* - Timer is armed at the edge of a tick |
|
* - Truncation of the expiry time in the outer wheel levels |
|
* |
|
* Round up with level granularity to prevent this. |
|
*/ |
|
expires = (expires + LVL_GRAN(lvl)) >> LVL_SHIFT(lvl); |
|
*bucket_expiry = expires << LVL_SHIFT(lvl); |
|
return LVL_OFFS(lvl) + (expires & LVL_MASK); |
|
} |
|
|
|
static int calc_wheel_index(unsigned long expires, unsigned long clk, |
|
unsigned long *bucket_expiry) |
|
{ |
|
unsigned long delta = expires - clk; |
|
unsigned int idx; |
|
|
|
if (delta < LVL_START(1)) { |
|
idx = calc_index(expires, 0, bucket_expiry); |
|
} else if (delta < LVL_START(2)) { |
|
idx = calc_index(expires, 1, bucket_expiry); |
|
} else if (delta < LVL_START(3)) { |
|
idx = calc_index(expires, 2, bucket_expiry); |
|
} else if (delta < LVL_START(4)) { |
|
idx = calc_index(expires, 3, bucket_expiry); |
|
} else if (delta < LVL_START(5)) { |
|
idx = calc_index(expires, 4, bucket_expiry); |
|
} else if (delta < LVL_START(6)) { |
|
idx = calc_index(expires, 5, bucket_expiry); |
|
} else if (delta < LVL_START(7)) { |
|
idx = calc_index(expires, 6, bucket_expiry); |
|
} else if (LVL_DEPTH > 8 && delta < LVL_START(8)) { |
|
idx = calc_index(expires, 7, bucket_expiry); |
|
} else if ((long) delta < 0) { |
|
idx = clk & LVL_MASK; |
|
*bucket_expiry = clk; |
|
} else { |
|
/* |
|
* Force expire obscene large timeouts to expire at the |
|
* capacity limit of the wheel. |
|
*/ |
|
if (delta >= WHEEL_TIMEOUT_CUTOFF) |
|
expires = clk + WHEEL_TIMEOUT_MAX; |
|
|
|
idx = calc_index(expires, LVL_DEPTH - 1, bucket_expiry); |
|
} |
|
return idx; |
|
} |
|
|
|
static void |
|
trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer) |
|
{ |
|
if (!is_timers_nohz_active()) |
|
return; |
|
|
|
/* |
|
* TODO: This wants some optimizing similar to the code below, but we |
|
* will do that when we switch from push to pull for deferrable timers. |
|
*/ |
|
if (timer->flags & TIMER_DEFERRABLE) { |
|
if (tick_nohz_full_cpu(base->cpu)) |
|
wake_up_nohz_cpu(base->cpu); |
|
return; |
|
} |
|
|
|
/* |
|
* We might have to IPI the remote CPU if the base is idle and the |
|
* timer is not deferrable. If the other CPU is on the way to idle |
|
* then it can't set base->is_idle as we hold the base lock: |
|
*/ |
|
if (base->is_idle) |
|
wake_up_nohz_cpu(base->cpu); |
|
} |
|
|
|
/* |
|
* Enqueue the timer into the hash bucket, mark it pending in |
|
* the bitmap, store the index in the timer flags then wake up |
|
* the target CPU if needed. |
|
*/ |
|
static void enqueue_timer(struct timer_base *base, struct timer_list *timer, |
|
unsigned int idx, unsigned long bucket_expiry) |
|
{ |
|
|
|
hlist_add_head(&timer->entry, base->vectors + idx); |
|
__set_bit(idx, base->pending_map); |
|
timer_set_idx(timer, idx); |
|
|
|
trace_timer_start(timer, timer->expires, timer->flags); |
|
|
|
/* |
|
* Check whether this is the new first expiring timer. The |
|
* effective expiry time of the timer is required here |
|
* (bucket_expiry) instead of timer->expires. |
|
*/ |
|
if (time_before(bucket_expiry, base->next_expiry)) { |
|
/* |
|
* Set the next expiry time and kick the CPU so it |
|
* can reevaluate the wheel: |
|
*/ |
|
base->next_expiry = bucket_expiry; |
|
base->next_expiry_recalc = false; |
|
trigger_dyntick_cpu(base, timer); |
|
} |
|
} |
|
|
|
static void internal_add_timer(struct timer_base *base, struct timer_list *timer) |
|
{ |
|
unsigned long bucket_expiry; |
|
unsigned int idx; |
|
|
|
idx = calc_wheel_index(timer->expires, base->clk, &bucket_expiry); |
|
enqueue_timer(base, timer, idx, bucket_expiry); |
|
} |
|
|
|
#ifdef CONFIG_DEBUG_OBJECTS_TIMERS |
|
|
|
static const struct debug_obj_descr timer_debug_descr; |
|
|
|
static void *timer_debug_hint(void *addr) |
|
{ |
|
return ((struct timer_list *) addr)->function; |
|
} |
|
|
|
static bool timer_is_static_object(void *addr) |
|
{ |
|
struct timer_list *timer = addr; |
|
|
|
return (timer->entry.pprev == NULL && |
|
timer->entry.next == TIMER_ENTRY_STATIC); |
|
} |
|
|
|
/* |
|
* fixup_init is called when: |
|
* - an active object is initialized |
|
*/ |
|
static bool 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 true; |
|
default: |
|
return false; |
|
} |
|
} |
|
|
|
/* Stub timer callback for improperly used timers. */ |
|
static void stub_timer(struct timer_list *unused) |
|
{ |
|
WARN_ON(1); |
|
} |
|
|
|
/* |
|
* fixup_activate is called when: |
|
* - an active object is activated |
|
* - an unknown non-static object is activated |
|
*/ |
|
static bool timer_fixup_activate(void *addr, enum debug_obj_state state) |
|
{ |
|
struct timer_list *timer = addr; |
|
|
|
switch (state) { |
|
case ODEBUG_STATE_NOTAVAILABLE: |
|
timer_setup(timer, stub_timer, 0); |
|
return true; |
|
|
|
case ODEBUG_STATE_ACTIVE: |
|
WARN_ON(1); |
|
fallthrough; |
|
default: |
|
return false; |
|
} |
|
} |
|
|
|
/* |
|
* fixup_free is called when: |
|
* - an active object is freed |
|
*/ |
|
static bool 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 true; |
|
default: |
|
return false; |
|
} |
|
} |
|
|
|
/* |
|
* fixup_assert_init is called when: |
|
* - an untracked/uninit-ed object is found |
|
*/ |
|
static bool timer_fixup_assert_init(void *addr, enum debug_obj_state state) |
|
{ |
|
struct timer_list *timer = addr; |
|
|
|
switch (state) { |
|
case ODEBUG_STATE_NOTAVAILABLE: |
|
timer_setup(timer, stub_timer, 0); |
|
return true; |
|
default: |
|
return false; |
|
} |
|
} |
|
|
|
static const struct debug_obj_descr timer_debug_descr = { |
|
.name = "timer_list", |
|
.debug_hint = timer_debug_hint, |
|
.is_static_object = timer_is_static_object, |
|
.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_assert_init(struct timer_list *timer) |
|
{ |
|
debug_object_assert_init(timer, &timer_debug_descr); |
|
} |
|
|
|
static void do_init_timer(struct timer_list *timer, |
|
void (*func)(struct timer_list *), |
|
unsigned int flags, |
|
const char *name, struct lock_class_key *key); |
|
|
|
void init_timer_on_stack_key(struct timer_list *timer, |
|
void (*func)(struct timer_list *), |
|
unsigned int flags, |
|
const char *name, struct lock_class_key *key) |
|
{ |
|
debug_object_init_on_stack(timer, &timer_debug_descr); |
|
do_init_timer(timer, func, 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_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, |
|
void (*func)(struct timer_list *), |
|
unsigned int flags, |
|
const char *name, struct lock_class_key *key) |
|
{ |
|
timer->entry.pprev = NULL; |
|
timer->function = func; |
|
if (WARN_ON_ONCE(flags & ~TIMER_INIT_FLAGS)) |
|
flags &= TIMER_INIT_FLAGS; |
|
timer->flags = flags | raw_smp_processor_id(); |
|
lockdep_init_map(&timer->lockdep_map, name, key, 0); |
|
} |
|
|
|
/** |
|
* init_timer_key - initialize a timer |
|
* @timer: the timer to be initialized |
|
* @func: timer callback function |
|
* @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, |
|
void (*func)(struct timer_list *), unsigned int flags, |
|
const char *name, struct lock_class_key *key) |
|
{ |
|
debug_init(timer); |
|
do_init_timer(timer, func, 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 int detach_if_pending(struct timer_list *timer, struct timer_base *base, |
|
bool clear_pending) |
|
{ |
|
unsigned idx = timer_get_idx(timer); |
|
|
|
if (!timer_pending(timer)) |
|
return 0; |
|
|
|
if (hlist_is_singular_node(&timer->entry, base->vectors + idx)) { |
|
__clear_bit(idx, base->pending_map); |
|
base->next_expiry_recalc = true; |
|
} |
|
|
|
detach_timer(timer, clear_pending); |
|
return 1; |
|
} |
|
|
|
static inline struct timer_base *get_timer_cpu_base(u32 tflags, u32 cpu) |
|
{ |
|
struct timer_base *base = per_cpu_ptr(&timer_bases[BASE_STD], cpu); |
|
|
|
/* |
|
* If the timer is deferrable and NO_HZ_COMMON is set then we need |
|
* to use the deferrable base. |
|
*/ |
|
if (IS_ENABLED(CONFIG_NO_HZ_COMMON) && (tflags & TIMER_DEFERRABLE)) |
|
base = per_cpu_ptr(&timer_bases[BASE_DEF], cpu); |
|
return base; |
|
} |
|
|
|
static inline struct timer_base *get_timer_this_cpu_base(u32 tflags) |
|
{ |
|
struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); |
|
|
|
/* |
|
* If the timer is deferrable and NO_HZ_COMMON is set then we need |
|
* to use the deferrable base. |
|
*/ |
|
if (IS_ENABLED(CONFIG_NO_HZ_COMMON) && (tflags & TIMER_DEFERRABLE)) |
|
base = this_cpu_ptr(&timer_bases[BASE_DEF]); |
|
return base; |
|
} |
|
|
|
static inline struct timer_base *get_timer_base(u32 tflags) |
|
{ |
|
return get_timer_cpu_base(tflags, tflags & TIMER_CPUMASK); |
|
} |
|
|
|
static inline struct timer_base * |
|
get_target_base(struct timer_base *base, unsigned tflags) |
|
{ |
|
#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON) |
|
if (static_branch_likely(&timers_migration_enabled) && |
|
!(tflags & TIMER_PINNED)) |
|
return get_timer_cpu_base(tflags, get_nohz_timer_target()); |
|
#endif |
|
return get_timer_this_cpu_base(tflags); |
|
} |
|
|
|
static inline void forward_timer_base(struct timer_base *base) |
|
{ |
|
unsigned long jnow = READ_ONCE(jiffies); |
|
|
|
/* |
|
* No need to forward if we are close enough below jiffies. |
|
* Also while executing timers, base->clk is 1 offset ahead |
|
* of jiffies to avoid endless requeuing to current jffies. |
|
*/ |
|
if ((long)(jnow - base->clk) < 1) |
|
return; |
|
|
|
/* |
|
* If the next expiry value is > jiffies, then we fast forward to |
|
* jiffies otherwise we forward to the next expiry value. |
|
*/ |
|
if (time_after(base->next_expiry, jnow)) { |
|
base->clk = jnow; |
|
} else { |
|
if (WARN_ON_ONCE(time_before(base->next_expiry, base->clk))) |
|
return; |
|
base->clk = base->next_expiry; |
|
} |
|
} |
|
|
|
|
|
/* |
|
* We are using hashed locking: Holding per_cpu(timer_bases[x]).lock means |
|
* that all timers which are tied to this base are locked, and the base itself |
|
* is locked too. |
|
* |
|
* So __run_timers/migrate_timers can safely modify all timers which could |
|
* be found in the base->vectors array. |
|
* |
|
* When a timer is migrating then the TIMER_MIGRATING flag is set and we need |
|
* to wait until the migration is done. |
|
*/ |
|
static struct timer_base *lock_timer_base(struct timer_list *timer, |
|
unsigned long *flags) |
|
__acquires(timer->base->lock) |
|
{ |
|
for (;;) { |
|
struct timer_base *base; |
|
u32 tf; |
|
|
|
/* |
|
* We need to use READ_ONCE() here, otherwise the compiler |
|
* might re-read @tf between the check for TIMER_MIGRATING |
|
* and spin_lock(). |
|
*/ |
|
tf = READ_ONCE(timer->flags); |
|
|
|
if (!(tf & TIMER_MIGRATING)) { |
|
base = get_timer_base(tf); |
|
raw_spin_lock_irqsave(&base->lock, *flags); |
|
if (timer->flags == tf) |
|
return base; |
|
raw_spin_unlock_irqrestore(&base->lock, *flags); |
|
} |
|
cpu_relax(); |
|
} |
|
} |
|
|
|
#define MOD_TIMER_PENDING_ONLY 0x01 |
|
#define MOD_TIMER_REDUCE 0x02 |
|
#define MOD_TIMER_NOTPENDING 0x04 |
|
|
|
static inline int |
|
__mod_timer(struct timer_list *timer, unsigned long expires, unsigned int options) |
|
{ |
|
unsigned long clk = 0, flags, bucket_expiry; |
|
struct timer_base *base, *new_base; |
|
unsigned int idx = UINT_MAX; |
|
int ret = 0; |
|
|
|
BUG_ON(!timer->function); |
|
|
|
/* |
|
* This is a common optimization triggered by the networking code - if |
|
* the timer is re-modified to have the same timeout or ends up in the |
|
* same array bucket then just return: |
|
*/ |
|
if (!(options & MOD_TIMER_NOTPENDING) && timer_pending(timer)) { |
|
/* |
|
* The downside of this optimization is that it can result in |
|
* larger granularity than you would get from adding a new |
|
* timer with this expiry. |
|
*/ |
|
long diff = timer->expires - expires; |
|
|
|
if (!diff) |
|
return 1; |
|
if (options & MOD_TIMER_REDUCE && diff <= 0) |
|
return 1; |
|
|
|
/* |
|
* We lock timer base and calculate the bucket index right |
|
* here. If the timer ends up in the same bucket, then we |
|
* just update the expiry time and avoid the whole |
|
* dequeue/enqueue dance. |
|
*/ |
|
base = lock_timer_base(timer, &flags); |
|
forward_timer_base(base); |
|
|
|
if (timer_pending(timer) && (options & MOD_TIMER_REDUCE) && |
|
time_before_eq(timer->expires, expires)) { |
|
ret = 1; |
|
goto out_unlock; |
|
} |
|
|
|
clk = base->clk; |
|
idx = calc_wheel_index(expires, clk, &bucket_expiry); |
|
|
|
/* |
|
* Retrieve and compare the array index of the pending |
|
* timer. If it matches set the expiry to the new value so a |
|
* subsequent call will exit in the expires check above. |
|
*/ |
|
if (idx == timer_get_idx(timer)) { |
|
if (!(options & MOD_TIMER_REDUCE)) |
|
timer->expires = expires; |
|
else if (time_after(timer->expires, expires)) |
|
timer->expires = expires; |
|
ret = 1; |
|
goto out_unlock; |
|
} |
|
} else { |
|
base = lock_timer_base(timer, &flags); |
|
forward_timer_base(base); |
|
} |
|
|
|
ret = detach_if_pending(timer, base, false); |
|
if (!ret && (options & MOD_TIMER_PENDING_ONLY)) |
|
goto out_unlock; |
|
|
|
new_base = get_target_base(base, timer->flags); |
|
|
|
if (base != new_base) { |
|
/* |
|
* We are trying to schedule the timer on the new base. |
|
* 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; |
|
|
|
raw_spin_unlock(&base->lock); |
|
base = new_base; |
|
raw_spin_lock(&base->lock); |
|
WRITE_ONCE(timer->flags, |
|
(timer->flags & ~TIMER_BASEMASK) | base->cpu); |
|
forward_timer_base(base); |
|
} |
|
} |
|
|
|
debug_timer_activate(timer); |
|
|
|
timer->expires = expires; |
|
/* |
|
* If 'idx' was calculated above and the base time did not advance |
|
* between calculating 'idx' and possibly switching the base, only |
|
* enqueue_timer() is required. Otherwise we need to (re)calculate |
|
* the wheel index via internal_add_timer(). |
|
*/ |
|
if (idx != UINT_MAX && clk == base->clk) |
|
enqueue_timer(base, timer, idx, bucket_expiry); |
|
else |
|
internal_add_timer(base, timer); |
|
|
|
out_unlock: |
|
raw_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, MOD_TIMER_PENDING_ONLY); |
|
} |
|
EXPORT_SYMBOL(mod_timer_pending); |
|
|
|
/** |
|
* 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) |
|
{ |
|
return __mod_timer(timer, expires, 0); |
|
} |
|
EXPORT_SYMBOL(mod_timer); |
|
|
|
/** |
|
* timer_reduce - Modify a timer's timeout if it would reduce the timeout |
|
* @timer: The timer to be modified |
|
* @expires: New timeout in jiffies |
|
* |
|
* timer_reduce() is very similar to mod_timer(), except that it will only |
|
* modify a running timer if that would reduce the expiration time (it will |
|
* start a timer that isn't running). |
|
*/ |
|
int timer_reduce(struct timer_list *timer, unsigned long expires) |
|
{ |
|
return __mod_timer(timer, expires, MOD_TIMER_REDUCE); |
|
} |
|
EXPORT_SYMBOL(timer_reduce); |
|
|
|
/** |
|
* add_timer - start a timer |
|
* @timer: the timer to be added |
|
* |
|
* The kernel will do a ->function(@timer) callback from the |
|
* timer interrupt at the ->expires point in the future. The |
|
* current time is 'jiffies'. |
|
* |
|
* The timer's ->expires, ->function 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, MOD_TIMER_NOTPENDING); |
|
} |
|
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 timer_base *new_base, *base; |
|
unsigned long flags; |
|
|
|
BUG_ON(timer_pending(timer) || !timer->function); |
|
|
|
new_base = get_timer_cpu_base(timer->flags, cpu); |
|
|
|
/* |
|
* 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; |
|
|
|
raw_spin_unlock(&base->lock); |
|
base = new_base; |
|
raw_spin_lock(&base->lock); |
|
WRITE_ONCE(timer->flags, |
|
(timer->flags & ~TIMER_BASEMASK) | cpu); |
|
} |
|
forward_timer_base(base); |
|
|
|
debug_timer_activate(timer); |
|
internal_add_timer(base, timer); |
|
raw_spin_unlock_irqrestore(&base->lock, flags); |
|
} |
|
EXPORT_SYMBOL_GPL(add_timer_on); |
|
|
|
/** |
|
* del_timer - deactivate 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 timer_base *base; |
|
unsigned long flags; |
|
int ret = 0; |
|
|
|
debug_assert_init(timer); |
|
|
|
if (timer_pending(timer)) { |
|
base = lock_timer_base(timer, &flags); |
|
ret = detach_if_pending(timer, base, true); |
|
raw_spin_unlock_irqrestore(&base->lock, flags); |
|
} |
|
|
|
return ret; |
|
} |
|
EXPORT_SYMBOL(del_timer); |
|
|
|
/** |
|
* try_to_del_timer_sync - Try to deactivate a timer |
|
* @timer: timer to delete |
|
* |
|
* 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 timer_base *base; |
|
unsigned long flags; |
|
int ret = -1; |
|
|
|
debug_assert_init(timer); |
|
|
|
base = lock_timer_base(timer, &flags); |
|
|
|
if (base->running_timer != timer) |
|
ret = detach_if_pending(timer, base, true); |
|
|
|
raw_spin_unlock_irqrestore(&base->lock, flags); |
|
|
|
return ret; |
|
} |
|
EXPORT_SYMBOL(try_to_del_timer_sync); |
|
|
|
bool timer_curr_running(struct timer_list *timer) |
|
{ |
|
int i; |
|
|
|
for (i = 0; i < NR_BASES; i++) { |
|
struct timer_base *base = this_cpu_ptr(&timer_bases[i]); |
|
|
|
if (base->running_timer == timer) |
|
return true; |
|
} |
|
|
|
return false; |
|
} |
|
|
|
#ifdef CONFIG_PREEMPT_RT |
|
static __init void timer_base_init_expiry_lock(struct timer_base *base) |
|
{ |
|
spin_lock_init(&base->expiry_lock); |
|
} |
|
|
|
static inline void timer_base_lock_expiry(struct timer_base *base) |
|
{ |
|
spin_lock(&base->expiry_lock); |
|
} |
|
|
|
static inline void timer_base_unlock_expiry(struct timer_base *base) |
|
{ |
|
spin_unlock(&base->expiry_lock); |
|
} |
|
|
|
/* |
|
* The counterpart to del_timer_wait_running(). |
|
* |
|
* If there is a waiter for base->expiry_lock, then it was waiting for the |
|
* timer callback to finish. Drop expiry_lock and reaquire it. That allows |
|
* the waiter to acquire the lock and make progress. |
|
*/ |
|
static void timer_sync_wait_running(struct timer_base *base) |
|
{ |
|
if (atomic_read(&base->timer_waiters)) { |
|
spin_unlock(&base->expiry_lock); |
|
spin_lock(&base->expiry_lock); |
|
} |
|
} |
|
|
|
/* |
|
* This function is called on PREEMPT_RT kernels when the fast path |
|
* deletion of a timer failed because the timer callback function was |
|
* running. |
|
* |
|
* This prevents priority inversion, if the softirq thread on a remote CPU |
|
* got preempted, and it prevents a life lock when the task which tries to |
|
* delete a timer preempted the softirq thread running the timer callback |
|
* function. |
|
*/ |
|
static void del_timer_wait_running(struct timer_list *timer) |
|
{ |
|
u32 tf; |
|
|
|
tf = READ_ONCE(timer->flags); |
|
if (!(tf & (TIMER_MIGRATING | TIMER_IRQSAFE))) { |
|
struct timer_base *base = get_timer_base(tf); |
|
|
|
/* |
|
* Mark the base as contended and grab the expiry lock, |
|
* which is held by the softirq across the timer |
|
* callback. Drop the lock immediately so the softirq can |
|
* expire the next timer. In theory the timer could already |
|
* be running again, but that's more than unlikely and just |
|
* causes another wait loop. |
|
*/ |
|
atomic_inc(&base->timer_waiters); |
|
spin_lock_bh(&base->expiry_lock); |
|
atomic_dec(&base->timer_waiters); |
|
spin_unlock_bh(&base->expiry_lock); |
|
} |
|
} |
|
#else |
|
static inline void timer_base_init_expiry_lock(struct timer_base *base) { } |
|
static inline void timer_base_lock_expiry(struct timer_base *base) { } |
|
static inline void timer_base_unlock_expiry(struct timer_base *base) { } |
|
static inline void timer_sync_wait_running(struct timer_base *base) { } |
|
static inline void del_timer_wait_running(struct timer_list *timer) { } |
|
#endif |
|
|
|
#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT) |
|
/** |
|
* 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) |
|
{ |
|
int ret; |
|
|
|
#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)); |
|
|
|
/* |
|
* Must be able to sleep on PREEMPT_RT because of the slowpath in |
|
* del_timer_wait_running(). |
|
*/ |
|
if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(timer->flags & TIMER_IRQSAFE)) |
|
lockdep_assert_preemption_enabled(); |
|
|
|
do { |
|
ret = try_to_del_timer_sync(timer); |
|
|
|
if (unlikely(ret < 0)) { |
|
del_timer_wait_running(timer); |
|
cpu_relax(); |
|
} |
|
} while (ret < 0); |
|
|
|
return ret; |
|
} |
|
EXPORT_SYMBOL(del_timer_sync); |
|
#endif |
|
|
|
static void call_timer_fn(struct timer_list *timer, |
|
void (*fn)(struct timer_list *), |
|
unsigned long baseclk) |
|
{ |
|
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, baseclk); |
|
fn(timer); |
|
trace_timer_expire_exit(timer); |
|
|
|
lock_map_release(&lockdep_map); |
|
|
|
if (count != preempt_count()) { |
|
WARN_ONCE(1, "timer: %pS 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); |
|
} |
|
} |
|
|
|
static void expire_timers(struct timer_base *base, struct hlist_head *head) |
|
{ |
|
/* |
|
* This value is required only for tracing. base->clk was |
|
* incremented directly before expire_timers was called. But expiry |
|
* is related to the old base->clk value. |
|
*/ |
|
unsigned long baseclk = base->clk - 1; |
|
|
|
while (!hlist_empty(head)) { |
|
struct timer_list *timer; |
|
void (*fn)(struct timer_list *); |
|
|
|
timer = hlist_entry(head->first, struct timer_list, entry); |
|
|
|
base->running_timer = timer; |
|
detach_timer(timer, true); |
|
|
|
fn = timer->function; |
|
|
|
if (timer->flags & TIMER_IRQSAFE) { |
|
raw_spin_unlock(&base->lock); |
|
call_timer_fn(timer, fn, baseclk); |
|
base->running_timer = NULL; |
|
raw_spin_lock(&base->lock); |
|
} else { |
|
raw_spin_unlock_irq(&base->lock); |
|
call_timer_fn(timer, fn, baseclk); |
|
base->running_timer = NULL; |
|
timer_sync_wait_running(base); |
|
raw_spin_lock_irq(&base->lock); |
|
} |
|
} |
|
} |
|
|
|
static int collect_expired_timers(struct timer_base *base, |
|
struct hlist_head *heads) |
|
{ |
|
unsigned long clk = base->clk = base->next_expiry; |
|
struct hlist_head *vec; |
|
int i, levels = 0; |
|
unsigned int idx; |
|
|
|
for (i = 0; i < LVL_DEPTH; i++) { |
|
idx = (clk & LVL_MASK) + i * LVL_SIZE; |
|
|
|
if (__test_and_clear_bit(idx, base->pending_map)) { |
|
vec = base->vectors + idx; |
|
hlist_move_list(vec, heads++); |
|
levels++; |
|
} |
|
/* Is it time to look at the next level? */ |
|
if (clk & LVL_CLK_MASK) |
|
break; |
|
/* Shift clock for the next level granularity */ |
|
clk >>= LVL_CLK_SHIFT; |
|
} |
|
return levels; |
|
} |
|
|
|
/* |
|
* Find the next pending bucket of a level. Search from level start (@offset) |
|
* + @clk upwards and if nothing there, search from start of the level |
|
* (@offset) up to @offset + clk. |
|
*/ |
|
static int next_pending_bucket(struct timer_base *base, unsigned offset, |
|
unsigned clk) |
|
{ |
|
unsigned pos, start = offset + clk; |
|
unsigned end = offset + LVL_SIZE; |
|
|
|
pos = find_next_bit(base->pending_map, end, start); |
|
if (pos < end) |
|
return pos - start; |
|
|
|
pos = find_next_bit(base->pending_map, start, offset); |
|
return pos < start ? pos + LVL_SIZE - start : -1; |
|
} |
|
|
|
/* |
|
* Search the first expiring timer in the various clock levels. Caller must |
|
* hold base->lock. |
|
*/ |
|
static unsigned long __next_timer_interrupt(struct timer_base *base) |
|
{ |
|
unsigned long clk, next, adj; |
|
unsigned lvl, offset = 0; |
|
|
|
next = base->clk + NEXT_TIMER_MAX_DELTA; |
|
clk = base->clk; |
|
for (lvl = 0; lvl < LVL_DEPTH; lvl++, offset += LVL_SIZE) { |
|
int pos = next_pending_bucket(base, offset, clk & LVL_MASK); |
|
unsigned long lvl_clk = clk & LVL_CLK_MASK; |
|
|
|
if (pos >= 0) { |
|
unsigned long tmp = clk + (unsigned long) pos; |
|
|
|
tmp <<= LVL_SHIFT(lvl); |
|
if (time_before(tmp, next)) |
|
next = tmp; |
|
|
|
/* |
|
* If the next expiration happens before we reach |
|
* the next level, no need to check further. |
|
*/ |
|
if (pos <= ((LVL_CLK_DIV - lvl_clk) & LVL_CLK_MASK)) |
|
break; |
|
} |
|
/* |
|
* Clock for the next level. If the current level clock lower |
|
* bits are zero, we look at the next level as is. If not we |
|
* need to advance it by one because that's going to be the |
|
* next expiring bucket in that level. base->clk is the next |
|
* expiring jiffie. So in case of: |
|
* |
|
* LVL5 LVL4 LVL3 LVL2 LVL1 LVL0 |
|
* 0 0 0 0 0 0 |
|
* |
|
* we have to look at all levels @index 0. With |
|
* |
|
* LVL5 LVL4 LVL3 LVL2 LVL1 LVL0 |
|
* 0 0 0 0 0 2 |
|
* |
|
* LVL0 has the next expiring bucket @index 2. The upper |
|
* levels have the next expiring bucket @index 1. |
|
* |
|
* In case that the propagation wraps the next level the same |
|
* rules apply: |
|
* |
|
* LVL5 LVL4 LVL3 LVL2 LVL1 LVL0 |
|
* 0 0 0 0 F 2 |
|
* |
|
* So after looking at LVL0 we get: |
|
* |
|
* LVL5 LVL4 LVL3 LVL2 LVL1 |
|
* 0 0 0 1 0 |
|
* |
|
* So no propagation from LVL1 to LVL2 because that happened |
|
* with the add already, but then we need to propagate further |
|
* from LVL2 to LVL3. |
|
* |
|
* So the simple check whether the lower bits of the current |
|
* level are 0 or not is sufficient for all cases. |
|
*/ |
|
adj = lvl_clk ? 1 : 0; |
|
clk >>= LVL_CLK_SHIFT; |
|
clk += adj; |
|
} |
|
|
|
base->next_expiry_recalc = false; |
|
|
|
return next; |
|
} |
|
|
|
#ifdef CONFIG_NO_HZ_COMMON |
|
/* |
|
* 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 timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); |
|
u64 expires = KTIME_MAX; |
|
unsigned long nextevt; |
|
bool is_max_delta; |
|
|
|
/* |
|
* 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; |
|
|
|
raw_spin_lock(&base->lock); |
|
if (base->next_expiry_recalc) |
|
base->next_expiry = __next_timer_interrupt(base); |
|
nextevt = base->next_expiry; |
|
is_max_delta = (nextevt == base->clk + NEXT_TIMER_MAX_DELTA); |
|
|
|
/* |
|
* We have a fresh next event. Check whether we can forward the |
|
* base. We can only do that when @basej is past base->clk |
|
* otherwise we might rewind base->clk. |
|
*/ |
|
if (time_after(basej, base->clk)) { |
|
if (time_after(nextevt, basej)) |
|
base->clk = basej; |
|
else if (time_after(nextevt, base->clk)) |
|
base->clk = nextevt; |
|
} |
|
|
|
if (time_before_eq(nextevt, basej)) { |
|
expires = basem; |
|
base->is_idle = false; |
|
} else { |
|
if (!is_max_delta) |
|
expires = basem + (u64)(nextevt - basej) * TICK_NSEC; |
|
/* |
|
* If we expect to sleep more than a tick, mark the base idle. |
|
* Also the tick is stopped so any added timer must forward |
|
* the base clk itself to keep granularity small. This idle |
|
* logic is only maintained for the BASE_STD base, deferrable |
|
* timers may still see large granularity skew (by design). |
|
*/ |
|
if ((expires - basem) > TICK_NSEC) |
|
base->is_idle = true; |
|
} |
|
raw_spin_unlock(&base->lock); |
|
|
|
return cmp_next_hrtimer_event(basem, expires); |
|
} |
|
|
|
/** |
|
* timer_clear_idle - Clear the idle state of the timer base |
|
* |
|
* Called with interrupts disabled |
|
*/ |
|
void timer_clear_idle(void) |
|
{ |
|
struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); |
|
|
|
/* |
|
* We do this unlocked. The worst outcome is a remote enqueue sending |
|
* a pointless IPI, but taking the lock would just make the window for |
|
* sending the IPI a few instructions smaller for the cost of taking |
|
* the lock in the exit from idle path. |
|
*/ |
|
base->is_idle = false; |
|
} |
|
#endif |
|
|
|
/** |
|
* __run_timers - run all expired timers (if any) on this CPU. |
|
* @base: the timer vector to be processed. |
|
*/ |
|
static inline void __run_timers(struct timer_base *base) |
|
{ |
|
struct hlist_head heads[LVL_DEPTH]; |
|
int levels; |
|
|
|
if (time_before(jiffies, base->next_expiry)) |
|
return; |
|
|
|
timer_base_lock_expiry(base); |
|
raw_spin_lock_irq(&base->lock); |
|
|
|
while (time_after_eq(jiffies, base->clk) && |
|
time_after_eq(jiffies, base->next_expiry)) { |
|
levels = collect_expired_timers(base, heads); |
|
/* |
|
* The only possible reason for not finding any expired |
|
* timer at this clk is that all matching timers have been |
|
* dequeued. |
|
*/ |
|
WARN_ON_ONCE(!levels && !base->next_expiry_recalc); |
|
base->clk++; |
|
base->next_expiry = __next_timer_interrupt(base); |
|
|
|
while (levels--) |
|
expire_timers(base, heads + levels); |
|
} |
|
raw_spin_unlock_irq(&base->lock); |
|
timer_base_unlock_expiry(base); |
|
} |
|
|
|
/* |
|
* This function runs timers and the timer-tq in bottom half context. |
|
*/ |
|
static __latent_entropy void run_timer_softirq(struct softirq_action *h) |
|
{ |
|
struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); |
|
|
|
__run_timers(base); |
|
if (IS_ENABLED(CONFIG_NO_HZ_COMMON)) |
|
__run_timers(this_cpu_ptr(&timer_bases[BASE_DEF])); |
|
} |
|
|
|
/* |
|
* Called by the local, per-CPU timer interrupt on SMP. |
|
*/ |
|
static void run_local_timers(void) |
|
{ |
|
struct timer_base *base = this_cpu_ptr(&timer_bases[BASE_STD]); |
|
|
|
hrtimer_run_queues(); |
|
/* Raise the softirq only if required. */ |
|
if (time_before(jiffies, base->next_expiry)) { |
|
if (!IS_ENABLED(CONFIG_NO_HZ_COMMON)) |
|
return; |
|
/* CPU is awake, so check the deferrable base. */ |
|
base++; |
|
if (time_before(jiffies, base->next_expiry)) |
|
return; |
|
} |
|
raise_softirq(TIMER_SOFTIRQ); |
|
} |
|
|
|
/* |
|
* 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; |
|
|
|
PRANDOM_ADD_NOISE(jiffies, user_tick, p, 0); |
|
|
|
/* Note: this timer irq context must be accounted for as well. */ |
|
account_process_tick(p, user_tick); |
|
run_local_timers(); |
|
rcu_sched_clock_irq(user_tick); |
|
#ifdef CONFIG_IRQ_WORK |
|
if (in_irq()) |
|
irq_work_tick(); |
|
#endif |
|
scheduler_tick(); |
|
if (IS_ENABLED(CONFIG_POSIX_TIMERS)) |
|
run_posix_cpu_timers(); |
|
} |
|
|
|
/* |
|
* Since schedule_timeout()'s timer is defined on the stack, it must store |
|
* the target task on the stack as well. |
|
*/ |
|
struct process_timer { |
|
struct timer_list timer; |
|
struct task_struct *task; |
|
}; |
|
|
|
static void process_timeout(struct timer_list *t) |
|
{ |
|
struct process_timer *timeout = from_timer(timeout, t, timer); |
|
|
|
wake_up_process(timeout->task); |
|
} |
|
|
|
/** |
|
* schedule_timeout - sleep until timeout |
|
* @timeout: timeout value in jiffies |
|
* |
|
* Make the current task sleep until @timeout jiffies have elapsed. |
|
* The function behavior depends on the current task state |
|
* (see also set_current_state() description): |
|
* |
|
* %TASK_RUNNING - the scheduler is called, but the task does not sleep |
|
* at all. That happens because sched_submit_work() does nothing for |
|
* tasks in %TASK_RUNNING state. |
|
* |
|
* %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to |
|
* pass before the routine returns unless the current task is explicitly |
|
* woken up, (e.g. by wake_up_process()). |
|
* |
|
* %TASK_INTERRUPTIBLE - the routine may return early if a signal is |
|
* delivered to the current task or the current task is explicitly woken |
|
* up. |
|
* |
|
* 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. |
|
* |
|
* Returns 0 when the timer has expired otherwise the remaining time in |
|
* jiffies will be returned. In all cases the return value is guaranteed |
|
* to be non-negative. |
|
*/ |
|
signed long __sched schedule_timeout(signed long timeout) |
|
{ |
|
struct process_timer 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; |
|
|
|
timer.task = current; |
|
timer_setup_on_stack(&timer.timer, process_timeout, 0); |
|
__mod_timer(&timer.timer, expire, MOD_TIMER_NOTPENDING); |
|
schedule(); |
|
del_singleshot_timer_sync(&timer.timer); |
|
|
|
/* Remove the timer from the object tracker */ |
|
destroy_timer_on_stack(&timer.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); |
|
|
|
/* |
|
* Like schedule_timeout_uninterruptible(), except this task will not contribute |
|
* to load average. |
|
*/ |
|
signed long __sched schedule_timeout_idle(signed long timeout) |
|
{ |
|
__set_current_state(TASK_IDLE); |
|
return schedule_timeout(timeout); |
|
} |
|
EXPORT_SYMBOL(schedule_timeout_idle); |
|
|
|
#ifdef CONFIG_HOTPLUG_CPU |
|
static void migrate_timer_list(struct timer_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); |
|
detach_timer(timer, false); |
|
timer->flags = (timer->flags & ~TIMER_BASEMASK) | cpu; |
|
internal_add_timer(new_base, timer); |
|
} |
|
} |
|
|
|
int timers_prepare_cpu(unsigned int cpu) |
|
{ |
|
struct timer_base *base; |
|
int b; |
|
|
|
for (b = 0; b < NR_BASES; b++) { |
|
base = per_cpu_ptr(&timer_bases[b], cpu); |
|
base->clk = jiffies; |
|
base->next_expiry = base->clk + NEXT_TIMER_MAX_DELTA; |
|
base->is_idle = false; |
|
} |
|
return 0; |
|
} |
|
|
|
int timers_dead_cpu(unsigned int cpu) |
|
{ |
|
struct timer_base *old_base; |
|
struct timer_base *new_base; |
|
int b, i; |
|
|
|
BUG_ON(cpu_online(cpu)); |
|
|
|
for (b = 0; b < NR_BASES; b++) { |
|
old_base = per_cpu_ptr(&timer_bases[b], cpu); |
|
new_base = get_cpu_ptr(&timer_bases[b]); |
|
/* |
|
* The caller is globally serialized and nobody else |
|
* takes two locks at once, deadlock is not possible. |
|
*/ |
|
raw_spin_lock_irq(&new_base->lock); |
|
raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING); |
|
|
|
/* |
|
* The current CPUs base clock might be stale. Update it |
|
* before moving the timers over. |
|
*/ |
|
forward_timer_base(new_base); |
|
|
|
BUG_ON(old_base->running_timer); |
|
|
|
for (i = 0; i < WHEEL_SIZE; i++) |
|
migrate_timer_list(new_base, old_base->vectors + i); |
|
|
|
raw_spin_unlock(&old_base->lock); |
|
raw_spin_unlock_irq(&new_base->lock); |
|
put_cpu_ptr(&timer_bases); |
|
} |
|
return 0; |
|
} |
|
|
|
#endif /* CONFIG_HOTPLUG_CPU */ |
|
|
|
static void __init init_timer_cpu(int cpu) |
|
{ |
|
struct timer_base *base; |
|
int i; |
|
|
|
for (i = 0; i < NR_BASES; i++) { |
|
base = per_cpu_ptr(&timer_bases[i], cpu); |
|
base->cpu = cpu; |
|
raw_spin_lock_init(&base->lock); |
|
base->clk = jiffies; |
|
base->next_expiry = base->clk + NEXT_TIMER_MAX_DELTA; |
|
timer_base_init_expiry_lock(base); |
|
} |
|
} |
|
|
|
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(); |
|
posix_cputimers_init_work(); |
|
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); |
|
|
|
/** |
|
* usleep_range - Sleep for an approximate time |
|
* @min: Minimum time in usecs to sleep |
|
* @max: Maximum time in usecs to sleep |
|
* |
|
* In non-atomic context where the exact wakeup time is flexible, use |
|
* usleep_range() instead of udelay(). The sleep improves responsiveness |
|
* by avoiding the CPU-hogging busy-wait of udelay(), and the range reduces |
|
* power usage by allowing hrtimers to take advantage of an already- |
|
* scheduled interrupt instead of scheduling a new one just for this sleep. |
|
*/ |
|
void __sched usleep_range(unsigned long min, unsigned long max) |
|
{ |
|
ktime_t exp = ktime_add_us(ktime_get(), min); |
|
u64 delta = (u64)(max - min) * NSEC_PER_USEC; |
|
|
|
for (;;) { |
|
__set_current_state(TASK_UNINTERRUPTIBLE); |
|
/* Do not return before the requested sleep time has elapsed */ |
|
if (!schedule_hrtimeout_range(&exp, delta, HRTIMER_MODE_ABS)) |
|
break; |
|
} |
|
} |
|
EXPORT_SYMBOL(usleep_range);
|
|
|