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Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

浏览代码 
Pull timer updates from Thomas Gleixner:
 "Nothing exciting, just the usual pile of fixes, updates and cleanups:

   - A bunch of clocksource driver updates

   - Removal of CONFIG_TIMER_STATS and the related /proc file

   - More posix timer slim down work

   - A scalability enhancement in the tick broadcast code

   - Math cleanups"

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  hrtimer: Catch invalid clockids again
  math64, tile: Fix build failure
  clocksource/drivers/arm_arch_timer:: Mark cyclecounter __ro_after_init
  timerfd: Protect the might cancel mechanism proper
  timer_list: Remove useless cast when printing
  time: Remove CONFIG_TIMER_STATS
  clocksource/drivers/arm_arch_timer: Work around Hisilicon erratum 161010101
  clocksource/drivers/arm_arch_timer: Introduce generic errata handling infrastructure
  clocksource/drivers/arm_arch_timer: Remove fsl-a008585 parameter
  clocksource/drivers/arm_arch_timer: Add dt binding for hisilicon-161010101 erratum
  clocksource/drivers/ostm: Add renesas-ostm timer driver
  clocksource/drivers/ostm: Document renesas-ostm timer DT bindings
  clocksource/drivers/tcb_clksrc: Use 32 bit tcb as sched_clock
  clocksource/drivers/gemini: Add driver for the Cortina Gemini
  clocksource: add DT bindings for Cortina Gemini
  clockevents: Add a clkevt-of mechanism like clksrc-of
  tick/broadcast: Reduce lock cacheline contention
  timers: Omit POSIX timer stuff from task_struct when disabled
  x86/timer: Make delay() work during early bootup
  delay: Add explanation of udelay() inaccuracy
  ...
这个提交包含在：
Linus Torvalds
2017-02-20 10:06:32 -08:00
父节点 c9b9f207b9 336a9cde10
当前提交 20dcfe1b7d
共修改 43 个文件，包含 1023 行新增和 847 行删除
下载 Patch 文件 下载 Diff 文件 展开所有文件 折叠所有文件

1
kernel/time/Makefile
查看文件

@@ -15,6 +15,5 @@ ifeq ($(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST),y)
endif
obj-$(CONFIG_GENERIC_SCHED_CLOCK) += sched_clock.o
obj-$(CONFIG_TICK_ONESHOT) += tick-oneshot.o tick-sched.o
obj-$(CONFIG_TIMER_STATS) += timer_stats.o
obj-$(CONFIG_DEBUG_FS) += timekeeping_debug.o
obj-$(CONFIG_TEST_UDELAY) += test_udelay.o

58
kernel/time/hrtimer.c
查看文件

@@ -94,17 +94,15 @@ DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
};
static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
/* Make sure we catch unsupported clockids */
[0 ... MAX_CLOCKS - 1] = HRTIMER_MAX_CLOCK_BASES,
[CLOCK_REALTIME] = HRTIMER_BASE_REALTIME,
[CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC,
[CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME,
[CLOCK_TAI] = HRTIMER_BASE_TAI,
};
static inline int hrtimer_clockid_to_base(clockid_t clock_id)
{
return hrtimer_clock_to_base_table[clock_id];
}
/*
* Functions and macros which are different for UP/SMP systems are kept in a
* single place
@@ -766,34 +764,6 @@ void hrtimers_resume(void)
clock_was_set_delayed();
}
static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
{
#ifdef CONFIG_TIMER_STATS
if (timer->start_site)
return;
timer->start_site = __builtin_return_address(0);
memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
timer->start_pid = current->pid;
#endif
}
static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
{
#ifdef CONFIG_TIMER_STATS
timer->start_site = NULL;
#endif
}
static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
{
#ifdef CONFIG_TIMER_STATS
if (likely(!timer_stats_active))
return;
timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
timer->function, timer->start_comm, 0);
#endif
}
/*
* Counterpart to lock_hrtimer_base above:
*/
@@ -932,7 +902,6 @@ remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, bool rest
* rare case and less expensive than a smp call.
*/
debug_deactivate(timer);
timer_stats_hrtimer_clear_start_info(timer);
reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
if (!restart)
@@ -990,8 +959,6 @@ void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
/* Switch the timer base, if necessary: */
new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
timer_stats_hrtimer_set_start_info(timer);
leftmost = enqueue_hrtimer(timer, new_base);
if (!leftmost)
goto unlock;
@@ -1112,6 +1079,18 @@ u64 hrtimer_get_next_event(void)
}
#endif
static inline int hrtimer_clockid_to_base(clockid_t clock_id)
{
if (likely(clock_id < MAX_CLOCKS)) {
int base = hrtimer_clock_to_base_table[clock_id];
if (likely(base != HRTIMER_MAX_CLOCK_BASES))
return base;
}
WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
return HRTIMER_BASE_MONOTONIC;
}
static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
enum hrtimer_mode mode)
{
@@ -1128,12 +1107,6 @@ static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
base = hrtimer_clockid_to_base(clock_id);
timer->base = &cpu_base->clock_base[base];
timerqueue_init(&timer->node);
#ifdef CONFIG_TIMER_STATS
timer->start_site = NULL;
timer->start_pid = -1;
memset(timer->start_comm, 0, TASK_COMM_LEN);
#endif
}
/**
@@ -1217,7 +1190,6 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
raw_write_seqcount_barrier(&cpu_base->seq);
__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
timer_stats_account_hrtimer(timer);
fn = timer->function;
/*

15
kernel/time/tick-broadcast.c
查看文件

@@ -29,12 +29,13 @@
*/
static struct tick_device tick_broadcast_device;
static cpumask_var_t tick_broadcast_mask;
static cpumask_var_t tick_broadcast_on;
static cpumask_var_t tmpmask;
static DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
static cpumask_var_t tick_broadcast_mask __cpumask_var_read_mostly;
static cpumask_var_t tick_broadcast_on __cpumask_var_read_mostly;
static cpumask_var_t tmpmask __cpumask_var_read_mostly;
static int tick_broadcast_forced;
static __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
#ifdef CONFIG_TICK_ONESHOT
static void tick_broadcast_clear_oneshot(int cpu);
static void tick_resume_broadcast_oneshot(struct clock_event_device *bc);
@@ -516,9 +517,9 @@ void tick_resume_broadcast(void)
#ifdef CONFIG_TICK_ONESHOT
static cpumask_var_t tick_broadcast_oneshot_mask;
static cpumask_var_t tick_broadcast_pending_mask;
static cpumask_var_t tick_broadcast_force_mask;
static cpumask_var_t tick_broadcast_oneshot_mask __cpumask_var_read_mostly;
static cpumask_var_t tick_broadcast_pending_mask __cpumask_var_read_mostly;
static cpumask_var_t tick_broadcast_force_mask __cpumask_var_read_mostly;
/*
* Exposed for debugging: see timer_list.c

39
kernel/time/timekeeping.c
查看文件

@@ -1275,27 +1275,8 @@ error: /* even if we error out, we forwarded the time, so call update */
}
EXPORT_SYMBOL(timekeeping_inject_offset);
/**
* timekeeping_get_tai_offset - Returns current TAI offset from UTC
*
*/
s32 timekeeping_get_tai_offset(void)
{
struct timekeeper *tk = &tk_core.timekeeper;
unsigned int seq;
s32 ret;
do {
seq = read_seqcount_begin(&tk_core.seq);
ret = tk->tai_offset;
} while (read_seqcount_retry(&tk_core.seq, seq));
return ret;
}
/**
* __timekeeping_set_tai_offset - Lock free worker function
* __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic
*
*/
static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
@@ -1304,24 +1285,6 @@ static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0));
}
/**
* timekeeping_set_tai_offset - Sets the current TAI offset from UTC
*
*/
void timekeeping_set_tai_offset(s32 tai_offset)
{
struct timekeeper *tk = &tk_core.timekeeper;
unsigned long flags;
raw_spin_lock_irqsave(&timekeeper_lock, flags);
write_seqcount_begin(&tk_core.seq);
__timekeeping_set_tai_offset(tk, tai_offset);
timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
write_seqcount_end(&tk_core.seq);
raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
clock_was_set();
}
/**
* change_clocksource - Swaps clocksources if a new one is available
*

2
kernel/time/timekeeping.h
查看文件

@@ -11,8 +11,6 @@ extern ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq,
extern int timekeeping_valid_for_hres(void);
extern u64 timekeeping_max_deferment(void);
extern int timekeeping_inject_offset(struct timespec *ts);
extern s32 timekeeping_get_tai_offset(void);
extern void timekeeping_set_tai_offset(s32 tai_offset);
extern int timekeeping_suspend(void);
extern void timekeeping_resume(void);

48
kernel/time/timer.c
查看文件

@@ -571,38 +571,6 @@ internal_add_timer(struct timer_base *base, struct timer_list *timer)
trigger_dyntick_cpu(base, timer);
}
#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;
@@ -789,11 +757,6 @@ static void do_init_timer(struct timer_list *timer, unsigned int flags,
{
timer->entry.pprev = NULL;
timer->flags = flags | raw_smp_processor_id();
#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);
}
@@ -1001,8 +964,6 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
base = lock_timer_base(timer, &flags);
}
timer_stats_timer_set_start_info(timer);
ret = detach_if_pending(timer, base, false);
if (!ret && pending_only)
goto out_unlock;
@@ -1130,7 +1091,6 @@ void add_timer_on(struct timer_list *timer, int cpu)
struct timer_base *new_base, *base;
unsigned long flags;
timer_stats_timer_set_start_info(timer);
BUG_ON(timer_pending(timer) || !timer->function);
new_base = get_timer_cpu_base(timer->flags, cpu);
@@ -1176,7 +1136,6 @@ int del_timer(struct timer_list *timer)
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);
@@ -1204,10 +1163,9 @@ int try_to_del_timer_sync(struct timer_list *timer)
base = lock_timer_base(timer, &flags);
if (base->running_timer != timer) {
timer_stats_timer_clear_start_info(timer);
if (base->running_timer != timer)
ret = detach_if_pending(timer, base, true);
}
spin_unlock_irqrestore(&base->lock, flags);
return ret;
@@ -1331,7 +1289,6 @@ static void expire_timers(struct timer_base *base, struct hlist_head *head)
unsigned long data;
timer = hlist_entry(head->first, struct timer_list, entry);
timer_stats_account_timer(timer);
base->running_timer = timer;
detach_timer(timer, true);
@@ -1868,7 +1825,6 @@ static void __init init_timer_cpus(void)
void __init init_timers(void)
{
init_timer_cpus();
init_timer_stats();
open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
}

12
kernel/time/timer_list.c
查看文件

@@ -62,21 +62,11 @@ static void
print_timer(struct seq_file *m, struct hrtimer *taddr, struct hrtimer *timer,
int idx, u64 now)
{
#ifdef CONFIG_TIMER_STATS
char tmp[TASK_COMM_LEN + 1];
#endif
SEQ_printf(m, " #%d: ", idx);
print_name_offset(m, taddr);
SEQ_printf(m, ", ");
print_name_offset(m, timer->function);
SEQ_printf(m, ", S:%02x", timer->state);
#ifdef CONFIG_TIMER_STATS
SEQ_printf(m, ", ");
print_name_offset(m, timer->start_site);
memcpy(tmp, timer->start_comm, TASK_COMM_LEN);
tmp[TASK_COMM_LEN] = 0;
SEQ_printf(m, ", %s/%d", tmp, timer->start_pid);
#endif
SEQ_printf(m, "\n");
SEQ_printf(m, " # expires at %Lu-%Lu nsecs [in %Ld to %Ld nsecs]\n",
(unsigned long long)ktime_to_ns(hrtimer_get_softexpires(timer)),
@@ -127,7 +117,7 @@ print_base(struct seq_file *m, struct hrtimer_clock_base *base, u64 now)
SEQ_printf(m, " .base: %pK\n", base);
SEQ_printf(m, " .index: %d\n", base->index);
SEQ_printf(m, " .resolution: %u nsecs\n", (unsigned) hrtimer_resolution);
SEQ_printf(m, " .resolution: %u nsecs\n", hrtimer_resolution);
SEQ_printf(m, " .get_time: ");
print_name_offset(m, base->get_time);

425
kernel/time/timer_stats.c
查看文件

@@ -1,425 +0,0 @@
/*
* kernel/time/timer_stats.c
*
* Collect timer usage statistics.
*
* Copyright(C) 2006, Red Hat, Inc., Ingo Molnar
* Copyright(C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
*
* timer_stats is based on timer_top, a similar functionality which was part of
* Con Kolivas dyntick patch set. It was developed by Daniel Petrini at the
* Instituto Nokia de Tecnologia - INdT - Manaus. timer_top's design was based
* on dynamic allocation of the statistics entries and linear search based
* lookup combined with a global lock, rather than the static array, hash
* and per-CPU locking which is used by timer_stats. It was written for the
* pre hrtimer kernel code and therefore did not take hrtimers into account.
* Nevertheless it provided the base for the timer_stats implementation and
* was a helpful source of inspiration. Kudos to Daniel and the Nokia folks
* for this effort.
*
* timer_top.c is
* Copyright (C) 2005 Instituto Nokia de Tecnologia - INdT - Manaus
* Written by Daniel Petrini <d.pensator@gmail.com>
* timer_top.c was released under the GNU General Public License version 2
*
* We export the addresses and counting of timer functions being called,
* the pid and cmdline from the owner process if applicable.
*
* Start/stop data collection:
* # echo [1|0] >/proc/timer_stats
*
* Display the information collected so far:
* # cat /proc/timer_stats
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/proc_fs.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/kallsyms.h>
#include <linux/uaccess.h>
/*
* This is our basic unit of interest: a timer expiry event identified
* by the timer, its start/expire functions and the PID of the task that
* started the timer. We count the number of times an event happens:
*/
struct entry {
/*
* Hash list:
*/
struct entry *next;
/*
* Hash keys:
*/
void *timer;
void *start_func;
void *expire_func;
pid_t pid;
/*
* Number of timeout events:
*/
unsigned long count;
u32 flags;
/*
* We save the command-line string to preserve
* this information past task exit:
*/
char comm[TASK_COMM_LEN + 1];
} ____cacheline_aligned_in_smp;
/*
* Spinlock protecting the tables - not taken during lookup:
*/
static DEFINE_RAW_SPINLOCK(table_lock);
/*
* Per-CPU lookup locks for fast hash lookup:
*/
static DEFINE_PER_CPU(raw_spinlock_t, tstats_lookup_lock);
/*
* Mutex to serialize state changes with show-stats activities:
*/
static DEFINE_MUTEX(show_mutex);
/*
* Collection status, active/inactive:
*/
int __read_mostly timer_stats_active;
/*
* Beginning/end timestamps of measurement:
*/
static ktime_t time_start, time_stop;
/*
* tstat entry structs only get allocated while collection is
* active and never freed during that time - this simplifies
* things quite a bit.
*
* They get freed when a new collection period is started.
*/
#define MAX_ENTRIES_BITS 10
#define MAX_ENTRIES (1UL << MAX_ENTRIES_BITS)
static unsigned long nr_entries;
static struct entry entries[MAX_ENTRIES];
static atomic_t overflow_count;
/*
* The entries are in a hash-table, for fast lookup:
*/
#define TSTAT_HASH_BITS (MAX_ENTRIES_BITS - 1)
#define TSTAT_HASH_SIZE (1UL << TSTAT_HASH_BITS)
#define TSTAT_HASH_MASK (TSTAT_HASH_SIZE - 1)
#define __tstat_hashfn(entry) \
(((unsigned long)(entry)->timer ^ \
(unsigned long)(entry)->start_func ^ \
(unsigned long)(entry)->expire_func ^ \
(unsigned long)(entry)->pid ) & TSTAT_HASH_MASK)
#define tstat_hashentry(entry) (tstat_hash_table + __tstat_hashfn(entry))
static struct entry *tstat_hash_table[TSTAT_HASH_SIZE] __read_mostly;
static void reset_entries(void)
{
nr_entries = 0;
memset(entries, 0, sizeof(entries));
memset(tstat_hash_table, 0, sizeof(tstat_hash_table));
atomic_set(&overflow_count, 0);
}
static struct entry *alloc_entry(void)
{
if (nr_entries >= MAX_ENTRIES)
return NULL;
return entries + nr_entries++;
}
static int match_entries(struct entry *entry1, struct entry *entry2)
{
return entry1->timer == entry2->timer &&
entry1->start_func == entry2->start_func &&
entry1->expire_func == entry2->expire_func &&
entry1->pid == entry2->pid;
}
/*
* Look up whether an entry matching this item is present
* in the hash already. Must be called with irqs off and the
* lookup lock held:
*/
static struct entry *tstat_lookup(struct entry *entry, char *comm)
{
struct entry **head, *curr, *prev;
head = tstat_hashentry(entry);
curr = *head;
/*
* The fastpath is when the entry is already hashed,
* we do this with the lookup lock held, but with the
* table lock not held:
*/
while (curr) {
if (match_entries(curr, entry))
return curr;
curr = curr->next;
}
/*
* Slowpath: allocate, set up and link a new hash entry:
*/
prev = NULL;
curr = *head;
raw_spin_lock(&table_lock);
/*
* Make sure we have not raced with another CPU:
*/
while (curr) {
if (match_entries(curr, entry))
goto out_unlock;
prev = curr;
curr = curr->next;
}
curr = alloc_entry();
if (curr) {
*curr = *entry;
curr->count = 0;
curr->next = NULL;
memcpy(curr->comm, comm, TASK_COMM_LEN);
smp_mb(); /* Ensure that curr is initialized before insert */
if (prev)
prev->next = curr;
else
*head = curr;
}
out_unlock:
raw_spin_unlock(&table_lock);
return curr;
}
/**
* timer_stats_update_stats - Update the statistics for a timer.
* @timer: pointer to either a timer_list or a hrtimer
* @pid: the pid of the task which set up the timer
* @startf: pointer to the function which did the timer setup
* @timerf: pointer to the timer callback function of the timer
* @comm: name of the process which set up the timer
* @tflags: The flags field of the timer
*
* When the timer is already registered, then the event counter is
* incremented. Otherwise the timer is registered in a free slot.
*/
void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
void *timerf, char *comm, u32 tflags)
{
/*
* It doesn't matter which lock we take:
*/
raw_spinlock_t *lock;
struct entry *entry, input;
unsigned long flags;
if (likely(!timer_stats_active))
return;
lock = &per_cpu(tstats_lookup_lock, raw_smp_processor_id());
input.timer = timer;
input.start_func = startf;
input.expire_func = timerf;
input.pid = pid;
input.flags = tflags;
raw_spin_lock_irqsave(lock, flags);
if (!timer_stats_active)
goto out_unlock;
entry = tstat_lookup(&input, comm);
if (likely(entry))
entry->count++;
else
atomic_inc(&overflow_count);
out_unlock:
raw_spin_unlock_irqrestore(lock, flags);
}
static void print_name_offset(struct seq_file *m, unsigned long addr)
{
char symname[KSYM_NAME_LEN];
if (lookup_symbol_name(addr, symname) < 0)
seq_printf(m, "<%p>", (void *)addr);
else
seq_printf(m, "%s", symname);
}
static int tstats_show(struct seq_file *m, void *v)
{
struct timespec64 period;
struct entry *entry;
unsigned long ms;
long events = 0;
ktime_t time;
int i;
mutex_lock(&show_mutex);
/*
* If still active then calculate up to now:
*/
if (timer_stats_active)
time_stop = ktime_get();
time = ktime_sub(time_stop, time_start);
period = ktime_to_timespec64(time);
ms = period.tv_nsec / 1000000;
seq_puts(m, "Timer Stats Version: v0.3\n");
seq_printf(m, "Sample period: %ld.%03ld s\n", (long)period.tv_sec, ms);
if (atomic_read(&overflow_count))
seq_printf(m, "Overflow: %d entries\n", atomic_read(&overflow_count));
seq_printf(m, "Collection: %s\n", timer_stats_active ? "active" : "inactive");
for (i = 0; i < nr_entries; i++) {
entry = entries + i;
if (entry->flags & TIMER_DEFERRABLE) {
seq_printf(m, "%4luD, %5d %-16s ",
entry->count, entry->pid, entry->comm);
} else {
seq_printf(m, " %4lu, %5d %-16s ",
entry->count, entry->pid, entry->comm);
}
print_name_offset(m, (unsigned long)entry->start_func);
seq_puts(m, " (");
print_name_offset(m, (unsigned long)entry->expire_func);
seq_puts(m, ")\n");
events += entry->count;
}
ms += period.tv_sec * 1000;
if (!ms)
ms = 1;
if (events && period.tv_sec)
seq_printf(m, "%ld total events, %ld.%03ld events/sec\n",
events, events * 1000 / ms,
(events * 1000000 / ms) % 1000);
else
seq_printf(m, "%ld total events\n", events);
mutex_unlock(&show_mutex);
return 0;
}
/*
* After a state change, make sure all concurrent lookup/update
* activities have stopped:
*/
static void sync_access(void)
{
unsigned long flags;
int cpu;
for_each_online_cpu(cpu) {
raw_spinlock_t *lock = &per_cpu(tstats_lookup_lock, cpu);
raw_spin_lock_irqsave(lock, flags);
/* nothing */
raw_spin_unlock_irqrestore(lock, flags);
}
}
static ssize_t tstats_write(struct file *file, const char __user *buf,
size_t count, loff_t *offs)
{
char ctl[2];
if (count != 2 || *offs)
return -EINVAL;
if (copy_from_user(ctl, buf, count))
return -EFAULT;
mutex_lock(&show_mutex);
switch (ctl[0]) {
case '0':
if (timer_stats_active) {
timer_stats_active = 0;
time_stop = ktime_get();
sync_access();
}
break;
case '1':
if (!timer_stats_active) {
reset_entries();
time_start = ktime_get();
smp_mb();
timer_stats_active = 1;
}
break;
default:
count = -EINVAL;
}
mutex_unlock(&show_mutex);
return count;
}
static int tstats_open(struct inode *inode, struct file *filp)
{
return single_open(filp, tstats_show, NULL);
}
static const struct file_operations tstats_fops = {
.open = tstats_open,
.read = seq_read,
.write = tstats_write,
.llseek = seq_lseek,
.release = single_release,
};
void __init init_timer_stats(void)
{
int cpu;
for_each_possible_cpu(cpu)
raw_spin_lock_init(&per_cpu(tstats_lookup_lock, cpu));
}
static int __init init_tstats_procfs(void)
{
struct proc_dir_entry *pe;
pe = proc_create("timer_stats", 0644, NULL, &tstats_fops);
if (!pe)
return -ENOMEM;
return 0;
}
__initcall(init_tstats_procfs);