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

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Pull timer fixes from Thomas Gleixner:
 "Two fixes from the timer departement:

   - Fix a long standing issue in the NOHZ tick code which causes RB
     tree corruption, delayed timers and other malfunctions. The cause
     for this is code which modifies the expiry time of an enqueued
     hrtimer.

   - Revert the CLOCK_MONOTONIC/CLOCK_BOOTTIME unification due to
     regression reports. Seems userspace _is_ relying on the documented
     behaviour despite our hope that it wont"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  Revert: Unify CLOCK_MONOTONIC and CLOCK_BOOTTIME
  tick/sched: Do not mess with an enqueued hrtimer
This commit is contained in:
Linus Torvalds
2018-04-29 09:03:25 -07:00
parent 7d9e55feae a3ed0e4393
commit 810fb07a9b
15 changed files with 119 additions and 109 deletions
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16
kernel/time/hrtimer.c
View File

@@ -90,6 +90,11 @@ DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
.clockid = CLOCK_REALTIME,
.get_time = &ktime_get_real,
},
{
.index = HRTIMER_BASE_BOOTTIME,
.clockid = CLOCK_BOOTTIME,
.get_time = &ktime_get_boottime,
},
{
.index = HRTIMER_BASE_TAI,
.clockid = CLOCK_TAI,
@@ -105,6 +110,11 @@ DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
.clockid = CLOCK_REALTIME,
.get_time = &ktime_get_real,
},
{
.index = HRTIMER_BASE_BOOTTIME_SOFT,
.clockid = CLOCK_BOOTTIME,
.get_time = &ktime_get_boottime,
},
{
.index = HRTIMER_BASE_TAI_SOFT,
.clockid = CLOCK_TAI,
@@ -119,7 +129,7 @@ static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
[CLOCK_REALTIME] = HRTIMER_BASE_REALTIME,
[CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC,
[CLOCK_BOOTTIME] = HRTIMER_BASE_MONOTONIC,
[CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME,
[CLOCK_TAI] = HRTIMER_BASE_TAI,
};
@@ -571,12 +581,14 @@ __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_
static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
{
ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
ktime_t now = ktime_get_update_offsets_now(&base->clock_was_set_seq,
offs_real, offs_tai);
offs_real, offs_boot, offs_tai);
base->clock_base[HRTIMER_BASE_REALTIME_SOFT].offset = *offs_real;
base->clock_base[HRTIMER_BASE_BOOTTIME_SOFT].offset = *offs_boot;
base->clock_base[HRTIMER_BASE_TAI_SOFT].offset = *offs_tai;
return now;

2
kernel/time/posix-stubs.c
View File

@@ -83,8 +83,6 @@ int do_clock_gettime(clockid_t which_clock, struct timespec64 *tp)
case CLOCK_BOOTTIME:
get_monotonic_boottime64(tp);
break;
case CLOCK_MONOTONIC_ACTIVE:
ktime_get_active_ts64(tp);
default:
return -EINVAL;
}

26
kernel/time/posix-timers.c
View File

@@ -252,16 +252,15 @@ static int posix_get_coarse_res(const clockid_t which_clock, struct timespec64 *
return 0;
}
static int posix_get_tai(clockid_t which_clock, struct timespec64 *tp)
static int posix_get_boottime(const clockid_t which_clock, struct timespec64 *tp)
{
timekeeping_clocktai64(tp);
get_monotonic_boottime64(tp);
return 0;
}
static int posix_get_monotonic_active(clockid_t which_clock,
struct timespec64 *tp)
static int posix_get_tai(clockid_t which_clock, struct timespec64 *tp)
{
ktime_get_active_ts64(tp);
timekeeping_clocktai64(tp);
return 0;
}
@@ -1317,9 +1316,19 @@ static const struct k_clock clock_tai = {
.timer_arm = common_hrtimer_arm,
};
static const struct k_clock clock_monotonic_active = {
static const struct k_clock clock_boottime = {
.clock_getres = posix_get_hrtimer_res,
.clock_get = posix_get_monotonic_active,
.clock_get = posix_get_boottime,
.nsleep = common_nsleep,
.timer_create = common_timer_create,
.timer_set = common_timer_set,
.timer_get = common_timer_get,
.timer_del = common_timer_del,
.timer_rearm = common_hrtimer_rearm,
.timer_forward = common_hrtimer_forward,
.timer_remaining = common_hrtimer_remaining,
.timer_try_to_cancel = common_hrtimer_try_to_cancel,
.timer_arm = common_hrtimer_arm,
};
static const struct k_clock * const posix_clocks[] = {
@@ -1330,11 +1339,10 @@ static const struct k_clock * const posix_clocks[] = {
[CLOCK_MONOTONIC_RAW] = &clock_monotonic_raw,
[CLOCK_REALTIME_COARSE] = &clock_realtime_coarse,
[CLOCK_MONOTONIC_COARSE] = &clock_monotonic_coarse,
[CLOCK_BOOTTIME] = &clock_monotonic,
[CLOCK_BOOTTIME] = &clock_boottime,
[CLOCK_REALTIME_ALARM] = &alarm_clock,
[CLOCK_BOOTTIME_ALARM] = &alarm_clock,
[CLOCK_TAI] = &clock_tai,
[CLOCK_MONOTONIC_ACTIVE] = &clock_monotonic_active,
};
static const struct k_clock *clockid_to_kclock(const clockid_t id)

15
kernel/time/tick-common.c
View File

@@ -419,19 +419,6 @@ void tick_suspend_local(void)
clockevents_shutdown(td->evtdev);
}
static void tick_forward_next_period(void)
{
ktime_t delta, now = ktime_get();
u64 n;
delta = ktime_sub(now, tick_next_period);
n = ktime_divns(delta, tick_period);
tick_next_period += n * tick_period;
if (tick_next_period < now)
tick_next_period += tick_period;
tick_sched_forward_next_period();
}
/**
* tick_resume_local - Resume the local tick device
*
@@ -444,8 +431,6 @@ void tick_resume_local(void)
struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
bool broadcast = tick_resume_check_broadcast();
tick_forward_next_period();
clockevents_tick_resume(td->evtdev);
if (!broadcast) {
if (td->mode == TICKDEV_MODE_PERIODIC)

6
kernel/time/tick-internal.h
View File

@@ -141,12 +141,6 @@ static inline void tick_check_oneshot_broadcast_this_cpu(void) { }
static inline bool tick_broadcast_oneshot_available(void) { return tick_oneshot_possible(); }
#endif /* !(BROADCAST && ONESHOT) */
#if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS)
extern void tick_sched_forward_next_period(void);
#else
static inline void tick_sched_forward_next_period(void) { }
#endif
/* NO_HZ_FULL internal */
#ifdef CONFIG_NO_HZ_FULL
extern void tick_nohz_init(void);

19
kernel/time/tick-sched.c
View File

@@ -51,15 +51,6 @@ struct tick_sched *tick_get_tick_sched(int cpu)
*/
static ktime_t last_jiffies_update;
/*
* Called after resume. Make sure that jiffies are not fast forwarded due to
* clock monotonic being forwarded by the suspended time.
*/
void tick_sched_forward_next_period(void)
{
last_jiffies_update = tick_next_period;
}
/*
* Must be called with interrupts disabled !
*/
@@ -804,12 +795,12 @@ static void tick_nohz_stop_tick(struct tick_sched *ts, int cpu)
return;
}
hrtimer_set_expires(&ts->sched_timer, tick);
if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED);
else
if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
hrtimer_start(&ts->sched_timer, tick, HRTIMER_MODE_ABS_PINNED);
} else {
hrtimer_set_expires(&ts->sched_timer, tick);
tick_program_event(tick, 1);
}
}
static void tick_nohz_retain_tick(struct tick_sched *ts)

78
kernel/time/timekeeping.c
View File

@@ -138,12 +138,7 @@ static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm)
static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
{
/* Update both bases so mono and raw stay coupled. */
tk->tkr_mono.base += delta;
tk->tkr_raw.base += delta;
/* Accumulate time spent in suspend */
tk->time_suspended += delta;
tk->offs_boot = ktime_add(tk->offs_boot, delta);
}
/*
@@ -473,6 +468,36 @@ u64 ktime_get_raw_fast_ns(void)
}
EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns);
/**
* ktime_get_boot_fast_ns - NMI safe and fast access to boot clock.
*
* To keep it NMI safe since we're accessing from tracing, we're not using a
* separate timekeeper with updates to monotonic clock and boot offset
* protected with seqlocks. This has the following minor side effects:
*
* (1) Its possible that a timestamp be taken after the boot offset is updated
* but before the timekeeper is updated. If this happens, the new boot offset
* is added to the old timekeeping making the clock appear to update slightly
* earlier:
* CPU 0 CPU 1
* timekeeping_inject_sleeptime64()
* __timekeeping_inject_sleeptime(tk, delta);
* timestamp();
* timekeeping_update(tk, TK_CLEAR_NTP...);
*
* (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be
* partially updated. Since the tk->offs_boot update is a rare event, this
* should be a rare occurrence which postprocessing should be able to handle.
*/
u64 notrace ktime_get_boot_fast_ns(void)
{
struct timekeeper *tk = &tk_core.timekeeper;
return (ktime_get_mono_fast_ns() + ktime_to_ns(tk->offs_boot));
}
EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
/*
* See comment for __ktime_get_fast_ns() vs. timestamp ordering
*/
@@ -764,6 +789,7 @@ EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
static ktime_t *offsets[TK_OFFS_MAX] = {
[TK_OFFS_REAL] = &tk_core.timekeeper.offs_real,
[TK_OFFS_BOOT] = &tk_core.timekeeper.offs_boot,
[TK_OFFS_TAI] = &tk_core.timekeeper.offs_tai,
};
@@ -860,39 +886,6 @@ void ktime_get_ts64(struct timespec64 *ts)
}
EXPORT_SYMBOL_GPL(ktime_get_ts64);
/**
* ktime_get_active_ts64 - Get the active non-suspended monotonic clock
* @ts: pointer to timespec variable
*
* The function calculates the monotonic clock from the realtime clock and
* the wall_to_monotonic offset, subtracts the accumulated suspend time and
* stores the result in normalized timespec64 format in the variable
* pointed to by @ts.
*/
void ktime_get_active_ts64(struct timespec64 *ts)
{
struct timekeeper *tk = &tk_core.timekeeper;
struct timespec64 tomono, tsusp;
u64 nsec, nssusp;
unsigned int seq;
WARN_ON(timekeeping_suspended);
do {
seq = read_seqcount_begin(&tk_core.seq);
ts->tv_sec = tk->xtime_sec;
nsec = timekeeping_get_ns(&tk->tkr_mono);
tomono = tk->wall_to_monotonic;
nssusp = tk->time_suspended;
} while (read_seqcount_retry(&tk_core.seq, seq));
ts->tv_sec += tomono.tv_sec;
ts->tv_nsec = 0;
timespec64_add_ns(ts, nsec + tomono.tv_nsec);
tsusp = ns_to_timespec64(nssusp);
*ts = timespec64_sub(*ts, tsusp);
}
/**
* ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
*
@@ -1593,6 +1586,7 @@ static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
return;
}
tk_xtime_add(tk, delta);
tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta));
tk_update_sleep_time(tk, timespec64_to_ktime(*delta));
tk_debug_account_sleep_time(delta);
}
@@ -2125,7 +2119,7 @@ out:
void getboottime64(struct timespec64 *ts)
{
struct timekeeper *tk = &tk_core.timekeeper;
ktime_t t = ktime_sub(tk->offs_real, tk->time_suspended);
ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot);
*ts = ktime_to_timespec64(t);
}
@@ -2188,6 +2182,7 @@ void do_timer(unsigned long ticks)
* ktime_get_update_offsets_now - hrtimer helper
* @cwsseq: pointer to check and store the clock was set sequence number
* @offs_real: pointer to storage for monotonic -> realtime offset
* @offs_boot: pointer to storage for monotonic -> boottime offset
* @offs_tai: pointer to storage for monotonic -> clock tai offset
*
* Returns current monotonic time and updates the offsets if the
@@ -2197,7 +2192,7 @@ void do_timer(unsigned long ticks)
* Called from hrtimer_interrupt() or retrigger_next_event()
*/
ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
ktime_t *offs_tai)
ktime_t *offs_boot, ktime_t *offs_tai)
{
struct timekeeper *tk = &tk_core.timekeeper;
unsigned int seq;
@@ -2214,6 +2209,7 @@ ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
if (*cwsseq != tk->clock_was_set_seq) {
*cwsseq = tk->clock_was_set_seq;
*offs_real = tk->offs_real;
*offs_boot = tk->offs_boot;
*offs_tai = tk->offs_tai;
}

1
kernel/time/timekeeping.h
View File

@@ -6,6 +6,7 @@
*/
extern ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq,
ktime_t *offs_real,
ktime_t *offs_boot,
ktime_t *offs_tai);
extern int timekeeping_valid_for_hres(void);

2
kernel/trace/trace.c
View File

@@ -1165,7 +1165,7 @@ static struct {
{ trace_clock, "perf", 1 },
{ ktime_get_mono_fast_ns, "mono", 1 },
{ ktime_get_raw_fast_ns, "mono_raw", 1 },
{ ktime_get_mono_fast_ns, "boot", 1 },
{ ktime_get_boot_fast_ns, "boot", 1 },
ARCH_TRACE_CLOCKS
};