This patch provides an attempt to get away from jiffies in msleep() and msleep_interruptible() to hrtimers-backed usleep_range() and usleep_range_interruptible(). Both of the latter now returns an amount of microseconds really spent in sleep; another rationale for this was to convert msleep()-based wait-for-hardware loops to usleep_range(), like this:
unsigned long timeout = jiffies + msecs_to_jiffies(1000); while (hw_is_not_ready()) { if (time_after(jiffies, timeout)) return -ETIMEDOUT; msleep(1); }
to:
unsigned long timeout = 0; while (hw_is_not_ready()) { if (timeout > USEC_PER_SEC) return -ETIMEDOUT; timeout += usleep_range(500, 1500); }
Signed-off-by: Dmitry Antipov dmitry.antipov@linaro.org --- fs/eventpoll.c | 3 ++- fs/select.c | 3 ++- include/linux/delay.h | 3 ++- include/linux/hrtimer.h | 8 +++++--- ipc/mqueue.c | 4 ++-- kernel/hrtimer.c | 38 +++++++++++++++++++++++++++++++------- kernel/timer.c | 39 +++++++++++++++++++++++++-------------- 7 files changed, 69 insertions(+), 29 deletions(-)
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index aabdfc3..a374944 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1349,7 +1349,8 @@ fetch_events: }
spin_unlock_irqrestore(&ep->lock, flags); - if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS)) + if (!schedule_hrtimeout_range(to, NULL, slack, + HRTIMER_MODE_ABS)) timed_out = 1;
spin_lock_irqsave(&ep->lock, flags); diff --git a/fs/select.c b/fs/select.c index d33418f..b4354b2 100644 --- a/fs/select.c +++ b/fs/select.c @@ -236,7 +236,8 @@ int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
set_current_state(state); if (!pwq->triggered) - rc = schedule_hrtimeout_range(expires, slack, HRTIMER_MODE_ABS); + rc = schedule_hrtimeout_range(expires, NULL, slack, + HRTIMER_MODE_ABS); __set_current_state(TASK_RUNNING);
/* diff --git a/include/linux/delay.h b/include/linux/delay.h index a6ecb34..bad6d49 100644 --- a/include/linux/delay.h +++ b/include/linux/delay.h @@ -45,7 +45,8 @@ extern unsigned long lpj_fine; void calibrate_delay(void); void msleep(unsigned int msecs); unsigned long msleep_interruptible(unsigned int msecs); -void usleep_range(unsigned long min, unsigned long max); +unsigned long usleep_range(unsigned long min, unsigned long max); +unsigned long usleep_range_interruptible(unsigned long min, unsigned long max);
static inline void ssleep(unsigned int seconds) { diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index fd0dc30..01d782b 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -126,6 +126,7 @@ struct hrtimer { * task is set to NULL, when the timer expires. */ struct hrtimer_sleeper { + ktime_t kt; struct hrtimer timer; struct task_struct *task; }; @@ -428,9 +429,10 @@ extern long hrtimer_nanosleep_restart(struct restart_block *restart_block); extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *tsk);
-extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta, - const enum hrtimer_mode mode); -extern int schedule_hrtimeout_range_clock(ktime_t *expires, +extern int schedule_hrtimeout_range(ktime_t *expires, ktime_t *elapsed, + unsigned long delta, + const enum hrtimer_mode mode); +extern int schedule_hrtimeout_range_clock(ktime_t *expires, ktime_t *elapsed, unsigned long delta, const enum hrtimer_mode mode, int clock); extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
diff --git a/ipc/mqueue.c b/ipc/mqueue.c index 9b7c8ab..e57d7c1 100644 --- a/ipc/mqueue.c +++ b/ipc/mqueue.c @@ -449,8 +449,8 @@ static int wq_sleep(struct mqueue_inode_info *info, int sr, set_current_state(TASK_INTERRUPTIBLE);
spin_unlock(&info->lock); - time = schedule_hrtimeout_range_clock(timeout, 0, - HRTIMER_MODE_ABS, CLOCK_REALTIME); + time = schedule_hrtimeout_range_clock(timeout, NULL, + 0, HRTIMER_MODE_ABS, CLOCK_REALTIME);
while (ewp->state == STATE_PENDING) cpu_relax(); diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index ae34bf5..8642c3f 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -1475,6 +1475,12 @@ static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer) struct hrtimer_sleeper *t = container_of(timer, struct hrtimer_sleeper, timer); struct task_struct *task = t->task; + struct hrtimer_clock_base *base; + unsigned long flags; + + base = lock_hrtimer_base(timer, &flags); + t->kt = ktime_sub(base->get_time(), t->kt); + unlock_hrtimer_base(timer, &flags);
t->task = NULL; if (task) @@ -1485,6 +1491,13 @@ static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *task) { + struct hrtimer_clock_base *base; + unsigned long flags; + + base = lock_hrtimer_base(&sl->timer, &flags); + sl->kt = base->get_time(); + unlock_hrtimer_base(&sl->timer, &flags); + sl->timer.function = hrtimer_wakeup; sl->task = task; } @@ -1747,12 +1760,14 @@ void __init hrtimers_init(void) /** * schedule_hrtimeout_range_clock - sleep until timeout * @expires: timeout value (ktime_t) + * @elapsed: pointer to ktime_t used to save time spent in sleep * @delta: slack in expires timeout (ktime_t) * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL * @clock: timer clock, CLOCK_MONOTONIC or CLOCK_REALTIME */ int __sched -schedule_hrtimeout_range_clock(ktime_t *expires, unsigned long delta, +schedule_hrtimeout_range_clock(ktime_t *expires, ktime_t *elapsed, + unsigned long delta, const enum hrtimer_mode mode, int clock) { struct hrtimer_sleeper t; @@ -1763,6 +1778,8 @@ schedule_hrtimeout_range_clock(ktime_t *expires, unsigned long delta, */ if (expires && !expires->tv64) { __set_current_state(TASK_RUNNING); + if (elapsed) + *elapsed = ktime_set(0, 0); return 0; }
@@ -1772,6 +1789,8 @@ schedule_hrtimeout_range_clock(ktime_t *expires, unsigned long delta, if (!expires) { schedule(); __set_current_state(TASK_RUNNING); + if (elapsed) + *elapsed = ktime_set(KTIME_SEC_MAX, 0); return -EINTR; }
@@ -1787,6 +1806,9 @@ schedule_hrtimeout_range_clock(ktime_t *expires, unsigned long delta, if (likely(t.task)) schedule();
+ if (elapsed) + *elapsed = t.kt; + hrtimer_cancel(&t.timer); destroy_hrtimer_on_stack(&t.timer);
@@ -1798,6 +1820,7 @@ schedule_hrtimeout_range_clock(ktime_t *expires, unsigned long delta, /** * schedule_hrtimeout_range - sleep until timeout * @expires: timeout value (ktime_t) + * @elapsed: pointer to ktime_t used to save time spent in sleep * @delta: slack in expires timeout (ktime_t) * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL * @@ -1823,17 +1846,19 @@ schedule_hrtimeout_range_clock(ktime_t *expires, unsigned long delta, * * Returns 0 when the timer has expired otherwise -EINTR */ -int __sched schedule_hrtimeout_range(ktime_t *expires, unsigned long delta, +int __sched schedule_hrtimeout_range(ktime_t *expires, ktime_t *elapsed, + unsigned long delta, const enum hrtimer_mode mode) { - return schedule_hrtimeout_range_clock(expires, delta, mode, - CLOCK_MONOTONIC); + return schedule_hrtimeout_range_clock(expires, elapsed, delta, + mode, CLOCK_MONOTONIC); } EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
/** * schedule_hrtimeout - sleep until timeout * @expires: timeout value (ktime_t) + * @elapsed: pointer to ktime_t used to save time spent in sleep * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL * * Make the current task sleep until the given expiry time has @@ -1853,9 +1878,8 @@ EXPORT_SYMBOL_GPL(schedule_hrtimeout_range); * * Returns 0 when the timer has expired otherwise -EINTR */ -int __sched schedule_hrtimeout(ktime_t *expires, - const enum hrtimer_mode mode) +int __sched schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode) { - return schedule_hrtimeout_range(expires, 0, mode); + return schedule_hrtimeout_range(expires, NULL, 0, mode); } EXPORT_SYMBOL_GPL(schedule_hrtimeout); diff --git a/kernel/timer.c b/kernel/timer.c index a297ffc..00acab6 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1796,12 +1796,12 @@ void __init init_timers(void) */ void msleep(unsigned int msecs) { - unsigned long timeout = msecs_to_jiffies(msecs) + 1; + unsigned long usecs = msecs * USEC_PER_MSEC; + unsigned long slack = rt_task(current) ? 0 : + current->timer_slack_ns / NSEC_PER_USEC;
- while (timeout) - timeout = schedule_timeout_uninterruptible(timeout); + usleep_range(usecs, usecs + slack); } - EXPORT_SYMBOL(msleep);
/** @@ -1810,23 +1810,27 @@ EXPORT_SYMBOL(msleep); */ unsigned long msleep_interruptible(unsigned int msecs) { - unsigned long timeout = msecs_to_jiffies(msecs) + 1; + unsigned long timeout, usecs, slack;
- while (timeout && !signal_pending(current)) - timeout = schedule_timeout_interruptible(timeout); - return jiffies_to_msecs(timeout); -} + timeout = 0; + usecs = msecs * USEC_PER_MSEC; + slack = rt_task(current) ? 0 : current->timer_slack_ns / NSEC_PER_USEC;
+ while (timeout < usecs && !signal_pending(current)) + timeout += usleep_range_interruptible(usecs, usecs + slack); + return timeout / USEC_PER_MSEC; +} EXPORT_SYMBOL(msleep_interruptible);
-static int __sched do_usleep_range(unsigned long min, unsigned long max) +static inline unsigned long do_usleep_range(unsigned long min, unsigned long max) { - ktime_t kmin; + ktime_t kmin, elapsed; unsigned long delta;
kmin = ktime_set(0, min * NSEC_PER_USEC); delta = (max - min) * NSEC_PER_USEC; - return schedule_hrtimeout_range(&kmin, delta, HRTIMER_MODE_REL); + return schedule_hrtimeout_range(&kmin, &elapsed, delta, HRTIMER_MODE_REL) + ? 0 : ktime_to_us(elapsed); }
/** @@ -1834,9 +1838,16 @@ static int __sched do_usleep_range(unsigned long min, unsigned long max) * @min: Minimum time in usecs to sleep * @max: Maximum time in usecs to sleep */ -void usleep_range(unsigned long min, unsigned long max) +unsigned long usleep_range(unsigned long min, unsigned long max) { __set_current_state(TASK_UNINTERRUPTIBLE); - do_usleep_range(min, max); + return do_usleep_range(min, max); } EXPORT_SYMBOL(usleep_range); + +unsigned long usleep_range_interruptible(unsigned long min, unsigned long max) +{ + __set_current_state(TASK_INTERRUPTIBLE); + return do_usleep_range(min, max); +} +EXPORT_SYMBOL(usleep_range_interruptible);