diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/relay.c | 7 | ||||
| -rw-r--r-- | kernel/sched.c | 43 | ||||
| -rw-r--r-- | kernel/time/clocksource.c | 2 | ||||
| -rw-r--r-- | kernel/timer.c | 10 |
4 files changed, 59 insertions, 3 deletions
diff --git a/kernel/relay.c b/kernel/relay.c index 4c035a8a248c..d6204a485818 100644 --- a/kernel/relay.c +++ b/kernel/relay.c @@ -736,7 +736,7 @@ static int relay_file_open(struct inode *inode, struct file *filp) kref_get(&buf->kref); filp->private_data = buf; - return 0; + return nonseekable_open(inode, filp); } /** @@ -1056,6 +1056,10 @@ static struct pipe_buf_operations relay_pipe_buf_ops = { .get = generic_pipe_buf_get, }; +static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i) +{ +} + /* * subbuf_splice_actor - splice up to one subbuf's worth of data */ @@ -1083,6 +1087,7 @@ static int subbuf_splice_actor(struct file *in, .partial = partial, .flags = flags, .ops = &relay_pipe_buf_ops, + .spd_release = relay_page_release, }; if (rbuf->subbufs_produced == rbuf->subbufs_consumed) diff --git a/kernel/sched.c b/kernel/sched.c index 28c73f07efb2..8dcdec6fe0fe 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -1052,6 +1052,49 @@ static void resched_cpu(int cpu) resched_task(cpu_curr(cpu)); spin_unlock_irqrestore(&rq->lock, flags); } + +#ifdef CONFIG_NO_HZ +/* + * When add_timer_on() enqueues a timer into the timer wheel of an + * idle CPU then this timer might expire before the next timer event + * which is scheduled to wake up that CPU. In case of a completely + * idle system the next event might even be infinite time into the + * future. wake_up_idle_cpu() ensures that the CPU is woken up and + * leaves the inner idle loop so the newly added timer is taken into + * account when the CPU goes back to idle and evaluates the timer + * wheel for the next timer event. + */ +void wake_up_idle_cpu(int cpu) +{ + struct rq *rq = cpu_rq(cpu); + + if (cpu == smp_processor_id()) + return; + + /* + * This is safe, as this function is called with the timer + * wheel base lock of (cpu) held. When the CPU is on the way + * to idle and has not yet set rq->curr to idle then it will + * be serialized on the timer wheel base lock and take the new + * timer into account automatically. + */ + if (rq->curr != rq->idle) + return; + + /* + * We can set TIF_RESCHED on the idle task of the other CPU + * lockless. The worst case is that the other CPU runs the + * idle task through an additional NOOP schedule() + */ + set_tsk_thread_flag(rq->idle, TIF_NEED_RESCHED); + + /* NEED_RESCHED must be visible before we test polling */ + smp_mb(); + if (!tsk_is_polling(rq->idle)) + smp_send_reschedule(cpu); +} +#endif + #else static void __resched_task(struct task_struct *p, int tif_bit) { diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 278534bbca95..7f60097d443a 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -174,7 +174,7 @@ static void clocksource_check_watchdog(struct clocksource *cs) if (watchdog) del_timer(&watchdog_timer); watchdog = cs; - init_timer_deferrable(&watchdog_timer); + init_timer(&watchdog_timer); watchdog_timer.function = clocksource_watchdog; /* Reset watchdog cycles */ diff --git a/kernel/timer.c b/kernel/timer.c index 99b00a25f88b..b024106daa70 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -451,10 +451,18 @@ void add_timer_on(struct timer_list *timer, int cpu) spin_lock_irqsave(&base->lock, flags); timer_set_base(timer, base); internal_add_timer(base, timer); + /* + * Check whether the other CPU is idle and needs to be + * triggered to reevaluate the timer wheel when nohz is + * active. We are protected against the other CPU fiddling + * with the timer by holding the timer base lock. This also + * makes sure that a CPU on the way to idle can not evaluate + * the timer wheel. + */ + wake_up_idle_cpu(cpu); spin_unlock_irqrestore(&base->lock, flags); } - /** * mod_timer - modify a timer's timeout * @timer: the timer to be modified |