timers: Make the cpu base lock raw
The timers cpu base lock could not be converted to a raw spinlock becaue the lock held time was non-deterministic due to cascading and long lasting timer wheel traversals. The rework of the timer wheel to the new non-cascading model removed also the wheel traversals and the lock held times are deterministic now. This allows to make the lock raw and thereby unbreaks NOHz* on preempt-RT. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Link: http://lkml.kernel.org/r/20170627161538.30257-1-bigeasy@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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@ -195,7 +195,7 @@ EXPORT_SYMBOL(jiffies_64);
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#endif
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struct timer_base {
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spinlock_t lock;
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raw_spinlock_t lock;
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struct timer_list *running_timer;
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unsigned long clk;
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unsigned long next_expiry;
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@ -913,10 +913,10 @@ static struct timer_base *lock_timer_base(struct timer_list *timer,
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if (!(tf & TIMER_MIGRATING)) {
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base = get_timer_base(tf);
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spin_lock_irqsave(&base->lock, *flags);
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raw_spin_lock_irqsave(&base->lock, *flags);
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if (timer->flags == tf)
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return base;
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spin_unlock_irqrestore(&base->lock, *flags);
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raw_spin_unlock_irqrestore(&base->lock, *flags);
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}
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cpu_relax();
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}
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@ -986,9 +986,9 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
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/* See the comment in lock_timer_base() */
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timer->flags |= TIMER_MIGRATING;
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spin_unlock(&base->lock);
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raw_spin_unlock(&base->lock);
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base = new_base;
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spin_lock(&base->lock);
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raw_spin_lock(&base->lock);
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WRITE_ONCE(timer->flags,
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(timer->flags & ~TIMER_BASEMASK) | base->cpu);
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}
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@ -1013,7 +1013,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
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}
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out_unlock:
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spin_unlock_irqrestore(&base->lock, flags);
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raw_spin_unlock_irqrestore(&base->lock, flags);
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return ret;
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}
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@ -1106,16 +1106,16 @@ void add_timer_on(struct timer_list *timer, int cpu)
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if (base != new_base) {
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timer->flags |= TIMER_MIGRATING;
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spin_unlock(&base->lock);
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raw_spin_unlock(&base->lock);
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base = new_base;
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spin_lock(&base->lock);
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raw_spin_lock(&base->lock);
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WRITE_ONCE(timer->flags,
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(timer->flags & ~TIMER_BASEMASK) | cpu);
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}
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debug_activate(timer, timer->expires);
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internal_add_timer(base, timer);
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spin_unlock_irqrestore(&base->lock, flags);
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raw_spin_unlock_irqrestore(&base->lock, flags);
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}
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EXPORT_SYMBOL_GPL(add_timer_on);
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@ -1141,7 +1141,7 @@ int del_timer(struct timer_list *timer)
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if (timer_pending(timer)) {
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base = lock_timer_base(timer, &flags);
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ret = detach_if_pending(timer, base, true);
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spin_unlock_irqrestore(&base->lock, flags);
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raw_spin_unlock_irqrestore(&base->lock, flags);
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}
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return ret;
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@ -1168,7 +1168,7 @@ int try_to_del_timer_sync(struct timer_list *timer)
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if (base->running_timer != timer)
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ret = detach_if_pending(timer, base, true);
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spin_unlock_irqrestore(&base->lock, flags);
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raw_spin_unlock_irqrestore(&base->lock, flags);
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return ret;
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}
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@ -1299,13 +1299,13 @@ static void expire_timers(struct timer_base *base, struct hlist_head *head)
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data = timer->data;
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if (timer->flags & TIMER_IRQSAFE) {
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spin_unlock(&base->lock);
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raw_spin_unlock(&base->lock);
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call_timer_fn(timer, fn, data);
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spin_lock(&base->lock);
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raw_spin_lock(&base->lock);
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} else {
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spin_unlock_irq(&base->lock);
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raw_spin_unlock_irq(&base->lock);
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call_timer_fn(timer, fn, data);
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spin_lock_irq(&base->lock);
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raw_spin_lock_irq(&base->lock);
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}
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}
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}
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@ -1474,7 +1474,7 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem)
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if (cpu_is_offline(smp_processor_id()))
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return expires;
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spin_lock(&base->lock);
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raw_spin_lock(&base->lock);
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nextevt = __next_timer_interrupt(base);
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is_max_delta = (nextevt == base->clk + NEXT_TIMER_MAX_DELTA);
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base->next_expiry = nextevt;
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@ -1502,7 +1502,7 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem)
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if ((expires - basem) > TICK_NSEC)
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base->is_idle = true;
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}
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spin_unlock(&base->lock);
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raw_spin_unlock(&base->lock);
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return cmp_next_hrtimer_event(basem, expires);
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}
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@ -1590,7 +1590,7 @@ static inline void __run_timers(struct timer_base *base)
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if (!time_after_eq(jiffies, base->clk))
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return;
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spin_lock_irq(&base->lock);
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raw_spin_lock_irq(&base->lock);
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while (time_after_eq(jiffies, base->clk)) {
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@ -1601,7 +1601,7 @@ static inline void __run_timers(struct timer_base *base)
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expire_timers(base, heads + levels);
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}
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base->running_timer = NULL;
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spin_unlock_irq(&base->lock);
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raw_spin_unlock_irq(&base->lock);
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}
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/*
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@ -1786,16 +1786,16 @@ int timers_dead_cpu(unsigned int cpu)
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* The caller is globally serialized and nobody else
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* takes two locks at once, deadlock is not possible.
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*/
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spin_lock_irq(&new_base->lock);
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spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
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raw_spin_lock_irq(&new_base->lock);
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raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
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BUG_ON(old_base->running_timer);
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for (i = 0; i < WHEEL_SIZE; i++)
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migrate_timer_list(new_base, old_base->vectors + i);
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spin_unlock(&old_base->lock);
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spin_unlock_irq(&new_base->lock);
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raw_spin_unlock(&old_base->lock);
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raw_spin_unlock_irq(&new_base->lock);
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put_cpu_ptr(&timer_bases);
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}
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return 0;
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@ -1811,7 +1811,7 @@ static void __init init_timer_cpu(int cpu)
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for (i = 0; i < NR_BASES; i++) {
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base = per_cpu_ptr(&timer_bases[i], cpu);
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base->cpu = cpu;
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spin_lock_init(&base->lock);
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raw_spin_lock_init(&base->lock);
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base->clk = jiffies;
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}
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}
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