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Message-ID: <tip-2287d8664fe7345ead891017eccd879fc605305e@git.kernel.org>
Date: Wed, 28 Jun 2017 15:33:56 -0700
From: tip-bot for Sebastian Andrzej Siewior <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: mingo@...nel.org, bigeasy@...utronix.de, tglx@...utronix.de,
hpa@...or.com, linux-kernel@...r.kernel.org
Subject: [tip:timers/core] timers: Make the cpu base lock raw
Commit-ID: 2287d8664fe7345ead891017eccd879fc605305e
Gitweb: http://git.kernel.org/tip/2287d8664fe7345ead891017eccd879fc605305e
Author: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate: Tue, 27 Jun 2017 18:15:38 +0200
Committer: Thomas Gleixner <tglx@...utronix.de>
CommitDate: Thu, 29 Jun 2017 00:27:24 +0200
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@...utronix.de>
Link: http://lkml.kernel.org/r/20170627161538.30257-1-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
kernel/time/timer.c | 48 ++++++++++++++++++++++++------------------------
1 file changed, 24 insertions(+), 24 deletions(-)
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 709a404..71ce3f4 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -195,7 +195,7 @@ EXPORT_SYMBOL(jiffies_64);
#endif
struct timer_base {
- spinlock_t lock;
+ raw_spinlock_t lock;
struct timer_list *running_timer;
unsigned long clk;
unsigned long next_expiry;
@@ -913,10 +913,10 @@ static struct timer_base *lock_timer_base(struct timer_list *timer,
if (!(tf & TIMER_MIGRATING)) {
base = get_timer_base(tf);
- spin_lock_irqsave(&base->lock, *flags);
+ raw_spin_lock_irqsave(&base->lock, *flags);
if (timer->flags == tf)
return base;
- spin_unlock_irqrestore(&base->lock, *flags);
+ raw_spin_unlock_irqrestore(&base->lock, *flags);
}
cpu_relax();
}
@@ -986,9 +986,9 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
/* See the comment in lock_timer_base() */
timer->flags |= TIMER_MIGRATING;
- spin_unlock(&base->lock);
+ raw_spin_unlock(&base->lock);
base = new_base;
- spin_lock(&base->lock);
+ raw_spin_lock(&base->lock);
WRITE_ONCE(timer->flags,
(timer->flags & ~TIMER_BASEMASK) | base->cpu);
}
@@ -1013,7 +1013,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
}
out_unlock:
- spin_unlock_irqrestore(&base->lock, flags);
+ raw_spin_unlock_irqrestore(&base->lock, flags);
return ret;
}
@@ -1106,16 +1106,16 @@ void add_timer_on(struct timer_list *timer, int cpu)
if (base != new_base) {
timer->flags |= TIMER_MIGRATING;
- spin_unlock(&base->lock);
+ raw_spin_unlock(&base->lock);
base = new_base;
- spin_lock(&base->lock);
+ raw_spin_lock(&base->lock);
WRITE_ONCE(timer->flags,
(timer->flags & ~TIMER_BASEMASK) | cpu);
}
debug_activate(timer, timer->expires);
internal_add_timer(base, timer);
- spin_unlock_irqrestore(&base->lock, flags);
+ raw_spin_unlock_irqrestore(&base->lock, flags);
}
EXPORT_SYMBOL_GPL(add_timer_on);
@@ -1141,7 +1141,7 @@ int del_timer(struct timer_list *timer)
if (timer_pending(timer)) {
base = lock_timer_base(timer, &flags);
ret = detach_if_pending(timer, base, true);
- spin_unlock_irqrestore(&base->lock, flags);
+ raw_spin_unlock_irqrestore(&base->lock, flags);
}
return ret;
@@ -1168,7 +1168,7 @@ int try_to_del_timer_sync(struct timer_list *timer)
if (base->running_timer != timer)
ret = detach_if_pending(timer, base, true);
- spin_unlock_irqrestore(&base->lock, flags);
+ raw_spin_unlock_irqrestore(&base->lock, flags);
return ret;
}
@@ -1299,13 +1299,13 @@ static void expire_timers(struct timer_base *base, struct hlist_head *head)
data = timer->data;
if (timer->flags & TIMER_IRQSAFE) {
- spin_unlock(&base->lock);
+ raw_spin_unlock(&base->lock);
call_timer_fn(timer, fn, data);
- spin_lock(&base->lock);
+ raw_spin_lock(&base->lock);
} else {
- spin_unlock_irq(&base->lock);
+ raw_spin_unlock_irq(&base->lock);
call_timer_fn(timer, fn, data);
- spin_lock_irq(&base->lock);
+ raw_spin_lock_irq(&base->lock);
}
}
}
@@ -1474,7 +1474,7 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem)
if (cpu_is_offline(smp_processor_id()))
return expires;
- spin_lock(&base->lock);
+ raw_spin_lock(&base->lock);
nextevt = __next_timer_interrupt(base);
is_max_delta = (nextevt == base->clk + NEXT_TIMER_MAX_DELTA);
base->next_expiry = nextevt;
@@ -1502,7 +1502,7 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem)
if ((expires - basem) > TICK_NSEC)
base->is_idle = true;
}
- spin_unlock(&base->lock);
+ raw_spin_unlock(&base->lock);
return cmp_next_hrtimer_event(basem, expires);
}
@@ -1590,7 +1590,7 @@ static inline void __run_timers(struct timer_base *base)
if (!time_after_eq(jiffies, base->clk))
return;
- spin_lock_irq(&base->lock);
+ raw_spin_lock_irq(&base->lock);
while (time_after_eq(jiffies, base->clk)) {
@@ -1601,7 +1601,7 @@ static inline void __run_timers(struct timer_base *base)
expire_timers(base, heads + levels);
}
base->running_timer = NULL;
- spin_unlock_irq(&base->lock);
+ raw_spin_unlock_irq(&base->lock);
}
/*
@@ -1786,16 +1786,16 @@ int timers_dead_cpu(unsigned int cpu)
* The caller is globally serialized and nobody else
* takes two locks at once, deadlock is not possible.
*/
- spin_lock_irq(&new_base->lock);
- spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
+ raw_spin_lock_irq(&new_base->lock);
+ raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
BUG_ON(old_base->running_timer);
for (i = 0; i < WHEEL_SIZE; i++)
migrate_timer_list(new_base, old_base->vectors + i);
- spin_unlock(&old_base->lock);
- spin_unlock_irq(&new_base->lock);
+ raw_spin_unlock(&old_base->lock);
+ raw_spin_unlock_irq(&new_base->lock);
put_cpu_ptr(&timer_bases);
}
return 0;
@@ -1811,7 +1811,7 @@ static void __init init_timer_cpu(int cpu)
for (i = 0; i < NR_BASES; i++) {
base = per_cpu_ptr(&timer_bases[i], cpu);
base->cpu = cpu;
- spin_lock_init(&base->lock);
+ raw_spin_lock_init(&base->lock);
base->clk = jiffies;
}
}
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