diff options
| author | Alex Frid <afrid@nvidia.com> | 2010-05-15 17:49:46 -0700 |
|---|---|---|
| committer | Gary King <gking@nvidia.com> | 2010-05-20 10:53:31 -0700 |
| commit | b344cce5024b2742219db782aeeb38772a05325a (patch) | |
| tree | 9285078fe841fe401cb0d8628126b4c01da41ff6 | |
| parent | 4bc4768e06afa53392678197d59b6394cdab5e1c (diff) | |
tegra timers: Added safety net for SMP tick handover.
Made sure that jiffies update duty is not stuck with off-line CPU: if this
situation is detected, re-assign the tick ownership respectively (should
fix bug 683277).
Replaced spin-locks in timer access code with local interrupt control:
local timers are "local", and do not need interprocessor protection.
Change-Id: Ib0d690d8558724f7da384aba8b5cdf3d5ea8fdbb
Reviewed-on: http://git-master/r/1415
Tested-by: Aleksandr Frid <afrid@nvidia.com>
Reviewed-by: Gary King <gking@nvidia.com>
| -rw-r--r-- | arch/arm/kernel/smp_twd.c | 22 | ||||
| -rw-r--r-- | kernel/time/tick-sched.c | 8 |
2 files changed, 18 insertions, 12 deletions
diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c index e7177d921b32..b170fe6bc82c 100644 --- a/arch/arm/kernel/smp_twd.c +++ b/arch/arm/kernel/smp_twd.c @@ -49,9 +49,6 @@ void __iomem *twd_base; #ifdef CONFIG_USE_ARM_TWD_PRESCALER /* dynamically updated by the platform code */ unsigned long timer_prescaler = 0; - -static spinlock_t timer_control_lock = SPIN_LOCK_UNLOCKED; -static unsigned long flags; #endif static unsigned long twd_timer_rate; @@ -60,6 +57,9 @@ static void twd_set_mode(enum clock_event_mode mode, struct clock_event_device *clk) { unsigned long ctrl; +#ifdef CONFIG_USE_ARM_TWD_PRESCALER + unsigned long flags; +#endif switch(mode) { case CLOCK_EVT_MODE_PERIODIC: @@ -77,12 +77,12 @@ static void twd_set_mode(enum clock_event_mode mode, ctrl = 0; } #ifdef CONFIG_USE_ARM_TWD_PRESCALER - spin_lock_irqsave(&timer_control_lock, flags); + local_irq_save(flags); ctrl |= (timer_prescaler << TWD_TIMER_CONTROL_PRESCALER_LSB); __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL); - spin_unlock_irqrestore(&timer_control_lock, flags); + local_irq_restore(flags); #else __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL); #endif @@ -92,9 +92,9 @@ static int twd_set_next_event(unsigned long evt, struct clock_event_device *unused) { #ifdef CONFIG_USE_ARM_TWD_PRESCALER - unsigned long ctrl; + unsigned long ctrl, flags; - spin_lock_irqsave(&timer_control_lock, flags); + local_irq_save(flags); ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL); ctrl &= (~TWD_TIMER_CONTROL_PRESCALER_FIELD); @@ -104,7 +104,7 @@ static int twd_set_next_event(unsigned long evt, __raw_writel(evt, twd_base + TWD_TIMER_COUNTER); __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL); - spin_unlock_irqrestore(&timer_control_lock, flags); + local_irq_restore(flags); #else unsigned long ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL); @@ -121,16 +121,16 @@ static int twd_set_next_event(unsigned long evt, */ void twd_set_prescaler(void* unused) { - unsigned long ctrl; + unsigned long ctrl, flags; - spin_lock_irqsave(&timer_control_lock, flags); + local_irq_save(flags); ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL); ctrl &= (~TWD_TIMER_CONTROL_PRESCALER_FIELD); ctrl |= (timer_prescaler << TWD_TIMER_CONTROL_PRESCALER_LSB); __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL); - spin_unlock_irqrestore(&timer_control_lock, flags); + local_irq_restore(flags); } #endif diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 4012da672821..6737d68fdb8d 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -639,9 +639,15 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer) * into a long sleep. If two cpus happen to assign themself to * this duty, then the jiffies update is still serialized by * xtime_lock. + * + * Also check if the do_timer duty is stuck with off-line cpu. + * Then, use the same remedy as for dropped duty: re-assign it + * to the cpu servicing this tick. */ - if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE)) + if ((unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE)) || + (!cpu_online(tick_do_timer_cpu))) { tick_do_timer_cpu = cpu; + } #endif /* Check, if the jiffies need an update */ |