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Commit ebc67da6 authored by Tony Lindgren's avatar Tony Lindgren Committed by Russell King
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[ARM] 3554/1: ARM: Fix dyntick locking 



Patch from Tony Lindgren

This patch fixes some dyntick locking issues on ARM as pointed
out by Russell King.

Signed-off-by: default avatarTony Lindgren <tony@atomide.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 36fe6a83

arch/arm/kernel/irq.c

+2 −2
Original line number Diff line number Diff line
@@ -342,10 +342,10 @@ __do_irq(unsigned int irq, struct irqaction *action, struct pt_regs *regs) 


#ifdef CONFIG_NO_IDLE_HZ

	if (!(action->flags & SA_TIMER) && system_timer->dyn_tick != NULL) {

		write_seqlock(&xtime_lock);

		spin_lock(&system_timer->dyn_tick->lock);

		if (system_timer->dyn_tick->state & DYN_TICK_ENABLED)

			system_timer->dyn_tick->handler(irq, 0, regs);

		write_sequnlock(&xtime_lock);

		spin_unlock(&system_timer->dyn_tick->lock);

	}

#endif

arch/arm/kernel/time.c

+17 −7
Original line number Diff line number Diff line
@@ -379,7 +379,7 @@ static int timer_dyn_tick_enable(void) 
	int ret = -ENODEV;



	if (dyn_tick) {

		write_seqlock_irqsave(&xtime_lock, flags);

		spin_lock_irqsave(&dyn_tick->lock, flags);

		ret = 0;

		if (!(dyn_tick->state & DYN_TICK_ENABLED)) {

			ret = dyn_tick->enable();
@@ -387,7 +387,7 @@ static int timer_dyn_tick_enable(void) 
			if (ret == 0)

				dyn_tick->state |= DYN_TICK_ENABLED;

		}

		write_sequnlock_irqrestore(&xtime_lock, flags);

		spin_unlock_irqrestore(&dyn_tick->lock, flags);

	}



	return ret;
@@ -400,7 +400,7 @@ static int timer_dyn_tick_disable(void) 
	int ret = -ENODEV;



	if (dyn_tick) {

		write_seqlock_irqsave(&xtime_lock, flags);

		spin_lock_irqsave(&dyn_tick->lock, flags);

		ret = 0;

		if (dyn_tick->state & DYN_TICK_ENABLED) {

			ret = dyn_tick->disable();
@@ -408,7 +408,7 @@ static int timer_dyn_tick_disable(void) 
			if (ret == 0)

				dyn_tick->state &= ~DYN_TICK_ENABLED;

		}

		write_sequnlock_irqrestore(&xtime_lock, flags);

		spin_unlock_irqrestore(&dyn_tick->lock, flags);

	}



	return ret;
@@ -422,15 +422,20 @@ static int timer_dyn_tick_disable(void) 
void timer_dyn_reprogram(void)

{

	struct dyn_tick_timer *dyn_tick = system_timer->dyn_tick;

	unsigned long next, seq;

	unsigned long next, seq, flags;



	if (dyn_tick && (dyn_tick->state & DYN_TICK_ENABLED)) {

	if (!dyn_tick)

		return;



	spin_lock_irqsave(&dyn_tick->lock, flags);

	if (dyn_tick->state & DYN_TICK_ENABLED) {

		next = next_timer_interrupt();

		do {

			seq = read_seqbegin(&xtime_lock);

			dyn_tick->reprogram(next_timer_interrupt() - jiffies);

			dyn_tick->reprogram(next - jiffies);

		} while (read_seqretry(&xtime_lock, seq));

	}

	spin_unlock_irqrestore(&dyn_tick->lock, flags);

}



static ssize_t timer_show_dyn_tick(struct sys_device *dev, char *buf)
@@ -499,5 +504,10 @@ void __init time_init(void) 
	if (system_timer->offset == NULL)

		system_timer->offset = dummy_gettimeoffset;

	system_timer->init();



#ifdef CONFIG_NO_IDLE_HZ

	if (system_timer->dyn_tick)

		system_timer->dyn_tick->lock = SPIN_LOCK_UNLOCKED;

#endif

}

include/asm-arm/mach/time.h

+1 −0
Original line number Diff line number Diff line
@@ -50,6 +50,7 @@ struct sys_timer { 
#define DYN_TICK_ENABLED	(1 << 1)



struct dyn_tick_timer {

	spinlock_t	lock;

	unsigned int	state;			/* Current state */

	int		(*enable)(void);	/* Enables dynamic tick */

	int		(*disable)(void);	/* Disables dynamic tick */