linux/kernel/irq/migration.c
Thomas Gleixner f1a06390d0 genirq: Prevent irq storm on migration
move_native_irq() masks and unmasks the interrupt line
unconditionally, but the interrupt line might be masked due to a
threaded oneshot handler in progress. Unmasking the line in that case
can lead to interrupt storms. Observed on PREEMPT_RT.

Originally-from: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@kernel.org
2011-02-02 22:15:08 +01:00

79 lines
1.8 KiB
C

#include <linux/irq.h>
#include <linux/interrupt.h>
#include "internals.h"
void move_masked_irq(int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
struct irq_chip *chip = desc->irq_data.chip;
if (likely(!(desc->status & IRQ_MOVE_PENDING)))
return;
/*
* Paranoia: cpu-local interrupts shouldn't be calling in here anyway.
*/
if (CHECK_IRQ_PER_CPU(desc->status)) {
WARN_ON(1);
return;
}
desc->status &= ~IRQ_MOVE_PENDING;
if (unlikely(cpumask_empty(desc->pending_mask)))
return;
if (!chip->irq_set_affinity)
return;
assert_raw_spin_locked(&desc->lock);
/*
* If there was a valid mask to work with, please
* do the disable, re-program, enable sequence.
* This is *not* particularly important for level triggered
* but in a edge trigger case, we might be setting rte
* when an active trigger is comming in. This could
* cause some ioapics to mal-function.
* Being paranoid i guess!
*
* For correct operation this depends on the caller
* masking the irqs.
*/
if (likely(cpumask_any_and(desc->pending_mask, cpu_online_mask)
< nr_cpu_ids))
if (!chip->irq_set_affinity(&desc->irq_data,
desc->pending_mask, false)) {
cpumask_copy(desc->irq_data.affinity, desc->pending_mask);
irq_set_thread_affinity(desc);
}
cpumask_clear(desc->pending_mask);
}
void move_native_irq(int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
bool masked;
if (likely(!(desc->status & IRQ_MOVE_PENDING)))
return;
if (unlikely(desc->status & IRQ_DISABLED))
return;
/*
* Be careful vs. already masked interrupts. If this is a
* threaded interrupt with ONESHOT set, we can end up with an
* interrupt storm.
*/
masked = desc->status & IRQ_MASKED;
if (!masked)
desc->irq_data.chip->irq_mask(&desc->irq_data);
move_masked_irq(irq);
if (!masked)
desc->irq_data.chip->irq_unmask(&desc->irq_data);
}