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genirq: Add IRQ affinity notifiers

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When initiating I/O on a multiqueue and multi-IRQ device, we may want
to select a queue for which the response will be handled on the same
or a nearby CPU.  This requires a reverse-map of IRQ affinity.  Add a
notification mechanism to support this.

This is based closely on work by Thomas Gleixner <tglx@linutronix.de>.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Cc: linux-net-drivers@solarflare.com
Cc: Tom Herbert <therbert@google.com>
Cc: David Miller <davem@davemloft.net>
LKML-Reference: <1295470904.11126.84.camel@bwh-desktop>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Ben Hutchings 2011-01-19 21:01:44 +00:00 committed by Thomas Gleixner
parent 1bae4ce27c
commit cd7eab44e9
3 changed files with 117 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

33
include/linux/interrupt.h
View file

@ -14,6 +14,8 @@
#include <linux/smp.h>
#include <linux/percpu.h>
#include <linux/hrtimer.h>
#include <linux/kref.h>
#include <linux/workqueue.h>
#include <asm/atomic.h>
#include <asm/ptrace.h>
@ -240,6 +242,35 @@ extern int irq_can_set_affinity(unsigned int irq);
extern int irq_select_affinity(unsigned int irq);
extern int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m);
/**
* struct irq_affinity_notify - context for notification of IRQ affinity changes
* @irq: Interrupt to which notification applies
* @kref: Reference count, for internal use
* @work: Work item, for internal use
* @notify: Function to be called on change. This will be
* called in process context.
* @release: Function to be called on release. This will be
* called in process context. Once registered, the
* structure must only be freed when this function is
* called or later.
*/
struct irq_affinity_notify {
unsigned int irq;
struct kref kref;
struct work_struct work;
void (*notify)(struct irq_affinity_notify *, const cpumask_t *mask);
void (*release)(struct kref *ref);
};
extern int
irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify);
static inline void irq_run_affinity_notifiers(void)
{
flush_scheduled_work();
}
#else /* CONFIG_SMP */
static inline int irq_set_affinity(unsigned int irq, const struct cpumask *m)
@ -255,7 +286,7 @@ static inline int irq_can_set_affinity(unsigned int irq)
static inline int irq_select_affinity(unsigned int irq) { return 0; }
static inline int irq_set_affinity_hint(unsigned int irq,
const struct cpumask *m)
const struct cpumask *m)
{
return -EINVAL;
}

3
include/linux/irqdesc.h
View file

@ -8,6 +8,7 @@
* For now it's included from <linux/irq.h>
*/
struct irq_affinity_notify;
struct proc_dir_entry;
struct timer_rand_state;
/**
@ -24,6 +25,7 @@ struct timer_rand_state;
* @last_unhandled: aging timer for unhandled count
* @irqs_unhandled: stats field for spurious unhandled interrupts
* @lock: locking for SMP
* @affinity_notify: context for notification of affinity changes
* @pending_mask: pending rebalanced interrupts
* @threads_active: number of irqaction threads currently running
* @wait_for_threads: wait queue for sync_irq to wait for threaded handlers
@ -70,6 +72,7 @@ struct irq_desc {
raw_spinlock_t lock;
#ifdef CONFIG_SMP
const struct cpumask *affinity_hint;
struct irq_affinity_notify *affinity_notify;
#ifdef CONFIG_GENERIC_PENDING_IRQ
cpumask_var_t pending_mask;
#endif

82
kernel/irq/manage.c
View file

@ -134,6 +134,10 @@ int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
irq_set_thread_affinity(desc);
}
#endif
if (desc->affinity_notify) {
kref_get(&desc->affinity_notify->kref);
schedule_work(&desc->affinity_notify->work);
}
desc->status |= IRQ_AFFINITY_SET;
raw_spin_unlock_irqrestore(&desc->lock, flags);
return 0;
@ -155,6 +159,79 @@ int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
}
EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
static void irq_affinity_notify(struct work_struct *work)
{
struct irq_affinity_notify *notify =
container_of(work, struct irq_affinity_notify, work);
struct irq_desc *desc = irq_to_desc(notify->irq);
cpumask_var_t cpumask;
unsigned long flags;
if (!desc)
goto out;
if (!alloc_cpumask_var(&cpumask, GFP_KERNEL))
goto out;
raw_spin_lock_irqsave(&desc->lock, flags);
#ifdef CONFIG_GENERIC_PENDING_IRQ
if (desc->status & IRQ_MOVE_PENDING)
cpumask_copy(cpumask, desc->pending_mask);
else
#endif
cpumask_copy(cpumask, desc->affinity);
raw_spin_unlock_irqrestore(&desc->lock, flags);
notify->notify(notify, cpumask);
free_cpumask_var(cpumask);
out:
kref_put(&notify->kref, notify->release);
}
/**
* irq_set_affinity_notifier - control notification of IRQ affinity changes
* @irq: Interrupt for which to enable/disable notification
* @notify: Context for notification, or %NULL to disable
* notification. Function pointers must be initialised;
* the other fields will be initialised by this function.
*
* Must be called in process context. Notification may only be enabled
* after the IRQ is allocated and must be disabled before the IRQ is
* freed using free_irq().
*/
int
irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
{
struct irq_desc *desc = irq_to_desc(irq);
struct irq_affinity_notify *old_notify;
unsigned long flags;
/* The release function is promised process context */
might_sleep();
if (!desc)
return -EINVAL;
/* Complete initialisation of *notify */
if (notify) {
notify->irq = irq;
kref_init(&notify->kref);
INIT_WORK(&notify->work, irq_affinity_notify);
}
raw_spin_lock_irqsave(&desc->lock, flags);
old_notify = desc->affinity_notify;
desc->affinity_notify = notify;
raw_spin_unlock_irqrestore(&desc->lock, flags);
if (old_notify)
kref_put(&old_notify->kref, old_notify->release);
return 0;
}
EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
#ifndef CONFIG_AUTO_IRQ_AFFINITY
/*
* Generic version of the affinity autoselector.
@ -1004,6 +1081,11 @@ void free_irq(unsigned int irq, void *dev_id)
if (!desc)
return;
#ifdef CONFIG_SMP
if (WARN_ON(desc->affinity_notify))
desc->affinity_notify = NULL;
#endif
chip_bus_lock(desc);
kfree(__free_irq(irq, dev_id));
chip_bus_sync_unlock(desc);