linux_dsm_epyc7002/kernel/irq/manage.c
Thomas Gleixner 69ab849439 genirq: Wake up irq thread after action has been installed
The wake_up_process() of the new irq thread in __setup_irq() is too
early as the irqaction is not yet fully initialized especially
action->irq is not yet set. The interrupt thread might dereference the
wrong irq descriptor.

Move the wakeup after the action is installed and action->irq has been
set.

Reported-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michael Buesch <mb@bu3sch.de>
2009-08-18 17:22:43 +02:00

1005 lines
24 KiB
C

/*
* linux/kernel/irq/manage.c
*
* Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
* Copyright (C) 2005-2006 Thomas Gleixner
*
* This file contains driver APIs to the irq subsystem.
*/
#include <linux/irq.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include "internals.h"
/**
* synchronize_irq - wait for pending IRQ handlers (on other CPUs)
* @irq: interrupt number to wait for
*
* This function waits for any pending IRQ handlers for this interrupt
* to complete before returning. If you use this function while
* holding a resource the IRQ handler may need you will deadlock.
*
* This function may be called - with care - from IRQ context.
*/
void synchronize_irq(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
unsigned int status;
if (!desc)
return;
do {
unsigned long flags;
/*
* Wait until we're out of the critical section. This might
* give the wrong answer due to the lack of memory barriers.
*/
while (desc->status & IRQ_INPROGRESS)
cpu_relax();
/* Ok, that indicated we're done: double-check carefully. */
spin_lock_irqsave(&desc->lock, flags);
status = desc->status;
spin_unlock_irqrestore(&desc->lock, flags);
/* Oops, that failed? */
} while (status & IRQ_INPROGRESS);
/*
* We made sure that no hardirq handler is running. Now verify
* that no threaded handlers are active.
*/
wait_event(desc->wait_for_threads, !atomic_read(&desc->threads_active));
}
EXPORT_SYMBOL(synchronize_irq);
#ifdef CONFIG_SMP
cpumask_var_t irq_default_affinity;
/**
* irq_can_set_affinity - Check if the affinity of a given irq can be set
* @irq: Interrupt to check
*
*/
int irq_can_set_affinity(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
!desc->chip->set_affinity)
return 0;
return 1;
}
/**
* irq_set_thread_affinity - Notify irq threads to adjust affinity
* @desc: irq descriptor which has affitnity changed
*
* We just set IRQTF_AFFINITY and delegate the affinity setting
* to the interrupt thread itself. We can not call
* set_cpus_allowed_ptr() here as we hold desc->lock and this
* code can be called from hard interrupt context.
*/
void irq_set_thread_affinity(struct irq_desc *desc)
{
struct irqaction *action = desc->action;
while (action) {
if (action->thread)
set_bit(IRQTF_AFFINITY, &action->thread_flags);
action = action->next;
}
}
/**
* irq_set_affinity - Set the irq affinity of a given irq
* @irq: Interrupt to set affinity
* @cpumask: cpumask
*
*/
int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
{
struct irq_desc *desc = irq_to_desc(irq);
unsigned long flags;
if (!desc->chip->set_affinity)
return -EINVAL;
spin_lock_irqsave(&desc->lock, flags);
#ifdef CONFIG_GENERIC_PENDING_IRQ
if (desc->status & IRQ_MOVE_PCNTXT) {
if (!desc->chip->set_affinity(irq, cpumask)) {
cpumask_copy(desc->affinity, cpumask);
irq_set_thread_affinity(desc);
}
}
else {
desc->status |= IRQ_MOVE_PENDING;
cpumask_copy(desc->pending_mask, cpumask);
}
#else
if (!desc->chip->set_affinity(irq, cpumask)) {
cpumask_copy(desc->affinity, cpumask);
irq_set_thread_affinity(desc);
}
#endif
desc->status |= IRQ_AFFINITY_SET;
spin_unlock_irqrestore(&desc->lock, flags);
return 0;
}
#ifndef CONFIG_AUTO_IRQ_AFFINITY
/*
* Generic version of the affinity autoselector.
*/
static int setup_affinity(unsigned int irq, struct irq_desc *desc)
{
if (!irq_can_set_affinity(irq))
return 0;
/*
* Preserve an userspace affinity setup, but make sure that
* one of the targets is online.
*/
if (desc->status & (IRQ_AFFINITY_SET | IRQ_NO_BALANCING)) {
if (cpumask_any_and(desc->affinity, cpu_online_mask)
< nr_cpu_ids)
goto set_affinity;
else
desc->status &= ~IRQ_AFFINITY_SET;
}
cpumask_and(desc->affinity, cpu_online_mask, irq_default_affinity);
set_affinity:
desc->chip->set_affinity(irq, desc->affinity);
return 0;
}
#else
static inline int setup_affinity(unsigned int irq, struct irq_desc *d)
{
return irq_select_affinity(irq);
}
#endif
/*
* Called when affinity is set via /proc/irq
*/
int irq_select_affinity_usr(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
unsigned long flags;
int ret;
spin_lock_irqsave(&desc->lock, flags);
ret = setup_affinity(irq, desc);
if (!ret)
irq_set_thread_affinity(desc);
spin_unlock_irqrestore(&desc->lock, flags);
return ret;
}
#else
static inline int setup_affinity(unsigned int irq, struct irq_desc *desc)
{
return 0;
}
#endif
void __disable_irq(struct irq_desc *desc, unsigned int irq, bool suspend)
{
if (suspend) {
if (!desc->action || (desc->action->flags & IRQF_TIMER))
return;
desc->status |= IRQ_SUSPENDED;
}
if (!desc->depth++) {
desc->status |= IRQ_DISABLED;
desc->chip->disable(irq);
}
}
/**
* disable_irq_nosync - disable an irq without waiting
* @irq: Interrupt to disable
*
* Disable the selected interrupt line. Disables and Enables are
* nested.
* Unlike disable_irq(), this function does not ensure existing
* instances of the IRQ handler have completed before returning.
*
* This function may be called from IRQ context.
*/
void disable_irq_nosync(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
unsigned long flags;
if (!desc)
return;
spin_lock_irqsave(&desc->lock, flags);
__disable_irq(desc, irq, false);
spin_unlock_irqrestore(&desc->lock, flags);
}
EXPORT_SYMBOL(disable_irq_nosync);
/**
* disable_irq - disable an irq and wait for completion
* @irq: Interrupt to disable
*
* Disable the selected interrupt line. Enables and Disables are
* nested.
* This function waits for any pending IRQ handlers for this interrupt
* to complete before returning. If you use this function while
* holding a resource the IRQ handler may need you will deadlock.
*
* This function may be called - with care - from IRQ context.
*/
void disable_irq(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
if (!desc)
return;
disable_irq_nosync(irq);
if (desc->action)
synchronize_irq(irq);
}
EXPORT_SYMBOL(disable_irq);
void __enable_irq(struct irq_desc *desc, unsigned int irq, bool resume)
{
if (resume)
desc->status &= ~IRQ_SUSPENDED;
switch (desc->depth) {
case 0:
err_out:
WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
break;
case 1: {
unsigned int status = desc->status & ~IRQ_DISABLED;
if (desc->status & IRQ_SUSPENDED)
goto err_out;
/* Prevent probing on this irq: */
desc->status = status | IRQ_NOPROBE;
check_irq_resend(desc, irq);
/* fall-through */
}
default:
desc->depth--;
}
}
/**
* enable_irq - enable handling of an irq
* @irq: Interrupt to enable
*
* Undoes the effect of one call to disable_irq(). If this
* matches the last disable, processing of interrupts on this
* IRQ line is re-enabled.
*
* This function may be called from IRQ context.
*/
void enable_irq(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
unsigned long flags;
if (!desc)
return;
spin_lock_irqsave(&desc->lock, flags);
__enable_irq(desc, irq, false);
spin_unlock_irqrestore(&desc->lock, flags);
}
EXPORT_SYMBOL(enable_irq);
static int set_irq_wake_real(unsigned int irq, unsigned int on)
{
struct irq_desc *desc = irq_to_desc(irq);
int ret = -ENXIO;
if (desc->chip->set_wake)
ret = desc->chip->set_wake(irq, on);
return ret;
}
/**
* set_irq_wake - control irq power management wakeup
* @irq: interrupt to control
* @on: enable/disable power management wakeup
*
* Enable/disable power management wakeup mode, which is
* disabled by default. Enables and disables must match,
* just as they match for non-wakeup mode support.
*
* Wakeup mode lets this IRQ wake the system from sleep
* states like "suspend to RAM".
*/
int set_irq_wake(unsigned int irq, unsigned int on)
{
struct irq_desc *desc = irq_to_desc(irq);
unsigned long flags;
int ret = 0;
/* wakeup-capable irqs can be shared between drivers that
* don't need to have the same sleep mode behaviors.
*/
spin_lock_irqsave(&desc->lock, flags);
if (on) {
if (desc->wake_depth++ == 0) {
ret = set_irq_wake_real(irq, on);
if (ret)
desc->wake_depth = 0;
else
desc->status |= IRQ_WAKEUP;
}
} else {
if (desc->wake_depth == 0) {
WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
} else if (--desc->wake_depth == 0) {
ret = set_irq_wake_real(irq, on);
if (ret)
desc->wake_depth = 1;
else
desc->status &= ~IRQ_WAKEUP;
}
}
spin_unlock_irqrestore(&desc->lock, flags);
return ret;
}
EXPORT_SYMBOL(set_irq_wake);
/*
* Internal function that tells the architecture code whether a
* particular irq has been exclusively allocated or is available
* for driver use.
*/
int can_request_irq(unsigned int irq, unsigned long irqflags)
{
struct irq_desc *desc = irq_to_desc(irq);
struct irqaction *action;
if (!desc)
return 0;
if (desc->status & IRQ_NOREQUEST)
return 0;
action = desc->action;
if (action)
if (irqflags & action->flags & IRQF_SHARED)
action = NULL;
return !action;
}
void compat_irq_chip_set_default_handler(struct irq_desc *desc)
{
/*
* If the architecture still has not overriden
* the flow handler then zap the default. This
* should catch incorrect flow-type setting.
*/
if (desc->handle_irq == &handle_bad_irq)
desc->handle_irq = NULL;
}
int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
unsigned long flags)
{
int ret;
struct irq_chip *chip = desc->chip;
if (!chip || !chip->set_type) {
/*
* IRQF_TRIGGER_* but the PIC does not support multiple
* flow-types?
*/
pr_debug("No set_type function for IRQ %d (%s)\n", irq,
chip ? (chip->name ? : "unknown") : "unknown");
return 0;
}
/* caller masked out all except trigger mode flags */
ret = chip->set_type(irq, flags);
if (ret)
pr_err("setting trigger mode %d for irq %u failed (%pF)\n",
(int)flags, irq, chip->set_type);
else {
if (flags & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
flags |= IRQ_LEVEL;
/* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK);
desc->status |= flags;
}
return ret;
}
static int irq_wait_for_interrupt(struct irqaction *action)
{
while (!kthread_should_stop()) {
set_current_state(TASK_INTERRUPTIBLE);
if (test_and_clear_bit(IRQTF_RUNTHREAD,
&action->thread_flags)) {
__set_current_state(TASK_RUNNING);
return 0;
}
schedule();
}
return -1;
}
#ifdef CONFIG_SMP
/*
* Check whether we need to change the affinity of the interrupt thread.
*/
static void
irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
{
cpumask_var_t mask;
if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
return;
/*
* In case we are out of memory we set IRQTF_AFFINITY again and
* try again next time
*/
if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
set_bit(IRQTF_AFFINITY, &action->thread_flags);
return;
}
spin_lock_irq(&desc->lock);
cpumask_copy(mask, desc->affinity);
spin_unlock_irq(&desc->lock);
set_cpus_allowed_ptr(current, mask);
free_cpumask_var(mask);
}
#else
static inline void
irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
#endif
/*
* Interrupt handler thread
*/
static int irq_thread(void *data)
{
struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO/2, };
struct irqaction *action = data;
struct irq_desc *desc = irq_to_desc(action->irq);
int wake;
sched_setscheduler(current, SCHED_FIFO, &param);
current->irqaction = action;
while (!irq_wait_for_interrupt(action)) {
irq_thread_check_affinity(desc, action);
atomic_inc(&desc->threads_active);
spin_lock_irq(&desc->lock);
if (unlikely(desc->status & IRQ_DISABLED)) {
/*
* CHECKME: We might need a dedicated
* IRQ_THREAD_PENDING flag here, which
* retriggers the thread in check_irq_resend()
* but AFAICT IRQ_PENDING should be fine as it
* retriggers the interrupt itself --- tglx
*/
desc->status |= IRQ_PENDING;
spin_unlock_irq(&desc->lock);
} else {
spin_unlock_irq(&desc->lock);
action->thread_fn(action->irq, action->dev_id);
}
wake = atomic_dec_and_test(&desc->threads_active);
if (wake && waitqueue_active(&desc->wait_for_threads))
wake_up(&desc->wait_for_threads);
}
/*
* Clear irqaction. Otherwise exit_irq_thread() would make
* fuzz about an active irq thread going into nirvana.
*/
current->irqaction = NULL;
return 0;
}
/*
* Called from do_exit()
*/
void exit_irq_thread(void)
{
struct task_struct *tsk = current;
if (!tsk->irqaction)
return;
printk(KERN_ERR
"exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
tsk->comm ? tsk->comm : "", tsk->pid, tsk->irqaction->irq);
/*
* Set the THREAD DIED flag to prevent further wakeups of the
* soon to be gone threaded handler.
*/
set_bit(IRQTF_DIED, &tsk->irqaction->flags);
}
/*
* Internal function to register an irqaction - typically used to
* allocate special interrupts that are part of the architecture.
*/
static int
__setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
{
struct irqaction *old, **old_ptr;
const char *old_name = NULL;
unsigned long flags;
int shared = 0;
int ret;
if (!desc)
return -EINVAL;
if (desc->chip == &no_irq_chip)
return -ENOSYS;
/*
* Some drivers like serial.c use request_irq() heavily,
* so we have to be careful not to interfere with a
* running system.
*/
if (new->flags & IRQF_SAMPLE_RANDOM) {
/*
* This function might sleep, we want to call it first,
* outside of the atomic block.
* Yes, this might clear the entropy pool if the wrong
* driver is attempted to be loaded, without actually
* installing a new handler, but is this really a problem,
* only the sysadmin is able to do this.
*/
rand_initialize_irq(irq);
}
/*
* Threaded handler ?
*/
if (new->thread_fn) {
struct task_struct *t;
t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
new->name);
if (IS_ERR(t))
return PTR_ERR(t);
/*
* We keep the reference to the task struct even if
* the thread dies to avoid that the interrupt code
* references an already freed task_struct.
*/
get_task_struct(t);
new->thread = t;
}
/*
* The following block of code has to be executed atomically
*/
spin_lock_irqsave(&desc->lock, flags);
old_ptr = &desc->action;
old = *old_ptr;
if (old) {
/*
* Can't share interrupts unless both agree to and are
* the same type (level, edge, polarity). So both flag
* fields must have IRQF_SHARED set and the bits which
* set the trigger type must match.
*/
if (!((old->flags & new->flags) & IRQF_SHARED) ||
((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
old_name = old->name;
goto mismatch;
}
#if defined(CONFIG_IRQ_PER_CPU)
/* All handlers must agree on per-cpuness */
if ((old->flags & IRQF_PERCPU) !=
(new->flags & IRQF_PERCPU))
goto mismatch;
#endif
/* add new interrupt at end of irq queue */
do {
old_ptr = &old->next;
old = *old_ptr;
} while (old);
shared = 1;
}
if (!shared) {
irq_chip_set_defaults(desc->chip);
init_waitqueue_head(&desc->wait_for_threads);
/* Setup the type (level, edge polarity) if configured: */
if (new->flags & IRQF_TRIGGER_MASK) {
ret = __irq_set_trigger(desc, irq,
new->flags & IRQF_TRIGGER_MASK);
if (ret)
goto out_thread;
} else
compat_irq_chip_set_default_handler(desc);
#if defined(CONFIG_IRQ_PER_CPU)
if (new->flags & IRQF_PERCPU)
desc->status |= IRQ_PER_CPU;
#endif
desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
if (!(desc->status & IRQ_NOAUTOEN)) {
desc->depth = 0;
desc->status &= ~IRQ_DISABLED;
desc->chip->startup(irq);
} else
/* Undo nested disables: */
desc->depth = 1;
/* Exclude IRQ from balancing if requested */
if (new->flags & IRQF_NOBALANCING)
desc->status |= IRQ_NO_BALANCING;
/* Set default affinity mask once everything is setup */
setup_affinity(irq, desc);
} else if ((new->flags & IRQF_TRIGGER_MASK)
&& (new->flags & IRQF_TRIGGER_MASK)
!= (desc->status & IRQ_TYPE_SENSE_MASK)) {
/* hope the handler works with the actual trigger mode... */
pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
(int)(new->flags & IRQF_TRIGGER_MASK));
}
new->irq = irq;
*old_ptr = new;
/* Reset broken irq detection when installing new handler */
desc->irq_count = 0;
desc->irqs_unhandled = 0;
/*
* Check whether we disabled the irq via the spurious handler
* before. Reenable it and give it another chance.
*/
if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
desc->status &= ~IRQ_SPURIOUS_DISABLED;
__enable_irq(desc, irq, false);
}
spin_unlock_irqrestore(&desc->lock, flags);
/*
* Strictly no need to wake it up, but hung_task complains
* when no hard interrupt wakes the thread up.
*/
if (new->thread)
wake_up_process(new->thread);
register_irq_proc(irq, desc);
new->dir = NULL;
register_handler_proc(irq, new);
return 0;
mismatch:
#ifdef CONFIG_DEBUG_SHIRQ
if (!(new->flags & IRQF_PROBE_SHARED)) {
printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
if (old_name)
printk(KERN_ERR "current handler: %s\n", old_name);
dump_stack();
}
#endif
ret = -EBUSY;
out_thread:
spin_unlock_irqrestore(&desc->lock, flags);
if (new->thread) {
struct task_struct *t = new->thread;
new->thread = NULL;
if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
kthread_stop(t);
put_task_struct(t);
}
return ret;
}
/**
* setup_irq - setup an interrupt
* @irq: Interrupt line to setup
* @act: irqaction for the interrupt
*
* Used to statically setup interrupts in the early boot process.
*/
int setup_irq(unsigned int irq, struct irqaction *act)
{
struct irq_desc *desc = irq_to_desc(irq);
return __setup_irq(irq, desc, act);
}
EXPORT_SYMBOL_GPL(setup_irq);
/*
* Internal function to unregister an irqaction - used to free
* regular and special interrupts that are part of the architecture.
*/
static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
{
struct irq_desc *desc = irq_to_desc(irq);
struct irqaction *action, **action_ptr;
unsigned long flags;
WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
if (!desc)
return NULL;
spin_lock_irqsave(&desc->lock, flags);
/*
* There can be multiple actions per IRQ descriptor, find the right
* one based on the dev_id:
*/
action_ptr = &desc->action;
for (;;) {
action = *action_ptr;
if (!action) {
WARN(1, "Trying to free already-free IRQ %d\n", irq);
spin_unlock_irqrestore(&desc->lock, flags);
return NULL;
}
if (action->dev_id == dev_id)
break;
action_ptr = &action->next;
}
/* Found it - now remove it from the list of entries: */
*action_ptr = action->next;
/* Currently used only by UML, might disappear one day: */
#ifdef CONFIG_IRQ_RELEASE_METHOD
if (desc->chip->release)
desc->chip->release(irq, dev_id);
#endif
/* If this was the last handler, shut down the IRQ line: */
if (!desc->action) {
desc->status |= IRQ_DISABLED;
if (desc->chip->shutdown)
desc->chip->shutdown(irq);
else
desc->chip->disable(irq);
}
spin_unlock_irqrestore(&desc->lock, flags);
unregister_handler_proc(irq, action);
/* Make sure it's not being used on another CPU: */
synchronize_irq(irq);
#ifdef CONFIG_DEBUG_SHIRQ
/*
* It's a shared IRQ -- the driver ought to be prepared for an IRQ
* event to happen even now it's being freed, so let's make sure that
* is so by doing an extra call to the handler ....
*
* ( We do this after actually deregistering it, to make sure that a
* 'real' IRQ doesn't run in * parallel with our fake. )
*/
if (action->flags & IRQF_SHARED) {
local_irq_save(flags);
action->handler(irq, dev_id);
local_irq_restore(flags);
}
#endif
if (action->thread) {
if (!test_bit(IRQTF_DIED, &action->thread_flags))
kthread_stop(action->thread);
put_task_struct(action->thread);
}
return action;
}
/**
* remove_irq - free an interrupt
* @irq: Interrupt line to free
* @act: irqaction for the interrupt
*
* Used to remove interrupts statically setup by the early boot process.
*/
void remove_irq(unsigned int irq, struct irqaction *act)
{
__free_irq(irq, act->dev_id);
}
EXPORT_SYMBOL_GPL(remove_irq);
/**
* free_irq - free an interrupt allocated with request_irq
* @irq: Interrupt line to free
* @dev_id: Device identity to free
*
* Remove an interrupt handler. The handler is removed and if the
* interrupt line is no longer in use by any driver it is disabled.
* On a shared IRQ the caller must ensure the interrupt is disabled
* on the card it drives before calling this function. The function
* does not return until any executing interrupts for this IRQ
* have completed.
*
* This function must not be called from interrupt context.
*/
void free_irq(unsigned int irq, void *dev_id)
{
kfree(__free_irq(irq, dev_id));
}
EXPORT_SYMBOL(free_irq);
/**
* request_threaded_irq - allocate an interrupt line
* @irq: Interrupt line to allocate
* @handler: Function to be called when the IRQ occurs.
* Primary handler for threaded interrupts
* @thread_fn: Function called from the irq handler thread
* If NULL, no irq thread is created
* @irqflags: Interrupt type flags
* @devname: An ascii name for the claiming device
* @dev_id: A cookie passed back to the handler function
*
* This call allocates interrupt resources and enables the
* interrupt line and IRQ handling. From the point this
* call is made your handler function may be invoked. Since
* your handler function must clear any interrupt the board
* raises, you must take care both to initialise your hardware
* and to set up the interrupt handler in the right order.
*
* If you want to set up a threaded irq handler for your device
* then you need to supply @handler and @thread_fn. @handler ist
* still called in hard interrupt context and has to check
* whether the interrupt originates from the device. If yes it
* needs to disable the interrupt on the device and return
* IRQ_WAKE_THREAD which will wake up the handler thread and run
* @thread_fn. This split handler design is necessary to support
* shared interrupts.
*
* Dev_id must be globally unique. Normally the address of the
* device data structure is used as the cookie. Since the handler
* receives this value it makes sense to use it.
*
* If your interrupt is shared you must pass a non NULL dev_id
* as this is required when freeing the interrupt.
*
* Flags:
*
* IRQF_SHARED Interrupt is shared
* IRQF_DISABLED Disable local interrupts while processing
* IRQF_SAMPLE_RANDOM The interrupt can be used for entropy
* IRQF_TRIGGER_* Specify active edge(s) or level
*
*/
int request_threaded_irq(unsigned int irq, irq_handler_t handler,
irq_handler_t thread_fn, unsigned long irqflags,
const char *devname, void *dev_id)
{
struct irqaction *action;
struct irq_desc *desc;
int retval;
/*
* handle_IRQ_event() always ignores IRQF_DISABLED except for
* the _first_ irqaction (sigh). That can cause oopsing, but
* the behavior is classified as "will not fix" so we need to
* start nudging drivers away from using that idiom.
*/
if ((irqflags & (IRQF_SHARED|IRQF_DISABLED)) ==
(IRQF_SHARED|IRQF_DISABLED)) {
pr_warning(
"IRQ %d/%s: IRQF_DISABLED is not guaranteed on shared IRQs\n",
irq, devname);
}
#ifdef CONFIG_LOCKDEP
/*
* Lockdep wants atomic interrupt handlers:
*/
irqflags |= IRQF_DISABLED;
#endif
/*
* Sanity-check: shared interrupts must pass in a real dev-ID,
* otherwise we'll have trouble later trying to figure out
* which interrupt is which (messes up the interrupt freeing
* logic etc).
*/
if ((irqflags & IRQF_SHARED) && !dev_id)
return -EINVAL;
desc = irq_to_desc(irq);
if (!desc)
return -EINVAL;
if (desc->status & IRQ_NOREQUEST)
return -EINVAL;
if (!handler)
return -EINVAL;
action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
if (!action)
return -ENOMEM;
action->handler = handler;
action->thread_fn = thread_fn;
action->flags = irqflags;
action->name = devname;
action->dev_id = dev_id;
retval = __setup_irq(irq, desc, action);
if (retval)
kfree(action);
#ifdef CONFIG_DEBUG_SHIRQ
if (irqflags & IRQF_SHARED) {
/*
* It's a shared IRQ -- the driver ought to be prepared for it
* to happen immediately, so let's make sure....
* We disable the irq to make sure that a 'real' IRQ doesn't
* run in parallel with our fake.
*/
unsigned long flags;
disable_irq(irq);
local_irq_save(flags);
handler(irq, dev_id);
local_irq_restore(flags);
enable_irq(irq);
}
#endif
return retval;
}
EXPORT_SYMBOL(request_threaded_irq);