linux/kernel/irq/irqdesc.c
Thomas Gleixner 425a5072dc genirq: Free irq_desc with rcu
The new VMD device driver needs to iterate over a list of
"demultiplexing" interrupts. Protecting that list with a lock is not
possible because the list is also required in code pathes which hold
irq descriptor lock. Therefor the demultiplexing interrupt handler
would create a lock inversion scenario if it calls a demux handler
with the list protection lock held.

A solution for this is to free the irq descriptor via RCU, so the
list can be walked with rcu read lock held.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Keith Busch <keith.busch@intel.com>
2015-12-14 10:03:46 +01:00

661 lines
15 KiB
C

/*
* Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
* Copyright (C) 2005-2006, Thomas Gleixner, Russell King
*
* This file contains the interrupt descriptor management code
*
* Detailed information is available in Documentation/DocBook/genericirq
*
*/
#include <linux/irq.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/radix-tree.h>
#include <linux/bitmap.h>
#include <linux/irqdomain.h>
#include "internals.h"
/*
* lockdep: we want to handle all irq_desc locks as a single lock-class:
*/
static struct lock_class_key irq_desc_lock_class;
#if defined(CONFIG_SMP)
static void __init init_irq_default_affinity(void)
{
alloc_cpumask_var(&irq_default_affinity, GFP_NOWAIT);
cpumask_setall(irq_default_affinity);
}
#else
static void __init init_irq_default_affinity(void)
{
}
#endif
#ifdef CONFIG_SMP
static int alloc_masks(struct irq_desc *desc, gfp_t gfp, int node)
{
if (!zalloc_cpumask_var_node(&desc->irq_common_data.affinity,
gfp, node))
return -ENOMEM;
#ifdef CONFIG_GENERIC_PENDING_IRQ
if (!zalloc_cpumask_var_node(&desc->pending_mask, gfp, node)) {
free_cpumask_var(desc->irq_common_data.affinity);
return -ENOMEM;
}
#endif
return 0;
}
static void desc_smp_init(struct irq_desc *desc, int node)
{
cpumask_copy(desc->irq_common_data.affinity, irq_default_affinity);
#ifdef CONFIG_GENERIC_PENDING_IRQ
cpumask_clear(desc->pending_mask);
#endif
#ifdef CONFIG_NUMA
desc->irq_common_data.node = node;
#endif
}
#else
static inline int
alloc_masks(struct irq_desc *desc, gfp_t gfp, int node) { return 0; }
static inline void desc_smp_init(struct irq_desc *desc, int node) { }
#endif
static void desc_set_defaults(unsigned int irq, struct irq_desc *desc, int node,
struct module *owner)
{
int cpu;
desc->irq_common_data.handler_data = NULL;
desc->irq_common_data.msi_desc = NULL;
desc->irq_data.common = &desc->irq_common_data;
desc->irq_data.irq = irq;
desc->irq_data.chip = &no_irq_chip;
desc->irq_data.chip_data = NULL;
irq_settings_clr_and_set(desc, ~0, _IRQ_DEFAULT_INIT_FLAGS);
irqd_set(&desc->irq_data, IRQD_IRQ_DISABLED);
desc->handle_irq = handle_bad_irq;
desc->depth = 1;
desc->irq_count = 0;
desc->irqs_unhandled = 0;
desc->name = NULL;
desc->owner = owner;
for_each_possible_cpu(cpu)
*per_cpu_ptr(desc->kstat_irqs, cpu) = 0;
desc_smp_init(desc, node);
}
int nr_irqs = NR_IRQS;
EXPORT_SYMBOL_GPL(nr_irqs);
static DEFINE_MUTEX(sparse_irq_lock);
static DECLARE_BITMAP(allocated_irqs, IRQ_BITMAP_BITS);
#ifdef CONFIG_SPARSE_IRQ
static RADIX_TREE(irq_desc_tree, GFP_KERNEL);
static void irq_insert_desc(unsigned int irq, struct irq_desc *desc)
{
radix_tree_insert(&irq_desc_tree, irq, desc);
}
struct irq_desc *irq_to_desc(unsigned int irq)
{
return radix_tree_lookup(&irq_desc_tree, irq);
}
EXPORT_SYMBOL(irq_to_desc);
static void delete_irq_desc(unsigned int irq)
{
radix_tree_delete(&irq_desc_tree, irq);
}
#ifdef CONFIG_SMP
static void free_masks(struct irq_desc *desc)
{
#ifdef CONFIG_GENERIC_PENDING_IRQ
free_cpumask_var(desc->pending_mask);
#endif
free_cpumask_var(desc->irq_common_data.affinity);
}
#else
static inline void free_masks(struct irq_desc *desc) { }
#endif
void irq_lock_sparse(void)
{
mutex_lock(&sparse_irq_lock);
}
void irq_unlock_sparse(void)
{
mutex_unlock(&sparse_irq_lock);
}
static struct irq_desc *alloc_desc(int irq, int node, struct module *owner)
{
struct irq_desc *desc;
gfp_t gfp = GFP_KERNEL;
desc = kzalloc_node(sizeof(*desc), gfp, node);
if (!desc)
return NULL;
/* allocate based on nr_cpu_ids */
desc->kstat_irqs = alloc_percpu(unsigned int);
if (!desc->kstat_irqs)
goto err_desc;
if (alloc_masks(desc, gfp, node))
goto err_kstat;
raw_spin_lock_init(&desc->lock);
lockdep_set_class(&desc->lock, &irq_desc_lock_class);
init_rcu_head(&desc->rcu);
desc_set_defaults(irq, desc, node, owner);
return desc;
err_kstat:
free_percpu(desc->kstat_irqs);
err_desc:
kfree(desc);
return NULL;
}
static void delayed_free_desc(struct rcu_head *rhp)
{
struct irq_desc *desc = container_of(rhp, struct irq_desc, rcu);
free_masks(desc);
free_percpu(desc->kstat_irqs);
kfree(desc);
}
static void free_desc(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
unregister_irq_proc(irq, desc);
/*
* sparse_irq_lock protects also show_interrupts() and
* kstat_irq_usr(). Once we deleted the descriptor from the
* sparse tree we can free it. Access in proc will fail to
* lookup the descriptor.
*/
mutex_lock(&sparse_irq_lock);
delete_irq_desc(irq);
mutex_unlock(&sparse_irq_lock);
/*
* We free the descriptor, masks and stat fields via RCU. That
* allows demultiplex interrupts to do rcu based management of
* the child interrupts.
*/
call_rcu(&desc->rcu, delayed_free_desc);
}
static int alloc_descs(unsigned int start, unsigned int cnt, int node,
struct module *owner)
{
struct irq_desc *desc;
int i;
for (i = 0; i < cnt; i++) {
desc = alloc_desc(start + i, node, owner);
if (!desc)
goto err;
mutex_lock(&sparse_irq_lock);
irq_insert_desc(start + i, desc);
mutex_unlock(&sparse_irq_lock);
}
return start;
err:
for (i--; i >= 0; i--)
free_desc(start + i);
mutex_lock(&sparse_irq_lock);
bitmap_clear(allocated_irqs, start, cnt);
mutex_unlock(&sparse_irq_lock);
return -ENOMEM;
}
static int irq_expand_nr_irqs(unsigned int nr)
{
if (nr > IRQ_BITMAP_BITS)
return -ENOMEM;
nr_irqs = nr;
return 0;
}
int __init early_irq_init(void)
{
int i, initcnt, node = first_online_node;
struct irq_desc *desc;
init_irq_default_affinity();
/* Let arch update nr_irqs and return the nr of preallocated irqs */
initcnt = arch_probe_nr_irqs();
printk(KERN_INFO "NR_IRQS:%d nr_irqs:%d %d\n", NR_IRQS, nr_irqs, initcnt);
if (WARN_ON(nr_irqs > IRQ_BITMAP_BITS))
nr_irqs = IRQ_BITMAP_BITS;
if (WARN_ON(initcnt > IRQ_BITMAP_BITS))
initcnt = IRQ_BITMAP_BITS;
if (initcnt > nr_irqs)
nr_irqs = initcnt;
for (i = 0; i < initcnt; i++) {
desc = alloc_desc(i, node, NULL);
set_bit(i, allocated_irqs);
irq_insert_desc(i, desc);
}
return arch_early_irq_init();
}
#else /* !CONFIG_SPARSE_IRQ */
struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
[0 ... NR_IRQS-1] = {
.handle_irq = handle_bad_irq,
.depth = 1,
.lock = __RAW_SPIN_LOCK_UNLOCKED(irq_desc->lock),
}
};
int __init early_irq_init(void)
{
int count, i, node = first_online_node;
struct irq_desc *desc;
init_irq_default_affinity();
printk(KERN_INFO "NR_IRQS:%d\n", NR_IRQS);
desc = irq_desc;
count = ARRAY_SIZE(irq_desc);
for (i = 0; i < count; i++) {
desc[i].kstat_irqs = alloc_percpu(unsigned int);
alloc_masks(&desc[i], GFP_KERNEL, node);
raw_spin_lock_init(&desc[i].lock);
lockdep_set_class(&desc[i].lock, &irq_desc_lock_class);
desc_set_defaults(i, &desc[i], node, NULL);
}
return arch_early_irq_init();
}
struct irq_desc *irq_to_desc(unsigned int irq)
{
return (irq < NR_IRQS) ? irq_desc + irq : NULL;
}
EXPORT_SYMBOL(irq_to_desc);
static void free_desc(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
unsigned long flags;
raw_spin_lock_irqsave(&desc->lock, flags);
desc_set_defaults(irq, desc, irq_desc_get_node(desc), NULL);
raw_spin_unlock_irqrestore(&desc->lock, flags);
}
static inline int alloc_descs(unsigned int start, unsigned int cnt, int node,
struct module *owner)
{
u32 i;
for (i = 0; i < cnt; i++) {
struct irq_desc *desc = irq_to_desc(start + i);
desc->owner = owner;
}
return start;
}
static int irq_expand_nr_irqs(unsigned int nr)
{
return -ENOMEM;
}
void irq_mark_irq(unsigned int irq)
{
mutex_lock(&sparse_irq_lock);
bitmap_set(allocated_irqs, irq, 1);
mutex_unlock(&sparse_irq_lock);
}
#ifdef CONFIG_GENERIC_IRQ_LEGACY
void irq_init_desc(unsigned int irq)
{
free_desc(irq);
}
#endif
#endif /* !CONFIG_SPARSE_IRQ */
/**
* generic_handle_irq - Invoke the handler for a particular irq
* @irq: The irq number to handle
*
*/
int generic_handle_irq(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
if (!desc)
return -EINVAL;
generic_handle_irq_desc(desc);
return 0;
}
EXPORT_SYMBOL_GPL(generic_handle_irq);
#ifdef CONFIG_HANDLE_DOMAIN_IRQ
/**
* __handle_domain_irq - Invoke the handler for a HW irq belonging to a domain
* @domain: The domain where to perform the lookup
* @hwirq: The HW irq number to convert to a logical one
* @lookup: Whether to perform the domain lookup or not
* @regs: Register file coming from the low-level handling code
*
* Returns: 0 on success, or -EINVAL if conversion has failed
*/
int __handle_domain_irq(struct irq_domain *domain, unsigned int hwirq,
bool lookup, struct pt_regs *regs)
{
struct pt_regs *old_regs = set_irq_regs(regs);
unsigned int irq = hwirq;
int ret = 0;
irq_enter();
#ifdef CONFIG_IRQ_DOMAIN
if (lookup)
irq = irq_find_mapping(domain, hwirq);
#endif
/*
* Some hardware gives randomly wrong interrupts. Rather
* than crashing, do something sensible.
*/
if (unlikely(!irq || irq >= nr_irqs)) {
ack_bad_irq(irq);
ret = -EINVAL;
} else {
generic_handle_irq(irq);
}
irq_exit();
set_irq_regs(old_regs);
return ret;
}
#endif
/* Dynamic interrupt handling */
/**
* irq_free_descs - free irq descriptors
* @from: Start of descriptor range
* @cnt: Number of consecutive irqs to free
*/
void irq_free_descs(unsigned int from, unsigned int cnt)
{
int i;
if (from >= nr_irqs || (from + cnt) > nr_irqs)
return;
for (i = 0; i < cnt; i++)
free_desc(from + i);
mutex_lock(&sparse_irq_lock);
bitmap_clear(allocated_irqs, from, cnt);
mutex_unlock(&sparse_irq_lock);
}
EXPORT_SYMBOL_GPL(irq_free_descs);
/**
* irq_alloc_descs - allocate and initialize a range of irq descriptors
* @irq: Allocate for specific irq number if irq >= 0
* @from: Start the search from this irq number
* @cnt: Number of consecutive irqs to allocate.
* @node: Preferred node on which the irq descriptor should be allocated
* @owner: Owning module (can be NULL)
*
* Returns the first irq number or error code
*/
int __ref
__irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node,
struct module *owner)
{
int start, ret;
if (!cnt)
return -EINVAL;
if (irq >= 0) {
if (from > irq)
return -EINVAL;
from = irq;
} else {
/*
* For interrupts which are freely allocated the
* architecture can force a lower bound to the @from
* argument. x86 uses this to exclude the GSI space.
*/
from = arch_dynirq_lower_bound(from);
}
mutex_lock(&sparse_irq_lock);
start = bitmap_find_next_zero_area(allocated_irqs, IRQ_BITMAP_BITS,
from, cnt, 0);
ret = -EEXIST;
if (irq >=0 && start != irq)
goto err;
if (start + cnt > nr_irqs) {
ret = irq_expand_nr_irqs(start + cnt);
if (ret)
goto err;
}
bitmap_set(allocated_irqs, start, cnt);
mutex_unlock(&sparse_irq_lock);
return alloc_descs(start, cnt, node, owner);
err:
mutex_unlock(&sparse_irq_lock);
return ret;
}
EXPORT_SYMBOL_GPL(__irq_alloc_descs);
#ifdef CONFIG_GENERIC_IRQ_LEGACY_ALLOC_HWIRQ
/**
* irq_alloc_hwirqs - Allocate an irq descriptor and initialize the hardware
* @cnt: number of interrupts to allocate
* @node: node on which to allocate
*
* Returns an interrupt number > 0 or 0, if the allocation fails.
*/
unsigned int irq_alloc_hwirqs(int cnt, int node)
{
int i, irq = __irq_alloc_descs(-1, 0, cnt, node, NULL);
if (irq < 0)
return 0;
for (i = irq; cnt > 0; i++, cnt--) {
if (arch_setup_hwirq(i, node))
goto err;
irq_clear_status_flags(i, _IRQ_NOREQUEST);
}
return irq;
err:
for (i--; i >= irq; i--) {
irq_set_status_flags(i, _IRQ_NOREQUEST | _IRQ_NOPROBE);
arch_teardown_hwirq(i);
}
irq_free_descs(irq, cnt);
return 0;
}
EXPORT_SYMBOL_GPL(irq_alloc_hwirqs);
/**
* irq_free_hwirqs - Free irq descriptor and cleanup the hardware
* @from: Free from irq number
* @cnt: number of interrupts to free
*
*/
void irq_free_hwirqs(unsigned int from, int cnt)
{
int i, j;
for (i = from, j = cnt; j > 0; i++, j--) {
irq_set_status_flags(i, _IRQ_NOREQUEST | _IRQ_NOPROBE);
arch_teardown_hwirq(i);
}
irq_free_descs(from, cnt);
}
EXPORT_SYMBOL_GPL(irq_free_hwirqs);
#endif
/**
* irq_get_next_irq - get next allocated irq number
* @offset: where to start the search
*
* Returns next irq number after offset or nr_irqs if none is found.
*/
unsigned int irq_get_next_irq(unsigned int offset)
{
return find_next_bit(allocated_irqs, nr_irqs, offset);
}
struct irq_desc *
__irq_get_desc_lock(unsigned int irq, unsigned long *flags, bool bus,
unsigned int check)
{
struct irq_desc *desc = irq_to_desc(irq);
if (desc) {
if (check & _IRQ_DESC_CHECK) {
if ((check & _IRQ_DESC_PERCPU) &&
!irq_settings_is_per_cpu_devid(desc))
return NULL;
if (!(check & _IRQ_DESC_PERCPU) &&
irq_settings_is_per_cpu_devid(desc))
return NULL;
}
if (bus)
chip_bus_lock(desc);
raw_spin_lock_irqsave(&desc->lock, *flags);
}
return desc;
}
void __irq_put_desc_unlock(struct irq_desc *desc, unsigned long flags, bool bus)
{
raw_spin_unlock_irqrestore(&desc->lock, flags);
if (bus)
chip_bus_sync_unlock(desc);
}
int irq_set_percpu_devid(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
if (!desc)
return -EINVAL;
if (desc->percpu_enabled)
return -EINVAL;
desc->percpu_enabled = kzalloc(sizeof(*desc->percpu_enabled), GFP_KERNEL);
if (!desc->percpu_enabled)
return -ENOMEM;
irq_set_percpu_devid_flags(irq);
return 0;
}
void kstat_incr_irq_this_cpu(unsigned int irq)
{
kstat_incr_irqs_this_cpu(irq_to_desc(irq));
}
/**
* kstat_irqs_cpu - Get the statistics for an interrupt on a cpu
* @irq: The interrupt number
* @cpu: The cpu number
*
* Returns the sum of interrupt counts on @cpu since boot for
* @irq. The caller must ensure that the interrupt is not removed
* concurrently.
*/
unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
{
struct irq_desc *desc = irq_to_desc(irq);
return desc && desc->kstat_irqs ?
*per_cpu_ptr(desc->kstat_irqs, cpu) : 0;
}
/**
* kstat_irqs - Get the statistics for an interrupt
* @irq: The interrupt number
*
* Returns the sum of interrupt counts on all cpus since boot for
* @irq. The caller must ensure that the interrupt is not removed
* concurrently.
*/
unsigned int kstat_irqs(unsigned int irq)
{
struct irq_desc *desc = irq_to_desc(irq);
int cpu;
unsigned int sum = 0;
if (!desc || !desc->kstat_irqs)
return 0;
for_each_possible_cpu(cpu)
sum += *per_cpu_ptr(desc->kstat_irqs, cpu);
return sum;
}
/**
* kstat_irqs_usr - Get the statistics for an interrupt
* @irq: The interrupt number
*
* Returns the sum of interrupt counts on all cpus since boot for
* @irq. Contrary to kstat_irqs() this can be called from any
* preemptible context. It's protected against concurrent removal of
* an interrupt descriptor when sparse irqs are enabled.
*/
unsigned int kstat_irqs_usr(unsigned int irq)
{
unsigned int sum;
irq_lock_sparse();
sum = kstat_irqs(irq);
irq_unlock_sparse();
return sum;
}