kernel/irq/proc.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
  *
  * This file contains the /proc/irq/ handling code.
  */

 #include <linux/irq.h>
 #include <linux/gfp.h>
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 #include <linux/interrupt.h>
 #include <linux/kernel_stat.h>
 #include <linux/mutex.h>

 #include "internals.h"

 /*
  * Access rules:
  *
  * procfs protects read/write of /proc/irq/N/ files against a
  * concurrent free of the interrupt descriptor. remove_proc_entry()
  * immediately prevents new read/writes to happen and waits for
  * already running read/write functions to complete.
  *
  * We remove the proc entries first and then delete the interrupt
  * descriptor from the radix tree and free it. So it is guaranteed
  * that irq_to_desc(N) is valid as long as the read/writes are
  * permitted by procfs.
  *
  * The read from /proc/interrupts is a different problem because there
  * is no protection. So the lookup and the access to irqdesc
  * information must be protected by sparse_irq_lock.
  */
 static struct proc_dir_entry *root_irq_dir;

 #ifdef CONFIG_SMP

 enum {
 	AFFINITY,
 	AFFINITY_LIST,
 	EFFECTIVE,
 	EFFECTIVE_LIST,
 };

 static int show_irq_affinity(int type, struct seq_file *m)
 {
 	struct irq_desc *desc = irq_to_desc((long)m->private);
 	const struct cpumask *mask;

 	switch (type) {
 	case AFFINITY:
 	case AFFINITY_LIST:
 		mask = desc->irq_common_data.affinity;
 #ifdef CONFIG_GENERIC_PENDING_IRQ
 		if (irqd_is_setaffinity_pending(&desc->irq_data))
 			mask = desc->pending_mask;
 #endif
 		break;
 	case EFFECTIVE:
 	case EFFECTIVE_LIST:
 #ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
 		mask = irq_data_get_effective_affinity_mask(&desc->irq_data);
 		break;
 #endif
 	default:
 		return -EINVAL;
 	}

 	switch (type) {
 	case AFFINITY_LIST:
 	case EFFECTIVE_LIST:
 		seq_printf(m, "%*pbl\n", cpumask_pr_args(mask));
 		break;
 	case AFFINITY:
 	case EFFECTIVE:
 		seq_printf(m, "%*pb\n", cpumask_pr_args(mask));
 		break;
 	}
 	return 0;
 }

 static int irq_affinity_hint_proc_show(struct seq_file *m, void *v)
 {
 	struct irq_desc *desc = irq_to_desc((long)m->private);
 	unsigned long flags;
 	cpumask_var_t mask;

 	if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
 		return -ENOMEM;

 	raw_spin_lock_irqsave(&desc->lock, flags);
 	if (desc->affinity_hint)
 		cpumask_copy(mask, desc->affinity_hint);
 	raw_spin_unlock_irqrestore(&desc->lock, flags);

 	seq_printf(m, "%*pb\n", cpumask_pr_args(mask));
 	free_cpumask_var(mask);

 	return 0;
 }

 int no_irq_affinity;
 static int irq_affinity_proc_show(struct seq_file *m, void *v)
 {
 	return show_irq_affinity(AFFINITY, m);
 }

 static int irq_affinity_list_proc_show(struct seq_file *m, void *v)
 {
 	return show_irq_affinity(AFFINITY_LIST, m);
 }

 #ifndef CONFIG_AUTO_IRQ_AFFINITY
 static inline int irq_select_affinity_usr(unsigned int irq)
 {
 	/*
 	 * If the interrupt is started up already then this fails. The
 	 * interrupt is assigned to an online CPU already. There is no
 	 * point to move it around randomly. Tell user space that the
 	 * selected mask is bogus.
 	 *
 	 * If not then any change to the affinity is pointless because the
 	 * startup code invokes irq_setup_affinity() which will select
 	 * a online CPU anyway.
 	 */
 	return -EINVAL;
 }
 #else
 /* ALPHA magic affinity auto selector. Keep it for historical reasons. */
 static inline int irq_select_affinity_usr(unsigned int irq)
 {
 	return irq_select_affinity(irq);
 }
 #endif

 static ssize_t write_irq_affinity(int type, struct file *file,
 		const char __user *buffer, size_t count, loff_t *pos)
 {
 	unsigned int irq = (int)(long)PDE_DATA(file_inode(file));
 	cpumask_var_t new_value;
 	int err;

 	if (!irq_can_set_affinity_usr(irq) || no_irq_affinity)
 		return -EIO;

 	if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
 		return -ENOMEM;

 	if (type)
 		err = cpumask_parselist_user(buffer, count, new_value);
 	else
 		err = cpumask_parse_user(buffer, count, new_value);
 	if (err)
 		goto free_cpumask;

 	/*
 	 * Do not allow disabling IRQs completely - it's a too easy
 	 * way to make the system unusable accidentally :-) At least
 	 * one online CPU still has to be targeted.
 	 */
 	if (!cpumask_intersects(new_value, cpu_online_mask)) {
 		/*
 		 * Special case for empty set - allow the architecture code
 		 * to set default SMP affinity.
 		 */
 		err = irq_select_affinity_usr(irq) ? -EINVAL : count;
 	} else {
 		err = irq_set_affinity(irq, new_value);
 		if (!err)
 			err = count;
 	}

 free_cpumask:
 	free_cpumask_var(new_value);
 	return err;
 }

 static ssize_t irq_affinity_proc_write(struct file *file,
 		const char __user *buffer, size_t count, loff_t *pos)
 {
 	return write_irq_affinity(0, file, buffer, count, pos);
 }

 static ssize_t irq_affinity_list_proc_write(struct file *file,
 		const char __user *buffer, size_t count, loff_t *pos)
 {
 	return write_irq_affinity(1, file, buffer, count, pos);
 }

 static int irq_affinity_proc_open(struct inode *inode, struct file *file)
 {
 	return single_open(file, irq_affinity_proc_show, PDE_DATA(inode));
 }

 static int irq_affinity_list_proc_open(struct inode *inode, struct file *file)
 {
 	return single_open(file, irq_affinity_list_proc_show, PDE_DATA(inode));
 }

 static const struct proc_ops irq_affinity_proc_ops = {
 	.proc_open	= irq_affinity_proc_open,
 	.proc_read	= seq_read,
 	.proc_lseek	= seq_lseek,
 	.proc_release	= single_release,
 	.proc_write	= irq_affinity_proc_write,
 };

 static const struct proc_ops irq_affinity_list_proc_ops = {
 	.proc_open	= irq_affinity_list_proc_open,
 	.proc_read	= seq_read,
 	.proc_lseek	= seq_lseek,
 	.proc_release	= single_release,
 	.proc_write	= irq_affinity_list_proc_write,
 };

 #ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
 static int irq_effective_aff_proc_show(struct seq_file *m, void *v)
 {
 	return show_irq_affinity(EFFECTIVE, m);
 }

 static int irq_effective_aff_list_proc_show(struct seq_file *m, void *v)
 {
 	return show_irq_affinity(EFFECTIVE_LIST, m);
 }
 #endif

 static int default_affinity_show(struct seq_file *m, void *v)
 {
 	seq_printf(m, "%*pb\n", cpumask_pr_args(irq_default_affinity));
 	return 0;
 }

 static ssize_t default_affinity_write(struct file *file,
 		const char __user *buffer, size_t count, loff_t *ppos)
 {
 	cpumask_var_t new_value;
 	int err;

 	if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
 		return -ENOMEM;

 	err = cpumask_parse_user(buffer, count, new_value);
 	if (err)
 		goto out;

 	/*
 	 * Do not allow disabling IRQs completely - it's a too easy
 	 * way to make the system unusable accidentally :-) At least
 	 * one online CPU still has to be targeted.
 	 */
 	if (!cpumask_intersects(new_value, cpu_online_mask)) {
 		err = -EINVAL;
 		goto out;
 	}

 	cpumask_copy(irq_default_affinity, new_value);
 	err = count;

 out:
 	free_cpumask_var(new_value);
 	return err;
 }

 static int default_affinity_open(struct inode *inode, struct file *file)
 {
 	return single_open(file, default_affinity_show, PDE_DATA(inode));
 }

 static const struct proc_ops default_affinity_proc_ops = {
 	.proc_open	= default_affinity_open,
 	.proc_read	= seq_read,
 	.proc_lseek	= seq_lseek,
 	.proc_release	= single_release,
 	.proc_write	= default_affinity_write,
 };

 static int irq_node_proc_show(struct seq_file *m, void *v)
 {
 	struct irq_desc *desc = irq_to_desc((long) m->private);

 	seq_printf(m, "%d\n", irq_desc_get_node(desc));
 	return 0;
 }
 #endif

 static int irq_spurious_proc_show(struct seq_file *m, void *v)
 {
 	struct irq_desc *desc = irq_to_desc((long) m->private);

 	seq_printf(m, "count %u\n" "unhandled %u\n" "last_unhandled %u ms\n",
 		   desc->irq_count, desc->irqs_unhandled,
 		   jiffies_to_msecs(desc->last_unhandled));
 	return 0;
 }

 #define MAX_NAMELEN 128

 static int name_unique(unsigned int irq, struct irqaction *new_action)
 {
 	struct irq_desc *desc = irq_to_desc(irq);
 	struct irqaction *action;
 	unsigned long flags;
 	int ret = 1;

 	raw_spin_lock_irqsave(&desc->lock, flags);
 	for_each_action_of_desc(desc, action) {
 		if ((action != new_action) && action->name &&
 				!strcmp(new_action->name, action->name)) {
 			ret = 0;
 			break;
 		}
 	}
 	raw_spin_unlock_irqrestore(&desc->lock, flags);
 	return ret;
 }

 void register_handler_proc(unsigned int irq, struct irqaction *action)
 {
 	char name [MAX_NAMELEN];
 	struct irq_desc *desc = irq_to_desc(irq);

 	if (!desc->dir || action->dir || !action->name ||
 					!name_unique(irq, action))
 		return;

 	snprintf(name, MAX_NAMELEN, "%s", action->name);

 	/* create /proc/irq/1234/handler/ */
 	action->dir = proc_mkdir(name, desc->dir);
 }

 #undef MAX_NAMELEN

 #define MAX_NAMELEN 10

 void register_irq_proc(unsigned int irq, struct irq_desc *desc)
 {
 	static DEFINE_MUTEX(register_lock);
 	void __maybe_unused *irqp = (void *)(unsigned long) irq;
 	char name [MAX_NAMELEN];

 	if (!root_irq_dir || (desc->irq_data.chip == &no_irq_chip))
 		return;

 	/*
 	 * irq directories are registered only when a handler is
 	 * added, not when the descriptor is created, so multiple
 	 * tasks might try to register at the same time.
 	 */
 	mutex_lock(&register_lock);

 	if (desc->dir)
 		goto out_unlock;

 	sprintf(name, "%d", irq);

 	/* create /proc/irq/1234 */
 	desc->dir = proc_mkdir(name, root_irq_dir);
 	if (!desc->dir)
 		goto out_unlock;

 #ifdef CONFIG_SMP
 	/* create /proc/irq/<irq>/smp_affinity */
 	proc_create_data("smp_affinity", 0644, desc->dir,
 			 &irq_affinity_proc_ops, irqp);

 	/* create /proc/irq/<irq>/affinity_hint */
 	proc_create_single_data("affinity_hint", 0444, desc->dir,
 			irq_affinity_hint_proc_show, irqp);

 	/* create /proc/irq/<irq>/smp_affinity_list */
 	proc_create_data("smp_affinity_list", 0644, desc->dir,
 			 &irq_affinity_list_proc_ops, irqp);

 	proc_create_single_data("node", 0444, desc->dir, irq_node_proc_show,
 			irqp);
 # ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
 	proc_create_single_data("effective_affinity", 0444, desc->dir,
 			irq_effective_aff_proc_show, irqp);
 	proc_create_single_data("effective_affinity_list", 0444, desc->dir,
 			irq_effective_aff_list_proc_show, irqp);
 # endif
 #endif
 	proc_create_single_data("spurious", 0444, desc->dir,
 			irq_spurious_proc_show, (void *)(long)irq);

 out_unlock:
 	mutex_unlock(&register_lock);
 }

 void unregister_irq_proc(unsigned int irq, struct irq_desc *desc)
 {
 	char name [MAX_NAMELEN];

 	if (!root_irq_dir || !desc->dir)
 		return;
 #ifdef CONFIG_SMP
 	remove_proc_entry("smp_affinity", desc->dir);
 	remove_proc_entry("affinity_hint", desc->dir);
 	remove_proc_entry("smp_affinity_list", desc->dir);
 	remove_proc_entry("node", desc->dir);
 # ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
 	remove_proc_entry("effective_affinity", desc->dir);
 	remove_proc_entry("effective_affinity_list", desc->dir);
 # endif
 #endif
 	remove_proc_entry("spurious", desc->dir);

 	sprintf(name, "%u", irq);
 	remove_proc_entry(name, root_irq_dir);
 }

 #undef MAX_NAMELEN

 void unregister_handler_proc(unsigned int irq, struct irqaction *action)
 {
 	proc_remove(action->dir);
 }

 static void register_default_affinity_proc(void)
 {
 #ifdef CONFIG_SMP
 	proc_create("irq/default_smp_affinity", 0644, NULL,
 		    &default_affinity_proc_ops);
 #endif
 }

 void init_irq_proc(void)
 {
 	unsigned int irq;
 	struct irq_desc *desc;

 	/* create /proc/irq */
 	root_irq_dir = proc_mkdir("irq", NULL);
 	if (!root_irq_dir)
 		return;

 	register_default_affinity_proc();

 	/*
 	 * Create entries for all existing IRQs.
 	 */
 	for_each_irq_desc(irq, desc)
 		register_irq_proc(irq, desc);
 }

 #ifdef CONFIG_GENERIC_IRQ_SHOW

 int __weak arch_show_interrupts(struct seq_file *p, int prec)
 {
 	return 0;
 }

 #ifndef ACTUAL_NR_IRQS
 # define ACTUAL_NR_IRQS nr_irqs
 #endif

 int show_interrupts(struct seq_file *p, void *v)
 {
 	static int prec;

 	unsigned long flags, any_count = 0;
 	int i = *(loff_t *) v, j;
 	struct irqaction *action;
 	struct irq_desc *desc;

 	if (i > ACTUAL_NR_IRQS)
 		return 0;

 	if (i == ACTUAL_NR_IRQS)
 		return arch_show_interrupts(p, prec);

 	/* print header and calculate the width of the first column */
 	if (i == 0) {
 		for (prec = 3, j = 1000; prec < 10 && j <= nr_irqs; ++prec)
 			j *= 10;

 		seq_printf(p, "%*s", prec + 8, "");
 		for_each_online_cpu(j)
 			seq_printf(p, "CPU%-8d", j);
 		seq_putc(p, '\n');
 	}

 	rcu_read_lock();
 	desc = irq_to_desc(i);
 	if (!desc || irq_settings_is_hidden(desc))
 		goto outsparse;

 	if (desc->kstat_irqs) {
 		for_each_online_cpu(j)
 			any_count |= data_race(*per_cpu_ptr(desc->kstat_irqs, j));
 	}

 	if ((!desc->action || irq_desc_is_chained(desc)) && !any_count)
 		goto outsparse;

 	seq_printf(p, "%*d: ", prec, i);
 	for_each_online_cpu(j)
 		seq_printf(p, "%10u ", desc->kstat_irqs ?
 					*per_cpu_ptr(desc->kstat_irqs, j) : 0);

 	raw_spin_lock_irqsave(&desc->lock, flags);
 	if (desc->irq_data.chip) {
 		if (desc->irq_data.chip->irq_print_chip)
 			desc->irq_data.chip->irq_print_chip(&desc->irq_data, p);
 		else if (desc->irq_data.chip->name)
 			seq_printf(p, " %8s", desc->irq_data.chip->name);
 		else
 			seq_printf(p, " %8s", "-");
 	} else {
 		seq_printf(p, " %8s", "None");
 	}
 	if (desc->irq_data.domain)
 		seq_printf(p, " %*d", prec, (int) desc->irq_data.hwirq);
 	else
 		seq_printf(p, " %*s", prec, "");
 #ifdef CONFIG_GENERIC_IRQ_SHOW_LEVEL
 	seq_printf(p, " %-8s", irqd_is_level_type(&desc->irq_data) ? "Level" : "Edge");
 #endif
 	if (desc->name)
 		seq_printf(p, "-%-8s", desc->name);

 	action = desc->action;
 	if (action) {
 		seq_printf(p, "  %s", action->name);
 		while ((action = action->next) != NULL)
 			seq_printf(p, ", %s", action->name);
 	}

 	seq_putc(p, '\n');
 	raw_spin_unlock_irqrestore(&desc->lock, flags);
 outsparse:
 	rcu_read_unlock();
 	return 0;
 }
 #endif
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
	*
	* This file contains the /proc/irq/ handling code.
	*/

	#include <linux/irq.h>
	#include <linux/gfp.h>
	#include <linux/proc_fs.h>
	#include <linux/seq_file.h>
	#include <linux/interrupt.h>
	#include <linux/kernel_stat.h>
	#include <linux/mutex.h>

	#include "internals.h"

	/*
	* Access rules:
	*
	* procfs protects read/write of /proc/irq/N/ files against a
	* concurrent free of the interrupt descriptor. remove_proc_entry()
	* immediately prevents new read/writes to happen and waits for
	* already running read/write functions to complete.
	*
	* We remove the proc entries first and then delete the interrupt
	* descriptor from the radix tree and free it. So it is guaranteed
	* that irq_to_desc(N) is valid as long as the read/writes are
	* permitted by procfs.
	*
	* The read from /proc/interrupts is a different problem because there
	* is no protection. So the lookup and the access to irqdesc
	* information must be protected by sparse_irq_lock.
	*/
	static struct proc_dir_entry *root_irq_dir;

	#ifdef CONFIG_SMP

	enum {
	AFFINITY,
	AFFINITY_LIST,
	EFFECTIVE,
	EFFECTIVE_LIST,
	};

	static int show_irq_affinity(int type, struct seq_file *m)
	{
	struct irq_desc *desc = irq_to_desc((long)m->private);
	const struct cpumask *mask;

	switch (type) {
	case AFFINITY:
	case AFFINITY_LIST:
	mask = desc->irq_common_data.affinity;
	#ifdef CONFIG_GENERIC_PENDING_IRQ
	if (irqd_is_setaffinity_pending(&desc->irq_data))
	mask = desc->pending_mask;
	#endif
	break;
	case EFFECTIVE:
	case EFFECTIVE_LIST:
	#ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
	mask = irq_data_get_effective_affinity_mask(&desc->irq_data);
	break;
	#endif
	default:
	return -EINVAL;
	}

	switch (type) {
	case AFFINITY_LIST:
	case EFFECTIVE_LIST:
	seq_printf(m, "%*pbl\n", cpumask_pr_args(mask));
	break;
	case AFFINITY:
	case EFFECTIVE:
	seq_printf(m, "%*pb\n", cpumask_pr_args(mask));
	break;
	}
	return 0;
	}

	static int irq_affinity_hint_proc_show(struct seq_file m, void v)
	{
	struct irq_desc *desc = irq_to_desc((long)m->private);
	unsigned long flags;
	cpumask_var_t mask;

	if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
	return -ENOMEM;

	raw_spin_lock_irqsave(&desc->lock, flags);
	if (desc->affinity_hint)
	cpumask_copy(mask, desc->affinity_hint);
	raw_spin_unlock_irqrestore(&desc->lock, flags);

	seq_printf(m, "%*pb\n", cpumask_pr_args(mask));
	free_cpumask_var(mask);

	return 0;
	}

	int no_irq_affinity;
	static int irq_affinity_proc_show(struct seq_file m, void v)
	{
	return show_irq_affinity(AFFINITY, m);
	}

	static int irq_affinity_list_proc_show(struct seq_file m, void v)
	{
	return show_irq_affinity(AFFINITY_LIST, m);
	}

	#ifndef CONFIG_AUTO_IRQ_AFFINITY
	static inline int irq_select_affinity_usr(unsigned int irq)
	{
	/*
	* If the interrupt is started up already then this fails. The
	* interrupt is assigned to an online CPU already. There is no
	* point to move it around randomly. Tell user space that the
	* selected mask is bogus.
	*
	* If not then any change to the affinity is pointless because the
	* startup code invokes irq_setup_affinity() which will select
	* a online CPU anyway.
	*/
	return -EINVAL;
	}
	#else
	/* ALPHA magic affinity auto selector. Keep it for historical reasons. */
	static inline int irq_select_affinity_usr(unsigned int irq)
	{
	return irq_select_affinity(irq);
	}
	#endif

	static ssize_t write_irq_affinity(int type, struct file *file,
	const char __user buffer, size_t count, loff_t pos)
	{
	unsigned int irq = (int)(long)PDE_DATA(file_inode(file));
	cpumask_var_t new_value;
	int err;

	if (!irq_can_set_affinity_usr(irq) \|\| no_irq_affinity)
	return -EIO;

	if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
	return -ENOMEM;

	if (type)
	err = cpumask_parselist_user(buffer, count, new_value);
	else
	err = cpumask_parse_user(buffer, count, new_value);
	if (err)
	goto free_cpumask;

	/*
	* Do not allow disabling IRQs completely - it's a too easy
	* way to make the system unusable accidentally :-) At least
	* one online CPU still has to be targeted.
	*/
	if (!cpumask_intersects(new_value, cpu_online_mask)) {
	/*
	* Special case for empty set - allow the architecture code
	* to set default SMP affinity.
	*/
	err = irq_select_affinity_usr(irq) ? -EINVAL : count;
	} else {
	err = irq_set_affinity(irq, new_value);
	if (!err)
	err = count;
	}

	free_cpumask:
	free_cpumask_var(new_value);
	return err;
	}

	static ssize_t irq_affinity_proc_write(struct file *file,
	const char __user buffer, size_t count, loff_t pos)
	{
	return write_irq_affinity(0, file, buffer, count, pos);
	}

	static ssize_t irq_affinity_list_proc_write(struct file *file,
	const char __user buffer, size_t count, loff_t pos)
	{
	return write_irq_affinity(1, file, buffer, count, pos);
	}

	static int irq_affinity_proc_open(struct inode inode, struct file file)
	{
	return single_open(file, irq_affinity_proc_show, PDE_DATA(inode));
	}

	static int irq_affinity_list_proc_open(struct inode inode, struct file file)
	{
	return single_open(file, irq_affinity_list_proc_show, PDE_DATA(inode));
	}

	static const struct proc_ops irq_affinity_proc_ops = {
	.proc_open = irq_affinity_proc_open,
	.proc_read = seq_read,
	.proc_lseek = seq_lseek,
	.proc_release = single_release,
	.proc_write = irq_affinity_proc_write,
	};

	static const struct proc_ops irq_affinity_list_proc_ops = {
	.proc_open = irq_affinity_list_proc_open,
	.proc_read = seq_read,
	.proc_lseek = seq_lseek,
	.proc_release = single_release,
	.proc_write = irq_affinity_list_proc_write,
	};

	#ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
	static int irq_effective_aff_proc_show(struct seq_file m, void v)
	{
	return show_irq_affinity(EFFECTIVE, m);
	}

	static int irq_effective_aff_list_proc_show(struct seq_file m, void v)
	{
	return show_irq_affinity(EFFECTIVE_LIST, m);
	}
	#endif

	static int default_affinity_show(struct seq_file m, void v)
	{
	seq_printf(m, "%*pb\n", cpumask_pr_args(irq_default_affinity));
	return 0;
	}

	static ssize_t default_affinity_write(struct file *file,
	const char __user buffer, size_t count, loff_t ppos)
	{
	cpumask_var_t new_value;
	int err;

	if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
	return -ENOMEM;

	err = cpumask_parse_user(buffer, count, new_value);
	if (err)
	goto out;

	/*
	* Do not allow disabling IRQs completely - it's a too easy
	* way to make the system unusable accidentally :-) At least
	* one online CPU still has to be targeted.
	*/
	if (!cpumask_intersects(new_value, cpu_online_mask)) {
	err = -EINVAL;
	goto out;
	}

	cpumask_copy(irq_default_affinity, new_value);
	err = count;

	out:
	free_cpumask_var(new_value);
	return err;
	}

	static int default_affinity_open(struct inode inode, struct file file)
	{
	return single_open(file, default_affinity_show, PDE_DATA(inode));
	}

	static const struct proc_ops default_affinity_proc_ops = {
	.proc_open = default_affinity_open,
	.proc_read = seq_read,
	.proc_lseek = seq_lseek,
	.proc_release = single_release,
	.proc_write = default_affinity_write,
	};

	static int irq_node_proc_show(struct seq_file m, void v)
	{
	struct irq_desc *desc = irq_to_desc((long) m->private);

	seq_printf(m, "%d\n", irq_desc_get_node(desc));
	return 0;
	}
	#endif

	static int irq_spurious_proc_show(struct seq_file m, void v)
	{
	struct irq_desc *desc = irq_to_desc((long) m->private);

	seq_printf(m, "count %u\n" "unhandled %u\n" "last_unhandled %u ms\n",
	desc->irq_count, desc->irqs_unhandled,
	jiffies_to_msecs(desc->last_unhandled));
	return 0;
	}

	#define MAX_NAMELEN 128

	static int name_unique(unsigned int irq, struct irqaction *new_action)
	{
	struct irq_desc *desc = irq_to_desc(irq);
	struct irqaction *action;
	unsigned long flags;
	int ret = 1;

	raw_spin_lock_irqsave(&desc->lock, flags);
	for_each_action_of_desc(desc, action) {
	if ((action != new_action) && action->name &&
	!strcmp(new_action->name, action->name)) {
	ret = 0;
	break;
	}
	}
	raw_spin_unlock_irqrestore(&desc->lock, flags);
	return ret;
	}

	void register_handler_proc(unsigned int irq, struct irqaction *action)
	{
	char name [MAX_NAMELEN];
	struct irq_desc *desc = irq_to_desc(irq);

	if (!desc->dir \|\| action->dir \|\| !action->name \|\|
	!name_unique(irq, action))
	return;

	snprintf(name, MAX_NAMELEN, "%s", action->name);

	/* create /proc/irq/1234/handler/ */
	action->dir = proc_mkdir(name, desc->dir);
	}

	#undef MAX_NAMELEN

	#define MAX_NAMELEN 10

	void register_irq_proc(unsigned int irq, struct irq_desc *desc)
	{
	static DEFINE_MUTEX(register_lock);
	void __maybe_unused irqp = (void )(unsigned long) irq;
	char name [MAX_NAMELEN];

	if (!root_irq_dir \|\| (desc->irq_data.chip == &no_irq_chip))
	return;

	/*
	* irq directories are registered only when a handler is
	* added, not when the descriptor is created, so multiple
	* tasks might try to register at the same time.
	*/
	mutex_lock(&register_lock);

	if (desc->dir)
	goto out_unlock;

	sprintf(name, "%d", irq);

	/* create /proc/irq/1234 */
	desc->dir = proc_mkdir(name, root_irq_dir);
	if (!desc->dir)
	goto out_unlock;

	#ifdef CONFIG_SMP
	/* create /proc/irq/<irq>/smp_affinity */
	proc_create_data("smp_affinity", 0644, desc->dir,
	&irq_affinity_proc_ops, irqp);

	/* create /proc/irq/<irq>/affinity_hint */
	proc_create_single_data("affinity_hint", 0444, desc->dir,
	irq_affinity_hint_proc_show, irqp);

	/* create /proc/irq/<irq>/smp_affinity_list */
	proc_create_data("smp_affinity_list", 0644, desc->dir,
	&irq_affinity_list_proc_ops, irqp);

	proc_create_single_data("node", 0444, desc->dir, irq_node_proc_show,
	irqp);
	# ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
	proc_create_single_data("effective_affinity", 0444, desc->dir,
	irq_effective_aff_proc_show, irqp);
	proc_create_single_data("effective_affinity_list", 0444, desc->dir,
	irq_effective_aff_list_proc_show, irqp);
	# endif
	#endif
	proc_create_single_data("spurious", 0444, desc->dir,
	irq_spurious_proc_show, (void *)(long)irq);

	out_unlock:
	mutex_unlock(&register_lock);
	}

	void unregister_irq_proc(unsigned int irq, struct irq_desc *desc)
	{
	char name [MAX_NAMELEN];

	if (!root_irq_dir \|\| !desc->dir)
	return;
	#ifdef CONFIG_SMP
	remove_proc_entry("smp_affinity", desc->dir);
	remove_proc_entry("affinity_hint", desc->dir);
	remove_proc_entry("smp_affinity_list", desc->dir);
	remove_proc_entry("node", desc->dir);
	# ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
	remove_proc_entry("effective_affinity", desc->dir);
	remove_proc_entry("effective_affinity_list", desc->dir);
	# endif
	#endif
	remove_proc_entry("spurious", desc->dir);

	sprintf(name, "%u", irq);
	remove_proc_entry(name, root_irq_dir);
	}

	#undef MAX_NAMELEN

	void unregister_handler_proc(unsigned int irq, struct irqaction *action)
	{
	proc_remove(action->dir);
	}

	static void register_default_affinity_proc(void)
	{
	#ifdef CONFIG_SMP
	proc_create("irq/default_smp_affinity", 0644, NULL,
	&default_affinity_proc_ops);
	#endif
	}

	void init_irq_proc(void)
	{
	unsigned int irq;
	struct irq_desc *desc;

	/* create /proc/irq */
	root_irq_dir = proc_mkdir("irq", NULL);
	if (!root_irq_dir)
	return;

	register_default_affinity_proc();

	/*
	* Create entries for all existing IRQs.
	*/
	for_each_irq_desc(irq, desc)
	register_irq_proc(irq, desc);
	}

	#ifdef CONFIG_GENERIC_IRQ_SHOW

	int __weak arch_show_interrupts(struct seq_file *p, int prec)
	{
	return 0;
	}

	#ifndef ACTUAL_NR_IRQS
	# define ACTUAL_NR_IRQS nr_irqs
	#endif

	int show_interrupts(struct seq_file p, void v)
	{
	static int prec;

	unsigned long flags, any_count = 0;
	int i = (loff_t ) v, j;
	struct irqaction *action;
	struct irq_desc *desc;

	if (i > ACTUAL_NR_IRQS)
	return 0;

	if (i == ACTUAL_NR_IRQS)
	return arch_show_interrupts(p, prec);

	/* print header and calculate the width of the first column */
	if (i == 0) {
	for (prec = 3, j = 1000; prec < 10 && j <= nr_irqs; ++prec)
	j *= 10;

	seq_printf(p, "%*s", prec + 8, "");
	for_each_online_cpu(j)
	seq_printf(p, "CPU%-8d", j);
	seq_putc(p, '\n');
	}

	rcu_read_lock();
	desc = irq_to_desc(i);
	if (!desc \|\| irq_settings_is_hidden(desc))
	goto outsparse;

	if (desc->kstat_irqs) {
	for_each_online_cpu(j)
	any_count \|= data_race(*per_cpu_ptr(desc->kstat_irqs, j));
	}

	if ((!desc->action \|\| irq_desc_is_chained(desc)) && !any_count)
	goto outsparse;

	seq_printf(p, "%*d: ", prec, i);
	for_each_online_cpu(j)
	seq_printf(p, "%10u ", desc->kstat_irqs ?
	*per_cpu_ptr(desc->kstat_irqs, j) : 0);

	raw_spin_lock_irqsave(&desc->lock, flags);
	if (desc->irq_data.chip) {
	if (desc->irq_data.chip->irq_print_chip)
	desc->irq_data.chip->irq_print_chip(&desc->irq_data, p);
	else if (desc->irq_data.chip->name)
	seq_printf(p, " %8s", desc->irq_data.chip->name);
	else
	seq_printf(p, " %8s", "-");
	} else {
	seq_printf(p, " %8s", "None");
	}
	if (desc->irq_data.domain)
	seq_printf(p, " %*d", prec, (int) desc->irq_data.hwirq);
	else
	seq_printf(p, " %*s", prec, "");
	#ifdef CONFIG_GENERIC_IRQ_SHOW_LEVEL
	seq_printf(p, " %-8s", irqd_is_level_type(&desc->irq_data) ? "Level" : "Edge");
	#endif
	if (desc->name)
	seq_printf(p, "-%-8s", desc->name);

	action = desc->action;
	if (action) {
	seq_printf(p, " %s", action->name);
	while ((action = action->next) != NULL)
	seq_printf(p, ", %s", action->name);
	}

	seq_putc(p, '\n');
	raw_spin_unlock_irqrestore(&desc->lock, flags);
	outsparse:
	rcu_read_unlock();
	return 0;
	}
	#endif