misc.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 *  Misc and compatibility things
  4 *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
  5 */
  6
  7#include <linux/init.h>
  8#include <linux/export.h>
  9#include <linux/moduleparam.h>
 10#include <linux/time.h>
 11#include <linux/slab.h>
 12#include <linux/ioport.h>
 13#include <linux/fs.h>
 14#include <sound/core.h>
 15
 16void release_and_free_resource(struct resource *res)
 17{
 18	if (res) {
 19		release_resource(res);
 20		kfree(res);
 21	}
 22}
 23EXPORT_SYMBOL(release_and_free_resource);
 24
 25#ifdef CONFIG_PCI
 26#include <linux/pci.h>
 27/**
 28 * snd_pci_quirk_lookup_id - look up a PCI SSID quirk list
 29 * @vendor: PCI SSV id
 30 * @device: PCI SSD id
 31 * @list: quirk list, terminated by a null entry
 32 *
 33 * Look through the given quirk list and finds a matching entry
 34 * with the same PCI SSID.  When subdevice is 0, all subdevice
 35 * values may match.
 36 *
 37 * Returns the matched entry pointer, or NULL if nothing matched.
 38 */
 39const struct snd_pci_quirk *
 40snd_pci_quirk_lookup_id(u16 vendor, u16 device,
 41			const struct snd_pci_quirk *list)
 42{
 43	const struct snd_pci_quirk *q;
 44
 45	for (q = list; q->subvendor || q->subdevice; q++) {
 46		if (q->subvendor != vendor)
 47			continue;
 48		if (!q->subdevice ||
 49		    (device & q->subdevice_mask) == q->subdevice)
 50			return q;
 51	}
 52	return NULL;
 53}
 54EXPORT_SYMBOL(snd_pci_quirk_lookup_id);
 55
 56/**
 57 * snd_pci_quirk_lookup - look up a PCI SSID quirk list
 58 * @pci: pci_dev handle
 59 * @list: quirk list, terminated by a null entry
 60 *
 61 * Look through the given quirk list and finds a matching entry
 62 * with the same PCI SSID.  When subdevice is 0, all subdevice
 63 * values may match.
 64 *
 65 * Returns the matched entry pointer, or NULL if nothing matched.
 66 */
 67const struct snd_pci_quirk *
 68snd_pci_quirk_lookup(struct pci_dev *pci, const struct snd_pci_quirk *list)
 69{
 70	if (!pci)
 71		return NULL;
 72	return snd_pci_quirk_lookup_id(pci->subsystem_vendor,
 73				       pci->subsystem_device,
 74				       list);
 75}
 76EXPORT_SYMBOL(snd_pci_quirk_lookup);
 77#endif
 78
 79/*
 80 * Deferred async signal helpers
 81 *
 82 * Below are a few helper functions to wrap the async signal handling
 83 * in the deferred work.  The main purpose is to avoid the messy deadlock
 84 * around tasklist_lock and co at the kill_fasync() invocation.
 85 * fasync_helper() and kill_fasync() are replaced with snd_fasync_helper()
 86 * and snd_kill_fasync(), respectively.  In addition, snd_fasync_free() has
 87 * to be called at releasing the relevant file object.
 88 */
 89struct snd_fasync {
 90	struct fasync_struct *fasync;
 91	int signal;
 92	int poll;
 93	int on;
 94	struct list_head list;
 95};
 96
 97static DEFINE_SPINLOCK(snd_fasync_lock);
 98static LIST_HEAD(snd_fasync_list);
 99
100static void snd_fasync_work_fn(struct work_struct *work)
101{
102	struct snd_fasync *fasync;
103
104	spin_lock_irq(&snd_fasync_lock);
105	while (!list_empty(&snd_fasync_list)) {
106		fasync = list_first_entry(&snd_fasync_list, struct snd_fasync, list);
107		list_del_init(&fasync->list);
108		spin_unlock_irq(&snd_fasync_lock);
109		if (fasync->on)
110			kill_fasync(&fasync->fasync, fasync->signal, fasync->poll);
111		spin_lock_irq(&snd_fasync_lock);
112	}
113	spin_unlock_irq(&snd_fasync_lock);
114}
115
116static DECLARE_WORK(snd_fasync_work, snd_fasync_work_fn);
117
118int snd_fasync_helper(int fd, struct file *file, int on,
119		      struct snd_fasync **fasyncp)
120{
121	struct snd_fasync *fasync = NULL;
122
123	if (on) {
124		fasync = kzalloc(sizeof(*fasync), GFP_KERNEL);
125		if (!fasync)
126			return -ENOMEM;
127		INIT_LIST_HEAD(&fasync->list);
128	}
129
130	scoped_guard(spinlock_irq, &snd_fasync_lock) {
131		if (*fasyncp) {
132			kfree(fasync);
133			fasync = *fasyncp;
134		} else {
135			if (!fasync)
136				return 0;
137			*fasyncp = fasync;
138		}
139		fasync->on = on;
140	}
141	return fasync_helper(fd, file, on, &fasync->fasync);
142}
143EXPORT_SYMBOL_GPL(snd_fasync_helper);
144
145void snd_kill_fasync(struct snd_fasync *fasync, int signal, int poll)
146{
147	if (!fasync || !fasync->on)
148		return;
149	guard(spinlock_irqsave)(&snd_fasync_lock);
150	fasync->signal = signal;
151	fasync->poll = poll;
152	list_move(&fasync->list, &snd_fasync_list);
153	schedule_work(&snd_fasync_work);
154}
155EXPORT_SYMBOL_GPL(snd_kill_fasync);
156
157void snd_fasync_free(struct snd_fasync *fasync)
158{
159	if (!fasync)
160		return;
161	fasync->on = 0;
162	flush_work(&snd_fasync_work);
163	kfree(fasync);
164}
165EXPORT_SYMBOL_GPL(snd_fasync_free);