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| 1 | +// SPDX-License-Identifier: GPL-2.0-or-later |
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1 | 2 | /* |
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2 | 3 | * Misc and compatibility things |
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3 | 4 | * Copyright (c) by Jaroslav Kysela <perex@perex.cz> |
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4 | | - * |
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5 | | - * |
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6 | | - * This program is free software; you can redistribute it and/or modify |
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7 | | - * it under the terms of the GNU General Public License as published by |
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8 | | - * the Free Software Foundation; either version 2 of the License, or |
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9 | | - * (at your option) any later version. |
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10 | | - * |
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11 | | - * This program is distributed in the hope that it will be useful, |
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12 | | - * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 | | - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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14 | | - * GNU General Public License for more details. |
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15 | | - * |
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16 | | - * You should have received a copy of the GNU General Public License |
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17 | | - * along with this program; if not, write to the Free Software |
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18 | | - * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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19 | | - * |
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20 | 5 | */ |
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21 | 6 | |
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22 | 7 | #include <linux/init.h> |
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.. | .. |
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25 | 10 | #include <linux/time.h> |
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26 | 11 | #include <linux/slab.h> |
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27 | 12 | #include <linux/ioport.h> |
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| 13 | +#include <linux/fs.h> |
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28 | 14 | #include <sound/core.h> |
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29 | 15 | |
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30 | 16 | #ifdef CONFIG_SND_DEBUG |
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.. | .. |
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160 | 146 | } |
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161 | 147 | EXPORT_SYMBOL(snd_pci_quirk_lookup); |
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162 | 148 | #endif |
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| 149 | + |
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| 150 | +/* |
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| 151 | + * Deferred async signal helpers |
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| 152 | + * |
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| 153 | + * Below are a few helper functions to wrap the async signal handling |
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| 154 | + * in the deferred work. The main purpose is to avoid the messy deadlock |
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| 155 | + * around tasklist_lock and co at the kill_fasync() invocation. |
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| 156 | + * fasync_helper() and kill_fasync() are replaced with snd_fasync_helper() |
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| 157 | + * and snd_kill_fasync(), respectively. In addition, snd_fasync_free() has |
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| 158 | + * to be called at releasing the relevant file object. |
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| 159 | + */ |
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| 160 | +struct snd_fasync { |
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| 161 | + struct fasync_struct *fasync; |
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| 162 | + int signal; |
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| 163 | + int poll; |
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| 164 | + int on; |
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| 165 | + struct list_head list; |
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| 166 | +}; |
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| 167 | + |
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| 168 | +static DEFINE_SPINLOCK(snd_fasync_lock); |
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| 169 | +static LIST_HEAD(snd_fasync_list); |
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| 170 | + |
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| 171 | +static void snd_fasync_work_fn(struct work_struct *work) |
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| 172 | +{ |
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| 173 | + struct snd_fasync *fasync; |
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| 174 | + |
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| 175 | + spin_lock_irq(&snd_fasync_lock); |
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| 176 | + while (!list_empty(&snd_fasync_list)) { |
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| 177 | + fasync = list_first_entry(&snd_fasync_list, struct snd_fasync, list); |
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| 178 | + list_del_init(&fasync->list); |
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| 179 | + spin_unlock_irq(&snd_fasync_lock); |
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| 180 | + if (fasync->on) |
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| 181 | + kill_fasync(&fasync->fasync, fasync->signal, fasync->poll); |
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| 182 | + spin_lock_irq(&snd_fasync_lock); |
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| 183 | + } |
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| 184 | + spin_unlock_irq(&snd_fasync_lock); |
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| 185 | +} |
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| 186 | + |
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| 187 | +static DECLARE_WORK(snd_fasync_work, snd_fasync_work_fn); |
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| 188 | + |
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| 189 | +int snd_fasync_helper(int fd, struct file *file, int on, |
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| 190 | + struct snd_fasync **fasyncp) |
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| 191 | +{ |
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| 192 | + struct snd_fasync *fasync = NULL; |
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| 193 | + |
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| 194 | + if (on) { |
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| 195 | + fasync = kzalloc(sizeof(*fasync), GFP_KERNEL); |
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| 196 | + if (!fasync) |
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| 197 | + return -ENOMEM; |
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| 198 | + INIT_LIST_HEAD(&fasync->list); |
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| 199 | + } |
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| 200 | + |
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| 201 | + spin_lock_irq(&snd_fasync_lock); |
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| 202 | + if (*fasyncp) { |
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| 203 | + kfree(fasync); |
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| 204 | + fasync = *fasyncp; |
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| 205 | + } else { |
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| 206 | + if (!fasync) { |
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| 207 | + spin_unlock_irq(&snd_fasync_lock); |
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| 208 | + return 0; |
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| 209 | + } |
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| 210 | + *fasyncp = fasync; |
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| 211 | + } |
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| 212 | + fasync->on = on; |
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| 213 | + spin_unlock_irq(&snd_fasync_lock); |
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| 214 | + return fasync_helper(fd, file, on, &fasync->fasync); |
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| 215 | +} |
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| 216 | +EXPORT_SYMBOL_GPL(snd_fasync_helper); |
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| 217 | + |
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| 218 | +void snd_kill_fasync(struct snd_fasync *fasync, int signal, int poll) |
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| 219 | +{ |
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| 220 | + unsigned long flags; |
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| 221 | + |
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| 222 | + if (!fasync || !fasync->on) |
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| 223 | + return; |
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| 224 | + spin_lock_irqsave(&snd_fasync_lock, flags); |
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| 225 | + fasync->signal = signal; |
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| 226 | + fasync->poll = poll; |
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| 227 | + list_move(&fasync->list, &snd_fasync_list); |
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| 228 | + schedule_work(&snd_fasync_work); |
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| 229 | + spin_unlock_irqrestore(&snd_fasync_lock, flags); |
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| 230 | +} |
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| 231 | +EXPORT_SYMBOL_GPL(snd_kill_fasync); |
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| 232 | + |
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| 233 | +void snd_fasync_free(struct snd_fasync *fasync) |
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| 234 | +{ |
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| 235 | + if (!fasync) |
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| 236 | + return; |
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| 237 | + fasync->on = 0; |
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| 238 | + flush_work(&snd_fasync_work); |
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| 239 | + kfree(fasync); |
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| 240 | +} |
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| 241 | +EXPORT_SYMBOL_GPL(snd_fasync_free); |
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