forked from luck/tmp_suning_uos_patched
6a34367e52
When a new timer instance is created and assigned to the active link in snd_timer_open(), the caller still doesn't (can't) set its callback and callback data. In both the user-timer and the sequencer-timer code, they do manually set up the callbacks after calling snd_timer_open(). This has a potential risk of race when the timer instance is added to the already running timer target, as the callback might get triggered during setting up the callback itself. This patch tries to address it by changing the API usage slightly: - An empty timer instance is created at first via the new function snd_timer_instance_new(). This object isn't linked to the timer list yet. - The caller sets up the callbacks and others stuff for the new timer instance. - The caller invokes snd_timer_open() with this instance, so that it's linked to the target timer. For closing, do similarly: - Call snd_timer_close(). This unlinks the timer instance from the timer list. - Free the timer instance via snd_timer_instance_free() after that. Signed-off-by: Takashi Iwai <tiwai@suse.de> Link: https://lore.kernel.org/r/20191107192008.32331-4-tiwai@suse.de Signed-off-by: Takashi Iwai <tiwai@suse.de>
134 lines
5.0 KiB
C
134 lines
5.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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#ifndef __SOUND_TIMER_H
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#define __SOUND_TIMER_H
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/*
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* Timer abstract layer
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* Copyright (c) by Jaroslav Kysela <perex@perex.cz>,
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* Abramo Bagnara <abramo@alsa-project.org>
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*/
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#include <sound/asound.h>
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#include <linux/interrupt.h>
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#define snd_timer_chip(timer) ((timer)->private_data)
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#define SNDRV_TIMER_DEVICES 16
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#define SNDRV_TIMER_DEV_FLG_PCM 0x10000000
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#define SNDRV_TIMER_HW_AUTO 0x00000001 /* auto trigger is supported */
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#define SNDRV_TIMER_HW_STOP 0x00000002 /* call stop before start */
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#define SNDRV_TIMER_HW_SLAVE 0x00000004 /* only slave timer (variable resolution) */
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#define SNDRV_TIMER_HW_FIRST 0x00000008 /* first tick can be incomplete */
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#define SNDRV_TIMER_HW_TASKLET 0x00000010 /* timer is called from tasklet */
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#define SNDRV_TIMER_IFLG_SLAVE 0x00000001
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#define SNDRV_TIMER_IFLG_RUNNING 0x00000002
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#define SNDRV_TIMER_IFLG_START 0x00000004
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#define SNDRV_TIMER_IFLG_AUTO 0x00000008 /* auto restart */
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#define SNDRV_TIMER_IFLG_FAST 0x00000010 /* fast callback (do not use tasklet) */
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#define SNDRV_TIMER_IFLG_CALLBACK 0x00000020 /* timer callback is active */
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#define SNDRV_TIMER_IFLG_EXCLUSIVE 0x00000040 /* exclusive owner - no more instances */
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#define SNDRV_TIMER_IFLG_EARLY_EVENT 0x00000080 /* write early event to the poll queue */
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#define SNDRV_TIMER_FLG_CHANGE 0x00000001
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#define SNDRV_TIMER_FLG_RESCHED 0x00000002 /* need reschedule */
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struct snd_timer;
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struct snd_timer_hardware {
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/* -- must be filled with low-level driver */
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unsigned int flags; /* various flags */
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unsigned long resolution; /* average timer resolution for one tick in nsec */
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unsigned long resolution_min; /* minimal resolution */
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unsigned long resolution_max; /* maximal resolution */
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unsigned long ticks; /* max timer ticks per interrupt */
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/* -- low-level functions -- */
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int (*open) (struct snd_timer * timer);
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int (*close) (struct snd_timer * timer);
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unsigned long (*c_resolution) (struct snd_timer * timer);
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int (*start) (struct snd_timer * timer);
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int (*stop) (struct snd_timer * timer);
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int (*set_period) (struct snd_timer * timer, unsigned long period_num, unsigned long period_den);
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int (*precise_resolution) (struct snd_timer * timer, unsigned long *num, unsigned long *den);
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};
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struct snd_timer {
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int tmr_class;
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struct snd_card *card;
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struct module *module;
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int tmr_device;
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int tmr_subdevice;
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char id[64];
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char name[80];
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unsigned int flags;
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int running; /* running instances */
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unsigned long sticks; /* schedule ticks */
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void *private_data;
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void (*private_free) (struct snd_timer *timer);
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struct snd_timer_hardware hw;
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spinlock_t lock;
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struct list_head device_list;
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struct list_head open_list_head;
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struct list_head active_list_head;
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struct list_head ack_list_head;
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struct list_head sack_list_head; /* slow ack list head */
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struct tasklet_struct task_queue;
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int max_instances; /* upper limit of timer instances */
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int num_instances; /* current number of timer instances */
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};
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struct snd_timer_instance {
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struct snd_timer *timer;
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char *owner;
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unsigned int flags;
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void *private_data;
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void (*private_free) (struct snd_timer_instance *ti);
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void (*callback) (struct snd_timer_instance *timeri,
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unsigned long ticks, unsigned long resolution);
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void (*ccallback) (struct snd_timer_instance * timeri,
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int event,
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struct timespec * tstamp,
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unsigned long resolution);
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void (*disconnect)(struct snd_timer_instance *timeri);
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void *callback_data;
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unsigned long ticks; /* auto-load ticks when expired */
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unsigned long cticks; /* current ticks */
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unsigned long pticks; /* accumulated ticks for callback */
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unsigned long resolution; /* current resolution for tasklet */
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unsigned long lost; /* lost ticks */
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int slave_class;
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unsigned int slave_id;
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struct list_head open_list;
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struct list_head active_list;
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struct list_head ack_list;
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struct list_head slave_list_head;
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struct list_head slave_active_head;
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struct snd_timer_instance *master;
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};
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/*
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* Registering
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*/
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int snd_timer_new(struct snd_card *card, char *id, struct snd_timer_id *tid, struct snd_timer **rtimer);
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void snd_timer_notify(struct snd_timer *timer, int event, struct timespec *tstamp);
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int snd_timer_global_new(char *id, int device, struct snd_timer **rtimer);
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int snd_timer_global_free(struct snd_timer *timer);
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int snd_timer_global_register(struct snd_timer *timer);
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struct snd_timer_instance *snd_timer_instance_new(const char *owner);
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void snd_timer_instance_free(struct snd_timer_instance *timeri);
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int snd_timer_open(struct snd_timer_instance *timeri, struct snd_timer_id *tid, unsigned int slave_id);
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void snd_timer_close(struct snd_timer_instance *timeri);
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unsigned long snd_timer_resolution(struct snd_timer_instance *timeri);
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int snd_timer_start(struct snd_timer_instance *timeri, unsigned int ticks);
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int snd_timer_stop(struct snd_timer_instance *timeri);
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int snd_timer_continue(struct snd_timer_instance *timeri);
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int snd_timer_pause(struct snd_timer_instance *timeri);
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void snd_timer_interrupt(struct snd_timer *timer, unsigned long ticks_left);
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#endif /* __SOUND_TIMER_H */
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