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snd_seq_check_queue() passes the current tick and time of the given queue as a pointer to snd_seq_prioq_cell_out(), but those might be updated concurrently by the seq timer update. Fix it by retrieving the current tick and time via the proper helper functions at first, and pass those values to snd_seq_prioq_cell_out() later in the loops. snd_seq_timer_get_cur_time() takes a new argument and adjusts with the current system time only when it's requested so; this update isn't needed for snd_seq_check_queue(), as it's called either from the interrupt handler or right after queuing. Also, snd_seq_timer_get_cur_tick() is changed to read the value in the spinlock for the concurrency, too. Reported-by: syzbot+fd5e0eaa1a32999173b2@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/20200214111316.26939-3-tiwai@suse.de Signed-off-by: Takashi Iwai <tiwai@suse.de>
135 lines
4.0 KiB
C
135 lines
4.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* ALSA sequencer Timer
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* Copyright (c) 1998-1999 by Frank van de Pol <fvdpol@coil.demon.nl>
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*/
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#ifndef __SND_SEQ_TIMER_H
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#define __SND_SEQ_TIMER_H
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#include <sound/timer.h>
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#include <sound/seq_kernel.h>
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struct snd_seq_timer_tick {
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snd_seq_tick_time_t cur_tick; /* current tick */
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unsigned long resolution; /* time per tick in nsec */
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unsigned long fraction; /* current time per tick in nsec */
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};
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struct snd_seq_timer {
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/* ... tempo / offset / running state */
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unsigned int running:1, /* running state of queue */
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initialized:1; /* timer is initialized */
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unsigned int tempo; /* current tempo, us/tick */
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int ppq; /* time resolution, ticks/quarter */
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snd_seq_real_time_t cur_time; /* current time */
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struct snd_seq_timer_tick tick; /* current tick */
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int tick_updated;
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int type; /* timer type */
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struct snd_timer_id alsa_id; /* ALSA's timer ID */
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struct snd_timer_instance *timeri; /* timer instance */
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unsigned int ticks;
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unsigned long preferred_resolution; /* timer resolution, ticks/sec */
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unsigned int skew;
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unsigned int skew_base;
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struct timespec64 last_update; /* time of last clock update, used for interpolation */
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spinlock_t lock;
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};
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/* create new timer (constructor) */
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struct snd_seq_timer *snd_seq_timer_new(void);
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/* delete timer (destructor) */
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void snd_seq_timer_delete(struct snd_seq_timer **tmr);
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/* */
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static inline void snd_seq_timer_update_tick(struct snd_seq_timer_tick *tick,
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unsigned long resolution)
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{
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if (tick->resolution > 0) {
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tick->fraction += resolution;
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tick->cur_tick += (unsigned int)(tick->fraction / tick->resolution);
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tick->fraction %= tick->resolution;
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}
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}
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/* compare timestamp between events */
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/* return 1 if a >= b; otherwise return 0 */
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static inline int snd_seq_compare_tick_time(snd_seq_tick_time_t *a, snd_seq_tick_time_t *b)
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{
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/* compare ticks */
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return (*a >= *b);
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}
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static inline int snd_seq_compare_real_time(snd_seq_real_time_t *a, snd_seq_real_time_t *b)
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{
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/* compare real time */
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if (a->tv_sec > b->tv_sec)
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return 1;
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if ((a->tv_sec == b->tv_sec) && (a->tv_nsec >= b->tv_nsec))
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return 1;
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return 0;
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}
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static inline void snd_seq_sanity_real_time(snd_seq_real_time_t *tm)
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{
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while (tm->tv_nsec >= 1000000000) {
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/* roll-over */
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tm->tv_nsec -= 1000000000;
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tm->tv_sec++;
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}
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}
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/* increment timestamp */
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static inline void snd_seq_inc_real_time(snd_seq_real_time_t *tm, snd_seq_real_time_t *inc)
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{
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tm->tv_sec += inc->tv_sec;
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tm->tv_nsec += inc->tv_nsec;
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snd_seq_sanity_real_time(tm);
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}
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static inline void snd_seq_inc_time_nsec(snd_seq_real_time_t *tm, unsigned long nsec)
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{
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tm->tv_nsec += nsec;
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snd_seq_sanity_real_time(tm);
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}
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/* called by timer isr */
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struct snd_seq_queue;
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int snd_seq_timer_open(struct snd_seq_queue *q);
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int snd_seq_timer_close(struct snd_seq_queue *q);
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int snd_seq_timer_midi_open(struct snd_seq_queue *q);
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int snd_seq_timer_midi_close(struct snd_seq_queue *q);
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void snd_seq_timer_defaults(struct snd_seq_timer *tmr);
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void snd_seq_timer_reset(struct snd_seq_timer *tmr);
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int snd_seq_timer_stop(struct snd_seq_timer *tmr);
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int snd_seq_timer_start(struct snd_seq_timer *tmr);
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int snd_seq_timer_continue(struct snd_seq_timer *tmr);
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int snd_seq_timer_set_tempo(struct snd_seq_timer *tmr, int tempo);
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int snd_seq_timer_set_tempo_ppq(struct snd_seq_timer *tmr, int tempo, int ppq);
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int snd_seq_timer_set_position_tick(struct snd_seq_timer *tmr, snd_seq_tick_time_t position);
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int snd_seq_timer_set_position_time(struct snd_seq_timer *tmr, snd_seq_real_time_t position);
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int snd_seq_timer_set_skew(struct snd_seq_timer *tmr, unsigned int skew, unsigned int base);
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snd_seq_real_time_t snd_seq_timer_get_cur_time(struct snd_seq_timer *tmr,
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bool adjust_ktime);
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snd_seq_tick_time_t snd_seq_timer_get_cur_tick(struct snd_seq_timer *tmr);
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extern int seq_default_timer_class;
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extern int seq_default_timer_sclass;
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extern int seq_default_timer_card;
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extern int seq_default_timer_device;
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extern int seq_default_timer_subdevice;
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extern int seq_default_timer_resolution;
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#endif
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