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authorArnd Bergmann <arnd@arndb.de>2016-06-17 17:10:32 +0200
committerTakashi Iwai <tiwai@suse.de>2016-06-17 22:56:13 +0200
commit3915bf2946520ace5bcc8104717a3cb0452d7430 (patch)
tree031c5d4fa69ee97585d8c0aa8b8ad163b06dee21 /sound/core
parentd169133889090903d9feb968deb9fa01240a58f5 (diff)
ALSA: seq_timer: use monotonic times internally
The sequencer client manager reports timestamps in units of unsigned 32-bit seconds/nanoseconds, but that does not suffer from the y2038 overflow because it stores only the delta since the 'last_update' time was recorded. However, the use of the do_gettimeofday() function is problematic and we have to replace it to avoid the overflow on on 32-bit architectures. This uses 'struct timespec64' to record 'last_update', and changes the code to use monotonic timestamps that do not suffer from leap seconds and settimeofday updates. As a side-effect, the code can now use the timespec64_sub() helper and become more readable and also avoid a multiplication to convert from microseconds to nanoseconds. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/core')
-rw-r--r--sound/core/seq/seq_timer.c23
-rw-r--r--sound/core/seq/seq_timer.h2
2 files changed, 10 insertions, 15 deletions
diff --git a/sound/core/seq/seq_timer.c b/sound/core/seq/seq_timer.c
index 293104926098..dcc102813aef 100644
--- a/sound/core/seq/seq_timer.c
+++ b/sound/core/seq/seq_timer.c
@@ -165,7 +165,7 @@ static void snd_seq_timer_interrupt(struct snd_timer_instance *timeri,
snd_seq_timer_update_tick(&tmr->tick, resolution);
/* register actual time of this timer update */
- do_gettimeofday(&tmr->last_update);
+ ktime_get_ts64(&tmr->last_update);
spin_unlock_irqrestore(&tmr->lock, flags);
@@ -392,7 +392,7 @@ static int seq_timer_start(struct snd_seq_timer *tmr)
return -EINVAL;
snd_timer_start(tmr->timeri, tmr->ticks);
tmr->running = 1;
- do_gettimeofday(&tmr->last_update);
+ ktime_get_ts64(&tmr->last_update);
return 0;
}
@@ -420,7 +420,7 @@ static int seq_timer_continue(struct snd_seq_timer *tmr)
}
snd_timer_start(tmr->timeri, tmr->ticks);
tmr->running = 1;
- do_gettimeofday(&tmr->last_update);
+ ktime_get_ts64(&tmr->last_update);
return 0;
}
@@ -444,17 +444,12 @@ snd_seq_real_time_t snd_seq_timer_get_cur_time(struct snd_seq_timer *tmr)
spin_lock_irqsave(&tmr->lock, flags);
cur_time = tmr->cur_time;
if (tmr->running) {
- struct timeval tm;
- int usec;
- do_gettimeofday(&tm);
- usec = (int)(tm.tv_usec - tmr->last_update.tv_usec);
- if (usec < 0) {
- cur_time.tv_nsec += (1000000 + usec) * 1000;
- cur_time.tv_sec += tm.tv_sec - tmr->last_update.tv_sec - 1;
- } else {
- cur_time.tv_nsec += usec * 1000;
- cur_time.tv_sec += tm.tv_sec - tmr->last_update.tv_sec;
- }
+ struct timespec64 tm;
+
+ ktime_get_ts64(&tm);
+ tm = timespec64_sub(tm, tmr->last_update);
+ cur_time.tv_nsec = tm.tv_nsec;
+ cur_time.tv_sec = tm.tv_sec;
snd_seq_sanity_real_time(&cur_time);
}
spin_unlock_irqrestore(&tmr->lock, flags);
diff --git a/sound/core/seq/seq_timer.h b/sound/core/seq/seq_timer.h
index 88dfb71805ae..9506b661fe5b 100644
--- a/sound/core/seq/seq_timer.h
+++ b/sound/core/seq/seq_timer.h
@@ -52,7 +52,7 @@ struct snd_seq_timer {
unsigned int skew;
unsigned int skew_base;
- struct timeval last_update; /* time of last clock update, used for interpolation */
+ struct timespec64 last_update; /* time of last clock update, used for interpolation */
spinlock_t lock;
};