Patch "ALSA: seq: Fix yet another races among ALSA timer accesses" has been added to the 3.14-stable tree

@@ -92,6 +92,9 @@ void snd_seq_timer_delete(struct snd_seq
 
 void snd_seq_timer_defaults(struct snd_seq_timer * tmr)
 {
+	unsigned long flags;
+
+	spin_lock_irqsave(&tmr->lock, flags);
 	/* setup defaults */
 	tmr->ppq = 96;		/* 96 PPQ */
 	tmr->tempo = 500000;	/* 120 BPM */

@@ -107,21 +110,25 @@ void snd_seq_timer_defaults(struct snd_s
 	tmr->preferred_resolution = seq_default_timer_resolution;
 
 	tmr->skew = tmr->skew_base = SKEW_BASE;
+	spin_unlock_irqrestore(&tmr->lock, flags);
 }
 
-void snd_seq_timer_reset(struct snd_seq_timer * tmr)
+static void seq_timer_reset(struct snd_seq_timer *tmr)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&tmr->lock, flags);
-
 	/* reset time & songposition */
 	tmr->cur_time.tv_sec = 0;
 	tmr->cur_time.tv_nsec = 0;
 
 	tmr->tick.cur_tick = 0;
 	tmr->tick.fraction = 0;
+}
+
+void snd_seq_timer_reset(struct snd_seq_timer *tmr)
+{
+	unsigned long flags;
 
+	spin_lock_irqsave(&tmr->lock, flags);
+	seq_timer_reset(tmr);
 	spin_unlock_irqrestore(&tmr->lock, flags);
 }
 

@@ -140,8 +147,11 @@ static void snd_seq_timer_interrupt(stru
 	tmr = q->timer;
 	if (tmr == NULL)
 		return;
-	if (!tmr->running)
+	spin_lock_irqsave(&tmr->lock, flags);
+	if (!tmr->running) {
+		spin_unlock_irqrestore(&tmr->lock, flags);
 		return;
+	}
 
 	resolution *= ticks;
 	if (tmr->skew != tmr->skew_base) {

@@ -150,8 +160,6 @@ static void snd_seq_timer_interrupt(stru
 			(((resolution & 0xffff) * tmr->skew) >> 16);
 	}
 
-	spin_lock_irqsave(&tmr->lock, flags);
-
 	/* update timer */
 	snd_seq_inc_time_nsec(&tmr->cur_time, resolution);
 

@@ -298,26 +306,30 @@ int snd_seq_timer_open(struct snd_seq_qu
 	t->callback = snd_seq_timer_interrupt;
 	t->callback_data = q;
 	t->flags |= SNDRV_TIMER_IFLG_AUTO;
+	spin_lock_irq(&tmr->lock);
 	tmr->timeri = t;
+	spin_unlock_irq(&tmr->lock);
 	return 0;
 }
 
 int snd_seq_timer_close(struct snd_seq_queue *q)
 {
 	struct snd_seq_timer *tmr;
+	struct snd_timer_instance *t;
 	
 	tmr = q->timer;
 	if (snd_BUG_ON(!tmr))
 		return -EINVAL;
-	if (tmr->timeri) {
-		snd_timer_stop(tmr->timeri);
-		snd_timer_close(tmr->timeri);
-		tmr->timeri = NULL;
-	}
+	spin_lock_irq(&tmr->lock);
+	t = tmr->timeri;
+	tmr->timeri = NULL;
+	spin_unlock_irq(&tmr->lock);
+	if (t)
+		snd_timer_close(t);
 	return 0;
 }
 
-int snd_seq_timer_stop(struct snd_seq_timer * tmr)
+static int seq_timer_stop(struct snd_seq_timer *tmr)
 {
 	if (! tmr->timeri)
 		return -EINVAL;

@@ -328,6 +340,17 @@ int snd_seq_timer_stop(struct snd_seq_ti
 	return 0;
 }
 
+int snd_seq_timer_stop(struct snd_seq_timer *tmr)
+{
+	unsigned long flags;
+	int err;
+
+	spin_lock_irqsave(&tmr->lock, flags);
+	err = seq_timer_stop(tmr);
+	spin_unlock_irqrestore(&tmr->lock, flags);
+	return err;
+}
+
 static int initialize_timer(struct snd_seq_timer *tmr)
 {
 	struct snd_timer *t;

@@ -360,13 +383,13 @@ static int initialize_timer(struct snd_s
 	return 0;
 }
 
-int snd_seq_timer_start(struct snd_seq_timer * tmr)
+static int seq_timer_start(struct snd_seq_timer *tmr)
 {
 	if (! tmr->timeri)
 		return -EINVAL;
 	if (tmr->running)
-		snd_seq_timer_stop(tmr);
-	snd_seq_timer_reset(tmr);
+		seq_timer_stop(tmr);
+	seq_timer_reset(tmr);
 	if (initialize_timer(tmr) < 0)
 		return -EINVAL;
 	snd_timer_start(tmr->timeri, tmr->ticks);

@@ -375,14 +398,25 @@ int snd_seq_timer_start(struct snd_seq_t
 	return 0;
 }
 
-int snd_seq_timer_continue(struct snd_seq_timer * tmr)
+int snd_seq_timer_start(struct snd_seq_timer *tmr)
+{
+	unsigned long flags;
+	int err;
+
+	spin_lock_irqsave(&tmr->lock, flags);
+	err = seq_timer_start(tmr);
+	spin_unlock_irqrestore(&tmr->lock, flags);
+	return err;
+}
+
+static int seq_timer_continue(struct snd_seq_timer *tmr)
 {
 	if (! tmr->timeri)
 		return -EINVAL;
 	if (tmr->running)
 		return -EBUSY;
 	if (! tmr->initialized) {
-		snd_seq_timer_reset(tmr);
+		seq_timer_reset(tmr);
 		if (initialize_timer(tmr) < 0)
 			return -EINVAL;
 	}

@@ -392,11 +426,24 @@ int snd_seq_timer_continue(struct snd_se
 	return 0;
 }
 
+int snd_seq_timer_continue(struct snd_seq_timer *tmr)
+{
+	unsigned long flags;
+	int err;
+
+	spin_lock_irqsave(&tmr->lock, flags);
+	err = seq_timer_continue(tmr);
+	spin_unlock_irqrestore(&tmr->lock, flags);
+	return err;
+}
+
 /* return current 'real' time. use timeofday() to get better granularity. */
 snd_seq_real_time_t snd_seq_timer_get_cur_time(struct snd_seq_timer *tmr)
 {
 	snd_seq_real_time_t cur_time;
+	unsigned long flags;
 
+	spin_lock_irqsave(&tmr->lock, flags);
 	cur_time = tmr->cur_time;
 	if (tmr->running) { 
 		struct timeval tm;

@@ -412,7 +459,7 @@ snd_seq_real_time_t snd_seq_timer_get_cu
 		}
 		snd_seq_sanity_real_time(&cur_time);
 	}
-                
+	spin_unlock_irqrestore(&tmr->lock, flags);
 	return cur_time;	
 }