diff --git a/us144mkii.c b/us144mkii.c
index 1d5fca7..ef0159c 100644
--- a/us144mkii.c
+++ b/us144mkii.c
@@ -157,9 +157,6 @@ void tascam_stop_work_handler(struct work_struct *work)
 
 	usb_kill_anchored_urbs(&tascam->playback_anchor);
 	usb_kill_anchored_urbs(&tascam->feedback_anchor);
-	usb_kill_anchored_urbs(&tascam->capture_anchor);
-	usb_kill_anchored_urbs(&tascam->midi_anchor);
-	atomic_set(&tascam->active_urbs, 0);
 }
 
 static void tascam_card_private_free(struct snd_card *card)
diff --git a/us144mkii_capture.c b/us144mkii_capture.c
index f56eb14..aab7054 100644
--- a/us144mkii_capture.c
+++ b/us144mkii_capture.c
@@ -195,11 +195,6 @@ void capture_urb_complete(struct urb *urb)
 		return;
 	}
 
-	if (!atomic_read(&tascam->capture_active)) {
-		atomic_dec(&tascam->active_urbs);
-		return;
-	}
-
 	substream = tascam->capture_substream;
 	if (!substream || !substream->runtime) {
 		atomic_dec(&tascam->active_urbs);
@@ -220,8 +215,14 @@ void capture_urb_complete(struct urb *urb)
 
 	if (frames_received > 0) {
 		spin_lock_irqsave(&tascam->lock, flags);
+
+		if (!atomic_read(&tascam->capture_active)) {
+			spin_unlock_irqrestore(&tascam->lock, flags);
+			atomic_dec(&tascam->active_urbs);
+			return;
+		}
+
 		write_pos = tascam->driver_capture_pos;
-		spin_unlock_irqrestore(&tascam->lock, flags);
 
 		u32 *dma_ptr = (u32 *)(runtime->dma_area + frames_to_bytes(runtime, write_pos));
 
@@ -235,7 +236,6 @@ void capture_urb_complete(struct urb *urb)
 			tascam_decode_capture_chunk(urb->transfer_buffer + (part1 * 64), (u32 *)runtime->dma_area, part2);
 		}
 
-		spin_lock_irqsave(&tascam->lock, flags);
 		tascam->driver_capture_pos += frames_received;
 		if (tascam->driver_capture_pos >= buffer_size)
 			tascam->driver_capture_pos -= buffer_size;
diff --git a/us144mkii_midi.c b/us144mkii_midi.c
index 005b301..d58f936 100644
--- a/us144mkii_midi.c
+++ b/us144mkii_midi.c
@@ -6,6 +6,7 @@
 static void tascam_midi_out_complete(struct urb *urb)
 {
 	struct tascam_card *tascam = urb->context;
+	struct snd_rawmidi_substream *substream;
 	unsigned long flags;
 	int count;
 	bool submit = false;
@@ -13,19 +14,20 @@ static void tascam_midi_out_complete(struct urb *urb)
 
 	spin_lock_irqsave(&tascam->midi_lock, flags);
 
-	if (urb->status || !tascam->midi_output) {
+	substream = tascam->midi_output;
+	active = tascam->midi_out_active;
+
+	if (urb->status || !substream) {
 		tascam->midi_out_active = false;
 		spin_unlock_irqrestore(&tascam->midi_lock, flags);
 		return;
 	}
-
-	active = tascam->midi_out_active;
 	spin_unlock_irqrestore(&tascam->midi_lock, flags);
 
 	if (!active)
 		return;
 
-	count = snd_rawmidi_transmit(tascam->midi_output, tascam->midi_out_buf, MIDI_PAYLOAD_SIZE);
+	count = snd_rawmidi_transmit(substream, tascam->midi_out_buf, MIDI_PAYLOAD_SIZE);
 	if (count > 0) {
 		if (count < MIDI_PAYLOAD_SIZE)
 			memset(tascam->midi_out_buf + count, 0xFD, MIDI_PAYLOAD_SIZE - count);
@@ -98,18 +100,24 @@ static void tascam_midi_output_trigger(struct snd_rawmidi_substream *substream,
 static void tascam_midi_in_complete(struct urb *urb)
 {
 	struct tascam_card *tascam = urb->context;
+	struct snd_rawmidi_substream *substream;
+	unsigned long flags;
 	int i;
 
 	if (urb->status)
 		return;
 
-	if (urb->actual_length == MIDI_PACKET_SIZE && tascam->midi_input) {
+	spin_lock_irqsave(&tascam->midi_lock, flags);
+	substream = tascam->midi_input;
+	spin_unlock_irqrestore(&tascam->midi_lock, flags);
+
+	if (urb->actual_length == MIDI_PACKET_SIZE && substream) {
 		u8 *data = urb->transfer_buffer;
 
 		for (i = 0; i < MIDI_PAYLOAD_SIZE; i++) {
 			if (data[i] == 0xFD)
 				break;
-			snd_rawmidi_receive(tascam->midi_input, &data[i], 1);
+			snd_rawmidi_receive(substream, &data[i], 1);
 		}
 	}
 
@@ -121,11 +129,14 @@ static void tascam_midi_in_complete(struct urb *urb)
 static void tascam_midi_input_trigger(struct snd_rawmidi_substream *substream, int up)
 {
 	struct tascam_card *tascam = substream->rmidi->private_data;
+	unsigned long flags;
 
+	spin_lock_irqsave(&tascam->midi_lock, flags);
 	if (up)
 		tascam->midi_input = substream;
 	else
 		tascam->midi_input = NULL;
+	spin_unlock_irqrestore(&tascam->midi_lock, flags);
 }
 
 static int tascam_midi_open(struct snd_rawmidi_substream *substream)
@@ -238,15 +249,15 @@ int tascam_create_midi(struct tascam_card *tascam)
 
 	return 0;
 
-err_in_buf:
+	err_in_buf:
 	usb_free_coherent(tascam->dev, MIDI_PACKET_SIZE,
 					  tascam->midi_out_buf, tascam->midi_out_urb->transfer_dma);
-err_out_buf:
+	err_out_buf:
 	usb_free_urb(tascam->midi_in_urb);
 	tascam->midi_in_urb = NULL;
-err_in_urb:
+	err_in_urb:
 	usb_free_urb(tascam->midi_out_urb);
 	tascam->midi_out_urb = NULL;
-err_out_urb:
+	err_out_urb:
 	return err;
 }
diff --git a/us144mkii_pcm.c b/us144mkii_pcm.c
index acc432f..86d0ad9 100644
--- a/us144mkii_pcm.c
+++ b/us144mkii_pcm.c
@@ -122,6 +122,10 @@ int tascam_pcm_hw_params(struct snd_pcm_substream *substream,
 	int err;
 
 	if (tascam->current_rate != rate) {
+		if (atomic_read(&tascam->playback_active) ||
+			atomic_read(&tascam->capture_active)) {
+			return -EBUSY;
+			}
 
 		usb_kill_anchored_urbs(&tascam->playback_anchor);
 		usb_kill_anchored_urbs(&tascam->feedback_anchor);
diff --git a/us144mkii_playback.c b/us144mkii_playback.c
index f2ed42c..860912c 100644
--- a/us144mkii_playback.c
+++ b/us144mkii_playback.c
@@ -214,10 +214,6 @@ void playback_urb_complete(struct urb *urb)
 		atomic_dec(&tascam->active_urbs);
 		return;
 	}
-	if (!atomic_read(&tascam->playback_active)) {
-		atomic_dec(&tascam->active_urbs);
-		return;
-	}
 
 	substream = tascam->playback_substream;
 	if (!substream || !substream->runtime) {
@@ -234,6 +230,13 @@ void playback_urb_complete(struct urb *urb)
 	period_size = runtime->period_size;
 
 	spin_lock_irqsave(&tascam->lock, flags);
+
+	if (!atomic_read(&tascam->playback_active)) {
+		spin_unlock_irqrestore(&tascam->lock, flags);
+		atomic_dec(&tascam->active_urbs);
+		return;
+	}
+
 	for (i = 0; i < urb->number_of_packets; i++) {
 		unsigned int frames_for_packet;
 
@@ -249,7 +252,6 @@ void playback_urb_complete(struct urb *urb)
 	offset_frames = tascam->driver_playback_pos;
 	frames_to_copy = bytes_to_frames(runtime, total_bytes_for_urb);
 	tascam->driver_playback_pos = (offset_frames + frames_to_copy) % buffer_size;
-	spin_unlock_irqrestore(&tascam->lock, flags);
 
 	if (total_bytes_for_urb > 0) {
 		u8 *dst_buf = urb->transfer_buffer;
@@ -265,7 +267,6 @@ void playback_urb_complete(struct urb *urb)
 		}
 	}
 
-	spin_lock_irqsave(&tascam->lock, flags);
 	tascam->playback_frames_consumed += frames_to_copy;
 
 	if (period_size > 0) {