locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE()

Please do not apply this to mainline directly, instead please re-run the
coccinelle script shown below and apply its output.

For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't harmful, and changing them results in
churn.

However, for some features, the read/write distinction is critical to
correct operation. To distinguish these cases, separate read/write
accessors must be used. This patch migrates (most) remaining
ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following
coccinelle script:

----
// Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and
// WRITE_ONCE()

// $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch

virtual patch

@ depends on patch @
expression E1, E2;
@@

- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)

@ depends on patch @
expression E;
@@

- ACCESS_ONCE(E)
+ READ_ONCE(E)
----

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

12 files changed, 51 insertions, 52 deletions

diff --git a/sound/firewire/amdtp-am824.c b/sound/firewire/amdtp-am824.c
index 23ccddb20de1..4210e5c6262e 100644
--- a/sound/firewire/amdtp-am824.c
+++ b/sound/firewire/amdtp-am824.c
@@ -247,7 +247,7 @@ void amdtp_am824_midi_trigger(struct amdtp_stream *s, unsigned int port,
 	struct amdtp_am824 *p = s->protocol;
 
 	if (port < p->midi_ports)
-		ACCESS_ONCE(p->midi[port]) = midi;
+		WRITE_ONCE(p->midi[port], midi);
 }
 EXPORT_SYMBOL_GPL(amdtp_am824_midi_trigger);
 
@@ -336,7 +336,7 @@ static unsigned int process_rx_data_blocks(struct amdtp_stream *s, __be32 *buffe
 					   unsigned int data_blocks, unsigned int *syt)
 {
 	struct amdtp_am824 *p = s->protocol;
-	struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
+	struct snd_pcm_substream *pcm = READ_ONCE(s->pcm);
 	unsigned int pcm_frames;
 
 	if (pcm) {
@@ -357,7 +357,7 @@ static unsigned int process_tx_data_blocks(struct amdtp_stream *s, __be32 *buffe
 					   unsigned int data_blocks, unsigned int *syt)
 {
 	struct amdtp_am824 *p = s->protocol;
-	struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
+	struct snd_pcm_substream *pcm = READ_ONCE(s->pcm);
 	unsigned int pcm_frames;
 
 	if (pcm) {
diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c
index 3fc581a5ad62..4a1dc145327b 100644
--- a/sound/firewire/amdtp-stream.c
+++ b/sound/firewire/amdtp-stream.c
@@ -376,7 +376,7 @@ static void update_pcm_pointers(struct amdtp_stream *s,
 	ptr = s->pcm_buffer_pointer + frames;
 	if (ptr >= pcm->runtime->buffer_size)
 		ptr -= pcm->runtime->buffer_size;
-	ACCESS_ONCE(s->pcm_buffer_pointer) = ptr;
+	WRITE_ONCE(s->pcm_buffer_pointer, ptr);
 
 	s->pcm_period_pointer += frames;
 	if (s->pcm_period_pointer >= pcm->runtime->period_size) {
@@ -388,7 +388,7 @@ static void update_pcm_pointers(struct amdtp_stream *s,
 static void pcm_period_tasklet(unsigned long data)
 {
 	struct amdtp_stream *s = (void *)data;
-	struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
+	struct snd_pcm_substream *pcm = READ_ONCE(s->pcm);
 
 	if (pcm)
 		snd_pcm_period_elapsed(pcm);
@@ -453,7 +453,7 @@ static int handle_out_packet(struct amdtp_stream *s,
 		s->data_block_counter =
 				(s->data_block_counter + data_blocks) & 0xff;
 
-	buffer[0] = cpu_to_be32(ACCESS_ONCE(s->source_node_id_field) |
+	buffer[0] = cpu_to_be32(READ_ONCE(s->source_node_id_field) |
 				(s->data_block_quadlets << CIP_DBS_SHIFT) |
 				((s->sph << CIP_SPH_SHIFT) & CIP_SPH_MASK) |
 				s->data_block_counter);
@@ -472,7 +472,7 @@ static int handle_out_packet(struct amdtp_stream *s,
 	if (queue_out_packet(s, payload_length) < 0)
 		return -EIO;
 
-	pcm = ACCESS_ONCE(s->pcm);
+	pcm = READ_ONCE(s->pcm);
 	if (pcm && pcm_frames > 0)
 		update_pcm_pointers(s, pcm, pcm_frames);
 
@@ -504,7 +504,7 @@ static int handle_out_packet_without_header(struct amdtp_stream *s,
 	if (queue_out_packet(s, payload_length) < 0)
 		return -EIO;
 
-	pcm = ACCESS_ONCE(s->pcm);
+	pcm = READ_ONCE(s->pcm);
 	if (pcm && pcm_frames > 0)
 		update_pcm_pointers(s, pcm, pcm_frames);
 
@@ -621,7 +621,7 @@ end:
 	if (queue_in_packet(s) < 0)
 		return -EIO;
 
-	pcm = ACCESS_ONCE(s->pcm);
+	pcm = READ_ONCE(s->pcm);
 	if (pcm && pcm_frames > 0)
 		update_pcm_pointers(s, pcm, pcm_frames);
 
@@ -649,7 +649,7 @@ static int handle_in_packet_without_header(struct amdtp_stream *s,
 	if (queue_in_packet(s) < 0)
 		return -EIO;
 
-	pcm = ACCESS_ONCE(s->pcm);
+	pcm = READ_ONCE(s->pcm);
 	if (pcm && pcm_frames > 0)
 		update_pcm_pointers(s, pcm, pcm_frames);
 
@@ -947,7 +947,7 @@ unsigned long amdtp_stream_pcm_pointer(struct amdtp_stream *s)
 	if (!in_interrupt() && amdtp_stream_running(s))
 		fw_iso_context_flush_completions(s->context);
 
-	return ACCESS_ONCE(s->pcm_buffer_pointer);
+	return READ_ONCE(s->pcm_buffer_pointer);
 }
 EXPORT_SYMBOL(amdtp_stream_pcm_pointer);
 
@@ -977,9 +977,8 @@ EXPORT_SYMBOL(amdtp_stream_pcm_ack);
 void amdtp_stream_update(struct amdtp_stream *s)
 {
 	/* Precomputing. */
-	ACCESS_ONCE(s->source_node_id_field) =
-		(fw_parent_device(s->unit)->card->node_id << CIP_SID_SHIFT) &
-								CIP_SID_MASK;
+	WRITE_ONCE(s->source_node_id_field,
+                   (fw_parent_device(s->unit)->card->node_id << CIP_SID_SHIFT) & CIP_SID_MASK);
 }
 EXPORT_SYMBOL(amdtp_stream_update);
 
@@ -1022,7 +1021,7 @@ void amdtp_stream_pcm_abort(struct amdtp_stream *s)
 {
 	struct snd_pcm_substream *pcm;
 
-	pcm = ACCESS_ONCE(s->pcm);
+	pcm = READ_ONCE(s->pcm);
 	if (pcm)
 		snd_pcm_stop_xrun(pcm);
 }
diff --git a/sound/firewire/amdtp-stream.h b/sound/firewire/amdtp-stream.h
index ed6eafd10992..f9abd8b07ce6 100644
--- a/sound/firewire/amdtp-stream.h
+++ b/sound/firewire/amdtp-stream.h
@@ -220,7 +220,7 @@ static inline bool amdtp_stream_pcm_running(struct amdtp_stream *s)
 static inline void amdtp_stream_pcm_trigger(struct amdtp_stream *s,
 					    struct snd_pcm_substream *pcm)
 {
-	ACCESS_ONCE(s->pcm) = pcm;
+	WRITE_ONCE(s->pcm, pcm);
 }
 
 static inline bool cip_sfc_is_base_44100(enum cip_sfc sfc)
diff --git a/sound/firewire/digi00x/amdtp-dot.c b/sound/firewire/digi00x/amdtp-dot.c
index 1453c34ce99f..4a884a335248 100644
--- a/sound/firewire/digi00x/amdtp-dot.c
+++ b/sound/firewire/digi00x/amdtp-dot.c
@@ -327,7 +327,7 @@ void amdtp_dot_midi_trigger(struct amdtp_stream *s, unsigned int port,
 	struct amdtp_dot *p = s->protocol;
 
 	if (port < MAX_MIDI_PORTS)
-		ACCESS_ONCE(p->midi[port]) = midi;
+		WRITE_ONCE(p->midi[port], midi);
 }
 
 static unsigned int process_tx_data_blocks(struct amdtp_stream *s,
@@ -338,7 +338,7 @@ static unsigned int process_tx_data_blocks(struct amdtp_stream *s,
 	struct snd_pcm_substream *pcm;
 	unsigned int pcm_frames;
 
-	pcm = ACCESS_ONCE(s->pcm);
+	pcm = READ_ONCE(s->pcm);
 	if (pcm) {
 		read_pcm_s32(s, pcm, buffer, data_blocks);
 		pcm_frames = data_blocks;
@@ -359,7 +359,7 @@ static unsigned int process_rx_data_blocks(struct amdtp_stream *s,
 	struct snd_pcm_substream *pcm;
 	unsigned int pcm_frames;
 
-	pcm = ACCESS_ONCE(s->pcm);
+	pcm = READ_ONCE(s->pcm);
 	if (pcm) {
 		write_pcm_s32(s, pcm, buffer, data_blocks);
 		pcm_frames = data_blocks;
diff --git a/sound/firewire/fireface/amdtp-ff.c b/sound/firewire/fireface/amdtp-ff.c
index 780da9deb2f0..77c7598b61ab 100644
--- a/sound/firewire/fireface/amdtp-ff.c
+++ b/sound/firewire/fireface/amdtp-ff.c
@@ -108,7 +108,7 @@ static unsigned int process_rx_data_blocks(struct amdtp_stream *s,
 					   unsigned int data_blocks,
 					   unsigned int *syt)
 {
-	struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
+	struct snd_pcm_substream *pcm = READ_ONCE(s->pcm);
 	unsigned int pcm_frames;
 
 	if (pcm) {
@@ -127,7 +127,7 @@ static unsigned int process_tx_data_blocks(struct amdtp_stream *s,
 					   unsigned int data_blocks,
 					   unsigned int *syt)
 {
-	struct snd_pcm_substream *pcm = ACCESS_ONCE(s->pcm);
+	struct snd_pcm_substream *pcm = READ_ONCE(s->pcm);
 	unsigned int pcm_frames;
 
 	if (pcm) {
diff --git a/sound/firewire/fireface/ff-midi.c b/sound/firewire/fireface/ff-midi.c
index 949ee56b4e0e..6a49611ee462 100644
--- a/sound/firewire/fireface/ff-midi.c
+++ b/sound/firewire/fireface/ff-midi.c
@@ -22,7 +22,7 @@ static int midi_playback_open(struct snd_rawmidi_substream *substream)
 	ff->running_status[substream->number] = 0;
 	ff->rx_midi_error[substream->number] = false;
 
-	ACCESS_ONCE(ff->rx_midi_substreams[substream->number]) = substream;
+	WRITE_ONCE(ff->rx_midi_substreams[substream->number], substream);
 
 	return 0;
 }
@@ -38,7 +38,7 @@ static int midi_playback_close(struct snd_rawmidi_substream *substream)
 	struct snd_ff *ff = substream->rmidi->private_data;
 
 	cancel_work_sync(&ff->rx_midi_work[substream->number]);
-	ACCESS_ONCE(ff->rx_midi_substreams[substream->number]) = NULL;
+	WRITE_ONCE(ff->rx_midi_substreams[substream->number], NULL);
 
 	return 0;
 }
@@ -52,10 +52,10 @@ static void midi_capture_trigger(struct snd_rawmidi_substream *substream,
 	spin_lock_irqsave(&ff->lock, flags);
 
 	if (up)
-		ACCESS_ONCE(ff->tx_midi_substreams[substream->number]) =
-								substream;
+		WRITE_ONCE(ff->tx_midi_substreams[substream->number],
+			   substream);
 	else
-		ACCESS_ONCE(ff->tx_midi_substreams[substream->number]) = NULL;
+		WRITE_ONCE(ff->tx_midi_substreams[substream->number], NULL);
 
 	spin_unlock_irqrestore(&ff->lock, flags);
 }
diff --git a/sound/firewire/fireface/ff-transaction.c b/sound/firewire/fireface/ff-transaction.c
index dd6c8e839647..332b29f8ed75 100644
--- a/sound/firewire/fireface/ff-transaction.c
+++ b/sound/firewire/fireface/ff-transaction.c
@@ -12,7 +12,7 @@ static void finish_transmit_midi_msg(struct snd_ff *ff, unsigned int port,
 				     int rcode)
 {
 	struct snd_rawmidi_substream *substream =
-				ACCESS_ONCE(ff->rx_midi_substreams[port]);
+				READ_ONCE(ff->rx_midi_substreams[port]);
 
 	if (rcode_is_permanent_error(rcode)) {
 		ff->rx_midi_error[port] = true;
@@ -60,7 +60,7 @@ static inline void fill_midi_buf(struct snd_ff *ff, unsigned int port,
 static void transmit_midi_msg(struct snd_ff *ff, unsigned int port)
 {
 	struct snd_rawmidi_substream *substream =
-			ACCESS_ONCE(ff->rx_midi_substreams[port]);
+			READ_ONCE(ff->rx_midi_substreams[port]);
 	u8 *buf = (u8 *)ff->msg_buf[port];
 	int i, len;
 
@@ -159,7 +159,7 @@ static void handle_midi_msg(struct fw_card *card, struct fw_request *request,
 		 */
 		index = (quad >> 8) & 0xff;
 		if (index > 0) {
-			substream = ACCESS_ONCE(ff->tx_midi_substreams[0]);
+			substream = READ_ONCE(ff->tx_midi_substreams[0]);
 			if (substream != NULL) {
 				byte = quad & 0xff;
 				snd_rawmidi_receive(substream, &byte, 1);
@@ -169,7 +169,7 @@ static void handle_midi_msg(struct fw_card *card, struct fw_request *request,
 		/* Message in second port. */
 		index = (quad >> 24) & 0xff;
 		if (index > 0) {
-			substream = ACCESS_ONCE(ff->tx_midi_substreams[1]);
+			substream = READ_ONCE(ff->tx_midi_substreams[1]);
 			if (substream != NULL) {
 				byte = (quad >> 16) & 0xff;
 				snd_rawmidi_receive(substream, &byte, 1);
diff --git a/sound/firewire/isight.c b/sound/firewire/isight.c
index 5826aa8362f1..46092fa3ff9b 100644
--- a/sound/firewire/isight.c
+++ b/sound/firewire/isight.c
@@ -96,7 +96,7 @@ static void isight_update_pointers(struct isight *isight, unsigned int count)
 	ptr += count;
 	if (ptr >= runtime->buffer_size)
 		ptr -= runtime->buffer_size;
-	ACCESS_ONCE(isight->buffer_pointer) = ptr;
+	WRITE_ONCE(isight->buffer_pointer, ptr);
 
 	isight->period_counter += count;
 	if (isight->period_counter >= runtime->period_size) {
@@ -111,7 +111,7 @@ static void isight_samples(struct isight *isight,
 	struct snd_pcm_runtime *runtime;
 	unsigned int count1;
 
-	if (!ACCESS_ONCE(isight->pcm_running))
+	if (!READ_ONCE(isight->pcm_running))
 		return;
 
 	runtime = isight->pcm->runtime;
@@ -131,7 +131,7 @@ static void isight_samples(struct isight *isight,
 
 static void isight_pcm_abort(struct isight *isight)
 {
-	if (ACCESS_ONCE(isight->pcm_active))
+	if (READ_ONCE(isight->pcm_active))
 		snd_pcm_stop_xrun(isight->pcm);
 }
 
@@ -141,7 +141,7 @@ static void isight_dropped_samples(struct isight *isight, unsigned int total)
 	u32 dropped;
 	unsigned int count1;
 
-	if (!ACCESS_ONCE(isight->pcm_running))
+	if (!READ_ONCE(isight->pcm_running))
 		return;
 
 	runtime = isight->pcm->runtime;
@@ -293,7 +293,7 @@ static int isight_hw_params(struct snd_pcm_substream *substream,
 	if (err < 0)
 		return err;
 
-	ACCESS_ONCE(isight->pcm_active) = true;
+	WRITE_ONCE(isight->pcm_active, true);
 
 	return 0;
 }
@@ -331,7 +331,7 @@ static int isight_hw_free(struct snd_pcm_substream *substream)
 {
 	struct isight *isight = substream->private_data;
 
-	ACCESS_ONCE(isight->pcm_active) = false;
+	WRITE_ONCE(isight->pcm_active, false);
 
 	mutex_lock(&isight->mutex);
 	isight_stop_streaming(isight);
@@ -424,10 +424,10 @@ static int isight_trigger(struct snd_pcm_substream *substream, int cmd)
 
 	switch (cmd) {
 	case SNDRV_PCM_TRIGGER_START:
-		ACCESS_ONCE(isight->pcm_running) = true;
+		WRITE_ONCE(isight->pcm_running, true);
 		break;
 	case SNDRV_PCM_TRIGGER_STOP:
-		ACCESS_ONCE(isight->pcm_running) = false;
+		WRITE_ONCE(isight->pcm_running, false);
 		break;
 	default:
 		return -EINVAL;
@@ -439,7 +439,7 @@ static snd_pcm_uframes_t isight_pointer(struct snd_pcm_substream *substream)
 {
 	struct isight *isight = substream->private_data;
 
-	return ACCESS_ONCE(isight->buffer_pointer);
+	return READ_ONCE(isight->buffer_pointer);
 }
 
 static int isight_create_pcm(struct isight *isight)
diff --git a/sound/firewire/motu/amdtp-motu.c b/sound/firewire/motu/amdtp-motu.c
index 96f0091144bb..f0555a24d90e 100644
--- a/sound/firewire/motu/amdtp-motu.c
+++ b/sound/firewire/motu/amdtp-motu.c
@@ -310,7 +310,7 @@ static unsigned int process_tx_data_blocks(struct amdtp_stream *s,
 	if (p->midi_ports)
 		read_midi_messages(s, buffer, data_blocks);
 
-	pcm = ACCESS_ONCE(s->pcm);
+	pcm = READ_ONCE(s->pcm);
 	if (data_blocks > 0 && pcm)
 		read_pcm_s32(s, pcm->runtime, buffer, data_blocks);
 
@@ -374,7 +374,7 @@ static unsigned int process_rx_data_blocks(struct amdtp_stream *s,
 	if (p->midi_ports)
 		write_midi_messages(s, buffer, data_blocks);
 
-	pcm = ACCESS_ONCE(s->pcm);
+	pcm = READ_ONCE(s->pcm);
 	if (pcm)
 		write_pcm_s32(s, pcm->runtime, buffer, data_blocks);
 	else
diff --git a/sound/firewire/oxfw/oxfw-scs1x.c b/sound/firewire/oxfw/oxfw-scs1x.c
index 02d595665898..f33497cdc706 100644
--- a/sound/firewire/oxfw/oxfw-scs1x.c
+++ b/sound/firewire/oxfw/oxfw-scs1x.c
@@ -112,7 +112,7 @@ static void handle_hss(struct fw_card *card, struct fw_request *request,
 	}
 
 	if (length >= 1) {
-		stream = ACCESS_ONCE(scs->input);
+		stream = READ_ONCE(scs->input);
 		if (stream)
 			midi_input_packet(scs, stream, data, length);
 	}
@@ -183,7 +183,7 @@ static void scs_output_work(struct work_struct *work)
 	if (scs->transaction_running)
 		return;
 
-	stream = ACCESS_ONCE(scs->output);
+	stream = READ_ONCE(scs->output);
 	if (!stream || scs->error) {
 		scs->output_idle = true;
 		wake_up(&scs->idle_wait);
@@ -291,9 +291,9 @@ static void midi_capture_trigger(struct snd_rawmidi_substream *stream, int up)
 
 	if (up) {
 		scs->input_escape_count = 0;
-		ACCESS_ONCE(scs->input) = stream;
+		WRITE_ONCE(scs->input, stream);
 	} else {
-		ACCESS_ONCE(scs->input) = NULL;
+		WRITE_ONCE(scs->input, NULL);
 	}
 }
 
@@ -319,10 +319,10 @@ static void midi_playback_trigger(struct snd_rawmidi_substream *stream, int up)
 		scs->transaction_bytes = 0;
 		scs->error = false;
 
-		ACCESS_ONCE(scs->output) = stream;
+		WRITE_ONCE(scs->output, stream);
 		schedule_work(&scs->work);
 	} else {
-		ACCESS_ONCE(scs->output) = NULL;
+		WRITE_ONCE(scs->output, NULL);
 	}
 }
 static void midi_playback_drain(struct snd_rawmidi_substream *stream)
diff --git a/sound/firewire/tascam/amdtp-tascam.c b/sound/firewire/tascam/amdtp-tascam.c
index 6aff1fc1c72d..ab482423c165 100644
--- a/sound/firewire/tascam/amdtp-tascam.c
+++ b/sound/firewire/tascam/amdtp-tascam.c
@@ -124,7 +124,7 @@ static unsigned int process_tx_data_blocks(struct amdtp_stream *s,
 {
 	struct snd_pcm_substream *pcm;
 
-	pcm = ACCESS_ONCE(s->pcm);
+	pcm = READ_ONCE(s->pcm);
 	if (data_blocks > 0 && pcm)
 		read_pcm_s32(s, pcm, buffer, data_blocks);
 
@@ -143,7 +143,7 @@ static unsigned int process_rx_data_blocks(struct amdtp_stream *s,
 	/* This field is not used. */
 	*syt = 0x0000;
 
-	pcm = ACCESS_ONCE(s->pcm);
+	pcm = READ_ONCE(s->pcm);
 	if (pcm)
 		write_pcm_s32(s, pcm, buffer, data_blocks);
 	else
diff --git a/sound/firewire/tascam/tascam-transaction.c b/sound/firewire/tascam/tascam-transaction.c
index 8967c52f5032..2ad692dd4b13 100644
--- a/sound/firewire/tascam/tascam-transaction.c
+++ b/sound/firewire/tascam/tascam-transaction.c
@@ -148,7 +148,7 @@ static void async_midi_port_callback(struct fw_card *card, int rcode,
 				     void *callback_data)
 {
 	struct snd_fw_async_midi_port *port = callback_data;
-	struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream);
+	struct snd_rawmidi_substream *substream = READ_ONCE(port->substream);
 
 	/* This port is closed. */
 	if (substream == NULL)
@@ -173,7 +173,7 @@ static void midi_port_work(struct work_struct *work)
 {
 	struct snd_fw_async_midi_port *port =
 			container_of(work, struct snd_fw_async_midi_port, work);
-	struct snd_rawmidi_substream *substream = ACCESS_ONCE(port->substream);
+	struct snd_rawmidi_substream *substream = READ_ONCE(port->substream);
 	int generation;
 
 	/* Under transacting or error state. */
@@ -282,7 +282,7 @@ static void handle_midi_tx(struct fw_card *card, struct fw_request *request,
 				bytes = 3;
 		}
 
-		substream = ACCESS_ONCE(tscm->tx_midi_substreams[port]);
+		substream = READ_ONCE(tscm->tx_midi_substreams[port]);
 		if (substream != NULL)
 			snd_rawmidi_receive(substream, b + 1, bytes);
 	}