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Commit 89b4ab21 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: seq: virmidi: Use READ_ONCE/WRITE_ONCE() macros 



The trigger flag in vmidi object can be referred in different contexts
concurrently, hence it's better to be put with READ_ONCE() and
WRITE_ONCE() macros to assure the accesses.

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent f7debfe5

include/sound/seq_virmidi.h

+1 −1
Original line number Diff line number Diff line
@@ -36,7 +36,7 @@ struct snd_virmidi { 
	int seq_mode;

	int client;

	int port;

	unsigned int trigger: 1;

	bool trigger;

	struct snd_midi_event *parser;

	struct snd_seq_event event;

	struct snd_virmidi_dev *rdev;

sound/core/seq/seq_virmidi.c

+5 −9
Original line number Diff line number Diff line
@@ -89,7 +89,7 @@ static int snd_virmidi_dev_receive_event(struct snd_virmidi_dev *rdev, 
	else

		down_read(&rdev->filelist_sem);

	list_for_each_entry(vmidi, &rdev->filelist, list) {

		if (!vmidi->trigger)

		if (!READ_ONCE(vmidi->trigger))

			continue;

		if (ev->type == SNDRV_SEQ_EVENT_SYSEX) {

			if ((ev->flags & SNDRV_SEQ_EVENT_LENGTH_MASK) != SNDRV_SEQ_EVENT_LENGTH_VARIABLE)
@@ -147,11 +147,7 @@ static void snd_virmidi_input_trigger(struct snd_rawmidi_substream *substream, i 
{

	struct snd_virmidi *vmidi = substream->runtime->private_data;



	if (up) {

		vmidi->trigger = 1;

	} else {

		vmidi->trigger = 0;

	}

	WRITE_ONCE(vmidi->trigger, !!up);

}



/* process rawmidi bytes and send events;
@@ -175,7 +171,7 @@ static void snd_vmidi_output_work(struct work_struct *work) 
		return;

	}



	while (vmidi->trigger) {

	while (READ_ONCE(vmidi->trigger)) {

		if (snd_rawmidi_transmit(substream, &input, 1) != 1)

			break;

		if (snd_midi_event_encode_byte(vmidi->parser, input,
@@ -201,7 +197,7 @@ static void snd_virmidi_output_trigger(struct snd_rawmidi_substream *substream, 
{

	struct snd_virmidi *vmidi = substream->runtime->private_data;



	vmidi->trigger = !!up;

	WRITE_ONCE(vmidi->trigger, !!up);

	if (up)

		queue_work(system_highpri_wq, &vmidi->output_work);

}
@@ -289,7 +285,7 @@ static int snd_virmidi_output_close(struct snd_rawmidi_substream *substream) 
{

	struct snd_virmidi *vmidi = substream->runtime->private_data;



	vmidi->trigger = 0; /* to be sure */

	WRITE_ONCE(vmidi->trigger, false); /* to be sure */

	cancel_work_sync(&vmidi->output_work);

	snd_midi_event_free(vmidi->parser);

	substream->runtime->private_data = NULL;