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: Takashi Iwai <tiwai@suse.de>

diff --git a/include/sound/seq_virmidi.h b/include/sound/seq_virmidi.h
index d488dcf..796ce77 100644 (file)
--- a/include/sound/seq_virmidi.h
+++ b/include/sound/seq_virmidi.h
@@ -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;

diff --git a/sound/core/seq/seq_virmidi.c b/sound/core/seq/seq_virmidi.c
index 67ea5d6..03ac5e7 100644 (file)
--- a/sound/core/seq/seq_virmidi.c
+++ b/sound/core/seq/seq_virmidi.c
@@ -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;