Introduce new struct to catch the root cause

virtio-snd.c

@@ -249,7 +249,13 @@ static int vsnd_dev_cnt = 0;
 
 // static struct CNFADriver *audio_host = NULL;
 
-static bool guest_playing = false;
+typedef struct {
+    bool guest_playing;
+    uint32_t stream_id;
+} vsnd_stream_sel_t;
+static vsnd_stream_sel_t v = {
+    .guest_playing = false,
+};
 
 /* Forward declaration */
 static void virtio_snd_cb(struct CNFADriver *dev,
@@ -389,13 +395,16 @@ static void virtio_snd_read_pcm_prepare(struct virtq_desc *vq_desc,
     virtio_snd_pcm_hdr_t *request = query;
     uint32_t stream_id = request->stream_id;
     vsnd_props[stream_id].pp.hdr.hdr.code = VIRTIO_SND_R_PCM_PREPARE;
-    vsnd_props[stream_id].audio_host = CNFAInit(
-        NULL, "semu-virtio-snd", virtio_snd_cb, 44100, 0, 1, 0,
-        vsnd_props[stream_id].pp.buffer_bytes, NULL, NULL, &guest_playing);
+    vsnd_props[stream_id].audio_host =
+        CNFAInit(NULL, "semu-virtio-snd", virtio_snd_cb, 44100, 0, 1, 0,
+                 vsnd_props[stream_id].pp.buffer_bytes, NULL, NULL, &v);
+    size_t sz = vsnd_props[stream_id].pp.buffer_bytes;
+    vsnd_props[stream_id].buf = malloc(sizeof(vsnd_props[stream_id].buf) * sz);
 
     /* Control the callback to prepare the buffer */
     /* TODO: add lock to avoid race condition */
-    guest_playing = false;
+    v.guest_playing = false;
+    v.stream_id = 0;
 
     fprintf(stderr, "virtio_snd_read_pcm_prepare\n");
 }
@@ -407,7 +416,7 @@ static void virtio_snd_read_pcm_start(struct virtq_desc *vq_desc,
 
     /* Control the callback to start playing */
     /* TODO: add lock to avoid race condition */
-    guest_playing = true;
+    v.guest_playing = true;
 
     fprintf(stderr, "virtio_snd_read_pcm_start\n");
 }
@@ -419,7 +428,7 @@ static void virtio_snd_read_pcm_stop(struct virtq_desc *vq_desc,
 
     /* Control the callback to stop playing */
     /* TODO: add lock to avoid race condition */
-    guest_playing = false;
+    v.guest_playing = false;
 
     fprintf(stderr, "virtio_snd_read_pcm_stop\n");
 }
@@ -429,7 +438,7 @@ static void virtio_snd_read_pcm_release(struct virtq_desc *vq_desc,
 {
     /* Control the callback to stop playing */
     /* TODO: add lock to avoid race condition */
-    guest_playing = false;
+    v.guest_playing = false;
 
     virtio_snd_pcm_hdr_t *request = query;
     uint32_t stream_id = request->stream_id;
@@ -446,20 +455,19 @@ static void virtio_snd_cb(struct CNFADriver *dev,
                           int framesp,
                           int framesr)
 {
-    /* TODO: apply lock on guest_playing and guest_playing_ptr */
-    int *guest_playing_ptr = (int *) dev->opaque;
+    /* TODO: apply lock on guest_playing */
+    vsnd_stream_sel_t *v_ptr = (vsnd_stream_sel_t *) dev->opaque;
+    bool playing = v_ptr->guest_playing;
+    uint32_t id = v_ptr->stream_id;
     int output_channels = dev->channelsPlay;
     int output_buf_sz = framesp * output_channels;
 
-    if (framesp > 0) {  // playback
-        if (!(*guest_playing_ptr)) {
-            memset(out, 0, sizeof(short) * output_buf_sz);
-            return;
-        }
-    } else {
-        fprintf(stderr, "virtio_snd_cb(%p, %p, %p, %d, %d)\n", dev, out, in,
-                framesp, framesr);
+    if (!(playing)) {
+        memset(out, 0, sizeof(short) * output_buf_sz);
+        return;
     }
+
+    memcpy(out, vsnd_props[id].buf, output_buf_sz);
 }
 
 #define VSND_DESC_CNT 3
@@ -595,17 +603,14 @@ static int virtio_snd_tx_desc_handler(virtio_snd_state_t *vsnd,
 
     /* Process the data */
     fprintf(stderr, "TX process header\n");
-    // fprintf(stderr, "stream %d got %ld bytes.\n", stream_id,
-    // sizeof(payload));
-    size_t sz = vsnd_props[stream_id].pp.period_bytes;
-    vsnd_props[stream_id].buf = malloc(sizeof(vsnd_props[stream_id].buf) * sz);
+    size_t sz = vsnd_props[stream_id].pp.buffer_bytes;
     memcpy(vsnd_props[stream_id].buf, payload, sz);
 
     /* Return the device status */
     fprintf(stderr, "TX return device status\n");
     response->status = VIRTIO_SND_S_OK;
     response->latency_bytes = 0; /* TODO: show the actual latency bytes */
-    *plen = vq_desc[1].len;
+    *plen = sz;
 
     return 0;
 }
@@ -791,6 +796,8 @@ static bool virtio_snd_reg_write(virtio_snd_state_t *vsnd,
             case VSND_QUEUE_TX:
                 virtio_queue_notify_handler(vsnd, value,
                                             virtio_snd_tx_desc_handler);
+                for (int i = 0; i < 10000000; i++)
+                    asm volatile("" ::: "memory");
                 break;
             case VSND_QUEUE_EVT:
                 fprintf(stderr, "EVT\n");