Fill buffer_bytes then go

Author: Cuda-Chen

virtio-snd.c

@@ -616,18 +616,22 @@ static void __virtio_snd_frame_dequeue(short *out,
                                        uint32_t stream_id)
 {
     virtio_snd_prop_t *props = &vsnd_props[stream_id];
+
+    pthread_mutex_lock(&props->ring.lock);
+
     uint32_t cons_head, prod_tail;
     uint32_t cons_next, entries;
     uint32_t mask = props->ring.cons.mask;
 
-    pthread_mutex_lock(&props->ring.lock);
-    while (props->ring.buf_ev_notity < 1) {
+    uint32_t buffer_bytes = props->pp.buffer_bytes;
+    cons_head = props->ring.cons.head;
+    prod_tail = props->ring.prod.tail;
+    while (props->ring.buf_ev_notity < 1 &&
+           prod_tail - cons_head < buffer_bytes) {
         fprintf(stderr, "---wait in deque---\n");
         pthread_cond_wait(&props->ring.readable, &props->ring.lock);
     }
 
-    cons_head = props->ring.cons.head;
-    prod_tail = props->ring.prod.tail;
     /* The subtraction is done between two unsigned 32bits value
      * (the result is always modulo 32 bits even if we have
      * cons_head > prod_tail). So 'entries' is always between 0
@@ -808,12 +812,14 @@ static void __virtio_snd_frame_enqueue(void *payload,
                                        uint32_t n,
                                        uint32_t stream_id)
 {
+    virtio_snd_prop_t *props = &vsnd_props[stream_id];
+
+    pthread_mutex_lock(&props->ring.lock);
+
     uint32_t prod_head, cons_tail;
     uint32_t prod_next, free_entries;
-    virtio_snd_prop_t *props = &vsnd_props[stream_id];
     uint32_t mask = props->ring.prod.mask;
 
-    pthread_mutex_lock(&props->ring.lock);
     while (props->ring.buf_ev_notity > 0) {
         fprintf(stderr, "---wait for enque---\n");
         pthread_cond_wait(&props->ring.writable, &props->ring.lock);