Changeset 9afd2a8 in mainline for uspace/lib/virtio/virtio.c

Timestamp:

2018-06-22T20:27:31Z (6 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

5609d3c

Parents:

b8ef198b

Message:

The idx of the avail ring must always grow

The index cannot wrap around the queue size or it would be 0 when all
buffers are made available in the queue. Instead, the standard mandates
idx always grows, naturally wrapping at 65536.

File:

• uspace/lib/virtio/virtio.c (modified) (1 diff)

uspace/lib/virtio/virtio.c

@@ -64 +64 @@
 
         uint16_t idx = pio_read_le16(&q->avail->idx);
-        pio_write_le16(&q->avail->ring[idx], descno);
+        pio_write_le16(&q->avail->ring[idx % q->queue_size], descno);
         write_barrier();
-        pio_write_le16(&q->avail->idx, (idx + 1) % q->queue_size);
+        pio_write_le16(&q->avail->idx, idx + 1);
         write_barrier();
         pio_write_le16(q->notify, num);