[dpdk-test-report] |WARNING| pw103702 [PATCH] vhost: fix packed ring descriptor update in async enqueue

[dpdklab at iol.unh.edu]

Test-Label: iol-testing
Test-Status: WARNING
http://dpdk.org/patch/103702

_apply patch failure_

Submitter: Jiayu Hu <jiayu.hu at intel.com>
Date: Thursday, November 04 2021 10:19:30 
Applied on: CommitID:5b08ac4e4a8dbc95f52b871b62a97fda57fa477e
Apply patch set 103702 failed:

Checking patch lib/vhost/virtio_net.c...
Hunk #1 succeeded at 1653 (offset 104 lines).
error: while searching for:
				uint16_t n_buffers)
{
	struct vhost_async *async = vq->async;
	uint16_t nr_left = n_buffers;
	uint16_t from, to;

	do {
		from = async->last_buffer_idx_packed;
		to = (from + nr_left) % vq->size;
		if (to > from) {
			vhost_update_used_packed(vq, async->buffers_packed + from, to - from);
			async->last_buffer_idx_packed += nr_left;
			nr_left = 0;
		} else {
			vhost_update_used_packed(vq, async->buffers_packed + from,
				vq->size - from);
			async->last_buffer_idx_packed = 0;
			nr_left -= vq->size - from;
		}
	} while (nr_left > 0);
}

static __rte_always_inline uint16_t

error: patch failed: lib/vhost/virtio_net.c:1819
Applying patch lib/vhost/virtio_net.c with 1 reject...
Hunk #1 applied cleanly.
Rejected hunk #2.
diff a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c	(rejected hunks)
@@ -1819,23 +1765,63 @@ write_back_completed_descs_packed(struct vhost_virtqueue *vq,
 				uint16_t n_buffers)
 {
 	struct vhost_async *async = vq->async;
-	uint16_t nr_left = n_buffers;
-	uint16_t from, to;
+	uint16_t from = async->last_buffer_idx_packed;
+	uint16_t used_idx = vq->last_used_idx;
+	uint16_t head_idx = vq->last_used_idx;
+	uint16_t head_flags = 0;
+	uint16_t i;
 
-	do {
-		from = async->last_buffer_idx_packed;
-		to = (from + nr_left) % vq->size;
-		if (to > from) {
-			vhost_update_used_packed(vq, async->buffers_packed + from, to - from);
-			async->last_buffer_idx_packed += nr_left;
-			nr_left = 0;
+	/* Split loop in two to save memory barriers */
+	for (i = 0; i < n_buffers; i++) {
+		vq->desc_packed[used_idx].id = async->buffers_packed[from].id;
+		vq->desc_packed[used_idx].len = async->buffers_packed[from].len;
+
+		used_idx += async->buffers_packed[from].count;
+		if (used_idx >= vq->size)
+			used_idx -= vq->size;
+
+		from++;
+		if (from >= vq->size)
+			from = 0;
+	}
+
+	/* The ordering for storing desc flags needs to be enforced. */
+	rte_atomic_thread_fence(__ATOMIC_RELEASE);
+
+	from = async->last_buffer_idx_packed;
+
+	for (i = 0; i < n_buffers; i++) {
+		uint16_t flags;
+
+		if (async->buffers_packed[from].len)
+			flags = VRING_DESC_F_WRITE;
+		else
+			flags = 0;
+
+		if (vq->used_wrap_counter) {
+			flags |= VRING_DESC_F_USED;
+			flags |= VRING_DESC_F_AVAIL;
 		} else {
-			vhost_update_used_packed(vq, async->buffers_packed + from,
-				vq->size - from);
-			async->last_buffer_idx_packed = 0;
-			nr_left -= vq->size - from;
+			flags &= ~VRING_DESC_F_USED;
+			flags &= ~VRING_DESC_F_AVAIL;
 		}
-	} while (nr_left > 0);
+
+		if (i > 0) {
+			vq->desc_packed[vq->last_used_idx].flags = flags;
+		} else {
+			head_idx = vq->last_used_idx;
+			head_flags = flags;
+		}
+
+		vq_inc_last_used_packed(vq, async->buffers_packed[from].count);
+
+		from++;
+		if (from == vq->size)
+			from = 0;
+	}
+
+	vq->desc_packed[head_idx].flags = head_flags;
+	async->last_buffer_idx_packed = from;
 }
 
 static __rte_always_inline uint16_t

https://lab.dpdk.org/results/dashboard/patchsets/19989/

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