gve: Reset Rx ring state in the ring-stop funcs

This does not fix any existing bug. In anticipation of the ndo queue api
hooks that alloc/free/start/stop a single Rx queue, the already existing
per-queue stop functions are being made more robust. Specifically for
this use case: rx_queue_n.stop() + rx_queue_n.start()

Note that this is not the use case being used in devmem tcp (the first
place these new ndo hooks would be used). There the usecase is:
new_queue.alloc() + old_queue.stop() + new_queue.start() + old_queue.free()
Tested-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Praveen Kaligineedi <pkaligineedi@google.com>
Reviewed-by: Harshitha Ramamurthy <hramamurthy@google.com>
Signed-off-by: Shailend Chand <shailend@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/google/gve/gve_rx.c

@@ -53,6 +53,41 @@ static void gve_rx_unfill_pages(struct gve_priv *priv,
 	rx->data.page_info = NULL;
 }
 
+static void gve_rx_ctx_clear(struct gve_rx_ctx *ctx)
+{
+	ctx->skb_head = NULL;
+	ctx->skb_tail = NULL;
+	ctx->total_size = 0;
+	ctx->frag_cnt = 0;
+	ctx->drop_pkt = false;
+}
+
+static void gve_rx_init_ring_state_gqi(struct gve_rx_ring *rx)
+{
+	rx->desc.seqno = 1;
+	rx->cnt = 0;
+	gve_rx_ctx_clear(&rx->ctx);
+}
+
+static void gve_rx_reset_ring_gqi(struct gve_priv *priv, int idx)
+{
+	struct gve_rx_ring *rx = &priv->rx[idx];
+	const u32 slots = priv->rx_desc_cnt;
+	size_t size;
+
+	/* Reset desc ring */
+	if (rx->desc.desc_ring) {
+		size = slots * sizeof(rx->desc.desc_ring[0]);
+		memset(rx->desc.desc_ring, 0, size);
+	}
+
+	/* Reset q_resources */
+	if (rx->q_resources)
+		memset(rx->q_resources, 0, sizeof(*rx->q_resources));
+
+	gve_rx_init_ring_state_gqi(rx);
+}
+
 void gve_rx_stop_ring_gqi(struct gve_priv *priv, int idx)
 {
 	int ntfy_idx = gve_rx_idx_to_ntfy(priv, idx);
@@ -62,6 +97,7 @@ void gve_rx_stop_ring_gqi(struct gve_priv *priv, int idx)
 
 	gve_remove_napi(priv, ntfy_idx);
 	gve_rx_remove_from_block(priv, idx);
+	gve_rx_reset_ring_gqi(priv, idx);
 }
 
 static void gve_rx_free_ring_gqi(struct gve_priv *priv, struct gve_rx_ring *rx,
@@ -222,15 +258,6 @@ static int gve_rx_prefill_pages(struct gve_rx_ring *rx,
 	return err;
 }
 
-static void gve_rx_ctx_clear(struct gve_rx_ctx *ctx)
-{
-	ctx->skb_head = NULL;
-	ctx->skb_tail = NULL;
-	ctx->total_size = 0;
-	ctx->frag_cnt = 0;
-	ctx->drop_pkt = false;
-}
-
 void gve_rx_start_ring_gqi(struct gve_priv *priv, int idx)
 {
 	int ntfy_idx = gve_rx_idx_to_ntfy(priv, idx);
@@ -309,9 +336,8 @@ static int gve_rx_alloc_ring_gqi(struct gve_priv *priv,
 		err = -ENOMEM;
 		goto abort_with_q_resources;
 	}
-	rx->cnt = 0;
 	rx->db_threshold = slots / 2;
-	rx->desc.seqno = 1;
+	gve_rx_init_ring_state_gqi(rx);
 
 	rx->packet_buffer_size = GVE_DEFAULT_RX_BUFFER_SIZE;
 	gve_rx_ctx_clear(&rx->ctx);

drivers/net/ethernet/google/gve/gve_rx_dqo.c

@@ -211,6 +211,82 @@ static void gve_rx_free_hdr_bufs(struct gve_priv *priv, struct gve_rx_ring *rx)
 	}
 }
 
+static void gve_rx_init_ring_state_dqo(struct gve_rx_ring *rx,
+				       const u32 buffer_queue_slots,
+				       const u32 completion_queue_slots)
+{
+	int i;
+
+	/* Set buffer queue state */
+	rx->dqo.bufq.mask = buffer_queue_slots - 1;
+	rx->dqo.bufq.head = 0;
+	rx->dqo.bufq.tail = 0;
+
+	/* Set completion queue state */
+	rx->dqo.complq.num_free_slots = completion_queue_slots;
+	rx->dqo.complq.mask = completion_queue_slots - 1;
+	rx->dqo.complq.cur_gen_bit = 0;
+	rx->dqo.complq.head = 0;
+
+	/* Set RX SKB context */
+	rx->ctx.skb_head = NULL;
+	rx->ctx.skb_tail = NULL;
+
+	/* Set up linked list of buffer IDs */
+	if (rx->dqo.buf_states) {
+		for (i = 0; i < rx->dqo.num_buf_states - 1; i++)
+			rx->dqo.buf_states[i].next = i + 1;
+		rx->dqo.buf_states[rx->dqo.num_buf_states - 1].next = -1;
+	}
+
+	rx->dqo.free_buf_states = 0;
+	rx->dqo.recycled_buf_states.head = -1;
+	rx->dqo.recycled_buf_states.tail = -1;
+	rx->dqo.used_buf_states.head = -1;
+	rx->dqo.used_buf_states.tail = -1;
+}
+
+static void gve_rx_reset_ring_dqo(struct gve_priv *priv, int idx)
+{
+	struct gve_rx_ring *rx = &priv->rx[idx];
+	size_t size;
+	int i;
+
+	const u32 buffer_queue_slots = priv->rx_desc_cnt;
+	const u32 completion_queue_slots = priv->rx_desc_cnt;
+
+	/* Reset buffer queue */
+	if (rx->dqo.bufq.desc_ring) {
+		size = sizeof(rx->dqo.bufq.desc_ring[0]) *
+			buffer_queue_slots;
+		memset(rx->dqo.bufq.desc_ring, 0, size);
+	}
+
+	/* Reset completion queue */
+	if (rx->dqo.complq.desc_ring) {
+		size = sizeof(rx->dqo.complq.desc_ring[0]) *
+			completion_queue_slots;
+		memset(rx->dqo.complq.desc_ring, 0, size);
+	}
+
+	/* Reset q_resources */
+	if (rx->q_resources)
+		memset(rx->q_resources, 0, sizeof(*rx->q_resources));
+
+	/* Reset buf states */
+	if (rx->dqo.buf_states) {
+		for (i = 0; i < rx->dqo.num_buf_states; i++) {
+			struct gve_rx_buf_state_dqo *bs = &rx->dqo.buf_states[i];
+
+			if (bs->page_info.page)
+				gve_free_page_dqo(priv, bs, !rx->dqo.qpl);
+		}
+	}
+
+	gve_rx_init_ring_state_dqo(rx, buffer_queue_slots,
+				   completion_queue_slots);
+}
+
 void gve_rx_stop_ring_dqo(struct gve_priv *priv, int idx)
 {
 	int ntfy_idx = gve_rx_idx_to_ntfy(priv, idx);
@@ -220,6 +296,7 @@ void gve_rx_stop_ring_dqo(struct gve_priv *priv, int idx)
 
 	gve_remove_napi(priv, ntfy_idx);
 	gve_rx_remove_from_block(priv, idx);
+	gve_rx_reset_ring_dqo(priv, idx);
 }
 
 static void gve_rx_free_ring_dqo(struct gve_priv *priv, struct gve_rx_ring *rx,
@@ -273,10 +350,10 @@ static void gve_rx_free_ring_dqo(struct gve_priv *priv, struct gve_rx_ring *rx,
 	netif_dbg(priv, drv, priv->dev, "freed rx ring %d\n", idx);
 }
 
-static int gve_rx_alloc_hdr_bufs(struct gve_priv *priv, struct gve_rx_ring *rx)
+static int gve_rx_alloc_hdr_bufs(struct gve_priv *priv, struct gve_rx_ring *rx,
+				 const u32 buf_count)
 {
 	struct device *hdev = &priv->pdev->dev;
-	int buf_count = rx->dqo.bufq.mask + 1;
 
 	rx->dqo.hdr_bufs.data = dma_alloc_coherent(hdev, priv->header_buf_size * buf_count,
 						   &rx->dqo.hdr_bufs.addr, GFP_KERNEL);
@@ -301,7 +378,6 @@ static int gve_rx_alloc_ring_dqo(struct gve_priv *priv,
 {
 	struct device *hdev = &priv->pdev->dev;
 	size_t size;
-	int i;
 
 	const u32 buffer_queue_slots = cfg->ring_size;
 	const u32 completion_queue_slots = cfg->ring_size;
@@ -311,11 +387,6 @@ static int gve_rx_alloc_ring_dqo(struct gve_priv *priv,
 	memset(rx, 0, sizeof(*rx));
 	rx->gve = priv;
 	rx->q_num = idx;
-	rx->dqo.bufq.mask = buffer_queue_slots - 1;
-	rx->dqo.complq.num_free_slots = completion_queue_slots;
-	rx->dqo.complq.mask = completion_queue_slots - 1;
-	rx->ctx.skb_head = NULL;
-	rx->ctx.skb_tail = NULL;
 
 	rx->dqo.num_buf_states = cfg->raw_addressing ?
 		min_t(s16, S16_MAX, buffer_queue_slots * 4) :
@@ -328,19 +399,9 @@ static int gve_rx_alloc_ring_dqo(struct gve_priv *priv,
 
 	/* Allocate header buffers for header-split */
 	if (cfg->enable_header_split)
-		if (gve_rx_alloc_hdr_bufs(priv, rx))
+		if (gve_rx_alloc_hdr_bufs(priv, rx, buffer_queue_slots))
 			goto err;
 
-	/* Set up linked list of buffer IDs */
-	for (i = 0; i < rx->dqo.num_buf_states - 1; i++)
-		rx->dqo.buf_states[i].next = i + 1;
-
-	rx->dqo.buf_states[rx->dqo.num_buf_states - 1].next = -1;
-	rx->dqo.recycled_buf_states.head = -1;
-	rx->dqo.recycled_buf_states.tail = -1;
-	rx->dqo.used_buf_states.head = -1;
-	rx->dqo.used_buf_states.tail = -1;
-
 	/* Allocate RX completion queue */
 	size = sizeof(rx->dqo.complq.desc_ring[0]) *
 		completion_queue_slots;
@@ -368,6 +429,9 @@ static int gve_rx_alloc_ring_dqo(struct gve_priv *priv,
 	if (!rx->q_resources)
 		goto err;
 
+	gve_rx_init_ring_state_dqo(rx, buffer_queue_slots,
+				   completion_queue_slots);
+
 	return 0;
 
 err: