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Date:   Mon, 27 Feb 2017 10:26:49 -0800
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, Stephen Hemminger <sthemmin@...rosoft.com>
Subject: [PATCH 3/5] netvsc: implement NAPI

Use NAPI (softirq), to handle receive packets and send completions.
Previously this was handled by tasklet.

Signed-off-by: Stephen Hemminger <sthemmin@...rosoft.com>
---
 drivers/net/hyperv/hyperv_net.h   |   2 +
 drivers/net/hyperv/netvsc.c       | 140 ++++++++++++++++++++++++++------------
 drivers/net/hyperv/netvsc_drv.c   |   5 --
 drivers/net/hyperv/rndis_filter.c |   2 +
 4 files changed, 102 insertions(+), 47 deletions(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index d3e73ac158ae..7433b164e513 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -196,6 +196,7 @@ int netvsc_recv_callback(struct net_device *net,
 			 const struct ndis_tcp_ip_checksum_info *csum_info,
 			 const struct ndis_pkt_8021q_info *vlan);
 void netvsc_channel_cb(void *context);
+int netvsc_poll(struct napi_struct *napi, int budget);
 int rndis_filter_open(struct netvsc_device *nvdev);
 int rndis_filter_close(struct netvsc_device *nvdev);
 int rndis_filter_device_add(struct hv_device *dev,
@@ -720,6 +721,7 @@ struct net_device_context {
 /* Per channel data */
 struct netvsc_channel {
 	struct vmbus_channel *channel;
+	struct napi_struct napi;
 	struct multi_send_data msd;
 	struct multi_recv_comp mrc;
 	atomic_t queue_sends;
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 3681fb59bdbe..b1328cef9d5a 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -556,6 +556,7 @@ void netvsc_device_remove(struct hv_device *device)
 	struct net_device *ndev = hv_get_drvdata(device);
 	struct net_device_context *net_device_ctx = netdev_priv(ndev);
 	struct netvsc_device *net_device = net_device_ctx->nvdev;
+	int i;
 
 	netvsc_disconnect_vsp(device);
 
@@ -570,6 +571,9 @@ void netvsc_device_remove(struct hv_device *device)
 	/* Now, we can close the channel safely */
 	vmbus_close(device->channel);
 
+	for (i = 0; i < VRSS_CHANNEL_MAX; i++)
+		napi_disable(&net_device->chan_table[0].napi);
+
 	/* Release all resources */
 	free_netvsc_device(net_device);
 }
@@ -1063,7 +1067,7 @@ static inline struct recv_comp_data *get_recv_comp_slot(
 	return rcd;
 }
 
-static void netvsc_receive(struct net_device *ndev,
+static int netvsc_receive(struct net_device *ndev,
 		   struct netvsc_device *net_device,
 		   struct net_device_context *net_device_ctx,
 		   struct hv_device *device,
@@ -1073,20 +1077,19 @@ static void netvsc_receive(struct net_device *ndev,
 {
 	const struct vmtransfer_page_packet_header *vmxferpage_packet
 		= container_of(desc, const struct vmtransfer_page_packet_header, d);
+	u16 q_idx = channel->offermsg.offer.sub_channel_index;
 	char *recv_buf = net_device->recv_buf;
 	u32 status = NVSP_STAT_SUCCESS;
 	int i;
 	int count = 0;
 	int ret;
-	struct recv_comp_data *rcd;
-	u16 q_idx = channel->offermsg.offer.sub_channel_index;
 
 	/* Make sure this is a valid nvsp packet */
 	if (unlikely(nvsp->hdr.msg_type != NVSP_MSG1_TYPE_SEND_RNDIS_PKT)) {
 		netif_err(net_device_ctx, rx_err, ndev,
 			  "Unknown nvsp packet type received %u\n",
 			  nvsp->hdr.msg_type);
-		return;
+		return 0;
 	}
 
 	if (unlikely(vmxferpage_packet->xfer_pageset_id != NETVSC_RECEIVE_BUFFER_ID)) {
@@ -1094,7 +1097,7 @@ static void netvsc_receive(struct net_device *ndev,
 			  "Invalid xfer page set id - expecting %x got %x\n",
 			  NETVSC_RECEIVE_BUFFER_ID,
 			  vmxferpage_packet->xfer_pageset_id);
-		return;
+		return 0;
 	}
 
 	count = vmxferpage_packet->range_cnt;
@@ -1110,26 +1113,26 @@ static void netvsc_receive(struct net_device *ndev,
 					      channel, data, buflen);
 	}
 
-	if (!net_device->chan_table[q_idx].mrc.buf) {
+	if (net_device->chan_table[q_idx].mrc.buf) {
+		struct recv_comp_data *rcd;
+
+		rcd = get_recv_comp_slot(net_device, channel, q_idx);
+		if (rcd) {
+			rcd->tid = vmxferpage_packet->d.trans_id;
+			rcd->status = status;
+		} else {
+			netdev_err(ndev, "Recv_comp full buf q:%hd, tid:%llx\n",
+				   q_idx, vmxferpage_packet->d.trans_id);
+		}
+	} else {
 		ret = netvsc_send_recv_completion(channel,
 						  vmxferpage_packet->d.trans_id,
 						  status);
 		if (ret)
 			netdev_err(ndev, "Recv_comp q:%hd, tid:%llx, err:%d\n",
 				   q_idx, vmxferpage_packet->d.trans_id, ret);
-		return;
 	}
-
-	rcd = get_recv_comp_slot(net_device, channel, q_idx);
-
-	if (!rcd) {
-		netdev_err(ndev, "Recv_comp full buf q:%hd, tid:%llx\n",
-			   q_idx, vmxferpage_packet->d.trans_id);
-		return;
-	}
-
-	rcd->tid = vmxferpage_packet->d.trans_id;
-	rcd->status = status;
+	return count;
 }
 
 static void netvsc_send_table(struct hv_device *hdev,
@@ -1179,12 +1182,12 @@ static inline void netvsc_receive_inband(struct hv_device *hdev,
 	}
 }
 
-static void netvsc_process_raw_pkt(struct hv_device *device,
-				   struct vmbus_channel *channel,
-				   struct netvsc_device *net_device,
-				   struct net_device *ndev,
-				   u64 request_id,
-				   const struct vmpacket_descriptor *desc)
+static int netvsc_process_raw_pkt(struct hv_device *device,
+				  struct vmbus_channel *channel,
+				  struct netvsc_device *net_device,
+				  struct net_device *ndev,
+				  u64 request_id,
+				  const struct vmpacket_descriptor *desc)
 {
 	struct net_device_context *net_device_ctx = netdev_priv(ndev);
 	struct nvsp_message *nvmsg = hv_pkt_data(desc);
@@ -1195,8 +1198,8 @@ static void netvsc_process_raw_pkt(struct hv_device *device,
 		break;
 
 	case VM_PKT_DATA_USING_XFER_PAGES:
-		netvsc_receive(ndev, net_device, net_device_ctx,
-			       device, channel, desc, nvmsg);
+		return netvsc_receive(ndev, net_device, net_device_ctx,
+				      device, channel, desc, nvmsg);
 		break;
 
 	case VM_PKT_DATA_INBAND:
@@ -1208,22 +1211,64 @@ static void netvsc_process_raw_pkt(struct hv_device *device,
 			   desc->type, request_id);
 		break;
 	}
+
+	return 0;
+}
+
+static struct hv_device *netvsc_channel_to_device(struct vmbus_channel *channel)
+{
+	struct vmbus_channel *primary = channel->primary_channel;
+
+	return primary ? primary->device_obj : channel->device_obj;
+}
+
+int netvsc_poll(struct napi_struct *napi, int budget)
+{
+	struct netvsc_channel *nvchan
+		= container_of(napi, struct netvsc_channel, napi);
+	struct vmbus_channel *channel = nvchan->channel;
+	struct hv_device *device = netvsc_channel_to_device(channel);
+	u16 q_idx = channel->offermsg.offer.sub_channel_index;
+	struct net_device *ndev = hv_get_drvdata(device);
+	struct netvsc_device *net_device = net_device_to_netvsc_device(ndev);
+	const struct vmpacket_descriptor *desc;
+	int work_done = 0;
+
+	desc = hv_pkt_iter_first(channel);
+	while (desc) {
+		int count;
+
+		count = netvsc_process_raw_pkt(device, channel, net_device,
+					       ndev, desc->trans_id, desc);
+		work_done += count;
+		desc = __hv_pkt_iter_next(channel, desc);
+
+		/* If receive packet budget is exhausted, reschedule */
+		if (work_done >= budget) {
+			work_done = budget;
+			break;
+		}
+	}
+	hv_pkt_iter_close(channel);
+
+	/* If ring is empty and NAPI is not doing polling */
+	if (work_done < budget &&
+	    napi_complete_done(napi, work_done) &&
+	    hv_end_read(&channel->inbound) != 0)
+		napi_reschedule(napi);
+
+	netvsc_chk_recv_comp(net_device, channel, q_idx);
+	return work_done;
 }
 
 void netvsc_channel_cb(void *context)
 {
 	struct vmbus_channel *channel = context;
+	struct hv_device *device = netvsc_channel_to_device(channel);
 	u16 q_idx = channel->offermsg.offer.sub_channel_index;
-	struct hv_device *device;
 	struct netvsc_device *net_device;
-	struct vmpacket_descriptor *desc;
 	struct net_device *ndev;
 
-	if (channel->primary_channel != NULL)
-		device = channel->primary_channel->device_obj;
-	else
-		device = channel->device_obj;
-
 	ndev = hv_get_drvdata(device);
 	if (unlikely(!ndev))
 		return;
@@ -1233,13 +1278,9 @@ void netvsc_channel_cb(void *context)
 	    netvsc_channel_idle(net_device, q_idx))
 		return;
 
-	foreach_vmbus_pkt(desc, channel) {
-		netvsc_process_raw_pkt(device, channel, net_device,
-				       ndev, desc->trans_id, desc);
-
-	}
-
-	netvsc_chk_recv_comp(net_device, channel, q_idx);
+	/* disable interupts from host */
+	hv_begin_read(&channel->inbound);
+	napi_schedule(&net_device->chan_table[q_idx].napi);
 }
 
 /*
@@ -1261,6 +1302,11 @@ int netvsc_device_add(struct hv_device *device,
 
 	net_device->ring_size = ring_size;
 
+	/* Because the device uses NAPI, all the interrupt batching and
+	 * control is done via Net softirq, not the channel handling
+	 */
+	set_channel_read_mode(device->channel, HV_CALL_ISR);
+
 	/* Open the channel */
 	ret = vmbus_open(device->channel, ring_size * PAGE_SIZE,
 			 ring_size * PAGE_SIZE, NULL, 0,
@@ -1278,8 +1324,16 @@ int netvsc_device_add(struct hv_device *device,
 	 * chn_table with the default channel to use it before subchannels are
 	 * opened.
 	 */
-	for (i = 0; i < VRSS_CHANNEL_MAX; i++)
-		net_device->chan_table[i].channel = device->channel;
+	for (i = 0; i < VRSS_CHANNEL_MAX; i++) {
+		struct netvsc_channel *nvchan = &net_device->chan_table[i];
+
+		nvchan->channel = device->channel;
+		netif_napi_add(ndev, &nvchan->napi,
+			       netvsc_poll, NAPI_POLL_WEIGHT);
+	}
+
+	/* Enable NAPI handler for init callbacks */
+	napi_enable(&net_device->chan_table[0].napi);
 
 	/* Writing nvdev pointer unlocks netvsc_send(), make sure chn_table is
 	 * populated.
@@ -1299,6 +1353,8 @@ int netvsc_device_add(struct hv_device *device,
 	return ret;
 
 close:
+	napi_disable(&net_device->chan_table[0].napi);
+
 	/* Now, we can close the channel safely */
 	vmbus_close(device->channel);
 
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 2d3cdb026a99..54b6cab5af23 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -690,11 +690,6 @@ int netvsc_recv_callback(struct net_device *net,
 		++rx_stats->multicast;
 	u64_stats_update_end(&rx_stats->syncp);
 
-	/*
-	 * Pass the skb back up. Network stack will deallocate the skb when it
-	 * is done.
-	 * TODO - use NAPI?
-	 */
 	netif_receive_skb(skb);
 	rcu_read_unlock();
 
diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 19356f56b7b1..d7b6311e6c19 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -1012,6 +1012,8 @@ static void netvsc_sc_open(struct vmbus_channel *new_sc)
 	if (ret == 0)
 		nvscdev->chan_table[chn_index].channel = new_sc;
 
+	napi_enable(&nvscdev->chan_table[chn_index].napi);
+
 	spin_lock_irqsave(&nvscdev->sc_lock, flags);
 	nvscdev->num_sc_offered--;
 	spin_unlock_irqrestore(&nvscdev->sc_lock, flags);
-- 
2.11.0

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