Commit b220f5f9 authored by Stephen Hemminger's avatar Stephen Hemminger Committed by Greg Kroah-Hartman
Browse files

Staging: hv: add transmit flow control 



Keep track of the number of pages sent over transmit and stop
before going over.

Signed-off-by: default avatarStephen Hemminger <shemminger@vyatta.com>
Acked-by: default avatarHank Janssen <hjanssen@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 6048718d

drivers/staging/hv/netvsc_drv.c

+27 −45
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ 
struct net_device_context {

	/* point back to our device context */

	struct vm_device *device_ctx;

	unsigned long avail;

};



struct netvsc_driver_context {
@@ -52,8 +53,10 @@ struct netvsc_driver_context { 
	struct netvsc_driver drv_obj;

};



/* Need at least MAX_SKB_FRAGS (18) + 1

   to handle worst case fragmented packet */

#define PACKET_PAGES_LOWATER  8

/* Need this many pages to handle worst case fragmented packet */

#define PACKET_PAGES_HIWATER  (MAX_SKB_FRAGS + 2)



static int ring_size = roundup_pow_of_two(2*MAX_SKB_FRAGS+1);

module_param(ring_size, int, S_IRUGO);

MODULE_PARM_DESC(ring_size, "Ring buffer size (# of pages)");
@@ -122,15 +125,14 @@ static void netvsc_xmit_completion(void *context) 


	if (skb) {

		struct net_device *net = skb->dev;

		dev_kfree_skb_any(skb);

		struct net_device_context *net_device_ctx = netdev_priv(net);

		unsigned int num_pages = skb_shinfo(skb)->nr_frags + 2;



		if (netif_queue_stopped(net)) {

			DPRINT_INFO(NETVSC_DRV, "net device (%p) waking up...",

				    net);

		dev_kfree_skb_any(skb);



		if ((net_device_ctx->avail += num_pages) >= PACKET_PAGES_HIWATER)

 			netif_wake_queue(net);

	}

	}



	DPRINT_EXIT(NETVSC_DRV);

}
@@ -146,7 +148,6 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net) 
	struct hv_netvsc_packet *packet;

	int ret;

	unsigned int i, num_pages;

	int retries = 0;



	DPRINT_ENTER(NETVSC_DRV);
@@ -155,14 +156,20 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net) 


	/* Add 1 for skb->data and additional one for RNDIS */

	num_pages = skb_shinfo(skb)->nr_frags + 1 + 1;

	if (num_pages > net_device_ctx->avail)

		return NETDEV_TX_BUSY;



	/* Allocate a netvsc packet based on # of frags. */

	packet = kzalloc(sizeof(struct hv_netvsc_packet) +

			 (num_pages * sizeof(struct hv_page_buffer)) +

			 net_drv_obj->RequestExtSize, GFP_ATOMIC);

	if (!packet) {

		/* out of memory, silently drop packet */

		DPRINT_ERR(NETVSC_DRV, "unable to allocate hv_netvsc_packet");

		return -1;



		dev_kfree_skb(skb);

		net->stats.tx_dropped++;

		return NETDEV_TX_OK;

	}



	packet->Extension = (void *)(unsigned long)packet +
@@ -198,52 +205,26 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net) 
	packet->Completion.Send.SendCompletionContext = packet;

	packet->Completion.Send.SendCompletionTid = (unsigned long)skb;



retry_send:

	ret = net_drv_obj->OnSend(&net_device_ctx->device_ctx->device_obj,

				  packet);



	if (ret == 0) {

		ret = NETDEV_TX_OK;

		net->stats.tx_bytes += skb->len;

		net->stats.tx_packets++;

	} else {

		retries++;

		if (retries < 4) {

			DPRINT_ERR(NETVSC_DRV, "unable to send..."

					"retrying %d...", retries);

			udelay(100);

			goto retry_send;

		}



		/* no more room or we are shutting down */

		DPRINT_ERR(NETVSC_DRV, "unable to send (%d)..."

			   "marking net device (%p) busy", ret, net);

		DPRINT_INFO(NETVSC_DRV, "net device (%p) stopping", net);



		ret = NETDEV_TX_BUSY;

		net->stats.tx_dropped++;



		netif_stop_queue(net);



		/*

		 * Null it since the caller will free it instead of the

		 * completion routine

		 */

		packet->Completion.Send.SendCompletionTid = 0;



		/*

		 * Release the resources since we will not get any send

		 * completion

		 */

		netvsc_xmit_completion((void *)packet);

	}



		DPRINT_DBG(NETVSC_DRV, "# of xmits %lu total size %lu",

			   net->stats.tx_packets,

			   net->stats.tx_bytes);



		if ((net_device_ctx->avail -= num_pages) < PACKET_PAGES_LOWATER)

			netif_stop_queue(net);

	} else {

		/* we are shutting down or bus overloaded, just drop packet */

		net->stats.tx_dropped++;

		netvsc_xmit_completion(packet);

	}



	DPRINT_EXIT(NETVSC_DRV);

	return ret;

	return NETDEV_TX_OK;

}



/*
@@ -382,6 +363,7 @@ static int netvsc_probe(struct device *device) 


	net_device_ctx = netdev_priv(net);

	net_device_ctx->device_ctx = device_ctx;

	net_device_ctx->avail = ring_size;

	dev_set_drvdata(device, net);



	/* Notify the netvsc driver of the new device */