Commit b35507a4 authored by Anton Ivanov's avatar Anton Ivanov Committed by Richard Weinberger
Browse files

um: Migrate vector drivers to NAPI 



Migrate UML vector drivers from a bespoke scheduling mechanism
to NAPI.

Signed-off-by: default avatarAnton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
parent 39508aab

arch/um/drivers/vector_kern.c

+49 −56
Original line number Diff line number Diff line
@@ -67,6 +67,7 @@ static LIST_HEAD(vector_devices); 
static int driver_registered;



static void vector_eth_configure(int n, struct arglist *def);

static int vector_mmsg_rx(struct vector_private *vp, int budget);



/* Argument accessors to set variables (and/or set default values)

 * mtu, buffer sizing, default headroom, etc
@@ -77,7 +78,6 @@ static void vector_eth_configure(int n, struct arglist *def); 
#define DEFAULT_VECTOR_SIZE 64

#define TX_SMALL_PACKET 128

#define MAX_IOV_SIZE (MAX_SKB_FRAGS + 1)

#define MAX_ITERATIONS 64



static const struct {

	const char string[ETH_GSTRING_LEN];
@@ -458,7 +458,6 @@ static int vector_send(struct vector_queue *qi) 
					vp->estats.tx_queue_running_average =

						(vp->estats.tx_queue_running_average + result) >> 1;

				}

				netif_trans_update(qi->dev);

				netif_wake_queue(qi->dev);

				/* if TX is busy, break out of the send loop,

				 *  poll write IRQ will reschedule xmit for us
@@ -470,8 +469,6 @@ static int vector_send(struct vector_queue *qi) 
			}

		}

		spin_unlock(&qi->head_lock);

	} else {

		tasklet_schedule(&vp->tx_poll);

	}

	return queue_depth;

}
@@ -608,7 +605,7 @@ static struct vector_queue *create_queue( 


/*

 * We do not use the RX queue as a proper wraparound queue for now

 * This is not necessary because the consumption via netif_rx()

 * This is not necessary because the consumption via napi_gro_receive()

 * happens in-line. While we can try using the return code of

 * netif_rx() for flow control there are no drivers doing this today.

 * For this RX specific use we ignore the tail/head locks and
@@ -896,7 +893,7 @@ static int vector_legacy_rx(struct vector_private *vp) 
			skb->protocol = eth_type_trans(skb, skb->dev);

			vp->dev->stats.rx_bytes += skb->len;

			vp->dev->stats.rx_packets++;

			netif_rx(skb);

			napi_gro_receive(&vp->napi, skb);

		} else {

			dev_kfree_skb_irq(skb);

		}
@@ -955,7 +952,7 @@ static int writev_tx(struct vector_private *vp, struct sk_buff *skb) 
 * mmsg vector matched to an skb vector which we prepared earlier.

 */



static int vector_mmsg_rx(struct vector_private *vp)

static int vector_mmsg_rx(struct vector_private *vp, int budget)

{

	int packet_count, i;

	struct vector_queue *qi = vp->rx_queue;
@@ -972,6 +969,9 @@ static int vector_mmsg_rx(struct vector_private *vp) 


	/* Fire the Lazy Gun - get as many packets as we can in one go. */



	if (budget > qi->max_depth)

		budget = qi->max_depth;



	packet_count = uml_vector_recvmmsg(

		vp->fds->rx_fd, qi->mmsg_vector, qi->max_depth, 0);
@@ -1021,7 +1021,7 @@ static int vector_mmsg_rx(struct vector_private *vp) 
			 */

			vp->dev->stats.rx_bytes += skb->len;

			vp->dev->stats.rx_packets++;

			netif_rx(skb);

			napi_gro_receive(&vp->napi, skb);

		} else {

			/* Overlay header too short to do anything - discard.

			 * We can actually keep this skb and reuse it,
@@ -1044,23 +1044,6 @@ static int vector_mmsg_rx(struct vector_private *vp) 
	return packet_count;

}



static void vector_rx(struct vector_private *vp)

{

	int err;

	int iter = 0;



	if ((vp->options & VECTOR_RX) > 0)

		while (((err = vector_mmsg_rx(vp)) > 0) && (iter < MAX_ITERATIONS))

			iter++;

	else

		while (((err = vector_legacy_rx(vp)) > 0) && (iter < MAX_ITERATIONS))

			iter++;

	if ((err != 0) && net_ratelimit())

		netdev_err(vp->dev, "vector_rx: error(%d)\n", err);

	if (iter == MAX_ITERATIONS)

		netdev_err(vp->dev, "vector_rx: device stuck, remote end may have closed the connection\n");

}



static int vector_net_start_xmit(struct sk_buff *skb, struct net_device *dev)

{

	struct vector_private *vp = netdev_priv(dev);
@@ -1085,25 +1068,15 @@ static int vector_net_start_xmit(struct sk_buff *skb, struct net_device *dev) 
	netdev_sent_queue(vp->dev, skb->len);

	queue_depth = vector_enqueue(vp->tx_queue, skb);



	/* if the device queue is full, stop the upper layers and

	 * flush it.

	 */



	if (queue_depth >= vp->tx_queue->max_depth - 1) {

		vp->estats.tx_kicks++;

		netif_stop_queue(dev);

		vector_send(vp->tx_queue);

		return NETDEV_TX_OK;

	}

	if (netdev_xmit_more()) {

	if (queue_depth < vp->tx_queue->max_depth && netdev_xmit_more()) {

		mod_timer(&vp->tl, vp->coalesce);

		return NETDEV_TX_OK;

	} else {

		queue_depth = vector_send(vp->tx_queue);

		if (queue_depth > 0)

			napi_schedule(&vp->napi);

	}

	if (skb->len < TX_SMALL_PACKET) {

		vp->estats.tx_kicks++;

		vector_send(vp->tx_queue);

	} else

		tasklet_schedule(&vp->tx_poll);



	return NETDEV_TX_OK;

}
@@ -1114,7 +1087,7 @@ static irqreturn_t vector_rx_interrupt(int irq, void *dev_id) 


	if (!netif_running(dev))

		return IRQ_NONE;

	vector_rx(vp);

	napi_schedule(&vp->napi);

	return IRQ_HANDLED;



}
@@ -1133,8 +1106,7 @@ static irqreturn_t vector_tx_interrupt(int irq, void *dev_id) 
	 * tweaking the IRQ mask less costly

	 */



	if (vp->in_write_poll)

		tasklet_schedule(&vp->tx_poll);

	napi_schedule(&vp->napi);

	return IRQ_HANDLED;



}
@@ -1161,7 +1133,8 @@ static int vector_net_close(struct net_device *dev) 
		um_free_irq(vp->tx_irq, dev);

		vp->tx_irq = 0;

	}

	tasklet_kill(&vp->tx_poll);

	napi_disable(&vp->napi);

	netif_napi_del(&vp->napi);

	if (vp->fds->rx_fd > 0) {

		if (vp->bpf)

			uml_vector_detach_bpf(vp->fds->rx_fd, vp->bpf);
@@ -1193,15 +1166,32 @@ static int vector_net_close(struct net_device *dev) 
	return 0;

}



/* TX tasklet */



static void vector_tx_poll(struct tasklet_struct *t)

static int vector_poll(struct napi_struct *napi, int budget)

{

	struct vector_private *vp = from_tasklet(vp, t, tx_poll);

	struct vector_private *vp = container_of(napi, struct vector_private, napi);

	int work_done = 0;

	int err;

	bool tx_enqueued = false;



	vp->estats.tx_kicks++;

	vector_send(vp->tx_queue);

	if ((vp->options & VECTOR_TX) != 0)

		tx_enqueued = (vector_send(vp->tx_queue) > 0);

	if ((vp->options & VECTOR_RX) > 0)

		err = vector_mmsg_rx(vp, budget);

	else {

		err = vector_legacy_rx(vp);

		if (err > 0)

			err = 1;

	}

	if (err > 0)

		work_done += err;



	if (tx_enqueued || err > 0)

		napi_schedule(napi);

	if (work_done < budget)

		napi_complete_done(napi, work_done);

	return work_done;

}



static void vector_reset_tx(struct work_struct *work)

{

	struct vector_private *vp =
@@ -1265,6 +1255,9 @@ static int vector_net_open(struct net_device *dev) 
			goto out_close;

	}



	netif_napi_add(vp->dev, &vp->napi, vector_poll, get_depth(vp->parsed));

	napi_enable(&vp->napi);



	/* READ IRQ */

	err = um_request_irq(

		irq_rr + VECTOR_BASE_IRQ, vp->fds->rx_fd,
@@ -1306,15 +1299,15 @@ static int vector_net_open(struct net_device *dev) 
		uml_vector_attach_bpf(vp->fds->rx_fd, vp->bpf);



	netif_start_queue(dev);

	vector_reset_stats(vp);



	/* clear buffer - it can happen that the host side of the interface

	 * is full when we get here. In this case, new data is never queued,

	 * SIGIOs never arrive, and the net never works.

	 */



	vector_rx(vp);

	napi_schedule(&vp->napi);



	vector_reset_stats(vp);

	vdevice = find_device(vp->unit);

	vdevice->opened = 1;
@@ -1543,15 +1536,16 @@ static const struct net_device_ops vector_netdev_ops = { 
#endif

};





static void vector_timer_expire(struct timer_list *t)

{

	struct vector_private *vp = from_timer(vp, t, tl);



	vp->estats.tx_kicks++;

	vector_send(vp->tx_queue);

	napi_schedule(&vp->napi);

}







static void vector_eth_configure(

		int n,

		struct arglist *def
@@ -1634,7 +1628,6 @@ static void vector_eth_configure( 
	});



	dev->features = dev->hw_features = (NETIF_F_SG | NETIF_F_FRAGLIST);

	tasklet_setup(&vp->tx_poll, vector_tx_poll);

	INIT_WORK(&vp->reset_tx, vector_reset_tx);



	timer_setup(&vp->tl, vector_timer_expire, 0);

arch/um/drivers/vector_kern.h

+2 −1
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/ctype.h>

#include <linux/workqueue.h>

#include <linux/interrupt.h>



#include "vector_user.h"



/* Queue structure specially adapted for multiple enqueue/dequeue
@@ -72,6 +73,7 @@ struct vector_private { 
	struct list_head list;

	spinlock_t lock;

	struct net_device *dev;

	struct napi_struct		napi	____cacheline_aligned;



	int unit;
@@ -115,7 +117,6 @@ struct vector_private { 


	spinlock_t stats_lock;



	struct tasklet_struct tx_poll;

	bool rexmit_scheduled;

	bool opened;

	bool in_write_poll;