um: Migrate vector drivers to NAPI

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

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c
index 4fc1a5d70dcf31fd11a8a479112fbef662ea4921..1d6f6a66766c685881c01790c60f27b8ea7bdb67 100644 (file)
--- a/arch/um/drivers/vector_kern.c
+++ b/arch/um/drivers/vector_kern.c
@@ -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 @@ out_fail:
 
 /*
  * 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 @@ drop:
  * 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);

diff --git a/arch/um/drivers/vector_kern.h b/arch/um/drivers/vector_kern.h
index 8fff93a75a927e0d69cd8528ada8d8616ac78151..2a1fa8e0f3e149c6f5617251d0bf8ef51975fcd1 100644 (file)
--- a/arch/um/drivers/vector_kern.h
+++ b/arch/um/drivers/vector_kern.h
@@ -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;