[PATCH] um: Migrate vector drivers to NAPI
anton.ivanov at cambridgegreys.com
anton.ivanov at cambridgegreys.com
Fri Jan 21 00:55:57 PST 2022
From: Anton Ivanov <anton.ivanov at cambridgegreys.com>
Migrate UML vector drivers from a bespoke scheduling mechanism
to NAPI.
Signed-off-by: Anton Ivanov <anton.ivanov at cambridgegreys.com>
---
arch/um/drivers/vector_kern.c | 99 ++++++++++++++++-------------------
arch/um/drivers/vector_kern.h | 3 +-
2 files changed, 48 insertions(+), 54 deletions(-)
diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c
index 4fc1a5d70dcf..1bad55cb116b 100644
--- 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);
/* Argument accessors to set variables (and/or set default values)
* mtu, buffer sizing, default headroom, etc
@@ -458,7 +459,6 @@ 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 +470,6 @@ static int vector_send(struct vector_queue *qi)
}
}
spin_unlock(&qi->head_lock);
- } else {
- tasklet_schedule(&vp->tx_poll);
}
return queue_depth;
}
@@ -608,7 +606,7 @@ 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 +894,7 @@ 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);
}
@@ -1021,7 +1019,7 @@ 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 +1042,6 @@ 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 +1066,15 @@ 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 +1085,7 @@ 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 +1104,7 @@ 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 +1131,7 @@ 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);
+ 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 +1163,32 @@ 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);
+ 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 =
@@ -1264,6 +1251,10 @@ static int vector_net_open(struct net_device *dev)
if (vp->header_txbuffer == NULL)
goto out_close;
}
+ /* NAPI */
+
+ netif_napi_add(vp->dev, &vp->napi, vector_poll, 64);
+ napi_enable(&vp->napi);
/* READ IRQ */
err = um_request_irq(
@@ -1312,9 +1303,11 @@ static int vector_net_open(struct net_device *dev)
* SIGIOs never arrive, and the net never works.
*/
- vector_rx(vp);
vector_reset_stats(vp);
+
+ napi_schedule(&vp->napi);
+
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 8fff93a75a92..2a1fa8e0f3e1 100644
--- 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;
--
2.30.2
More information about the linux-um
mailing list