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um: Migrate vector drivers to NAPI

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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>
This commit is contained in:
Anton Ivanov 2022-01-21 11:11:49 +00:00 committed by Richard Weinberger
parent 39508aab4a
commit b35507a4cf
2 changed files with 51 additions and 57 deletions
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105
arch/um/drivers/vector_kern.c
View File

@ -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);

3
arch/um/drivers/vector_kern.h
View File

@ -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;