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mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-25 05:34:00 +08:00
linux-next/net/core/gro_cells.c
David S. Miller b5cdae3291 net: Generic XDP
This provides a generic SKB based non-optimized XDP path which is used
if either the driver lacks a specific XDP implementation, or the user
requests it via a new IFLA_XDP_FLAGS value named XDP_FLAGS_SKB_MODE.

It is arguable that perhaps I should have required something like
this as part of the initial XDP feature merge.

I believe this is critical for two reasons:

1) Accessibility.  More people can play with XDP with less
   dependencies.  Yes I know we have XDP support in virtio_net, but
   that just creates another depedency for learning how to use this
   facility.

   I wrote this to make life easier for the XDP newbies.

2) As a model for what the expected semantics are.  If there is a pure
   generic core implementation, it serves as a semantic example for
   driver folks adding XDP support.

One thing I have not tried to address here is the issue of
XDP_PACKET_HEADROOM, thanks to Daniel for spotting that.  It seems
incredibly expensive to do a skb_cow(skb, XDP_PACKET_HEADROOM) or
whatever even if the XDP program doesn't try to push headers at all.
I think we really need the verifier to somehow propagate whether
certain XDP helpers are used or not.

v5:
 - Handle both negative and positive offset after running prog
 - Fix mac length in XDP_TX case (Alexei)
 - Use rcu_dereference_protected() in free_netdev (kbuild test robot)

v4:
 - Fix MAC header adjustmnet before calling prog (David Ahern)
 - Disable LRO when generic XDP is installed (Michael Chan)
 - Bypass qdisc et al. on XDP_TX and record the event (Alexei)
 - Do not perform generic XDP on reinjected packets (DaveM)

v3:
 - Make sure XDP program sees packet at MAC header, push back MAC
   header if we do XDP_TX.  (Alexei)
 - Elide GRO when generic XDP is in use.  (Alexei)
 - Add XDP_FLAG_SKB_MODE flag which the user can use to request generic
   XDP even if the driver has an XDP implementation.  (Alexei)
 - Report whether SKB mode is in use in rtnl_xdp_fill() via XDP_FLAGS
   attribute.  (Daniel)

v2:
 - Add some "fall through" comments in switch statements based
   upon feedback from Andrew Lunn
 - Use RCU for generic xdp_prog, thanks to Johannes Berg.

Tested-by: Andy Gospodarek <andy@greyhouse.net>
Tested-by: Jesper Dangaard Brouer <brouer@redhat.com>
Tested-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-25 13:33:49 -04:00

93 lines
2.0 KiB
C

#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <net/gro_cells.h>
struct gro_cell {
struct sk_buff_head napi_skbs;
struct napi_struct napi;
};
int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
{
struct net_device *dev = skb->dev;
struct gro_cell *cell;
if (!gcells->cells || skb_cloned(skb) || netif_elide_gro(dev))
return netif_rx(skb);
cell = this_cpu_ptr(gcells->cells);
if (skb_queue_len(&cell->napi_skbs) > netdev_max_backlog) {
atomic_long_inc(&dev->rx_dropped);
kfree_skb(skb);
return NET_RX_DROP;
}
__skb_queue_tail(&cell->napi_skbs, skb);
if (skb_queue_len(&cell->napi_skbs) == 1)
napi_schedule(&cell->napi);
return NET_RX_SUCCESS;
}
EXPORT_SYMBOL(gro_cells_receive);
/* called under BH context */
static int gro_cell_poll(struct napi_struct *napi, int budget)
{
struct gro_cell *cell = container_of(napi, struct gro_cell, napi);
struct sk_buff *skb;
int work_done = 0;
while (work_done < budget) {
skb = __skb_dequeue(&cell->napi_skbs);
if (!skb)
break;
napi_gro_receive(napi, skb);
work_done++;
}
if (work_done < budget)
napi_complete_done(napi, work_done);
return work_done;
}
int gro_cells_init(struct gro_cells *gcells, struct net_device *dev)
{
int i;
gcells->cells = alloc_percpu(struct gro_cell);
if (!gcells->cells)
return -ENOMEM;
for_each_possible_cpu(i) {
struct gro_cell *cell = per_cpu_ptr(gcells->cells, i);
__skb_queue_head_init(&cell->napi_skbs);
set_bit(NAPI_STATE_NO_BUSY_POLL, &cell->napi.state);
netif_napi_add(dev, &cell->napi, gro_cell_poll,
NAPI_POLL_WEIGHT);
napi_enable(&cell->napi);
}
return 0;
}
EXPORT_SYMBOL(gro_cells_init);
void gro_cells_destroy(struct gro_cells *gcells)
{
int i;
if (!gcells->cells)
return;
for_each_possible_cpu(i) {
struct gro_cell *cell = per_cpu_ptr(gcells->cells, i);
netif_napi_del(&cell->napi);
__skb_queue_purge(&cell->napi_skbs);
}
free_percpu(gcells->cells);
gcells->cells = NULL;
}
EXPORT_SYMBOL(gro_cells_destroy);