net/core/gro_cells.c

Source file repositories/reference/linux-study-clean/net/core/gro_cells.c

File Facts

System
Linux kernel
Corpus path
net/core/gro_cells.c
Extension
.c
Size
3546 bytes
Lines
149
Domain
Networking Core
Bucket
Sockets, Protocols, Packet Path, And Network Policy
Inferred role
Networking Core: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Networking stack implementation surface: socket APIs, protocol dispatch, packet flow, routing, filtering, and network namespaces.

Dependency Surface

Detected Declarations

Annotated Snippet

struct gro_cell {
	struct sk_buff_head	napi_skbs;
	struct napi_struct	napi;
	local_lock_t		bh_lock;
};

int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
{
	struct net_device *dev = skb->dev;
	bool have_bh_lock = false;
	struct gro_cell *cell;
	int res;

	rcu_read_lock();
	if (unlikely(!(dev->flags & IFF_UP)))
		goto drop;

	if (!gcells->cells || skb_cloned(skb) || netif_elide_gro(dev)) {
		res = netif_rx(skb);
		goto unlock;
	}

	local_lock_nested_bh(&gcells->cells->bh_lock);
	have_bh_lock = true;
	cell = this_cpu_ptr(gcells->cells);

	if (skb_queue_len(&cell->napi_skbs) > READ_ONCE(net_hotdata.max_backlog)) {
drop:
		dev_core_stats_rx_dropped_inc(dev);
		kfree_skb(skb);
		res = NET_RX_DROP;
		goto unlock;
	}

	__skb_queue_tail(&cell->napi_skbs, skb);
	if (skb_queue_len(&cell->napi_skbs) == 1)
		napi_schedule(&cell->napi);

	res = NET_RX_SUCCESS;

unlock:
	if (have_bh_lock)
		local_unlock_nested_bh(&gcells->cells->bh_lock);
	rcu_read_unlock();
	return res;
}
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) {
		__local_lock_nested_bh(&cell->bh_lock);
		skb = __skb_dequeue(&cell->napi_skbs);
		__local_unlock_nested_bh(&cell->bh_lock);
		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);
		local_lock_init(&cell->bh_lock);

		set_bit(NAPI_STATE_NO_BUSY_POLL, &cell->napi.state);

		netif_napi_add(dev, &cell->napi, gro_cell_poll);
		napi_enable(&cell->napi);
	}
	return 0;

Annotation

Implementation Notes