gro_cells.h

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#ifndef _NET_GRO_CELLS_H
#define _NET_GRO_CELLS_H

#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/netdevice.h>

struct gro_cell {
    struct sk_buff_head napi_skbs;
    struct napi_struct  napi;
} ____cacheline_aligned_in_smp;

struct gro_cells {
    unsigned int        gro_cells_mask;
    struct gro_cell     *cells;
};

static inline void gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
{
    unsigned long flags;
    struct gro_cell *cell = gcells->cells;
    struct net_device *dev = skb->dev;

    if (!cell || skb_cloned(skb) || !(dev->features & NETIF_F_GRO)) {
        netif_rx(skb);
        return;
    }

    if (skb_rx_queue_recorded(skb))
        cell += skb_get_rx_queue(skb) & gcells->gro_cells_mask;

    if (skb_queue_len(&cell->napi_skbs) > netdev_max_backlog) {
        atomic_long_inc(&dev->rx_dropped);
        kfree_skb(skb);
        return;
    }

    spin_lock_irqsave(&cell->napi_skbs.lock, flags);

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

    spin_unlock_irqrestore(&cell->napi_skbs.lock, flags);
}

static inline 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(napi);
    return work_done;
}

static inline int gro_cells_init(struct gro_cells *gcells, struct net_device *dev)
{
    int i;

    gcells->gro_cells_mask = roundup_pow_of_two(netif_get_num_default_rss_queues()) - 1;
    gcells->cells = kcalloc(sizeof(struct gro_cell),
                gcells->gro_cells_mask + 1,
                GFP_KERNEL);
    if (!gcells->cells)
        return -ENOMEM;

    for (i = 0; i <= gcells->gro_cells_mask; i++) {
        struct gro_cell *cell = gcells->cells + i;

        skb_queue_head_init(&cell->napi_skbs);
        netif_napi_add(dev, &cell->napi, gro_cell_poll, 64);
        napi_enable(&cell->napi);
    }
    return 0;
}

static inline void gro_cells_destroy(struct gro_cells *gcells)
{
    struct gro_cell *cell = gcells->cells;
    int i;

    if (!cell)
        return;
    for (i = 0; i <= gcells->gro_cells_mask; i++,cell++) {
        netif_napi_del(&cell->napi);
        skb_queue_purge(&cell->napi_skbs);
    }
    kfree(gcells->cells);
    gcells->cells = NULL;
}

#endif