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2543a6000e
After cited commit, gro_cells_destroy() became damn slow
on hosts with a lot of cores.
This is because we have one additional synchronize_net() per cpu as
stated in the changelog.
gro_cells_init() is setting NAPI_STATE_NO_BUSY_POLL, and this was enough
to not have one synchronize_net() call per netif_napi_del()
We can factorize all the synchronize_net() to a single one,
right before freeing per-cpu memory.
Fixes: 5198d545db ("net: remove napi_hash_del() from driver-facing API")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20201124203822.1360107-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
114 lines
2.3 KiB
C
114 lines
2.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/skbuff.h>
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#include <linux/slab.h>
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#include <linux/netdevice.h>
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#include <net/gro_cells.h>
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struct gro_cell {
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struct sk_buff_head napi_skbs;
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struct napi_struct napi;
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};
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int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
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{
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struct net_device *dev = skb->dev;
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struct gro_cell *cell;
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int res;
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rcu_read_lock();
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if (unlikely(!(dev->flags & IFF_UP)))
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goto drop;
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if (!gcells->cells || skb_cloned(skb) || netif_elide_gro(dev)) {
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res = netif_rx(skb);
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goto unlock;
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}
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cell = this_cpu_ptr(gcells->cells);
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if (skb_queue_len(&cell->napi_skbs) > netdev_max_backlog) {
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drop:
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atomic_long_inc(&dev->rx_dropped);
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kfree_skb(skb);
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res = NET_RX_DROP;
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goto unlock;
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}
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__skb_queue_tail(&cell->napi_skbs, skb);
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if (skb_queue_len(&cell->napi_skbs) == 1)
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napi_schedule(&cell->napi);
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res = NET_RX_SUCCESS;
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unlock:
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rcu_read_unlock();
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return res;
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}
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EXPORT_SYMBOL(gro_cells_receive);
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/* called under BH context */
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static int gro_cell_poll(struct napi_struct *napi, int budget)
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{
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struct gro_cell *cell = container_of(napi, struct gro_cell, napi);
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struct sk_buff *skb;
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int work_done = 0;
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while (work_done < budget) {
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skb = __skb_dequeue(&cell->napi_skbs);
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if (!skb)
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break;
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napi_gro_receive(napi, skb);
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work_done++;
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}
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if (work_done < budget)
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napi_complete_done(napi, work_done);
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return work_done;
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}
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int gro_cells_init(struct gro_cells *gcells, struct net_device *dev)
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{
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int i;
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gcells->cells = alloc_percpu(struct gro_cell);
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if (!gcells->cells)
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return -ENOMEM;
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for_each_possible_cpu(i) {
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struct gro_cell *cell = per_cpu_ptr(gcells->cells, i);
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__skb_queue_head_init(&cell->napi_skbs);
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set_bit(NAPI_STATE_NO_BUSY_POLL, &cell->napi.state);
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netif_napi_add(dev, &cell->napi, gro_cell_poll,
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NAPI_POLL_WEIGHT);
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napi_enable(&cell->napi);
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}
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return 0;
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}
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EXPORT_SYMBOL(gro_cells_init);
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void gro_cells_destroy(struct gro_cells *gcells)
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{
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int i;
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if (!gcells->cells)
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return;
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for_each_possible_cpu(i) {
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struct gro_cell *cell = per_cpu_ptr(gcells->cells, i);
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napi_disable(&cell->napi);
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__netif_napi_del(&cell->napi);
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__skb_queue_purge(&cell->napi_skbs);
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}
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/* This barrier is needed because netpoll could access dev->napi_list
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* under rcu protection.
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*/
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synchronize_net();
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free_percpu(gcells->cells);
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gcells->cells = NULL;
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}
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EXPORT_SYMBOL(gro_cells_destroy);
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