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e88a276614
Rolf Neugebauer reported very long delays at netns dismantle.
Eric W. Biederman was kind enough to look at this problem
and noticed synchronize_net() occurring from netif_napi_del() that was
added in linux-4.5
Busy polling makes no sense for tunnels NAPI.
If busy poll is used for sessions over tunnels, the poller will need to
poll the physical device queue anyway.
netif_tx_napi_add() could be used here, but function name is misleading,
and renaming it is not stable material, so set NAPI_STATE_NO_BUSY_POLL
bit directly.
This will avoid inserting gro_cells napi structures in napi_hash[]
and avoid the problematic synchronize_net() (per possible cpu) that
Rolf reported.
Fixes: 93d05d4a32 ("net: provide generic busy polling to all NAPI drivers")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Rolf Neugebauer <rolf.neugebauer@docker.com>
Reported-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Tested-by: Rolf Neugebauer <rolf.neugebauer@docker.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
96 lines
2 KiB
C
96 lines
2 KiB
C
#ifndef _NET_GRO_CELLS_H
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#define _NET_GRO_CELLS_H
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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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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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struct gro_cells {
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struct gro_cell __percpu *cells;
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};
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static inline int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)
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{
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struct gro_cell *cell;
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struct net_device *dev = skb->dev;
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if (!gcells->cells || skb_cloned(skb) || !(dev->features & NETIF_F_GRO))
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return netif_rx(skb);
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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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atomic_long_inc(&dev->rx_dropped);
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kfree_skb(skb);
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return NET_RX_DROP;
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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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return NET_RX_SUCCESS;
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}
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/* called under BH context */
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static inline 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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static inline 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, 64);
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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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static inline 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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netif_napi_del(&cell->napi);
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__skb_queue_purge(&cell->napi_skbs);
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}
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free_percpu(gcells->cells);
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gcells->cells = NULL;
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}
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#endif
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