1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/skbuff.h> 3 #include <linux/slab.h> 4 #include <linux/netdevice.h> 5 #include <net/gro_cells.h> 6 #include <net/hotdata.h> 7 8 struct gro_cell { 9 struct sk_buff_head napi_skbs; 10 struct napi_struct napi; 11 local_lock_t bh_lock; 12 }; 13 14 int gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb) 15 { 16 struct net_device *dev = skb->dev; 17 bool have_bh_lock = false; 18 struct gro_cell *cell; 19 int res; 20 21 rcu_read_lock(); 22 if (unlikely(!(dev->flags & IFF_UP))) 23 goto drop; 24 25 if (!gcells->cells || skb_cloned(skb) || netif_elide_gro(dev)) { 26 res = netif_rx(skb); 27 goto unlock; 28 } 29 30 local_lock_nested_bh(&gcells->cells->bh_lock); 31 have_bh_lock = true; 32 cell = this_cpu_ptr(gcells->cells); 33 34 if (skb_queue_len(&cell->napi_skbs) > READ_ONCE(net_hotdata.max_backlog)) { 35 drop: 36 dev_core_stats_rx_dropped_inc(dev); 37 kfree_skb(skb); 38 res = NET_RX_DROP; 39 goto unlock; 40 } 41 42 __skb_queue_tail(&cell->napi_skbs, skb); 43 if (skb_queue_len(&cell->napi_skbs) == 1) 44 napi_schedule(&cell->napi); 45 46 res = NET_RX_SUCCESS; 47 48 unlock: 49 if (have_bh_lock) 50 local_unlock_nested_bh(&gcells->cells->bh_lock); 51 rcu_read_unlock(); 52 return res; 53 } 54 EXPORT_SYMBOL(gro_cells_receive); 55 56 /* called under BH context */ 57 static int gro_cell_poll(struct napi_struct *napi, int budget) 58 { 59 struct gro_cell *cell = container_of(napi, struct gro_cell, napi); 60 struct sk_buff *skb; 61 int work_done = 0; 62 63 __local_lock_nested_bh(&cell->bh_lock); 64 while (work_done < budget) { 65 skb = __skb_dequeue(&cell->napi_skbs); 66 if (!skb) 67 break; 68 napi_gro_receive(napi, skb); 69 work_done++; 70 } 71 72 if (work_done < budget) 73 napi_complete_done(napi, work_done); 74 __local_unlock_nested_bh(&cell->bh_lock); 75 return work_done; 76 } 77 78 int gro_cells_init(struct gro_cells *gcells, struct net_device *dev) 79 { 80 int i; 81 82 gcells->cells = alloc_percpu(struct gro_cell); 83 if (!gcells->cells) 84 return -ENOMEM; 85 86 for_each_possible_cpu(i) { 87 struct gro_cell *cell = per_cpu_ptr(gcells->cells, i); 88 89 __skb_queue_head_init(&cell->napi_skbs); 90 local_lock_init(&cell->bh_lock); 91 92 set_bit(NAPI_STATE_NO_BUSY_POLL, &cell->napi.state); 93 94 netif_napi_add(dev, &cell->napi, gro_cell_poll); 95 napi_enable(&cell->napi); 96 } 97 return 0; 98 } 99 EXPORT_SYMBOL(gro_cells_init); 100 101 struct percpu_free_defer { 102 struct rcu_head rcu; 103 void __percpu *ptr; 104 }; 105 106 static void percpu_free_defer_callback(struct rcu_head *head) 107 { 108 struct percpu_free_defer *defer; 109 110 defer = container_of(head, struct percpu_free_defer, rcu); 111 free_percpu(defer->ptr); 112 kfree(defer); 113 } 114 115 void gro_cells_destroy(struct gro_cells *gcells) 116 { 117 struct percpu_free_defer *defer; 118 int i; 119 120 if (!gcells->cells) 121 return; 122 for_each_possible_cpu(i) { 123 struct gro_cell *cell = per_cpu_ptr(gcells->cells, i); 124 125 napi_disable(&cell->napi); 126 __netif_napi_del(&cell->napi); 127 __skb_queue_purge(&cell->napi_skbs); 128 } 129 /* We need to observe an rcu grace period before freeing ->cells, 130 * because netpoll could access dev->napi_list under rcu protection. 131 * Try hard using call_rcu() instead of synchronize_rcu(), 132 * because we might be called from cleanup_net(), and we 133 * definitely do not want to block this critical task. 134 */ 135 defer = kmalloc(sizeof(*defer), GFP_KERNEL | __GFP_NOWARN); 136 if (likely(defer)) { 137 defer->ptr = gcells->cells; 138 call_rcu(&defer->rcu, percpu_free_defer_callback); 139 } else { 140 /* We do not hold RTNL at this point, synchronize_net() 141 * would not be able to expedite this sync. 142 */ 143 synchronize_rcu_expedited(); 144 free_percpu(gcells->cells); 145 } 146 gcells->cells = NULL; 147 } 148 EXPORT_SYMBOL(gro_cells_destroy); 149