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| author | Eric Dumazet <edumazet@google.com> | 2019-06-12 09:52:30 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2019-06-14 18:52:14 -0700 |
| commit | 8e8e2951e3095732d7e780c241f61ea130955a57 (patch) | |
| tree | 41257e97418486993cb2ea69aaadbc0524eef7f3 | |
| parent | 0338a14523e3864524dafb6a66c7b82e94201317 (diff) | |
| download | linux-8e8e2951e3095732d7e780c241f61ea130955a57.tar.gz linux-8e8e2951e3095732d7e780c241f61ea130955a57.tar.bz2 linux-8e8e2951e3095732d7e780c241f61ea130955a57.zip | |
net/packet: make tp_drops atomic
Under DDOS, we want to be able to increment tp_drops without
touching the spinlock. This will help readers to drain
the receive queue slightly faster :/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/packet/af_packet.c | 20 | ||||
| -rw-r--r-- | net/packet/internal.h | 1 |
2 files changed, 12 insertions, 9 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index a0564855ed9d..2d499679811a 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -758,7 +758,7 @@ static void prb_close_block(struct tpacket_kbdq_core *pkc1, struct tpacket_hdr_v1 *h1 = &pbd1->hdr.bh1; struct sock *sk = &po->sk; - if (po->stats.stats3.tp_drops) + if (atomic_read(&po->tp_drops)) status |= TP_STATUS_LOSING; last_pkt = (struct tpacket3_hdr *)pkc1->prev; @@ -2128,10 +2128,8 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev, drop_n_acct: is_drop_n_account = true; - spin_lock(&sk->sk_receive_queue.lock); - po->stats.stats1.tp_drops++; + atomic_inc(&po->tp_drops); atomic_inc(&sk->sk_drops); - spin_unlock(&sk->sk_receive_queue.lock); drop_n_restore: if (skb_head != skb->data && skb_shared(skb)) { @@ -2265,7 +2263,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, * Anyways, moving it for V1/V2 only as V3 doesn't need this * at packet level. */ - if (po->stats.stats1.tp_drops) + if (atomic_read(&po->tp_drops)) status |= TP_STATUS_LOSING; } @@ -2381,9 +2379,9 @@ drop: return 0; drop_n_account: - is_drop_n_account = true; - po->stats.stats1.tp_drops++; spin_unlock(&sk->sk_receive_queue.lock); + atomic_inc(&po->tp_drops); + is_drop_n_account = true; sk->sk_data_ready(sk); kfree_skb(copy_skb); @@ -3879,6 +3877,7 @@ static int packet_getsockopt(struct socket *sock, int level, int optname, void *data = &val; union tpacket_stats_u st; struct tpacket_rollover_stats rstats; + int drops; if (level != SOL_PACKET) return -ENOPROTOOPT; @@ -3895,14 +3894,17 @@ static int packet_getsockopt(struct socket *sock, int level, int optname, memcpy(&st, &po->stats, sizeof(st)); memset(&po->stats, 0, sizeof(po->stats)); spin_unlock_bh(&sk->sk_receive_queue.lock); + drops = atomic_xchg(&po->tp_drops, 0); if (po->tp_version == TPACKET_V3) { lv = sizeof(struct tpacket_stats_v3); - st.stats3.tp_packets += st.stats3.tp_drops; + st.stats3.tp_drops = drops; + st.stats3.tp_packets += drops; data = &st.stats3; } else { lv = sizeof(struct tpacket_stats); - st.stats1.tp_packets += st.stats1.tp_drops; + st.stats1.tp_drops = drops; + st.stats1.tp_packets += drops; data = &st.stats1; } diff --git a/net/packet/internal.h b/net/packet/internal.h index 3bb7c5fb3bff..b5bcff2b7a43 100644 --- a/net/packet/internal.h +++ b/net/packet/internal.h @@ -131,6 +131,7 @@ struct packet_sock { struct net_device __rcu *cached_dev; int (*xmit)(struct sk_buff *skb); struct packet_type prot_hook ____cacheline_aligned_in_smp; + atomic_t tp_drops ____cacheline_aligned_in_smp; }; static struct packet_sock *pkt_sk(struct sock *sk) |