| From 313c7e169977077914f2763250911f20d030a2e1 Mon Sep 17 00:00:00 2001 |
| From: Eric Dumazet <edumazet@google.com> |
| Date: Wed, 12 Jun 2019 09:52:30 -0700 |
| Subject: [PATCH] net/packet: make tp_drops atomic |
| |
| commit 8e8e2951e3095732d7e780c241f61ea130955a57 upstream. |
| |
| 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> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c |
| index ce2c11834fa9..1b42badb40f1 100644 |
| --- a/net/packet/af_packet.c |
| +++ b/net/packet/af_packet.c |
| @@ -759,7 +759,7 @@ 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; |
| @@ -2136,10 +2136,8 @@ 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)) { |
| @@ -2288,7 +2286,7 @@ 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; |
| } |
| |
| @@ -2401,9 +2399,9 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, |
| 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); |
| @@ -3920,6 +3918,7 @@ 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; |
| @@ -3936,14 +3935,17 @@ 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 f10294800aaf..907f4cd2a718 100644 |
| --- a/net/packet/internal.h |
| +++ b/net/packet/internal.h |
| @@ -135,6 +135,7 @@ 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) |
| -- |
| 2.27.0 |
| |