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tcp: add new SNMP counter for drops when try to queue in rcv queue 

When sk_rmem_alloc is larger than the receive buffer and we can't
schedule more memory for it, the skb will be dropped.

In above situation, if this skb is put into the ofo queue,
LINUX_MIB_TCPOFODROP is incremented to track it.

While if this skb is put into the receive queue, there's no record.
So a new SNMP counter is introduced to track this behavior.

LINUX_MIB_TCPRCVQDROP:  Number of packets meant to be queued in rcv queue
			but dropped because socket rcvbuf limit hit.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yafang Shao 2018-06-28 00:22:56 -04:00 committed by David S. Miller
parent 83607344d6
commit ea5d0c3249
3 changed files with 8 additions and 2 deletions
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1
include/uapi/linux/snmp.h
View File

@ -280,6 +280,7 @@ enum
LINUX_MIB_TCPDELIVEREDCE, /* TCPDeliveredCE */
LINUX_MIB_TCPACKCOMPRESSED, /* TCPAckCompressed */
LINUX_MIB_TCPZEROWINDOWDROP, /* TCPZeroWindowDrop */
LINUX_MIB_TCPRCVQDROP, /* TCPRcvQDrop */
__LINUX_MIB_MAX
};

1
net/ipv4/proc.c
View File

@ -288,6 +288,7 @@ static const struct snmp_mib snmp4_net_list[] = {
SNMP_MIB_ITEM("TCPDeliveredCE", LINUX_MIB_TCPDELIVEREDCE),
SNMP_MIB_ITEM("TCPAckCompressed", LINUX_MIB_TCPACKCOMPRESSED),
SNMP_MIB_ITEM("TCPZeroWindowDrop", LINUX_MIB_TCPZEROWINDOWDROP),
SNMP_MIB_ITEM("TCPRcvQDrop", LINUX_MIB_TCPRCVQDROP),
SNMP_MIB_SENTINEL
};

8
net/ipv4/tcp_input.c
View File

@ -4611,8 +4611,10 @@ int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size)
skb->data_len = data_len;
skb->len = size;
if (tcp_try_rmem_schedule(sk, skb, skb->truesize))
if (tcp_try_rmem_schedule(sk, skb, skb->truesize)) {
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRCVQDROP);
goto err_free;
}
err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, size);
if (err)
@ -4677,8 +4679,10 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
queue_and_out:
if (skb_queue_len(&sk->sk_receive_queue) == 0)
sk_forced_mem_schedule(sk, skb->truesize);
else if (tcp_try_rmem_schedule(sk, skb, skb->truesize))
else if (tcp_try_rmem_schedule(sk, skb, skb->truesize)) {
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRCVQDROP);
goto drop;
}
eaten = tcp_queue_rcv(sk, skb, 0, &fragstolen);
tcp_rcv_nxt_update(tp, TCP_SKB_CB(skb)->end_seq);