Commit ea5d0c32 authored by Yafang Shao's avatar Yafang Shao Committed by David S. Miller
Browse files

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: default avatarYafang Shao <laoar.shao@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 83607344

include/uapi/linux/snmp.h

+1 −0
Original line number Diff line number Diff line
@@ -280,6 +280,7 @@ enum 
	LINUX_MIB_TCPDELIVEREDCE,		/* TCPDeliveredCE */

	LINUX_MIB_TCPACKCOMPRESSED,		/* TCPAckCompressed */

	LINUX_MIB_TCPZEROWINDOWDROP,		/* TCPZeroWindowDrop */

	LINUX_MIB_TCPRCVQDROP,			/* TCPRcvQDrop */

	__LINUX_MIB_MAX

};

net/ipv4/proc.c

+1 −0
Original line number Diff line number Diff line
@@ -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

};

net/ipv4/tcp_input.c

+6 −2
Original line number Diff line number Diff line
@@ -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);

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