On 02/12/2019 03:31 AM, Yafang Shao wrote:
> SOCK_DEBUG is a very ancient debugging interface, and it's not very useful
> for debugging.
> So this patch removes the SOCK_DEBUG() and introduce a new function
> tcp_stats() to trace this kind of events.
> Some MIBs are added for these events.
>
> Regarding the SO_DEBUG in sock_{s,g}etsockopt, I think it is better to
> keep as-is, because if we return an errno to tell the application that
> this optname isn't supported for TCP, it may break the application.
> The application still can use this option but don't take any effect for
> TCP.
>
> Signed-off-by: Yafang Shao <laoar.s...@gmail.com>
> ---
> include/uapi/linux/snmp.h | 3 +++
> net/ipv4/proc.c | 3 +++
> net/ipv4/tcp_input.c | 26 +++++++++++---------------
> net/ipv6/tcp_ipv6.c | 2 --
> 4 files changed, 17 insertions(+), 17 deletions(-)
>
> diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
> index 86dc24a..fd5c09c 100644
> --- a/include/uapi/linux/snmp.h
> +++ b/include/uapi/linux/snmp.h
> @@ -283,6 +283,9 @@ enum
> LINUX_MIB_TCPACKCOMPRESSED, /* TCPAckCompressed */
> LINUX_MIB_TCPZEROWINDOWDROP, /* TCPZeroWindowDrop */
> LINUX_MIB_TCPRCVQDROP, /* TCPRcvQDrop */
> + LINUX_MIB_TCPINVALIDACK, /* TCPInvalidAck */
> + LINUX_MIB_TCPOLDACK, /* TCPOldAck */
> + LINUX_MIB_TCPPARTIALPACKET, /* TCPPartialPacket */
> __LINUX_MIB_MAX
> };
>
> diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
> index c3610b3..1b0320a 100644
> --- a/net/ipv4/proc.c
> +++ b/net/ipv4/proc.c
> @@ -291,6 +291,9 @@ static int sockstat_seq_show(struct seq_file *seq, void
> *v)
> SNMP_MIB_ITEM("TCPAckCompressed", LINUX_MIB_TCPACKCOMPRESSED),
> SNMP_MIB_ITEM("TCPZeroWindowDrop", LINUX_MIB_TCPZEROWINDOWDROP),
> SNMP_MIB_ITEM("TCPRcvQDrop", LINUX_MIB_TCPRCVQDROP),
> + SNMP_MIB_ITEM("TCPInvalidAck", LINUX_MIB_TCPINVALIDACK),
> + SNMP_MIB_ITEM("TCPOldAck", LINUX_MIB_TCPOLDACK),
> + SNMP_MIB_ITEM("TCPPartialPacket", LINUX_MIB_TCPPARTIALPACKET),
> SNMP_MIB_SENTINEL
> };
>
> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index 7a027dec..88deb1f 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -3554,6 +3554,11 @@ static u32 tcp_newly_delivered(struct sock *sk, u32
> prior_delivered, int flag)
> return delivered;
> }
>
> +static void tcp_stats(struct sock *sk, int mib_idx)
> +{
> + NET_INC_STATS(sock_net(sk), mib_idx);
> +}
This is not a very descriptive name.
Why is it static, and in net/ipv4/tcp_input.c ???
> +
> /* This routine deals with incoming acks, but not outgoing ones. */
> static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
> {
> @@ -3715,7 +3720,7 @@ static int tcp_ack(struct sock *sk, const struct
> sk_buff *skb, int flag)
> return 1;
>
> invalid_ack:
> - SOCK_DEBUG(sk, "Ack %u after %u:%u\n", ack, tp->snd_una, tp->snd_nxt);
> + tcp_stats(sk, LINUX_MIB_TCPINVALIDACK);
> return -1;
>
> old_ack:
> @@ -3731,7 +3736,7 @@ static int tcp_ack(struct sock *sk, const struct
> sk_buff *skb, int flag)
> tcp_xmit_recovery(sk, rexmit);
> }
>
> - SOCK_DEBUG(sk, "Ack %u before %u:%u\n", ack, tp->snd_una, tp->snd_nxt);
> + tcp_stats(sk, LINUX_MIB_TCPOLDACK);
> return 0;
> }
>
These counters will add noise to an already crowded MIB space.
What bug do you expect to track and fix with these ?
I see many TCP patches coming adding icache pressure, enabling companies to
build their own modified
TCP stack, but no real meat.
