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author | David S. Miller <davem@davemloft.net> | 2022-02-20 13:55:31 +0000 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2022-02-20 13:55:31 +0000 |
commit | adfb62dbda49d66eba6340324547ff89b09a66eb (patch) | |
tree | 1fa0f39a846de21459ed1cb7cdada1ffea216917 /include/linux | |
parent | 48c77bdf729a91fa7f65765d3f60f01e0ac320c5 (diff) | |
parent | d25e481be0c519d1a458b14191dc8c2a8bb3e24a (diff) |
Merge branch 'tcp_drop_reason'
Menglong Dong says:
====================
net: add skb drop reasons to TCP packet receive
In the commit c504e5c2f964 ("net: skb: introduce kfree_skb_reason()"),
we added the support of reporting the reasons of skb drops to kfree_skb
tracepoint. And in this series patches, reasons for skb drops are added
to TCP layer (both TCPv4 and TCPv6 are considered).
Following functions are processed:
tcp_v4_rcv()
tcp_v6_rcv()
tcp_v4_inbound_md5_hash()
tcp_v6_inbound_md5_hash()
tcp_add_backlog()
tcp_v4_do_rcv()
tcp_v6_do_rcv()
tcp_rcv_established()
tcp_data_queue()
tcp_data_queue_ofo()
The functions we handled are mostly for packet ingress, as skb drops
hardly happens in the egress path of TCP layer. However, it's a little
complex for TCP state processing, as I find that it's hard to report skb
drop reasons to where it is freed. For example, when skb is dropped in
tcp_rcv_state_process(), the reason can be caused by the call of
tcp_v4_conn_request(), and it's hard to return a drop reason from
tcp_v4_conn_request(). So such cases are skipped for this moment.
Following new drop reasons are introduced (what they mean can be see
in the document for them):
/* SKB_DROP_REASON_TCP_MD5* corresponding to LINUX_MIB_TCPMD5* */
SKB_DROP_REASON_TCP_MD5NOTFOUND
SKB_DROP_REASON_TCP_MD5UNEXPECTED
SKB_DROP_REASON_TCP_MD5FAILURE
SKB_DROP_REASON_SOCKET_BACKLOG
SKB_DROP_REASON_TCP_FLAGS
SKB_DROP_REASON_TCP_ZEROWINDOW
SKB_DROP_REASON_TCP_OLD_DATA
SKB_DROP_REASON_TCP_OVERWINDOW
/* corresponding to LINUX_MIB_TCPOFOMERGE */
SKB_DROP_REASON_TCP_OFOMERGE
Here is a example to get TCP packet drop reasons from ftrace:
$ echo 1 > /sys/kernel/debug/tracing/events/skb/kfree_skb/enable
$ cat /sys/kernel/debug/tracing/trace
$ <idle>-0 [036] ..s1. 647.428165: kfree_skb: skbaddr=000000004d037db6 protocol=2048 location=0000000074cd1243 reason: NO_SOCKET
$ <idle>-0 [020] ..s2. 639.676674: kfree_skb: skbaddr=00000000bcbfa42d protocol=2048 location=00000000bfe89d35 reason: PROTO_MEM
From the reason 'PROTO_MEM' we can know that the skb is dropped because
the memory configured in net.ipv4.tcp_mem is up to the limition.
Changes since v2:
- remove the 'inline' of tcp_drop() in the 1th patch, as Jakub
suggested
Changes since v1:
- enrich the document for this series patches in the cover letter,
as Eric suggested
- fix compile warning report by Jakub in the 6th patch
- let NO_SOCKET trump the XFRM failure in the 2th and 3th patches
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux')
-rw-r--r-- | include/linux/skbuff.h | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index a5adbf6b51e8..a3e90efe6586 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -346,6 +346,40 @@ enum skb_drop_reason { * udp packet drop out of * udp_memory_allocated. */ + SKB_DROP_REASON_TCP_MD5NOTFOUND, /* no MD5 hash and one + * expected, corresponding + * to LINUX_MIB_TCPMD5NOTFOUND + */ + SKB_DROP_REASON_TCP_MD5UNEXPECTED, /* MD5 hash and we're not + * expecting one, corresponding + * to LINUX_MIB_TCPMD5UNEXPECTED + */ + SKB_DROP_REASON_TCP_MD5FAILURE, /* MD5 hash and its wrong, + * corresponding to + * LINUX_MIB_TCPMD5FAILURE + */ + SKB_DROP_REASON_SOCKET_BACKLOG, /* failed to add skb to socket + * backlog (see + * LINUX_MIB_TCPBACKLOGDROP) + */ + SKB_DROP_REASON_TCP_FLAGS, /* TCP flags invalid */ + SKB_DROP_REASON_TCP_ZEROWINDOW, /* TCP receive window size is zero, + * see LINUX_MIB_TCPZEROWINDOWDROP + */ + SKB_DROP_REASON_TCP_OLD_DATA, /* the TCP data reveived is already + * received before (spurious retrans + * may happened), see + * LINUX_MIB_DELAYEDACKLOST + */ + SKB_DROP_REASON_TCP_OVERWINDOW, /* the TCP data is out of window, + * the seq of the first byte exceed + * the right edges of receive + * window + */ + SKB_DROP_REASON_TCP_OFOMERGE, /* the data of skb is already in + * the ofo queue, corresponding to + * LINUX_MIB_TCPOFOMERGE + */ SKB_DROP_REASON_MAX, }; |