[PATCH] net: tcp_drop adds `reason` parameter for tracing v2
From: Zhongya Yan
Date: Wed Aug 25 2021 - 11:41:06 EST
In this version, fix and modify some code issues. Changed the reason for `tcp_drop` from an enumeration to a mask and enumeration usage in the trace output.
By shifting `__LINE__` left by 6 bits to accommodate the `tcp_drop` call method source, 6 bits are enough to use. This allows for a more granular identification of the reason for calling `tcp_drop` without conflicts and essentially without overflow.
Example.
```
enum {
TCP_OFO_QUEUE = 1
}
reason = __LINE__ << 6
reason |= TCP_OFO_QUEUE
```
Suggestions from Jakub Kicinski, Eric Dumazet, much appreciated.
Modified the expression of the enumeration, and the use of the output under the trace definition.
Suggestion from Steven Rostedt. Thanks.
Signed-off-by: Zhongya Yan <yan2228598786@xxxxxxxxx>
---
include/net/tcp.h | 18 +++---
include/trace/events/tcp.h | 39 +++++++++++--
net/ipv4/tcp_input.c | 114 ++++++++++++++++++++++---------------
3 files changed, 112 insertions(+), 59 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index dd8cd8d6f2f1..75614a252675 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -256,15 +256,19 @@ extern unsigned long tcp_memory_pressure;
enum tcp_drop_reason {
TCP_OFO_QUEUE = 1,
- TCP_DATA_QUEUE_OFO = 2,
- TCP_DATA_QUEUE = 3,
- TCP_PRUNE_OFO_QUEUE = 4,
- TCP_VALIDATE_INCOMING = 5,
- TCP_RCV_ESTABLISHED = 6,
- TCP_RCV_SYNSENT_STATE_PROCESS = 7,
- TCP_RCV_STATE_PROCESS = 8
+ TCP_DATA_QUEUE_OFO,
+ TCP_DATA_QUEUE,
+ TCP_PRUNE_OFO_QUEUE,
+ TCP_VALIDATE_INCOMING,
+ TCP_RCV_ESTABLISHED,
+ TCP_RCV_SYNSENT_STATE_PROCESS,
+ TCP_RCV_STATE_PROCESS
};
+#define TCP_DROP_MASK(line, code) ((line << 6) | code) /* reason for masking */
+#define TCP_DROP_LINE(mask) (mask >> 6) /* Cause decode to get unique identifier */
+#define TCP_DROP_CODE(mask) (mask&0x3F) /* Cause decode get function code */
+
/* optimized version of sk_under_memory_pressure() for TCP sockets */
static inline bool tcp_under_memory_pressure(const struct sock *sk)
{
diff --git a/include/trace/events/tcp.h b/include/trace/events/tcp.h
index a0d3d31eb591..699539702ea9 100644
--- a/include/trace/events/tcp.h
+++ b/include/trace/events/tcp.h
@@ -371,8 +371,26 @@ DEFINE_EVENT(tcp_event_skb, tcp_bad_csum,
TP_ARGS(skb)
);
+// from author @{Steven Rostedt}
+#define TCP_DROP_REASON \
+ REASON_STRING(TCP_OFO_QUEUE, ofo_queue) \
+ REASON_STRING(TCP_DATA_QUEUE_OFO, data_queue_ofo) \
+ REASON_STRING(TCP_DATA_QUEUE, data_queue) \
+ REASON_STRING(TCP_PRUNE_OFO_QUEUE, prune_ofo_queue) \
+ REASON_STRING(TCP_VALIDATE_INCOMING, validate_incoming) \
+ REASON_STRING(TCP_RCV_ESTABLISHED, rcv_established) \
+ REASON_STRING(TCP_RCV_SYNSENT_STATE_PROCESS, rcv_synsent_state_process) \
+ REASON_STRINGe(TCP_RCV_STATE_PROCESS, rcv_state_proces)
+
+#undef REASON_STRING
+#undef REASON_STRINGe
+
+#define REASON_STRING(code, name) {code , #name},
+#define REASON_STRINGe(code, name) {code, #name}
+
+
TRACE_EVENT(tcp_drop,
- TP_PROTO(struct sock *sk, struct sk_buff *skb, enum tcp_drop_reason reason),
+ TP_PROTO(struct sock *sk, struct sk_buff *skb, __u32 reason),
TP_ARGS(sk, skb, reason),
@@ -392,6 +410,8 @@ TRACE_EVENT(tcp_drop,
__field(__u32, rcv_wnd)
__field(__u64, sock_cookie)
__field(__u32, reason)
+ __field(__u32, reason_code)
+ __field(__u32, reason_line)
),
TP_fast_assign(
@@ -415,16 +435,23 @@ TRACE_EVENT(tcp_drop,
__entry->snd_wnd = tp->snd_wnd;
__entry->rcv_wnd = tp->rcv_wnd;
__entry->ssthresh = tcp_current_ssthresh(sk);
- __entry->srtt = tp->srtt_us >> 3;
- __entry->sock_cookie = sock_gen_cookie(sk);
- __entry->reason = reason;
+ __entry->srtt = tp->srtt_us >> 3;
+ __entry->sock_cookie = sock_gen_cookie(sk);
+ __entry->reason = reason;
+ __entry->reason_code = TCP_DROP_CODE(reason);
+ __entry->reason_line = TCP_DROP_LINE(reason);
),
- TP_printk("src=%pISpc dest=%pISpc mark=%#x data_len=%d snd_nxt=%#x snd_una=%#x snd_cwnd=%u ssthresh=%u snd_wnd=%u srtt=%u rcv_wnd=%u sock_cookie=%llx reason=%d",
+ TP_printk("src=%pISpc dest=%pISpc mark=%#x data_len=%d snd_nxt=%#x snd_una=%#x \
+ snd_cwnd=%u ssthresh=%u snd_wnd=%u srtt=%u rcv_wnd=%u \
+ sock_cookie=%llx reason=%d reason_type=%s reason_line=%d",
__entry->saddr, __entry->daddr, __entry->mark,
__entry->data_len, __entry->snd_nxt, __entry->snd_una,
__entry->snd_cwnd, __entry->ssthresh, __entry->snd_wnd,
- __entry->srtt, __entry->rcv_wnd, __entry->sock_cookie, __entry->reason)
+ __entry->srtt, __entry->rcv_wnd, __entry->sock_cookie,
+ __entry->reason,
+ __print_symbolic(__entry->reason_code, TCP_DROP_REASON),
+ __entry->reason_line)
);
#endif /* _TRACE_TCP_H */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 83e31661876b..7dfcc4253c35 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4643,20 +4643,14 @@ static bool tcp_ooo_try_coalesce(struct sock *sk,
return res;
}
-static void __tcp_drop(struct sock *sk,
- struct sk_buff *skb)
-{
- sk_drops_add(sk, skb);
- __kfree_skb(skb);
-}
-/* tcp_drop whit reason,for epbf trace
+/* tcp_drop with reason
*/
static void tcp_drop(struct sock *sk, struct sk_buff *skb,
- enum tcp_drop_reason reason)
+ __u32 reason)
{
trace_tcp_drop(sk, skb, reason);
- __tcp_drop(sk, skb);
+ __kfree_skb(skb);
}
/* This one checks to see if we can put data from the
@@ -5621,7 +5615,8 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
LINUX_MIB_TCPACKSKIPPEDPAWS,
&tp->last_oow_ack_time))
tcp_send_dupack(sk, skb);
- goto discard;
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_VALIDATE_INCOMING));
+ goto end;
}
/* Reset is accepted even if it did not pass PAWS. */
}
@@ -5644,7 +5639,8 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
} else if (tcp_reset_check(sk, skb)) {
tcp_reset(sk, skb);
}
- goto discard;
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_VALIDATE_INCOMING));
+ goto end;
}
/* Step 2: check RST bit */
@@ -5689,7 +5685,8 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
tcp_fastopen_active_disable(sk);
tcp_send_challenge_ack(sk, skb);
}
- goto discard;
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_VALIDATE_INCOMING));
+ goto end;
}
/* step 3: check security and precedence [ignored] */
@@ -5703,15 +5700,15 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS);
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSYNCHALLENGE);
tcp_send_challenge_ack(sk, skb);
- goto discard;
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_VALIDATE_INCOMING));
+ goto end;
}
bpf_skops_parse_hdr(sk, skb);
return true;
-discard:
- tcp_drop(sk, skb, TCP_VALIDATE_INCOMING);
+end:
return false;
}
@@ -5829,7 +5826,8 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
return;
} else { /* Header too small */
TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS);
- goto discard;
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_ESTABLISHED));
+ goto end;
}
} else {
int eaten = 0;
@@ -5883,8 +5881,10 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
if (len < (th->doff << 2) || tcp_checksum_complete(skb))
goto csum_error;
- if (!th->ack && !th->rst && !th->syn)
- goto discard;
+ if (!th->ack && !th->rst && !th->syn) {
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_ESTABLISHED));
+ goto end;
+ }
/*
* Standard slow path.
@@ -5894,8 +5894,10 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
return;
step5:
- if (tcp_ack(sk, skb, FLAG_SLOWPATH | FLAG_UPDATE_TS_RECENT) < 0)
- goto discard;
+ if (tcp_ack(sk, skb, FLAG_SLOWPATH | FLAG_UPDATE_TS_RECENT) < 0) {
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_ESTABLISHED));
+ goto end;
+ }
tcp_rcv_rtt_measure_ts(sk, skb);
@@ -5913,9 +5915,9 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb)
trace_tcp_bad_csum(skb);
TCP_INC_STATS(sock_net(sk), TCP_MIB_CSUMERRORS);
TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS);
-
-discard:
- tcp_drop(sk, skb, TCP_RCV_ESTABLISHED);
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_ESTABLISHED));
+end:
+ return;
}
EXPORT_SYMBOL(tcp_rcv_established);
@@ -6115,7 +6117,8 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
if (th->rst) {
tcp_reset(sk, skb);
- goto discard;
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_SYNSENT_STATE_PROCESS));
+ goto end;
}
/* rfc793:
@@ -6204,9 +6207,9 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
tcp_enter_quickack_mode(sk, TCP_MAX_QUICKACKS);
inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
TCP_DELACK_MAX, TCP_RTO_MAX);
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_SYNSENT_STATE_PROCESS));
-discard:
- tcp_drop(sk, skb, TCP_RCV_SYNSENT_STATE_PROCESS);
+end:
return 0;
} else {
tcp_send_ack(sk);
@@ -6279,7 +6282,8 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
*/
return -1;
#else
- goto discard;
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_SYNSENT_STATE_PROCESS));
+ goto end;
#endif
}
/* "fifth, if neither of the SYN or RST bits is set then
@@ -6289,7 +6293,8 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
discard_and_undo:
tcp_clear_options(&tp->rx_opt);
tp->rx_opt.mss_clamp = saved_clamp;
- goto discard;
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_SYNSENT_STATE_PROCESS));
+ goto end;
reset_and_undo:
tcp_clear_options(&tp->rx_opt);
@@ -6347,18 +6352,23 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
switch (sk->sk_state) {
case TCP_CLOSE:
- goto discard;
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_STATE_PROCESS));
+ goto end;
case TCP_LISTEN:
if (th->ack)
return 1;
- if (th->rst)
- goto discard;
+ if (th->rst) {
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_STATE_PROCESS));
+ goto end;
+ }
if (th->syn) {
- if (th->fin)
- goto discard;
+ if (th->fin) {
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_STATE_PROCESS));
+ goto end;
+ }
/* It is possible that we process SYN packets from backlog,
* so we need to make sure to disable BH and RCU right there.
*/
@@ -6373,7 +6383,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
consume_skb(skb);
return 0;
}
- goto discard;
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_STATE_PROCESS));
+ goto end;
case TCP_SYN_SENT:
tp->rx_opt.saw_tstamp = 0;
@@ -6399,12 +6410,16 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV &&
sk->sk_state != TCP_FIN_WAIT1);
- if (!tcp_check_req(sk, skb, req, true, &req_stolen))
- goto discard;
+ if (!tcp_check_req(sk, skb, req, true, &req_stolen)) {
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_STATE_PROCESS));
+ goto end;
+ }
}
- if (!th->ack && !th->rst && !th->syn)
- goto discard;
+ if (!th->ack && !th->rst && !th->syn) {
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_STATE_PROCESS));
+ goto end;
+ }
if (!tcp_validate_incoming(sk, skb, th, 0))
return 0;
@@ -6418,7 +6433,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
if (sk->sk_state == TCP_SYN_RECV)
return 1; /* send one RST */
tcp_send_challenge_ack(sk, skb);
- goto discard;
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_STATE_PROCESS));
+ goto end;
}
switch (sk->sk_state) {
case TCP_SYN_RECV:
@@ -6511,7 +6527,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
inet_csk_reset_keepalive_timer(sk, tmo);
} else {
tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
- goto discard;
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_STATE_PROCESS));
+ goto end;
}
break;
}
@@ -6519,7 +6536,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
case TCP_CLOSING:
if (tp->snd_una == tp->write_seq) {
tcp_time_wait(sk, TCP_TIME_WAIT, 0);
- goto discard;
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_STATE_PROCESS));
+ goto end;
}
break;
@@ -6527,7 +6545,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
if (tp->snd_una == tp->write_seq) {
tcp_update_metrics(sk);
tcp_done(sk);
- goto discard;
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_STATE_PROCESS));
+ goto end;
}
break;
}
@@ -6544,8 +6563,10 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
/* If a subflow has been reset, the packet should not
* continue to be processed, drop the packet.
*/
- if (sk_is_mptcp(sk) && !mptcp_incoming_options(sk, skb))
- goto discard;
+ if (sk_is_mptcp(sk) && !mptcp_incoming_options(sk, skb)) {
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_STATE_PROCESS));
+ goto end;
+ }
break;
}
fallthrough;
@@ -6577,9 +6598,10 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
}
if (!queued) {
-discard:
- tcp_drop(sk, skb, TCP_RCV_STATE_PROCESS);
+ tcp_drop(sk, skb, TCP_DROP_MASK(__LINE__, TCP_RCV_STATE_PROCESS));
}
+
+end:
return 0;
}
EXPORT_SYMBOL(tcp_rcv_state_process);
--
2.25.1