netdev - [PATCH net-next] TCP: make seq # error messages more readable

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Date:   Thu, 12 Jul 2018 17:48:50 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>
Cc:     積丹尼 Dan Jacobson <jidanni@...anni.org>
Subject: [PATCH net-next] TCP: make seq # error messages more readable

From: Randy Dunlap <rdunlap@...radead.org>

Attempt to make cryptic TCP seq number error messages clearer by
(1) adding the function name, (2) identifying the errors as "seq # bug",
and (3) grouping the field identifiers and values by separating them
with commas.

E.g., the following message is changed from:

recvmsg bug 2: copied 73BCB6CD seq 70F17CBE rcvnxt 73BCB9AA fl 0
WARNING: CPU: 2 PID: 1501 at /linux/net/ipv4/tcp.c:1881 tcp_recvmsg+0x649/0xb90

to:

tcp_recvmsg: TCP recvmsg seq # bug 2: copied 73BCB6CD, seq 70F17CBE, rcvnxt 73BCB9AA, fl 0
WARNING: CPU: 2 PID: 1501 at /linux/net/ipv4/tcp.c:2011 tcp_recvmsg+0x694/0xba0

Suggested-by: 積丹尼 Dan Jacobson <jidanni@...anni.org>
Signed-off-by: Randy Dunlap <rdunlap@...radead.org>
---
 net/ipv4/tcp.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

--- linux-next-20180712.orig/net/ipv4/tcp.c
+++ linux-next-20180712/net/ipv4/tcp.c
@@ -1994,9 +1994,9 @@ int tcp_recvmsg(struct sock *sk, struct
 			 * shouldn't happen.
 			 */
 			if (WARN(before(*seq, TCP_SKB_CB(skb)->seq),
-				 "recvmsg bug: copied %X seq %X rcvnxt %X fl %X\n",
-				 *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt,
-				 flags))
+				 "%s: TCP recvmsg seq # bug: copied %X, seq %X, rcvnxt %X, fl %X\n",
+				 __func__, *seq,
+				 TCP_SKB_CB(skb)->seq, tp->rcv_nxt, flags))
 				break;
 
 			offset = *seq - TCP_SKB_CB(skb)->seq;
@@ -2009,8 +2009,9 @@ int tcp_recvmsg(struct sock *sk, struct
 			if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
 				goto found_fin_ok;
 			WARN(!(flags & MSG_PEEK),
-			     "recvmsg bug 2: copied %X seq %X rcvnxt %X fl %X\n",
-			     *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt, flags);
+			     "%s: TCP recvmsg seq # bug 2: copied %X, seq %X, rcvnxt %X, fl %X\n",
+			     __func__, *seq,
+			     TCP_SKB_CB(skb)->seq, tp->rcv_nxt, flags);
 		}
 
 		/* Well, if we have backlog, try to process it now yet. */