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Message-Id: <20221208154656.60623-1-leitao@debian.org>
Date: Thu, 8 Dec 2022 07:46:56 -0800
From: Breno Leitao <leitao@...ian.org>
To: edumazet@...gle.com, davem@...emloft.net, kuba@...nel.org,
pabeni@...hat.com, kuniyu@...zon.com
Cc: netdev@...r.kernel.org, leit@...com, yoshfuji@...ux-ipv6.org,
dsahern@...nel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 net-next] tcp: socket-specific version of WARN_ON_ONCE()
There are cases where we need relevant information about the socket
during a warning, so, it could help us to find bugs that happens and do
not have an easy repro.
This patch creates a TCP-socket specific version of WARN_ON_ONCE(), which
dumps revelant information about the TCP socket when it hits rare
warnings, which is super useful for debugging purposes.
Hooking this warning tcp_snd_cwnd_set() for now, but, the intent is to
convert more TCP warnings to this helper later.
Signed-off-by: Breno Leitao <leitao@...ian.org>
---
include/net/tcp.h | 3 ++-
include/net/tcp_debug.h | 10 ++++++++++
net/ipv4/tcp.c | 30 ++++++++++++++++++++++++++++++
3 files changed, 42 insertions(+), 1 deletion(-)
create mode 100644 include/net/tcp_debug.h
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 14d45661a84d..e490af8e6fdc 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -40,6 +40,7 @@
#include <net/inet_ecn.h>
#include <net/dst.h>
#include <net/mptcp.h>
+#include <net/tcp_debug.h>
#include <linux/seq_file.h>
#include <linux/memcontrol.h>
@@ -1229,7 +1230,7 @@ static inline u32 tcp_snd_cwnd(const struct tcp_sock *tp)
static inline void tcp_snd_cwnd_set(struct tcp_sock *tp, u32 val)
{
- WARN_ON_ONCE((int)val <= 0);
+ TCP_SOCK_WARN_ON_ONCE(tp, (int)val <= 0);
tp->snd_cwnd = val;
}
diff --git a/include/net/tcp_debug.h b/include/net/tcp_debug.h
new file mode 100644
index 000000000000..50e96d87d335
--- /dev/null
+++ b/include/net/tcp_debug.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_TCP_DEBUG_H
+#define _LINUX_TCP_DEBUG_H
+
+void tcp_sock_warn(const struct tcp_sock *tp);
+
+#define TCP_SOCK_WARN_ON_ONCE(tcp_sock, condition) \
+ DO_ONCE_LITE_IF(condition, tcp_sock_warn, tcp_sock)
+
+#endif /* _LINUX_TCP_DEBUG_H */
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 54836a6b81d6..5985ba9c4231 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -4705,6 +4705,36 @@ int tcp_abort(struct sock *sk, int err)
}
EXPORT_SYMBOL_GPL(tcp_abort);
+void tcp_sock_warn(const struct tcp_sock *tp)
+{
+ const struct sock *sk = (const struct sock *)tp;
+ struct inet_sock *inet = inet_sk(sk);
+ struct inet_connection_sock *icsk = inet_csk(sk);
+
+ WARN_ON(1);
+
+ pr_warn("Socket Info: family=%u state=%d ccname=%s cwnd=%u",
+ sk->sk_family, sk->sk_state, icsk->icsk_ca_ops->name,
+ tcp_snd_cwnd(tp));
+
+ switch (sk->sk_family) {
+ case AF_INET:
+ pr_warn("saddr=%pI4:%u daddr=%pI4:%u", &inet->inet_saddr,
+ ntohs(inet->inet_sport), &inet->inet_daddr,
+ ntohs(inet->inet_dport));
+
+ break;
+#if IS_ENABLED(CONFIG_IPV6)
+ case AF_INET6:
+ pr_warn("saddr=[%pI6]:%u daddr=[%pI6]:%u", &sk->sk_v6_rcv_saddr,
+ ntohs(inet->inet_sport), &sk->sk_v6_daddr,
+ ntohs(inet->inet_dport));
+ break;
+#endif
+ }
+}
+EXPORT_SYMBOL_GPL(tcp_sock_warn);
+
extern struct tcp_congestion_ops tcp_reno;
static __initdata unsigned long thash_entries;
--
2.30.2
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