linux-kernel - [PATCH RFC net-next 1/2] netconsole: extract message fragmentation into write_msg

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Message-Id: <20251121-nbcon-v1-1-503d17b2b4af@debian.org>
Date: Fri, 21 Nov 2025 03:26:07 -0800
From: Breno Leitao <leitao@...ian.org>
To: Breno Leitao <leitao@...ian.org>, Jakub Kicinski <kuba@...nel.org>, 
 horms@...nel.org, efault@....de, john.ogness@...utronix.de, 
 pmladek@...e.com
Cc: Andrew Lunn <andrew+netdev@...n.ch>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org, 
 linux-kernel@...r.kernel.org, calvin@...nvd.org, asml.silence@...il.com, 
 kernel-team@...a.com, gustavold@...il.com, asantostc@...il.com
Subject: [PATCH RFC net-next 1/2] netconsole: extract message fragmentation
 into write_msg_target()

Refactor the message fragmentation logic in write_msg() by extracting it
into a separate write_msg_target() helper function. This makes the code
more maintainable and prepares for future reuse in nbcon support for
non-extended consoles.

The helper function takes a target, message, and length, then handles
splitting the message into MAX_PRINT_CHUNK-sized fragments for sending
via send_udp().

No functional change intended.

Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 drivers/net/netconsole.c | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index bb6e03a92956..f4b1706fb081 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -1559,6 +1559,20 @@ static void append_release(char *buf)
 	scnprintf(buf, MAX_PRINT_CHUNK, "%s,", release);
 }

+static void write_msg_target(struct netconsole_target *nt, const char *msg,
+			     unsigned int len)
+{
+	const char *tmp = msg;
+	int frag, left = len;
+
+	while (left > 0) {
+		frag = min(left, MAX_PRINT_CHUNK);
+		send_udp(nt, tmp, frag);
+		tmp += frag;
+		left -= frag;
+	}
+}
+
 static void send_fragmented_body(struct netconsole_target *nt,
 				 const char *msgbody, int header_len,
 				 int msgbody_len, int extradata_len)
@@ -1728,10 +1742,8 @@ static void write_ext_msg(struct console *con, const char *msg,

 static void write_msg(struct console *con, const char *msg, unsigned int len)
 {
-	int frag, left;
-	unsigned long flags;
 	struct netconsole_target *nt;
-	const char *tmp;
+	unsigned long flags;

 	if (oops_only && !oops_in_progress)
 		return;
@@ -1748,13 +1760,7 @@ static void write_msg(struct console *con, const char *msg, unsigned int len)
 			 * at least one target if we die inside here, instead
 			 * of unnecessarily keeping all targets in lock-step.
 			 */
-			tmp = msg;
-			for (left = len; left;) {
-				frag = min(left, MAX_PRINT_CHUNK);
-				send_udp(nt, tmp, frag);
-				tmp += frag;
-				left -= frag;
-			}
+			write_msg_target(nt, msg, len);
 		}
 	}
 	spin_unlock_irqrestore(&target_list_lock, flags);

-- 
2.47.3