netdev - [PATCH net-next 6/9] net: netconsole: track explicitly if msgbody was written to buffer

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Message-ID: <20240903140757.2802765-7-leitao@debian.org>
Date: Tue,  3 Sep 2024 07:07:49 -0700
From: Breno Leitao <leitao@...ian.org>
To: kuba@...nel.org,
	davem@...emloft.net,
	edumazet@...gle.com,
	pabeni@...hat.com
Cc: thepacketgeek@...il.com,
	horms@...nel.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	davej@...emonkey.org.uk,
	thevlad@...a.com,
	max@...sevol.com
Subject: [PATCH net-next 6/9] net: netconsole: track explicitly if msgbody was written to buffer

The current check to determine if the message body was fully sent is
difficult to follow. To improve clarity, introduce a variable that
explicitly tracks whether the message body (msgbody) has been completely
sent, indicating when it's time to begin sending userdata.

Additionally, add comments to make the code more understandable for
others who may work with it.

Signed-off-by: Breno Leitao <leitao@...ian.org>
---
 drivers/net/netconsole.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index 22ccd9aa016a..c8a23a7684e5 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -1102,6 +1102,7 @@ static void send_msg_fragmented(struct netconsole_target *nt,
 	 */
 	while (offset < body_len) {
 		int this_header = header_len;
+		bool msgbody_written = false;
 		int this_offset = 0;
 		int this_chunk = 0;
 
@@ -1119,12 +1120,22 @@ static void send_msg_fragmented(struct netconsole_target *nt,
 			memcpy(buf + this_header, msgbody + offset, this_chunk);
 			this_offset += this_chunk;
 		}
+
+		if (offset + this_offset >= msgbody_len)
+			/* msgbody was finally written, either in the previous messages
+			 * and/or in the current buf. Time to write the userdata.
+			 */
+			msgbody_written = true;
+
 		/* Msg body is fully written and there is pending userdata to write,
 		 * append userdata in this chunk
 		 */
-		if (offset + this_offset >= msgbody_len &&
-		    offset + this_offset < body_len) {
+		if (msgbody_written && offset + this_offset < body_len) {
+			/* Track how much user data was already sent. First time here, sent_userdata
+			 * is zero
+			 */
 			int sent_userdata = (offset + this_offset) - msgbody_len;
+			/* offset of bytes used in current buf */
 			int preceding_bytes = this_chunk + this_header;
 
 			if (WARN_ON_ONCE(sent_userdata < 0))
-- 
2.43.5