1 files changed, 132 insertions, 65 deletions

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index de20928f7402..4ea44a2f48f7 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -1058,102 +1058,105 @@ static struct notifier_block netconsole_netdev_notifier = {
 	.notifier_call  = netconsole_netdev_event,
 };
 
-/**
- * send_ext_msg_udp - send extended log message to target
- * @nt: target to send message to
- * @msg: extended log message to send
- * @msg_len: length of message
- *
- * Transfer extended log @msg to @nt.  If @msg is longer than
- * MAX_PRINT_CHUNK, it'll be split and transmitted in multiple chunks with
- * ncfrag header field added to identify them.
- */
-static void send_ext_msg_udp(struct netconsole_target *nt, const char *msg,
-			     int msg_len)
+static void send_msg_no_fragmentation(struct netconsole_target *nt,
+				      const char *msg,
+				      int msg_len,
+				      int release_len)
 {
 	static char buf[MAX_PRINT_CHUNK]; /* protected by target_list_lock */
-	const char *header, *body;
-	int offset = 0;
-	int header_len, body_len;
-	const char *msg_ready = msg;
+	const char *userdata = NULL;
 	const char *release;
-	int release_len = 0;
-	int userdata_len = 0;
-	char *userdata = NULL;
 
 #ifdef CONFIG_NETCONSOLE_DYNAMIC
 	userdata = nt->userdata_complete;
-	userdata_len = nt->userdata_length;
 #endif
 
-	if (nt->release) {
+	if (release_len) {
 		release = init_utsname()->release;
-		release_len = strlen(release) + 1;
+
+		scnprintf(buf, MAX_PRINT_CHUNK, "%s,%s", release, msg);
+		msg_len += release_len;
+	} else {
+		memcpy(buf, msg, msg_len);
 	}
 
-	if (msg_len + release_len + userdata_len <= MAX_PRINT_CHUNK) {
-		/* No fragmentation needed */
-		if (nt->release) {
-			scnprintf(buf, MAX_PRINT_CHUNK, "%s,%s", release, msg);
-			msg_len += release_len;
-		} else {
-			memcpy(buf, msg, msg_len);
-		}
+	if (userdata)
+		msg_len += scnprintf(&buf[msg_len],
+				     MAX_PRINT_CHUNK - msg_len,
+				     "%s", userdata);
 
-		if (userdata)
-			msg_len += scnprintf(&buf[msg_len],
-					     MAX_PRINT_CHUNK - msg_len,
-					     "%s", userdata);
+	netpoll_send_udp(&nt->np, buf, msg_len);
+}
 
-		msg_ready = buf;
-		netpoll_send_udp(&nt->np, msg_ready, msg_len);
-		return;
-	}
+static void append_release(char *buf)
+{
+	const char *release;
 
-	/* need to insert extra header fields, detect header and body */
-	header = msg;
-	body = memchr(msg, ';', msg_len);
-	if (WARN_ON_ONCE(!body))
-		return;
+	release = init_utsname()->release;
+	scnprintf(buf, MAX_PRINT_CHUNK, "%s,", release);
+}
 
-	header_len = body - header;
-	body_len = msg_len - header_len - 1;
-	body++;
+static void send_fragmented_body(struct netconsole_target *nt, char *buf,
+				 const char *msgbody, int header_len,
+				 int msgbody_len)
+{
+	const char *userdata = NULL;
+	int body_len, offset = 0;
+	int userdata_len = 0;
 
-	/*
-	 * Transfer multiple chunks with the following extra header.
-	 * "ncfrag=<byte-offset>/<total-bytes>"
+#ifdef CONFIG_NETCONSOLE_DYNAMIC
+	userdata = nt->userdata_complete;
+	userdata_len = nt->userdata_length;
+#endif
+
+	/* body_len represents the number of bytes that will be sent. This is
+	 * bigger than MAX_PRINT_CHUNK, thus, it will be split in multiple
+	 * packets
 	 */
-	if (nt->release)
-		scnprintf(buf, MAX_PRINT_CHUNK, "%s,", release);
-	memcpy(buf + release_len, header, header_len);
-	header_len += release_len;
+	body_len = msgbody_len + userdata_len;
 
-	while (offset < body_len + userdata_len) {
+	/* In each iteration of the while loop below, we send a packet
+	 * containing the header and a portion of the body. The body is
+	 * composed of two parts: msgbody and userdata. We keep track of how
+	 * many bytes have been sent so far using the offset variable, which
+	 * ranges from 0 to the total length of the body.
+	 */
+	while (offset < body_len) {
 		int this_header = header_len;
+		bool msgbody_written = false;
 		int this_offset = 0;
 		int this_chunk = 0;
 
 		this_header += scnprintf(buf + this_header,
-					 sizeof(buf) - this_header,
+					 MAX_PRINT_CHUNK - this_header,
 					 ",ncfrag=%d/%d;", offset,
-					 body_len + userdata_len);
+					 body_len);
 
-		/* Not all body data has been written yet */
-		if (offset < body_len) {
-			this_chunk = min(body_len - offset,
+		/* Not all msgbody data has been written yet */
+		if (offset < msgbody_len) {
+			this_chunk = min(msgbody_len - offset,
 					 MAX_PRINT_CHUNK - this_header);
 			if (WARN_ON_ONCE(this_chunk <= 0))
 				return;
-			memcpy(buf + this_header, body + offset, this_chunk);
+			memcpy(buf + this_header, msgbody + offset, this_chunk);
 			this_offset += this_chunk;
 		}
-		/* Body is fully written and there is pending userdata to write,
-		 * append userdata in this chunk
+
+		/* msgbody was finally written, either in the previous
+		 * messages and/or in the current buf. Time to write
+		 * the userdata.
 		 */
-		if (offset + this_offset >= body_len &&
-		    offset + this_offset < userdata_len + body_len) {
-			int sent_userdata = (offset + this_offset) - body_len;
+		msgbody_written |= offset + this_offset >= msgbody_len;
+
+		/* Msg body is fully written and there is pending userdata to
+		 * write, append userdata in this chunk
+		 */
+		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))
@@ -1180,6 +1183,70 @@ static void send_ext_msg_udp(struct netconsole_target *nt, const char *msg,
 	}
 }
 
+static void send_msg_fragmented(struct netconsole_target *nt,
+				const char *msg,
+				int msg_len,
+				int release_len)
+{
+	static char buf[MAX_PRINT_CHUNK]; /* protected by target_list_lock */
+	int header_len, msgbody_len;
+	const char *msgbody;
+
+	/* need to insert extra header fields, detect header and msgbody */
+	msgbody = memchr(msg, ';', msg_len);
+	if (WARN_ON_ONCE(!msgbody))
+		return;
+
+	header_len = msgbody - msg;
+	msgbody_len = msg_len - header_len - 1;
+	msgbody++;
+
+	/*
+	 * Transfer multiple chunks with the following extra header.
+	 * "ncfrag=<byte-offset>/<total-bytes>"
+	 */
+	if (release_len)
+		append_release(buf);
+
+	/* Copy the header into the buffer */
+	memcpy(buf + release_len, msg, header_len);
+	header_len += release_len;
+
+	/* for now on, the header will be persisted, and the msgbody
+	 * will be replaced
+	 */
+	send_fragmented_body(nt, buf, msgbody, header_len, msgbody_len);
+}
+
+/**
+ * send_ext_msg_udp - send extended log message to target
+ * @nt: target to send message to
+ * @msg: extended log message to send
+ * @msg_len: length of message
+ *
+ * Transfer extended log @msg to @nt.  If @msg is longer than
+ * MAX_PRINT_CHUNK, it'll be split and transmitted in multiple chunks with
+ * ncfrag header field added to identify them.
+ */
+static void send_ext_msg_udp(struct netconsole_target *nt, const char *msg,
+			     int msg_len)
+{
+	int userdata_len = 0;
+	int release_len = 0;
+
+#ifdef CONFIG_NETCONSOLE_DYNAMIC
+	userdata_len = nt->userdata_length;
+#endif
+
+	if (nt->release)
+		release_len = strlen(init_utsname()->release) + 1;
+
+	if (msg_len + release_len + userdata_len <= MAX_PRINT_CHUNK)
+		return send_msg_no_fragmentation(nt, msg, msg_len, release_len);
+
+	return send_msg_fragmented(nt, msg, msg_len, release_len);
+}
+
 static void write_ext_msg(struct console *con, const char *msg,
 			  unsigned int len)
 {