Subject: Re: [PATCH net-next 8/9] net: netconsole: split send_msg_fragmented

From: Simon Horman <[email-masked]>
Date: Wed, 4 Sep 2024 12:16:36 +0100

On Tue, Sep 03, 2024 at 07:07:51AM -0700, Breno Leitao wrote:
> Refactor the send_msg_fragmented() function by extracting the logic for
> sending the message body into a new function called
> send_fragmented_body().
> 
> Now, send_msg_fragmented() handles appending the release and header, and
> then delegates the task of sending the body to send_fragmented_body().

I think it would be good to expand a bit on why here.

> Signed-off-by: Breno Leitao <[email-masked]>
> ---
>  drivers/net/netconsole.c | 85 +++++++++++++++++++++++-----------------
>  1 file changed, 48 insertions(+), 37 deletions(-)
> 
> diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
> index be23def330e9..81d7d2b09988 100644
> --- a/drivers/net/netconsole.c
> +++ b/drivers/net/netconsole.c
> @@ -1066,45 +1066,21 @@ static void append_release(char *buf)
>  	scnprintf(buf, MAX_PRINT_CHUNK, "%s,", release);
>  }
>  
> -static void send_msg_fragmented(struct netconsole_target *nt,
> -				const char *msg,
> -				const char *userdata,
> -				int msg_len,
> -				int release_len)
> +static void send_fragmented_body(struct netconsole_target *nt, char *buf,
> +				 const char *msgbody, int header_len,
> +				 int msgbody_len)
>  {
> -	int header_len, msgbody_len, body_len;
> -	static char buf[MAX_PRINT_CHUNK]; /* protected by target_list_lock */
> -	int offset = 0, userdata_len = 0;
> -	const char *header, *msgbody;
> -
> -	if (userdata)
> -		userdata_len = nt->userdata_length;
> -
> -	/* need to insert extra header fields, detect header and msgbody */
> -	header = msg;
> -	msgbody = memchr(msg, ';', msg_len);
> -	if (WARN_ON_ONCE(!msgbody))
> -		return;
> -
> -	header_len = msgbody - header;
> -	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);
> +	int body_len, offset = 0;
> +	const char *userdata = NULL;
> +	int userdata_len = 0;
>  
> -	/* Copy the header into the buffer */
> -	memcpy(buf + release_len, header, header_len);
> -	header_len += release_len;
> +#ifdef CONFIG_NETCONSOLE_DYNAMIC
> +	userdata = nt->userdata_complete;
> +	userdata_len = nt->userdata_length;
> +#endif

I think that dropping the userdata parameter of send_msg_fragmented() ought
to part of an earlier patch or separate patch. It doesn't seem strictly
related to this patch.

>  
>  	body_len = msgbody_len + userdata_len;
> -	/* for now on, the header will be persisted, and the msgbody
> -	 * will be replaced
> -	 */
> +
>  	while (offset < body_len) {
>  		int this_header = header_len;
>  		bool msgbody_written = false;

...

> @@ -1161,6 +1137,41 @@ static void send_msg_fragmented(struct netconsole_target *nt,
>  	}
>  }
>  
> +static void send_msg_fragmented(struct netconsole_target *nt,
> +				const char *msg,
> +				int msg_len,
> +				int release_len)

...