linux-kernel - Re: [PATCH] batman-adv: batman-adv: handle tvlv unicast send errors

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Message-ID: <22646445.EfDdHjke4D@ripper>
Date: Tue, 01 Apr 2025 10:48:59 +0200
From: Sven Eckelmann <sven@...fation.org>
To: mareklindner@...mailbox.ch, sw@...onwunderlich.de, a@...table.cc,
 davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
 horms@...nel.org, Wentao Liang <vulab@...as.ac.cn>
Cc: b.a.t.m.a.n@...ts.open-mesh.org, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, Wentao Liang <vulab@...as.ac.cn>,
 stable@...r.kernel.org
Subject: Re: [PATCH] batman-adv: batman-adv: handle tvlv unicast send errors

On Tuesday, 1 April 2025 10:39:00 CEST Wentao Liang wrote:
> In batadv_tvlv_unicast_send(), the return value of
> batadv_send_skb_to_orig() is ignored. This could silently
> drop send failures, making it difficult to detect connectivity
> issues.
> 
> Add error checking for batadv_send_skb_to_orig() and log failures
> via batadv_dbg() to improve error visibility.

This looks more like patch you've added for printk-debugging and nothing for 
stable. And you ignore that it can also return things like -EINPROGRESS. Which 
is not an error.

You can also see that this was just for printk-debugging because the error 
class and message has nothing to do with the actual code.

> 
> Fixes: 1ad5bcb2a032 ("batman-adv: Consume skb in batadv_send_skb_to_orig")
> Cc: stable@...r.kernel.org # 4.10+
> Signed-off-by: Wentao Liang <vulab@...as.ac.cn>
> ---
>  net/batman-adv/tvlv.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/net/batman-adv/tvlv.c b/net/batman-adv/tvlv.c
> index 2a583215d439..f081136cc5b7 100644
> --- a/net/batman-adv/tvlv.c
> +++ b/net/batman-adv/tvlv.c
> @@ -625,6 +625,7 @@ void batadv_tvlv_unicast_send(struct batadv_priv 
*bat_priv, const u8 *src,
>  	unsigned char *tvlv_buff;
>  	unsigned int tvlv_len;
>  	ssize_t hdr_len = sizeof(*unicast_tvlv_packet);
> +	int r;
>  
>  	orig_node = batadv_orig_hash_find(bat_priv, dst);
>  	if (!orig_node)
> @@ -657,7 +658,10 @@ void batadv_tvlv_unicast_send(struct batadv_priv 
*bat_priv, const u8 *src,
>  	tvlv_buff += sizeof(*tvlv_hdr);
>  	memcpy(tvlv_buff, tvlv_value, tvlv_value_len);
>  
> -	batadv_send_skb_to_orig(skb, orig_node, NULL);
> +	r = batadv_send_skb_to_orig(skb, orig_node, NULL);
> +	if (r != NET_XMIT_SUCCESS)
> +		batadv_dbg(BATADV_DBG_TP_METER, bat_priv,
> +			   "Fail to send the ack.");

No, this is definitely the wrong error class. And why do you think that it is 
an ack?
>  out:
>  	batadv_orig_node_put(orig_node);
>  }
> 

Kind regards,
	Sven

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