linux-kernel - Re: [PATCH V2] net: qrtr: Do not do DEL_SERVER broadcast after DEL

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Message-ID: <20230331080216.GA6352@thinkpad>
Date:   Fri, 31 Mar 2023 13:32:16 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Sricharan Ramabadhran <quic_srichara@...cinc.com>
Cc:     mani@...nel.org, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, linux-arm-msm@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2] net: qrtr: Do not do DEL_SERVER broadcast after
 DEL_CLIENT

On Fri, Mar 31, 2023 at 01:18:57PM +0530, Sricharan Ramabadhran wrote:
> On the remote side, when QRTR socket is removed, af_qrtr will call
> qrtr_port_remove() which broadcasts the DEL_CLIENT packet to all neighbours
> including local NS. NS upon receiving the DEL_CLIENT packet, will remove
> the lookups associated with the node:port and broadcasts the DEL_SERVER
> packet.
> 
> But on the host side, due to the arrival of the DEL_CLIENT packet, the NS
> would've already deleted the server belonging to that port. So when the
> remote's NS again broadcasts the DEL_SERVER for that port, it throws below
> error message on the host:
> 
> "failed while handling packet from 2:-2"
> 
> So fix this error by not broadcasting the DEL_SERVER packet when the
> DEL_CLIENT packet gets processed."
> 
> Fixes: 0c2204a4ad71 ("net: qrtr: Migrate nameservice to kernel from userspace")
> Signed-off-by: Sricharan Ramabadhran <quic_srichara@...cinc.com>
> Signed-off-by: Ram Kumar Dharuman <quic_ramd@...cinc.com>
> ---
> [v2] Fixed comments from Manivannan and Jakub Kicinski
> Note: Functionally tested on 5.4 and compile tested on 6.3 TOT
> 
>  net/qrtr/ns.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/net/qrtr/ns.c b/net/qrtr/ns.c
> index 722936f..0f25a38 100644
> --- a/net/qrtr/ns.c
> +++ b/net/qrtr/ns.c
> @@ -274,7 +274,7 @@ static struct qrtr_server *server_add(unsigned int service,
>  	return NULL;
>  }
>  
> -static int server_del(struct qrtr_node *node, unsigned int port)
> +static int server_del(struct qrtr_node *node, unsigned int port, bool bcast)
>  {
>  	struct qrtr_lookup *lookup;
>  	struct qrtr_server *srv;
> @@ -287,7 +287,7 @@ static int server_del(struct qrtr_node *node, unsigned int port)
>  	radix_tree_delete(&node->servers, port);
>  
>  	/* Broadcast the removal of local servers */
> -	if (srv->node == qrtr_ns.local_node)
> +	if (srv->node == qrtr_ns.local_node && bcast)
>  		service_announce_del(&qrtr_ns.bcast_sq, srv);
>  
>  	/* Announce the service's disappearance to observers */
> @@ -373,7 +373,7 @@ static int ctrl_cmd_bye(struct sockaddr_qrtr *from)
>  		}
>  		slot = radix_tree_iter_resume(slot, &iter);
>  		rcu_read_unlock();
> -		server_del(node, srv->port);
> +		server_del(node, srv->port, true);
>  		rcu_read_lock();
>  	}
>  	rcu_read_unlock();
> @@ -459,10 +459,13 @@ static int ctrl_cmd_del_client(struct sockaddr_qrtr *from,
>  		kfree(lookup);
>  	}
>  
> -	/* Remove the server belonging to this port */
> +	/* Remove the server belonging to this port but don't broadcast

This is still not as per the multi line comment style perferred in kernel.
Please read: https://www.kernel.org/doc/html/latest/process/coding-style.html#commenting

- Mani

> +	 * DEL_SERVER. Neighbours would've already removed the server belonging
> +	 * to this port due to the DEL_CLIENT broadcast from qrtr_port_remove().
> +	 */
>  	node = node_get(node_id);
>  	if (node)
> -		server_del(node, port);
> +		server_del(node, port, false);
>  
>  	/* Advertise the removal of this client to all local servers */
>  	local_node = node_get(qrtr_ns.local_node);
> @@ -567,7 +570,7 @@ static int ctrl_cmd_del_server(struct sockaddr_qrtr *from,
>  	if (!node)
>  		return -ENOENT;
>  
> -	return server_del(node, port);
> +	return server_del(node, port, true);
>  }
>  
>  static int ctrl_cmd_new_lookup(struct sockaddr_qrtr *from,
> -- 
> 2.7.4
> 

-- 
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