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

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Message-ID: <20230330112716.GA84386@thinkpad>
Date:   Thu, 30 Mar 2023 18:09:50 +0530
From:   Manivannan Sadhasivam <mani@...nel.org>
To:     Sricharan R <quic_srichara@...cinc.com>
Cc:     manivannan.sadhasivam@...aro.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] net: qrtr: Do not do DEL_SERVER broadcast after
 DEL_CLIENT

On Wed, Mar 29, 2023 at 06:37:30PM +0530, Sricharan R wrote:
> When the qrtr socket is released, qrtr_port_remove gets called, which
> broadcasts a DEL_CLIENT. After this DEL_SERVER is also additionally
> broadcasted, which becomes NOP, but triggers the below error msg.
> 
> "failed while handling packet from 2:-2", since remote node already
> acted upon on receiving the DEL_CLIENT, once again when it receives
> the DEL_SERVER, it returns -ENOENT.
> 
> Fixing it by not sending a 'DEL_SERVER' to remote when a 'DEL_CLIENT'
> was sent for that port.
> 

How about:

"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."

> Signed-off-by: Ram Kumar D <quic_ramd@...cinc.com>
> Signed-off-by: Sricharan R <quic_srichara@...cinc.com>
> ---
> Note: Functionally tested on 5.4 kernel and compile tested on 6.3 TOT
> 
>  net/qrtr/ns.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/net/qrtr/ns.c b/net/qrtr/ns.c
> index 722936f..6fbb195 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 del_server)

s/bool del_server/bool bcast/g

>  {
>  	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 && del_server)
>  		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 +459,14 @@ 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
> +	 * Given that DEL_CLIENT is already broadcasted
> +	 * by port_remove, no need to send DEL_SERVER for
> +	 * the same port to remote
> +	 */

	/*
 	 * Remove the server belonging to this port but don't broadcast
	 * DEL_SERVER. Neighbours would've already removed the server belonging
	 * to this port due to the DEL_CLIENT broadcast from qrtr_port_remove().
	 */
- Mani

>  	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 +571,7 @@ 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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