Re: [PATCH] net: qrtr: Update packets cloning when broadcasting

[Chris Lew <quic_clew@quicinc.com>]

Hi Youssef,

On 9/16/2024 10:08 AM, Youssef Samir wrote:
> When broadcasting data to multiple nodes via MHI, using skb_clone()
> causes all nodes to receive the same header data. This can result in
> packets being discarded by endpoints, leading to lost data.
> 
> This issue occurs when a socket is closed, and a QRTR_TYPE_DEL_CLIENT
> packet is broadcasted. All nodes receive the same destination node ID,
> causing the node connected to the client to discard the packet and
> remain unaware of the client's deletion.
> 

I guess this never happens for the SMD/RPMSG transport because the skb 
is consumed within the context of qrtr_node_enqueue where as MHI queues 
the skb to be transmitted later.

Does the duplicate destination node ID match the last node in the 
qrtr_all_nodes list?


> Replace skb_clone() with pskb_copy(), to create a separate copy of
> the header for each sk_buff.
> 
> Fixes: bdabad3e363d ("net: Add Qualcomm IPC router")
> Signed-off-by: Youssef Samir <quic_yabdulra@quicinc.com>
> Reviewed-by: Jeffery Hugo <quic_jhugo@quicinc.com>
> Reviewed-by: Carl Vanderlip <quic_carlv@quicinc.com>
> ---
>   net/qrtr/af_qrtr.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/qrtr/af_qrtr.c b/net/qrtr/af_qrtr.c
> index 41ece61eb57a..00c51cf693f3 100644
> --- a/net/qrtr/af_qrtr.c
> +++ b/net/qrtr/af_qrtr.c
> @@ -884,7 +884,7 @@ static int qrtr_bcast_enqueue(struct qrtr_node *node, struct sk_buff *skb,
>   
>   	mutex_lock(&qrtr_node_lock);
>   	list_for_each_entry(node, &qrtr_all_nodes, item) {
> -		skbn = skb_clone(skb, GFP_KERNEL);
> +		skbn = pskb_copy(skb, GFP_KERNEL);
>   		if (!skbn)
>   			break;
>   		skb_set_owner_w(skbn, skb->sk);