linux-kernel - Re: [PATCH 1/2] net: qrtr: Respond to HELLO message

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Date:   Mon, 2 Mar 2020 11:20:25 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 1/2] net: qrtr: Respond to HELLO message

Hi Bjorn,

Thanks for the fix. I have tested this and it works perfectly!

On Sun, Mar 01, 2020 at 07:25:26PM -0800, Bjorn Andersson wrote:
> Lost in the translation from the user space implementation was the
> detail that HELLO mesages must be exchanged between each node pair.  As
> such the incoming HELLO must be replied to.
> 

Err. I thought the say_hello() part in ctrl_cmd_hello() was redundant, so
removed it :P

Sorry for that.

> Similar to the previous implementation no effort is made to prevent two
> Linux boxes from continuously sending HELLO messages back and forth,
> this is left to a follow up patch.
> 
> say_hello() is moved, to facilitate the new call site.
> 
> Fixes: 0c2204a4ad71 ("net: qrtr: Migrate nameservice to kernel from userspace")
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
>  net/qrtr/ns.c | 54 ++++++++++++++++++++++++++++-----------------------
>  1 file changed, 30 insertions(+), 24 deletions(-)
> 
> diff --git a/net/qrtr/ns.c b/net/qrtr/ns.c
> index 7bfde01f4e8a..e3f11052b5f6 100644
> --- a/net/qrtr/ns.c
> +++ b/net/qrtr/ns.c
> @@ -286,9 +286,38 @@ static int server_del(struct qrtr_node *node, unsigned int port)
>  	return 0;
>  }
>  
> +static int say_hello(struct sockaddr_qrtr *dest)
> +{
> +	struct qrtr_ctrl_pkt pkt;
> +	struct msghdr msg = { };
> +	struct kvec iv;
> +	int ret;
> +
> +	iv.iov_base = &pkt;
> +	iv.iov_len = sizeof(pkt);
> +
> +	memset(&pkt, 0, sizeof(pkt));
> +	pkt.cmd = cpu_to_le32(QRTR_TYPE_HELLO);
> +
> +	msg.msg_name = (struct sockaddr *)dest;
> +	msg.msg_namelen = sizeof(*dest);
> +
> +	ret = kernel_sendmsg(qrtr_ns.sock, &msg, &iv, 1, sizeof(pkt));
> +	if (ret < 0)
> +		pr_err("failed to send hello msg\n");
> +
> +	return ret;
> +}
> +
>  /* Announce the list of servers registered on the local node */
>  static int ctrl_cmd_hello(struct sockaddr_qrtr *sq)
>  {
> +	int ret;
> +
> +	ret = say_hello(sq);
> +	if (ret < 0)
> +		return ret;
> +
>  	return announce_servers(sq);
>  }
>  
> @@ -566,29 +595,6 @@ static void ctrl_cmd_del_lookup(struct sockaddr_qrtr *from,
>  	}
>  }
>  
> -static int say_hello(void)
> -{
> -	struct qrtr_ctrl_pkt pkt;
> -	struct msghdr msg = { };
> -	struct kvec iv;
> -	int ret;
> -
> -	iv.iov_base = &pkt;
> -	iv.iov_len = sizeof(pkt);
> -
> -	memset(&pkt, 0, sizeof(pkt));
> -	pkt.cmd = cpu_to_le32(QRTR_TYPE_HELLO);
> -
> -	msg.msg_name = (struct sockaddr *)&qrtr_ns.bcast_sq;
> -	msg.msg_namelen = sizeof(qrtr_ns.bcast_sq);
> -
> -	ret = kernel_sendmsg(qrtr_ns.sock, &msg, &iv, 1, sizeof(pkt));
> -	if (ret < 0)
> -		pr_err("failed to send hello msg\n");
> -
> -	return ret;
> -}
> -
>  static void qrtr_ns_worker(struct work_struct *work)
>  {
>  	const struct qrtr_ctrl_pkt *pkt;
> @@ -725,7 +731,7 @@ void qrtr_ns_init(struct work_struct *work)
>  	if (!qrtr_ns.workqueue)
>  		goto err_sock;
>  
> -	ret = say_hello();
> +	ret = say_hello(&qrtr_ns.bcast_sq);

Why do you want to pass a global variable here? Why can't it be used directly
in say_hello() as done before?

Other than that,

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Tested-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>

Thanks,
Mani

>  	if (ret < 0)
>  		goto err_wq;
>  
> -- 
> 2.24.0
>