[1/2] net: qrtr: Respond to HELLO message

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.

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@linaro.org>
---
 net/qrtr/ns.c | 54 ++++++++++++++++++++++++++++-----------------------
 1 file changed, 30 insertions(+), 24 deletions(-)

On Sun 01 Mar 21:50 PST 2020, Manivannan Sadhasivam wrote:

> 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.
> 

No worries.

> > 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@linaro.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?
> 

Because I changed the prototype of say_hello() so that we pass the
destination address; here that's the broadcast address, in
ctrl_cmd_hello() it's the specific sender of the incoming hello that we
want to respond to.

Regards,
Bjorn

> Other than that,
> 
> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> Tested-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> 
> Thanks,
> Mani
> 
> >  	if (ret < 0)
> >  		goto err_wq;
> >  
> > -- 
> > 2.24.0
> >