On Thu, 12 Dec 2019 18:53:19 -0700, subashab@codeaurora.org wrote:

On 2019-12-12 17:57, Lorenzo Colitti wrote:

quoted

On Fri, Dec 13, 2019 at 9:47 AM Jakub Kicinski wrote:  

quoted

How are the ports which get reserved communicated between the baseband
and the AP? Is this part of the standard? Is the driver that talks to
the base band in the user space and it knows which ports to reserve
statically? Or does the modem dynamically request ports to
reserve/inform the host of ports in use?  

I'm not an expert in that part of the system, but my understanding is
that the primary way this is used is to pre-allocate a block of ports
to be used by the modem on boot, before other applications can bind to
ports. Subash, do you have more details?  

AFAIK these ports are randomly picked and not from a standard.
Userspace gets this information through qrtr during boot.

Atleast in our case, there cannot be any existing user of these ports
since these ports are blocked prior to mobile connection establishment.

Not even a listening socket?

We could call SOCK_DIAG_DESTROY on these ports from userspace as a
precaution as applications would gracefully handle the socket errors.

Right, or kernel could walk them, since presumably every application
using this functionality should do it, anyway? But no strong feeling 
on this if nobody else feels this is needed.