Re: [RFC PATCH net-next v3 1/5] gtp: Allow to create GTP device without FDs

Hi Harald,

Sorry for long delay in reply.

On 05-Feb-22 17:34, Harald Welte wrote:

Hi Marcin, Wojciech,

thanks for the revised patch. In general it looks fine to me.

Do you have a public git tree with your patchset applied?  I'm asking as
we do have automatic testing in place at https://jenkins.osmocom.org/ where I
just need to specify a remote git repo andit will build this kernel and
run the test suite.

I've created a public fork with our patchset applied, please see [1].

Some minor remarks below, all not critical, just some thoughts.

It might make sense to mention in the commit log that this patch by itself
would create GTP-U without GTP ECHO capabilities, and that a subsequent
patch will address this.

quoted

This patch allows to create GTP device without providing
IFLA_GTP_FD0 and IFLA_GTP_FD1 arguments. If the user does not
provide file handles to the sockets, then GTP module takes care
of creating UDP sockets by itself. 

I'm wondering if we should make this more explicit, i.e. rather than
implicitly creating the kernel socket automagically, make this mode
explicit upon request by some netlink attribute.

quoted

Sockets are created with the
commonly known UDP ports used for GTP protocol (GTP0_PORT and
GTP1U_PORT).

I'm wondering if there are use cases that need to operate on
non-standard ports.  The current module can be used that way (as the
socket is created in user space). If the "kernel socket mode" was
requested explicitly via netlink attribute, one could just as well
pass along the port number[s] this way.

[1] https://github.com/mszycik/linux/tree/cpk_switchdev_gtp