Re: [PATCH 0/24] kernel: add a netlink interface to get information about processes (v2)

On Fri, Dec 04, 2015 at 12:43:29AM +0100, Arnd Bergmann wrote:

On Thursday 03 December 2015 15:20:30 Andy Lutomirski wrote:

quoted

quoted

* Netlink is designed for such type of workloads. It allows to expand
  the interface and save backward compatibility. It allows to generates
  packets with a different set of parameters.
* If we use a file descriptor, we can create it and decrease
  capabilities of the current process. It's a good feature which will be
  unavailable if we decide to create a system call.

If this is actually a real goal and it matters, then I'd suggest doing
it right.  Make a way to create an fd that represents a pidns and,
specifically, the right to query non-secret properties of the
processes in the pidns.

My first thought about doing an interface here was to create a virtual
file system that can be queried rather than using netlink, but then I
realized that the idea was to avoid procfs ;-)

No, we doesn't have an idea to avoid using of procfs. The idea is to
create a new interace to get information about tasks, which will work
faster and will be more convenient for using from applications.

More seriously, maybe the answer is to have a transaction file in
procfs itself. Procfs already knows about namespaces, so adding
a /proc/task-diag file as the entry point into the kernel could
get that out of the way.

The simple_transaction infrastructure that we have is limited to
a little under a page for the total data size, but something similar
could be used.

Thank you for the idea.

	Arnd