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

From: Andrew Vagin
Date: Mon Dec 14 2015 - 03:06:00 EST


On Fri, Dec 04, 2015 at 12:43:29AM +0100, Arnd Bergmann wrote:
> On Thursday 03 December 2015 15:20:30 Andy Lutomirski wrote:
> > > * 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
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