Re: [PATCH v9 01/10] btf: Add a new kfunc flag which allows to mark a function to be sleepable

[Daniel Borkmann]

On 8/10/22 4:25 PM, Benjamin Tissoires wrote:
> On Wed, Aug 10, 2022 at 3:44 PM Roberto Sassu <roberto.sassu@xxxxxxxxxx> wrote:
> > > From: Jarkko Sakkinen [mailto:jarkko@xxxxxxxxxx]
> > > Sent: Tuesday, August 9, 2022 6:55 PM
> > > On Tue, Aug 09, 2022 at 03:45:54PM +0200, Roberto Sassu wrote:
> > > > From: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
> > > >
> > > > From: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
> > > >
> > > > This allows to declare a kfunc as sleepable and prevents its use in
> > > > a non sleepable program.
> > >
> > > Nit: "Declare a kfunc as sleepable and prevent its use in a
> > > non-sleepable program."
> > >
> > > It's missing the part *how* the patch accomplishes its goals.
> >
> > I will add:
> >
> > If an eBPF program is going to call a kfunc declared as sleepable,
> > eBPF will look at the eBPF program flags. If BPF_F_SLEEPABLE is
> > not set, execution of that program is denied.
>
> All those changes are looking good to me.
>
> Thanks a lot for keeping pushing on this patch :)

This single one from the series got already applied here:

  https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/commit/?id=fa96b24204af42274ec13dfb2f2e6990d7510e55

> > > > Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
> > > > Co-developed-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
> > > > Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
> > > > Signed-off-by: Hao Luo <haoluo@xxxxxxxxxx>
> > > > ---
> > > >   Documentation/bpf/kfuncs.rst | 6 ++++++
> > > >   include/linux/btf.h          | 1 +
> > > >   kernel/bpf/btf.c             | 9 +++++++++
> > > >   3 files changed, 16 insertions(+)
> > > >
> > > > diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst
> > > > index c0b7dae6dbf5..c8b21de1c772 100644
> > > > --- a/Documentation/bpf/kfuncs.rst
> > > > +++ b/Documentation/bpf/kfuncs.rst
> > > > @@ -146,6 +146,12 @@ that operate (change some property, perform some
> > > operation) on an object that
> > > >   was obtained using an acquire kfunc. Such kfuncs need an unchanged pointer
> > > to
> > > >   ensure the integrity of the operation being performed on the expected object.