bpf.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: KP Singh <kpsingh@chromium.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>,
	"David S. Miller" <davem@davemloft.net>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Network Development <netdev@vger.kernel.org>,
	bpf <bpf@vger.kernel.org>, Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH v5 bpf-next 2/5] bpf: Introduce sleepable BPF programs
Date: Wed, 1 Jul 2020 21:03:00 +0200	[thread overview]
Message-ID: <CACYkzJ4286FaB4k7ZF7UdU5q_UTAy_M4QyWGEXXGPu8pVeX3LA@mail.gmail.com> (raw)
In-Reply-To: <CAADnVQKF4z1kGduHdoRdNqmFQSoQ+b9skyb7n23YQj7X0qx8TA@mail.gmail.com>

On Wed, Jul 1, 2020 at 5:14 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Wed, Jul 1, 2020 at 2:17 AM Daniel Borkmann <daniel@iogearbox.net> wrote:
> > ("bpf: Replace cant_sleep() with cant_migrate()"). So perhaps one way to catch
> > bugs for sleepable progs is to add a __might_sleep() into __bpf_prog_enter_sleepable()
>
> that's a good idea.
>
> > in order to trigger the assertion generally for DEBUG_ATOMIC_SLEEP configured
> > kernels when we're in non-sleepable sections? Still not perfect since the code
> > needs to be exercised first but better than nothing at all.
> >
> > >> What about others like security_sock_rcv_skb() for example which could be
> > >> bh_lock_sock()'ed (or, generally hooks running in softirq context)?
> > >
> > > ahh. it's in running in bh at that point? then it should be added to blacklist.
> >
> > Yep.
>
> I'm assuming KP will take care of it soon.

I found one other hook, file_send_sigiotask, which mentions
"Note that this hook is sometimes called from interrupt." So I think
we should add it to the list as well.

Given some more due diligence done here
and Daniel's proposal of adding __might_sleep() to
the __bpf_prog_enter_sleepable() we should be able to
iterate on finding other non-sleepable hooks (if they exist)
and eventually augmenting the LSM_HOOK macro for a
more structured way to store this information.

- KP

> If not I'll come back to this set some time in August.
>
> In the meantime I've pushed patch 1 that removes redundant sync_rcu to bpf-next,
> since it's independent and it benefits from being in the tree as much
> as possible.

  reply	other threads:[~2020-07-01 19:03 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-30  4:33 [PATCH v5 bpf-next 0/5] bpf: Introduce minimal support for sleepable progs Alexei Starovoitov
2020-06-30  4:33 ` [PATCH v5 bpf-next 1/5] bpf: Remove redundant synchronize_rcu Alexei Starovoitov
2020-06-30 20:55   ` Paul E. McKenney
2020-06-30  4:33 ` [PATCH v5 bpf-next 2/5] bpf: Introduce sleepable BPF programs Alexei Starovoitov
2020-06-30 22:04   ` Paul E. McKenney
2020-06-30 23:26   ` Daniel Borkmann
2020-06-30 23:41     ` Alexei Starovoitov
2020-07-01  9:15       ` KP Singh
2020-07-01  9:34         ` Daniel Borkmann
2020-07-01 15:21           ` Alexei Starovoitov
2020-07-10 17:00             ` Arnaldo Carvalho de Melo
2020-07-10 22:59               ` Alexei Starovoitov
2020-07-01  9:17       ` Daniel Borkmann
2020-07-01 15:14         ` Alexei Starovoitov
2020-07-01 19:03           ` KP Singh [this message]
2020-06-30  4:33 ` [PATCH v5 bpf-next 3/5] bpf: Add bpf_copy_from_user() helper Alexei Starovoitov
2020-06-30 11:41   ` KP Singh
2020-06-30  4:33 ` [PATCH v5 bpf-next 4/5] libbpf: support sleepable progs Alexei Starovoitov
2020-06-30  4:33 ` [PATCH v5 bpf-next 5/5] selftests/bpf: Add sleepable tests Alexei Starovoitov
2020-06-30  5:14 ` [PATCH v5 bpf-next 0/5] bpf: Introduce minimal support for sleepable progs Andrii Nakryiko

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CACYkzJ4286FaB4k7ZF7UdU5q_UTAy_M4QyWGEXXGPu8pVeX3LA@mail.gmail.com \
    --to=kpsingh@chromium.org \
    --cc=alexei.starovoitov@gmail.com \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=davem@davemloft.net \
    --cc=kernel-team@fb.com \
    --cc=netdev@vger.kernel.org \
    --cc=paulmck@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).