On Wed, Aug 7, 2019 at 2:01 PM Jakub Kicinski
<jakub.kicin...@netronome.com> wrote:
>
> On Wed, 7 Aug 2019 12:59:00 -0400, Willem de Bruijn wrote:
> > On Wed, Aug 7, 2019 at 2:06 AM Jakub Kicinski wrote:
> > > diff --git a/net/core/sock.c b/net/core/sock.c
> > > index d57b0cc995a0..0f9619b0892f 100644
> > > --- a/net/core/sock.c
> > > +++ b/net/core/sock.c
> > > @@ -1992,6 +1992,20 @@ void skb_set_owner_w(struct sk_buff *skb, struct
> > > sock *sk)
> > > }
> > > EXPORT_SYMBOL(skb_set_owner_w);
> > >
> > > +static bool can_skb_orphan_partial(const struct sk_buff *skb)
> > > +{
> > > +#ifdef CONFIG_TLS_DEVICE
> > > + /* Drivers depend on in-order delivery for crypto offload,
> > > + * partial orphan breaks out-of-order-OK logic.
> > > + */
> > > + if (skb->decrypted)
> > > + return false;
> > > +#endif
> > > + return (IS_ENABLED(CONFIG_INET) &&
> > > + skb->destructor == tcp_wfree) ||
> >
> > Please add parentheses around IS_ENABLED(CONFIG_INET) &&
> > skb->destructor == tcp_wfree
>
> Mm.. there are parenthesis around them, maybe I'm being slow,
> could you show me how?
I mean
return (skb->destructor == sock_wfree ||
(IS_ENABLED(CONFIG_INET) && skb->destructor == tcp_wfree))
In other words, (a || (b && c)) instead of (a || b && c). Though the
existing code also eschews the extra parentheses.
> > I was also surprised that this works when tcp_wfree is not defined if
> > !CONFIG_INET. But apparently it does (at -O2?) :)
>
> I was surprised to but in essence it should work the same as
>
> if (IS_ENABLED(CONFIG_xyz))
> call_some_xyz_code();
>
> from compiler's perspective, and we do that a lot. Perhaps kbuild
> bot will prove us wrong :)
>
> > > @@ -984,6 +984,9 @@ ssize_t do_tcp_sendpages(struct sock *sk, struct page
> > > *page, int offset,
> > > if (!skb)
> > > goto wait_for_memory;
> > >
> > > +#ifdef CONFIG_TLS_DEVICE
> > > + skb->decrypted = !!(flags &
> > > MSG_SENDPAGE_DECRYPTED);
> > > +#endif
> >
> > Nothing is stopping userspace from passing this new flag. In send
> > (tcp_sendmsg_locked) it is ignored. But can it reach do_tcp_sendpages
> > through tcp_bpf_sendmsg?
>
> Ah, I think you're right, thanks for checking that :( I don't entirely
> follow how 0608c69c9a80 ("bpf: sk_msg, sock{map|hash} redirect through
> ULP") is safe then.
>
> One option would be to clear the flags kernel would previously ignore
> in tcp_bpf_sendmsg(). But I feel like we should just go back to marking
> the socket, since we don't need the per-message flexibility of a flag.
>
> WDYT?
I don't feel strongly either way. Passing flags from send through
tcp_bpf_sendmsg is probably unintentional, so should probably be
addressed anyway? Then this is a bit simpler.
> > > skb_entail(sk, skb);
> > > copy = size_goal;
> > > }
> > > diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> > > index 6e4afc48d7bb..979520e46e33 100644
> > > --- a/net/ipv4/tcp_output.c
> > > +++ b/net/ipv4/tcp_output.c
> > > @@ -1320,6 +1320,7 @@ int tcp_fragment(struct sock *sk, enum tcp_queue
> > > tcp_queue,
> > > buff = sk_stream_alloc_skb(sk, nsize, gfp, true);
> > > if (!buff)
> > > return -ENOMEM; /* We'll just try again later. */
> > > + skb_copy_decrypted(buff, skb);
> >
> > This code has to copy timestamps, tx_flags, zerocopy state and now
> > this in three locations. Eventually we'll want a single helper for all
> > of them..
>
> Ack, should I take an action on that for net-next or was it a
> note-to-self? :)
Note-to-self :)
As a matter of fact, your patch showed me that we actually miss the
tstamp case in tcp_mtu_probe..
