netdev - Re: [PATCH bpf 1/2] net: introduce __sk_rmem

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Date: Thu, 27 Jul 2023 12:16:02 -0700
From: John Fastabend <john.fastabend@...il.com>
To: Eric Dumazet <edumazet@...gle.com>, 
 Liu Jian <liujian56@...wei.com>
Cc: davem@...emloft.net, 
 kuba@...nel.org, 
 pabeni@...hat.com, 
 john.fastabend@...il.com, 
 jakub@...udflare.com, 
 dsahern@...nel.org, 
 ast@...nel.org, 
 daniel@...earbox.net, 
 netdev@...r.kernel.org, 
 bpf@...r.kernel.org
Subject: Re: [PATCH bpf 1/2] net: introduce __sk_rmem_schedule() helper

Eric Dumazet wrote:
> On Wed, Jul 26, 2023 at 4:15 PM Liu Jian <liujian56@...wei.com> wrote:
> >
> > Compared with sk_wmem_schedule(), sk_rmem_schedule() not only performs
> > rmem accounting, but also checks skb_pfmemalloc. The __sk_rmem_schedule()
> > helper function is introduced here to perform only rmem accounting related
> > activities.
> >
> 
> Why not care about pfmemalloc ? Why is it safe ?
> 
> You need to give more details, or simply reuse the existing helper.

I would just use the existing helper. Seems it should be fine.

> 
> > Signed-off-by: Liu Jian <liujian56@...wei.com>
> > ---
> >  include/net/sock.h | 12 ++++++++----
> >  1 file changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/include/net/sock.h b/include/net/sock.h
> > index 2eb916d1ff64..58bf26c5c041 100644
> > --- a/include/net/sock.h
> > +++ b/include/net/sock.h
> > @@ -1617,16 +1617,20 @@ static inline bool sk_wmem_schedule(struct sock *sk, int size)
> >         return delta <= 0 || __sk_mem_schedule(sk, delta, SK_MEM_SEND);
> >  }
> >
> > -static inline bool
> > -sk_rmem_schedule(struct sock *sk, struct sk_buff *skb, int size)
> > +static inline bool __sk_rmem_schedule(struct sock *sk, int size)
> >  {
> >         int delta;
> >
> >         if (!sk_has_account(sk))
> >                 return true;
> >         delta = size - sk->sk_forward_alloc;
> > -       return delta <= 0 || __sk_mem_schedule(sk, delta, SK_MEM_RECV) ||
> > -               skb_pfmemalloc(skb);
> > +       return delta <= 0 || __sk_mem_schedule(sk, delta, SK_MEM_RECV);
> > +}
> > +
> > +static inline bool
> > +sk_rmem_schedule(struct sock *sk, struct sk_buff *skb, int size)
> > +{
> > +       return __sk_rmem_schedule(sk, size) || skb_pfmemalloc(skb);
> >  }
> >
> >  static inline int sk_unused_reserved_mem(const struct sock *sk)
> > --
> > 2.34.1
> >