Re: [PATCH bpf-next 1/2] bpf: net: Add SO_DETACH_REUSEPORT_BPF

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On Thu, Jun 13, 2019 at 01:14:46PM -0700, Andrii Nakryiko wrote:
> On Wed, Jun 12, 2019 at 12:08 PM Martin KaFai Lau <kafai@xxxxxx> wrote:
> >
> > There is SO_ATTACH_REUSEPORT_[CE]BPF but there is no DETACH.
> > This patch adds SO_DETACH_REUSEPORT_BPF sockopt.  The same
> > sockopt can be used to undo both SO_ATTACH_REUSEPORT_[CE]BPF.
> >
> > reseport_detach_prog() is added and it is mostly a mirror
> > of the existing reuseport_attach_prog().  The differences are,
> > it does not call reuseport_alloc() and returns -ENOENT when
> > there is no old prog.
> >
> > Cc: Craig Gallek <kraig@xxxxxxxxxx>
> > Signed-off-by: Martin KaFai Lau <kafai@xxxxxx>
> > ---
> >  arch/alpha/include/uapi/asm/socket.h  |  2 ++
> >  arch/mips/include/uapi/asm/socket.h   |  2 ++
> >  arch/parisc/include/uapi/asm/socket.h |  2 ++
> >  arch/sparc/include/uapi/asm/socket.h  |  2 ++
> >  include/net/sock_reuseport.h          |  2 ++
> >  include/uapi/asm-generic/socket.h     |  2 ++
> >  net/core/sock.c                       |  4 ++++
> >  net/core/sock_reuseport.c             | 24 ++++++++++++++++++++++++
> >  8 files changed, 40 insertions(+)
> >
> > diff --git a/arch/alpha/include/uapi/asm/socket.h b/arch/alpha/include/uapi/asm/socket.h
> > index 976e89b116e5..de6c4df61082 100644
> > --- a/arch/alpha/include/uapi/asm/socket.h
> > +++ b/arch/alpha/include/uapi/asm/socket.h
> > @@ -122,6 +122,8 @@
> >  #define SO_RCVTIMEO_NEW         66
> >  #define SO_SNDTIMEO_NEW         67
> >
> > +#define SO_DETACH_REUSEPORT_BPF 68
> > +
> >  #if !defined(__KERNEL__)
> >
> >  #if __BITS_PER_LONG == 64
> > diff --git a/arch/mips/include/uapi/asm/socket.h b/arch/mips/include/uapi/asm/socket.h
> > index d41765cfbc6e..d0a9ed2ca2d6 100644
> > --- a/arch/mips/include/uapi/asm/socket.h
> > +++ b/arch/mips/include/uapi/asm/socket.h
> > @@ -133,6 +133,8 @@
> >  #define SO_RCVTIMEO_NEW         66
> >  #define SO_SNDTIMEO_NEW         67
> >
> > +#define SO_DETACH_REUSEPORT_BPF 68
> > +
> >  #if !defined(__KERNEL__)
> >
> >  #if __BITS_PER_LONG == 64
> > diff --git a/arch/parisc/include/uapi/asm/socket.h b/arch/parisc/include/uapi/asm/socket.h
> > index 66c5dd245ac7..10173c32195e 100644
> > --- a/arch/parisc/include/uapi/asm/socket.h
> > +++ b/arch/parisc/include/uapi/asm/socket.h
> > @@ -114,6 +114,8 @@
> >  #define SO_RCVTIMEO_NEW         0x4040
> >  #define SO_SNDTIMEO_NEW         0x4041
> >
> > +#define SO_DETACH_REUSEPORT_BPF 0x4042
> > +
> >  #if !defined(__KERNEL__)
> >
> >  #if __BITS_PER_LONG == 64
> > diff --git a/arch/sparc/include/uapi/asm/socket.h b/arch/sparc/include/uapi/asm/socket.h
> > index 9265a9eece15..1895ac112a24 100644
> > --- a/arch/sparc/include/uapi/asm/socket.h
> > +++ b/arch/sparc/include/uapi/asm/socket.h
> > @@ -115,6 +115,8 @@
> >  #define SO_RCVTIMEO_NEW          0x0044
> >  #define SO_SNDTIMEO_NEW          0x0045
> >
> > +#define SO_DETACH_REUSEPORT_BPF  0x0046
> 
> 
> Oh, it's so nasty, there is
> 
> #define SO_TIMESTAMP_NEW         0x0046
> 
> few lines above this, completely out of order. Let's reorder it to
> avoid issues like this one.
I probably will not reorder any existing one in v3.  SO_TIMESTAMP_NEW
seems not the only one.  It may worth a separate patch effort.

I will use 0x0047.

>
> > +
> >  #if !defined(__KERNEL__)
> >
> >
> > diff --git a/include/net/sock_reuseport.h b/include/net/sock_reuseport.h
> > index 8a5f70c7cdf2..d9112de85261 100644
> > --- a/include/net/sock_reuseport.h
> > +++ b/include/net/sock_reuseport.h
> > @@ -35,6 +35,8 @@ extern struct sock *reuseport_select_sock(struct sock *sk,
> >                                           struct sk_buff *skb,
> >                                           int hdr_len);
> >  extern int reuseport_attach_prog(struct sock *sk, struct bpf_prog *prog);
> > +extern int reuseport_detach_prog(struct sock *sk);
> > +
> >  int reuseport_get_id(struct sock_reuseport *reuse);
> >
> >  #endif  /* _SOCK_REUSEPORT_H */
> > diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
> > index 8c1391c89171..77f7c1638eb1 100644
> > --- a/include/uapi/asm-generic/socket.h
> > +++ b/include/uapi/asm-generic/socket.h
> > @@ -117,6 +117,8 @@
> >  #define SO_RCVTIMEO_NEW         66
> >  #define SO_SNDTIMEO_NEW         67
> >
> > +#define SO_DETACH_REUSEPORT_BPF 68
> > +
> >  #if !defined(__KERNEL__)
> >
> >  #if __BITS_PER_LONG == 64 || (defined(__x86_64__) && defined(__ILP32__))
> > diff --git a/net/core/sock.c b/net/core/sock.c
> > index 75b1c950b49f..06be30737b69 100644
> > --- a/net/core/sock.c
> > +++ b/net/core/sock.c
> > @@ -1045,6 +1045,10 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
> >                 }
> >                 break;
> >
> > +       case SO_DETACH_REUSEPORT_BPF:
> > +               ret = reuseport_detach_prog(sk);
> > +               break;
> > +
> >         case SO_DETACH_FILTER:
> >                 ret = sk_detach_filter(sk);
> >                 break;
> > diff --git a/net/core/sock_reuseport.c b/net/core/sock_reuseport.c
> > index dc4aefdf2a08..e0cb29469fa7 100644
> > --- a/net/core/sock_reuseport.c
> > +++ b/net/core/sock_reuseport.c
> > @@ -332,3 +332,27 @@ int reuseport_attach_prog(struct sock *sk, struct bpf_prog *prog)
> >         return 0;
> >  }
> >  EXPORT_SYMBOL(reuseport_attach_prog);
> > +
> > +int reuseport_detach_prog(struct sock *sk)
> > +{
> > +       struct sock_reuseport *reuse;
> > +       struct bpf_prog *old_prog;
> > +
> > +       if (!rcu_access_pointer(sk->sk_reuseport_cb))
> > +               return sk->sk_reuseport ? -ENOENT : -EINVAL;
> > +
> > +       spin_lock_bh(&reuseport_lock);
> > +       reuse = rcu_dereference_protected(sk->sk_reuseport_cb,
> > +                                         lockdep_is_held(&reuseport_lock));
> > +       old_prog = rcu_dereference_protected(reuse->prog,
> > +                                            lockdep_is_held(&reuseport_lock));
> > +       RCU_INIT_POINTER(reuse->prog, NULL);
> > +       spin_unlock_bh(&reuseport_lock);
> > +
> > +       if (!old_prog)
> > +               return -ENOENT;
> > +
> > +       sk_reuseport_prog_free(old_prog);
> > +       return 0;
> > +}
> > +EXPORT_SYMBOL(reuseport_detach_prog);
> > --
> > 2.17.1
> >




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