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Message-ID: <20190613211856.2b54i5tlgqexmcmc@kafai-mbp.dhcp.thefacebook.com>
Date: Thu, 13 Jun 2019 21:18:58 +0000
From: Martin Lau <kafai@...com>
To: Andrii Nakryiko <andrii.nakryiko@...il.com>
CC: bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>,
"Alexei Starovoitov" <ast@...com>,
Daniel Borkmann <daniel@...earbox.net>,
"David Miller" <davem@...emloft.net>,
Kernel Team <Kernel-team@...com>,
Craig Gallek <kraig@...gle.com>
Subject: Re: [PATCH bpf-next 1/2] bpf: net: Add SO_DETACH_REUSEPORT_BPF
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@...com> 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@...gle.com>
> > Signed-off-by: Martin KaFai Lau <kafai@...com>
> > ---
> > 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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