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Message-ID: <20190613000215.GD9056@mini-arch>
Date: Wed, 12 Jun 2019 17:02:15 -0700
From: Stanislav Fomichev <sdf@...ichev.me>
To: Martin KaFai Lau <kafai@...com>
Cc: bpf@...r.kernel.org, netdev@...r.kernel.org,
Alexei Starovoitov <ast@...com>,
Daniel Borkmann <daniel@...earbox.net>,
David Miller <davem@...emloft.net>, kernel-team@...com,
Craig Gallek <kraig@...gle.com>
Subject: Re: [PATCH v2 bpf-next 1/3] bpf: net: Add SO_DETACH_REUSEPORT_BPF
On 06/12, Martin KaFai Lau 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
> +
> #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);
Nit, optionally can do the following instead:
struct bpf_prog *old_prog = NULL;
...
spin_lock_bh(&reuseport_lock);
reuse = rcu_dereference_protected(...);
rcu_swap_protected(reuse->prog, old_prog, lockdep_is_held(...));
spin_unlock_bh(&reuseport_lock);
if (!old_prog)
....
...
rcu_swap_protected does rcu_dereference_protected+rcu_assign_pointer,
can save you one line :-)
> + 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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