* [PATCH bpf-next] xsk: proper AF_XDP socket teardown ordering
@ 2018-10-05 11:25 Björn Töpel
2018-10-05 16:41 ` Song Liu
2018-10-08 8:11 ` Daniel Borkmann
0 siblings, 2 replies; 3+ messages in thread
From: Björn Töpel @ 2018-10-05 11:25 UTC (permalink / raw)
To: ast, daniel, netdev, brouer
Cc: Björn Töpel, magnus.karlsson, magnus.karlsson
From: Björn Töpel <bjorn.topel@intel.com>
The AF_XDP socket struct can exist in three different, implicit
states: setup, bound and released. Setup is prior the socket has been
bound to a device. Bound is when the socket is active for receive and
send. Released is when the process/userspace side of the socket is
released, but the sock object is still lingering, e.g. when there is a
reference to the socket in an XSKMAP after process termination.
The Rx fast-path code uses the "dev" member of struct xdp_sock to
check whether a socket is bound or relased, and the Tx code uses the
struct xdp_umem "xsk_list" member in conjunction with "dev" to
determine the state of a socket.
However, the transition from bound to released did not tear the socket
down in correct order.
On the Rx side "dev" was cleared after synchronize_net() making the
synchronization useless. On the Tx side, the internal queues were
destroyed prior removing them from the "xsk_list".
This commit corrects the cleanup order, and by doing so
xdp_del_sk_umem() can be simplified and one synchronize_net() can be
removed.
Fixes: 965a99098443 ("xsk: add support for bind for Rx")
Fixes: ac98d8aab61b ("xsk: wire upp Tx zero-copy functions")
Reported-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
---
net/xdp/xdp_umem.c | 11 +++--------
net/xdp/xsk.c | 13 ++++++++-----
2 files changed, 11 insertions(+), 13 deletions(-)
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index c6007c58231c..a264cf2accd0 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -32,14 +32,9 @@ void xdp_del_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs)
{
unsigned long flags;
- if (xs->dev) {
- spin_lock_irqsave(&umem->xsk_list_lock, flags);
- list_del_rcu(&xs->list);
- spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
-
- if (umem->zc)
- synchronize_net();
- }
+ spin_lock_irqsave(&umem->xsk_list_lock, flags);
+ list_del_rcu(&xs->list);
+ spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
}
/* The umem is stored both in the _rx struct and the _tx struct as we do
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index caeddad15b7c..0577cd49aa72 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -355,12 +355,18 @@ static int xsk_release(struct socket *sock)
local_bh_enable();
if (xs->dev) {
+ struct net_device *dev = xs->dev;
+
/* Wait for driver to stop using the xdp socket. */
- synchronize_net();
- dev_put(xs->dev);
+ xdp_del_sk_umem(xs->umem, xs);
xs->dev = NULL;
+ synchronize_net();
+ dev_put(dev);
}
+ xskq_destroy(xs->rx);
+ xskq_destroy(xs->tx);
+
sock_orphan(sk);
sock->sk = NULL;
@@ -714,9 +720,6 @@ static void xsk_destruct(struct sock *sk)
if (!sock_flag(sk, SOCK_DEAD))
return;
- xskq_destroy(xs->rx);
- xskq_destroy(xs->tx);
- xdp_del_sk_umem(xs->umem, xs);
xdp_put_umem(xs->umem);
sk_refcnt_debug_dec(sk);
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH bpf-next] xsk: proper AF_XDP socket teardown ordering
2018-10-05 11:25 [PATCH bpf-next] xsk: proper AF_XDP socket teardown ordering Björn Töpel
@ 2018-10-05 16:41 ` Song Liu
2018-10-08 8:11 ` Daniel Borkmann
1 sibling, 0 replies; 3+ messages in thread
From: Song Liu @ 2018-10-05 16:41 UTC (permalink / raw)
To: bjorn.topel
Cc: Alexei Starovoitov, Daniel Borkmann, Networking,
Jesper Dangaard Brouer, Björn Töpel, Magnus Karlsson,
magnus.karlsson
On Fri, Oct 5, 2018 at 4:28 AM Björn Töpel <bjorn.topel@gmail.com> wrote:
>
> From: Björn Töpel <bjorn.topel@intel.com>
>
> The AF_XDP socket struct can exist in three different, implicit
> states: setup, bound and released. Setup is prior the socket has been
> bound to a device. Bound is when the socket is active for receive and
> send. Released is when the process/userspace side of the socket is
> released, but the sock object is still lingering, e.g. when there is a
> reference to the socket in an XSKMAP after process termination.
>
> The Rx fast-path code uses the "dev" member of struct xdp_sock to
> check whether a socket is bound or relased, and the Tx code uses the
> struct xdp_umem "xsk_list" member in conjunction with "dev" to
> determine the state of a socket.
>
> However, the transition from bound to released did not tear the socket
> down in correct order.
>
> On the Rx side "dev" was cleared after synchronize_net() making the
> synchronization useless. On the Tx side, the internal queues were
> destroyed prior removing them from the "xsk_list".
>
> This commit corrects the cleanup order, and by doing so
> xdp_del_sk_umem() can be simplified and one synchronize_net() can be
> removed.
>
> Fixes: 965a99098443 ("xsk: add support for bind for Rx")
> Fixes: ac98d8aab61b ("xsk: wire upp Tx zero-copy functions")
> Reported-by: Jesper Dangaard Brouer <brouer@redhat.com>
> Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Song Liu <songliubraving@fb.com>
> ---
> net/xdp/xdp_umem.c | 11 +++--------
> net/xdp/xsk.c | 13 ++++++++-----
> 2 files changed, 11 insertions(+), 13 deletions(-)
>
> diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
> index c6007c58231c..a264cf2accd0 100644
> --- a/net/xdp/xdp_umem.c
> +++ b/net/xdp/xdp_umem.c
> @@ -32,14 +32,9 @@ void xdp_del_sk_umem(struct xdp_umem *umem, struct xdp_sock *xs)
> {
> unsigned long flags;
>
> - if (xs->dev) {
> - spin_lock_irqsave(&umem->xsk_list_lock, flags);
> - list_del_rcu(&xs->list);
> - spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
> -
> - if (umem->zc)
> - synchronize_net();
> - }
> + spin_lock_irqsave(&umem->xsk_list_lock, flags);
> + list_del_rcu(&xs->list);
> + spin_unlock_irqrestore(&umem->xsk_list_lock, flags);
> }
>
> /* The umem is stored both in the _rx struct and the _tx struct as we do
> diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
> index caeddad15b7c..0577cd49aa72 100644
> --- a/net/xdp/xsk.c
> +++ b/net/xdp/xsk.c
> @@ -355,12 +355,18 @@ static int xsk_release(struct socket *sock)
> local_bh_enable();
>
> if (xs->dev) {
> + struct net_device *dev = xs->dev;
> +
> /* Wait for driver to stop using the xdp socket. */
nit: I guess we should move this comment together with synchronize_net().
> - synchronize_net();
> - dev_put(xs->dev);
> + xdp_del_sk_umem(xs->umem, xs);
> xs->dev = NULL;
> + synchronize_net();
> + dev_put(dev);
> }
>
> + xskq_destroy(xs->rx);
> + xskq_destroy(xs->tx);
> +
> sock_orphan(sk);
> sock->sk = NULL;
>
> @@ -714,9 +720,6 @@ static void xsk_destruct(struct sock *sk)
> if (!sock_flag(sk, SOCK_DEAD))
> return;
>
> - xskq_destroy(xs->rx);
> - xskq_destroy(xs->tx);
> - xdp_del_sk_umem(xs->umem, xs);
> xdp_put_umem(xs->umem);
>
> sk_refcnt_debug_dec(sk);
> --
> 2.17.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH bpf-next] xsk: proper AF_XDP socket teardown ordering
2018-10-05 11:25 [PATCH bpf-next] xsk: proper AF_XDP socket teardown ordering Björn Töpel
2018-10-05 16:41 ` Song Liu
@ 2018-10-08 8:11 ` Daniel Borkmann
1 sibling, 0 replies; 3+ messages in thread
From: Daniel Borkmann @ 2018-10-08 8:11 UTC (permalink / raw)
To: Björn Töpel, ast, netdev, brouer
Cc: Björn Töpel, magnus.karlsson, magnus.karlsson
On 10/05/2018 01:25 PM, Björn Töpel wrote:
> From: Björn Töpel <bjorn.topel@intel.com>
>
> The AF_XDP socket struct can exist in three different, implicit
> states: setup, bound and released. Setup is prior the socket has been
> bound to a device. Bound is when the socket is active for receive and
> send. Released is when the process/userspace side of the socket is
> released, but the sock object is still lingering, e.g. when there is a
> reference to the socket in an XSKMAP after process termination.
>
> The Rx fast-path code uses the "dev" member of struct xdp_sock to
> check whether a socket is bound or relased, and the Tx code uses the
> struct xdp_umem "xsk_list" member in conjunction with "dev" to
> determine the state of a socket.
>
> However, the transition from bound to released did not tear the socket
> down in correct order.
>
> On the Rx side "dev" was cleared after synchronize_net() making the
> synchronization useless. On the Tx side, the internal queues were
> destroyed prior removing them from the "xsk_list".
>
> This commit corrects the cleanup order, and by doing so
> xdp_del_sk_umem() can be simplified and one synchronize_net() can be
> removed.
>
> Fixes: 965a99098443 ("xsk: add support for bind for Rx")
> Fixes: ac98d8aab61b ("xsk: wire upp Tx zero-copy functions")
> Reported-by: Jesper Dangaard Brouer <brouer@redhat.com>
> Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Applied to bpf-next, thanks Björn!
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2018-10-08 15:21 UTC | newest]
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2018-10-05 11:25 [PATCH bpf-next] xsk: proper AF_XDP socket teardown ordering Björn Töpel
2018-10-05 16:41 ` Song Liu
2018-10-08 8:11 ` Daniel Borkmann
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