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Message-ID: <t4ltq5zni4x7ahcntnhjeyzaj5hxciqzto3t6ubjfn2klb5ici@zhhlqjw33lie>
Date: Wed, 30 Apr 2025 15:50:35 +0200
From: Stefano Garzarella <sgarzare@...hat.com>
To: Michal Luczaj <mhal@...x.co>
Cc: "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
"Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>,
Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, Eugenio Pérez <eperezma@...hat.com>,
Stefan Hajnoczi <stefanha@...hat.com>, virtualization@...ts.linux.dev, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH net-next v3 3/4] vsock: Move lingering logic to af_vsock
core
On Wed, Apr 30, 2025 at 01:11:48PM +0200, Michal Luczaj wrote:
>On 4/30/25 12:37, Stefano Garzarella wrote:
>> On Wed, 30 Apr 2025 at 12:33, Michal Luczaj <mhal@...x.co> wrote:
>>>
>>> On 4/30/25 11:36, Stefano Garzarella wrote:
>>>> On Wed, Apr 30, 2025 at 11:10:29AM +0200, Michal Luczaj wrote:
>>>>> Lingering should be transport-independent in the long run. In preparation
>>>>> for supporting other transports, as well the linger on shutdown(), move
>>>>> code to core.
>>>>>
>>>>> Guard against an unimplemented vsock_transport::unsent_bytes() callback.
>>>>>
>>>>> Suggested-by: Stefano Garzarella <sgarzare@...hat.com>
>>>>> Signed-off-by: Michal Luczaj <mhal@...x.co>
>>>>> ---
>>>>> include/net/af_vsock.h | 1 +
>>>>> net/vmw_vsock/af_vsock.c | 25 +++++++++++++++++++++++++
>>>>> net/vmw_vsock/virtio_transport_common.c | 23 +----------------------
>>>>> 3 files changed, 27 insertions(+), 22 deletions(-)
>>>>>
>>>>> diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
>>>>> index 9e85424c834353d016a527070dd62e15ff3bfce1..bd8b88d70423051dd05fc445fe37971af631ba03 100644
>>>>> --- a/include/net/af_vsock.h
>>>>> +++ b/include/net/af_vsock.h
>>>>> @@ -221,6 +221,7 @@ void vsock_for_each_connected_socket(struct vsock_transport *transport,
>>>>> void (*fn)(struct sock *sk));
>>>>> int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk);
>>>>> bool vsock_find_cid(unsigned int cid);
>>>>> +void vsock_linger(struct sock *sk, long timeout);
>>>>>
>>>>> /**** TAP ****/
>>>>>
>>>>> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>>>>> index fc6afbc8d6806a4d98c66abc3af4bd139c583b08..946b37de679a0e68b84cd982a3af2a959c60ee57 100644
>>>>> --- a/net/vmw_vsock/af_vsock.c
>>>>> +++ b/net/vmw_vsock/af_vsock.c
>>>>> @@ -1013,6 +1013,31 @@ static int vsock_getname(struct socket *sock,
>>>>> return err;
>>>>> }
>>>>>
>>>>> +void vsock_linger(struct sock *sk, long timeout)
>>>>> +{
>>>>> + DEFINE_WAIT_FUNC(wait, woken_wake_function);
>>>>> + ssize_t (*unsent)(struct vsock_sock *vsk);
>>>>> + struct vsock_sock *vsk = vsock_sk(sk);
>>>>> +
>>>>> + if (!timeout)
>>>>> + return;
>>>>> +
>>>>> + /* unsent_bytes() may be unimplemented. */
>>>>> + unsent = vsk->transport->unsent_bytes;
>>>>> + if (!unsent)
>>>>> + return;
>>>>> +
>>>>> + add_wait_queue(sk_sleep(sk), &wait);
>>>>> +
>>>>> + do {
>>>>> + if (sk_wait_event(sk, &timeout, unsent(vsk) == 0, &wait))
>>>>> + break;
>>>>> + } while (!signal_pending(current) && timeout);
>>>>> +
>>>>> + remove_wait_queue(sk_sleep(sk), &wait);
>>>>> +}
>>>>> +EXPORT_SYMBOL_GPL(vsock_linger);
>>>>> +
>>>>> static int vsock_shutdown(struct socket *sock, int mode)
>>>>> {
>>>>> int err;
>>>>> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
>>>>> index 4425802c5d718f65aaea425ea35886ad64e2fe6e..9230b8358ef2ac1f6e72a5961bae39f9093c8884 100644
>>>>> --- a/net/vmw_vsock/virtio_transport_common.c
>>>>> +++ b/net/vmw_vsock/virtio_transport_common.c
>>>>> @@ -1192,27 +1192,6 @@ static void virtio_transport_remove_sock(struct vsock_sock *vsk)
>>>>> vsock_remove_sock(vsk);
>>>>> }
>>>>>
>>>>> -static void virtio_transport_wait_close(struct sock *sk, long timeout)
>>>>> -{
>>>>> - DEFINE_WAIT_FUNC(wait, woken_wake_function);
>>>>> - ssize_t (*unsent)(struct vsock_sock *vsk);
>>>>> - struct vsock_sock *vsk = vsock_sk(sk);
>>>>> -
>>>>> - if (!timeout)
>>>>> - return;
>>>>> -
>>>>> - unsent = vsk->transport->unsent_bytes;
>>>>> -
>>>>> - add_wait_queue(sk_sleep(sk), &wait);
>>>>> -
>>>>> - do {
>>>>> - if (sk_wait_event(sk, &timeout, unsent(vsk) == 0, &wait))
>>>>> - break;
>>>>> - } while (!signal_pending(current) && timeout);
>>>>> -
>>>>> - remove_wait_queue(sk_sleep(sk), &wait);
>>>>> -}
>>>>> -
>>>>> static void virtio_transport_cancel_close_work(struct vsock_sock *vsk,
>>>>> bool cancel_timeout)
>>>>> {
>>>>> @@ -1283,7 +1262,7 @@ static bool virtio_transport_close(struct vsock_sock *vsk)
>>>>> (void)virtio_transport_shutdown(vsk, SHUTDOWN_MASK);
>>>>>
>>>>> if (sock_flag(sk, SOCK_LINGER) && !(current->flags & PF_EXITING))
>>>>> - virtio_transport_wait_close(sk, sk->sk_lingertime);
>>>>> + vsock_linger(sk, sk->sk_lingertime);
>>>>
>>>> Ah, I'd also move the check in that function, I mean:
>>>>
>>>> void vsock_linger(struct sock *sk) {
>>>> ...
>>>> if (!sock_flag(sk, SOCK_LINGER) || (current->flags & PF_EXITING))
>>>> return;
>>>>
>>>> ...
>>>> }
>>>
>>> One note: if we ever use vsock_linger() in vsock_shutdown(), the PF_EXITING
>>> condition would be unnecessary checked for that caller, right?
>>
>> Right, for shutdown it should always be false, so maybe better to keep
>> the check in the caller.
>
>Or split it? Check `!sock_flag(sk, SOCK_LINGER) || !timeout` in
>vsock_linger() and defer `!(flags & PF_EXITING)` to whoever does the socket
>release?
>
Yep, this is also fine with me!
Stefano
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