Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [RFC PATCH v8 19/19] af_vsock: serialize writes to shared socket
To:     Stefan Hajnoczi <stefanha@redhat.com>,
        Stefano Garzarella <sgarzare@redhat.com>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Jorgen Hansen <jhansen@vmware.com>,
        Colin Ian King <colin.king@canonical.com>,
        Norbert Slusarek <nslusarek@gmx.net>,
        Andra Paraschiv <andraprs@amazon.com>,
        Jeff Vander Stoep <jeffv@google.com>,
        Alexander Popov <alex.popov@linux.com>
CC:     "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "virtualization@lists.linux-foundation.org" 
        <virtualization@lists.linux-foundation.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stsp2@yandex.ru" <stsp2@yandex.ru>,
        "oxffffaa@gmail.com" <oxffffaa@gmail.com>
References: <20210413123954.3396314-1-arseny.krasnov@kaspersky.com>
 <20210413124739.3408031-1-arseny.krasnov@kaspersky.com>
From:   Arseny Krasnov <arseny.krasnov@kaspersky.com>
Message-ID: <7d433ed9-8d4c-707a-9149-ff0e65d7f943@kaspersky.com>
Date:   Wed, 14 Apr 2021 13:51:17 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <20210413124739.3408031-1-arseny.krasnov@kaspersky.com>
Content-Type: text/plain; charset="koi8-r"
Content-Transfer-Encoding: 7bit
Content-Language: en-US
X-KSE-AttachmentFiltering-Interceptor-Info: no applicable attachment filtering
 rules found
X-KSE-Antivirus-Interceptor-Info: scan successful
X-KSE-Antivirus-Info: Clean, bases: 14.04.2021 8:59:00
X-KSE-BulkMessagesFiltering-Scan-Result: InTheLimit
X-KSE-AttachmentFiltering-Interceptor-Info: no applicable attachment filtering
 rules found
X-KSE-BulkMessagesFiltering-Scan-Result: InTheLimit
X-KLMS-Rule-ID: 52
X-KLMS-Message-Action: clean
X-KLMS-AntiSpam-Status: not scanned, disabled by settings
X-KLMS-AntiSpam-Interceptor-Info: not scanned
X-KLMS-AntiPhishing: Clean, bases: 2021/04/14 09:29:00
X-KLMS-AntiVirus: Kaspersky Security for Linux Mail Server, version 8.0.3.30, bases: 2021/04/14 08:59:00 #16593747
X-KLMS-AntiVirus-Status: Clean, skipped
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org


On 13.04.2021 15:47, Arseny Krasnov wrote:
> This add logic, that serializes write access to single socket
> by multiple threads. It is implemented be adding field with TID
> of current writer. When writer tries to send something, it checks
> that field is -1(free), else it sleep in the same way as waiting
> for free space at peers' side.
>
> This implementation is PoC and not related to SEQPACKET close, so
> i've placed it after whole patchset.
>
> Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
> ---
>  include/net/af_vsock.h   |  1 +
>  net/vmw_vsock/af_vsock.c | 10 +++++++++-
>  2 files changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
> index 53d3f33dbdbf..786df80b9fc3 100644
> --- a/include/net/af_vsock.h
> +++ b/include/net/af_vsock.h
> @@ -69,6 +69,7 @@ struct vsock_sock {
>  	u64 buffer_size;
>  	u64 buffer_min_size;
>  	u64 buffer_max_size;
> +	pid_t tid_owner;
>  
>  	/* Private to transport. */
>  	void *trans;
> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> index 54bee7e643f4..d00f8c07a9d3 100644
> --- a/net/vmw_vsock/af_vsock.c
> +++ b/net/vmw_vsock/af_vsock.c
> @@ -1765,7 +1765,9 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
>  		ssize_t written;
>  
>  		add_wait_queue(sk_sleep(sk), &wait);
> -		while (vsock_stream_has_space(vsk) == 0 &&
> +		while ((vsock_stream_has_space(vsk) == 0 ||
> +			(vsk->tid_owner != current->pid &&
> +			 vsk->tid_owner != -1)) &&
>  		       sk->sk_err == 0 &&
>  		       !(sk->sk_shutdown & SEND_SHUTDOWN) &&
>  		       !(vsk->peer_shutdown & RCV_SHUTDOWN)) {
> @@ -1796,6 +1798,8 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
>  				goto out_err;
>  			}
>  		}
> +
> +		vsk->tid_owner = current->pid;
>  		remove_wait_queue(sk_sleep(sk), &wait);
>  
>  		/* These checks occur both as part of and after the loop
> @@ -1852,7 +1856,10 @@ static int vsock_connectible_sendmsg(struct socket *sock, struct msghdr *msg,
>  			err = total_written;
>  	}
>  out:
> +	vsk->tid_owner = -1;
>  	release_sock(sk);
> +	sk->sk_write_space(sk);
> +
>  	return err;
>  }
>  
> @@ -2199,6 +2206,7 @@ static int vsock_create(struct net *net, struct socket *sock,
>  		return -ENOMEM;
>  
>  	vsk = vsock_sk(sk);
> +	vsk->tid_owner = -1;
This must be moved to '__vsock_create()'
>  
>  	if (sock->type == SOCK_DGRAM) {
>  		ret = vsock_assign_transport(vsk, NULL);