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Message-ID: <20220808102335.nkviqobpgcmcaqhn@sgarzare-redhat>
Date: Mon, 8 Aug 2022 12:23:35 +0200
From: Stefano Garzarella <sgarzare@...hat.com>
To: Arseniy Krasnov <AVKrasnov@...rdevices.ru>
Cc: "David S. Miller" <davem@...emloft.net>,
"edumazet@...gle.com" <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
"kys@...rosoft.com" <kys@...rosoft.com>,
"haiyangz@...rosoft.com" <haiyangz@...rosoft.com>,
"sthemmin@...rosoft.com" <sthemmin@...rosoft.com>,
"wei.liu@...nel.org" <wei.liu@...nel.org>,
Dexuan Cui <decui@...rosoft.com>,
Stefan Hajnoczi <stefanha@...hat.com>,
Bryan Tan <bryantan@...are.com>,
Vishnu Dasa <vdasa@...are.com>,
VMware PV-Drivers Reviewers <pv-drivers@...are.com>,
Krasnov Arseniy <oxffffaa@...il.com>,
"virtualization@...ts.linux-foundation.org"
<virtualization@...ts.linux-foundation.org>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
kernel <kernel@...rdevices.ru>
Subject: Re: [RFC PATCH v3 1/9] vsock: SO_RCVLOWAT transport set callback
On Wed, Aug 03, 2022 at 01:51:05PM +0000, Arseniy Krasnov wrote:
>This adds transport specific callback for SO_RCVLOWAT, because in some
>transports it may be difficult to know current available number of bytes
>ready to read. Thus, when SO_RCVLOWAT is set, transport may reject it.
>
>Signed-off-by: Arseniy Krasnov <AVKrasnov@...rdevices.ru>
>---
> include/net/af_vsock.h | 1 +
> net/vmw_vsock/af_vsock.c | 25 +++++++++++++++++++++++++
> 2 files changed, 26 insertions(+)
>
>diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
>index f742e50207fb..eae5874bae35 100644
>--- a/include/net/af_vsock.h
>+++ b/include/net/af_vsock.h
>@@ -134,6 +134,7 @@ struct vsock_transport {
> u64 (*stream_rcvhiwat)(struct vsock_sock *);
> bool (*stream_is_active)(struct vsock_sock *);
> bool (*stream_allow)(u32 cid, u32 port);
>+ int (*set_rcvlowat)(struct vsock_sock *, int);
checkpatch suggests to add identifier names. For some we put them in,
for others we didn't, but I suggest putting them in for the new ones
because I think it's clearer too.
WARNING: function definition argument 'struct vsock_sock *' should also
have an identifier name
#25: FILE: include/net/af_vsock.h:137:
+ int (*set_rcvlowat)(struct vsock_sock *, int);
WARNING: function definition argument 'int' should also have an identifier name
#25: FILE: include/net/af_vsock.h:137:
+ int (*set_rcvlowat)(struct vsock_sock *, int);
total: 0 errors, 2 warnings, 0 checks, 44 lines checked
>
> /* SEQ_PACKET. */
> ssize_t (*seqpacket_dequeue)(struct vsock_sock *vsk, struct msghdr *msg,
>diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
>index f04abf662ec6..016ad5ff78b7 100644
>--- a/net/vmw_vsock/af_vsock.c
>+++ b/net/vmw_vsock/af_vsock.c
>@@ -2129,6 +2129,30 @@ vsock_connectible_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
> return err;
> }
>
>+static int vsock_set_rcvlowat(struct sock *sk, int val)
>+{
>+ const struct vsock_transport *transport;
>+ struct vsock_sock *vsk;
>+ int err = 0;
>+
>+ vsk = vsock_sk(sk);
>+
>+ if (val > vsk->buffer_size)
>+ return -EINVAL;
>+
>+ transport = vsk->transport;
>+
>+ if (!transport)
>+ return -EOPNOTSUPP;
I don't know whether it is better in this case to write it in
sk->sk_rcvlowat, maybe we can return EOPNOTSUPP only when the trasport
is assigned and set_rcvlowat is not defined. This is because usually the
options are set just after creation, when the transport is practically
unassigned.
I mean something like this:
if (transport) {
if (transport->set_rcvlowat)
return transport->set_rcvlowat(vsk, val);
else
return -EOPNOTSUPP;
}
WRITE_ONCE(sk->sk_rcvlowat, val ? : 1);
return 0;
>+
>+ if (transport->set_rcvlowat)
>+ err = transport->set_rcvlowat(vsk, val);
>+ else
>+ WRITE_ONCE(sk->sk_rcvlowat, val ? : 1);
>+
>+ return err;
>+}
>+
> static const struct proto_ops vsock_stream_ops = {
> .family = PF_VSOCK,
> .owner = THIS_MODULE,
>@@ -2148,6 +2172,7 @@ static const struct proto_ops vsock_stream_ops = {
> .recvmsg = vsock_connectible_recvmsg,
> .mmap = sock_no_mmap,
> .sendpage = sock_no_sendpage,
>+ .set_rcvlowat = vsock_set_rcvlowat,
> };
>
> static const struct proto_ops vsock_seqpacket_ops = {
>--
>2.25.1
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