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Fri, 16 Oct 2026 07:31:12 -0700 (PDT) Date: Fri, 16 Oct 2026 07:31:10 -0700 From: Bobby Eshleman To: Stefano Garzarella Cc: Jia Jia , stefanha@redhat.com, mst@redhat.com, jasowangio@gmail.com, eperezma@redhat.com, xuanzhuo@linux.alibaba.com, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, virtualization@lists.linux.dev, kvm@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next v4 1/4] vsock/virtio: split socket lookup from locked RX processing Message-ID: References: <20261014115640.184286-1-physicalmtea@gmail.com> <20261014115640.184286-2-physicalmtea@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Oct 16, 2026 at 03:47:33PM +0200, Stefano Garzarella wrote: > On Wed, Oct 14, 2026 at 07:56:37PM +0800, Jia Jia wrote: > > Split virtio_transport_recv_pkt() so socket lookup is separate from > > receive state machine processing under the socket lock. This prepares the > > receive path to keep a looked-up socket across multiple packets in a later > > change. > > > > Keep virtio_transport_recv_pkt() on its existing per-packet locking path. > > The locked helper obtains packet-specific addresses from the skb and uses > > the matched socket namespace for reset replies. Preserve source validation > > and failure handling. > > > > No functional change intended. > > > > Signed-off-by: Jia Jia > > --- > > net/vmw_vsock/virtio_transport_common.c | 128 ++++++++++++++---------- > > 1 file changed, 75 insertions(+), 53 deletions(-) > > > > diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c > > index f225f53ed4bab..61ee3bc205d5d 100644 > > --- a/net/vmw_vsock/virtio_transport_common.c > > +++ b/net/vmw_vsock/virtio_transport_common.c > > @@ -1774,81 +1774,60 @@ static bool virtio_transport_valid_type(u16 type) > > (type == VIRTIO_VSOCK_TYPE_SEQPACKET); > > } > > > > -/* We are under the virtio-vsock's vsock->rx_lock or vhost-vsock's vq->mutex > > - * lock. > > - */ > > -void virtio_transport_recv_pkt(struct virtio_transport *t, > > - struct sk_buff *skb, struct net *net) > > +static struct sock * > > +virtio_transport_find_socket(struct sk_buff *skb, struct sockaddr_vm *src, > > + struct sockaddr_vm *dst, struct net *net) > > { > > struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb); > > - struct sockaddr_vm src, dst; > > - struct vsock_sock *vsk; > > struct sock *sk; > > - bool space_available; > > - > > - vsock_addr_init(&src, le64_to_cpu(hdr->src_cid), > > - le32_to_cpu(hdr->src_port)); > > - vsock_addr_init(&dst, le64_to_cpu(hdr->dst_cid), > > - le32_to_cpu(hdr->dst_port)); > > - > > - trace_virtio_transport_recv_pkt(src.svm_cid, src.svm_port, > > - dst.svm_cid, dst.svm_port, > > - le32_to_cpu(hdr->len), > > - le16_to_cpu(hdr->type), > > - le16_to_cpu(hdr->op), > > - le32_to_cpu(hdr->flags), > > - le32_to_cpu(hdr->buf_alloc), > > - le32_to_cpu(hdr->fwd_cnt)); > > > > - if (!virtio_transport_valid_type(le16_to_cpu(hdr->type))) { > > - (void)virtio_transport_reset_no_sock(t, skb, net); > > - goto free_pkt; > > - } > > + if (!virtio_transport_valid_type(le16_to_cpu(hdr->type))) > > + return NULL; > > > > - /* The socket must be in connected or bound table > > - * otherwise send reset back > > - */ > > - sk = vsock_find_connected_socket_net(&src, &dst, net); > > - if (!sk) { > > - sk = vsock_find_bound_socket_net(&dst, net); > > - if (!sk) { > > - (void)virtio_transport_reset_no_sock(t, skb, net); > > - goto free_pkt; > > - } > > - } > > + sk = vsock_find_connected_socket_net(src, dst, net); > > + if (!sk) > > + sk = vsock_find_bound_socket_net(dst, net); > > + if (!sk) > > + return NULL; > > > > if (virtio_transport_get_type(sk) != le16_to_cpu(hdr->type)) { > > - (void)virtio_transport_reset_no_sock(t, skb, net); > > sock_put(sk); > > - goto free_pkt; > > + return NULL; > > } > > > > - if (!skb_set_owner_sk_safe(skb, sk)) { > > - WARN_ONCE(1, "receiving vsock socket has sk_refcnt == 0\n"); > > - goto free_pkt; > > - } > > + return sk; > > +} > > > > - vsk = vsock_sk(sk); > > +/* > > + * The caller holds sk's socket lock and must free skb if this returns true. > > Why the skb must be freed by the caller and not by this function itself? > > > + */ > > +static bool > > +virtio_transport_recv_pkt_locked(struct virtio_transport *t, > > + struct sk_buff *skb, struct sock *sk) > > +{ > > + struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb); > > + struct sockaddr_vm src; > > + struct vsock_sock *vsk = vsock_sk(sk); > > + bool space_available; > > Please, follow the netdev convection for ordering local variables: https://www.kernel.org/doc/html/v7.2/process/maintainer-netdev.html#local-variable-ordering-reverse-xmas-tree-rcs > > > > > - lock_sock(sk); > > + vsock_addr_init(&src, le64_to_cpu(hdr->src_cid), > > + le32_to_cpu(hdr->src_port)); > > > > - /* Check if sk has been closed or assigned to another transport before > > - * lock_sock (note: listener sockets are not assigned to any transport) > > + /* Listener sockets accept packets from any source and are not assigned to > > + * a transport. > > */ > > Why changing this comment in this commit? > > Oh because we moved out lock_sock, right? > > I think we should keep in some way the old info that was much more > informative that the current comment that just say what the check is doing > and not why. > > > if (sock_flag(sk, SOCK_DONE) || > > (sk->sk_state != TCP_LISTEN && > > !vsock_check_source(vsk, &t->transport, &src))) { > > - (void)virtio_transport_reset_no_sock(t, skb, net); > > - release_sock(sk); > > - sock_put(sk); > > - goto free_pkt; > > + (void)virtio_transport_reset_no_sock(t, skb, sock_net(sk)); > > We need to be careful here, IIRC Bobby used the net from the caller for a > reason. > > Are you sure it's fine this change? Why not passing net as parameter and > minimize changes? I think you may be remembering this issue: a6ae12a599e0 ("virtio: set skb owner of virtio_transport_reset_no_sock() reply") ? If so, sock_net(sk) might still be okay, but I 100% agree we shouldn't change things haphazardly if avoidable. > > > + return true; > > } > > > > space_available = virtio_transport_space_update(sk, skb); > > > > /* Update CID in case it has changed after a transport reset event */ > > if (vsk->local_addr.svm_cid != VMADDR_CID_ANY) > > - vsk->local_addr.svm_cid = dst.svm_cid; > > + vsk->local_addr.svm_cid = le64_to_cpu(hdr->dst_cid); > > > > if (space_available) > > sk->sk_write_space(sk); > > @@ -1870,17 +1849,60 @@ void virtio_transport_recv_pkt(struct virtio_transport *t, > > kfree_skb(skb); > > break; > > default: > > - (void)virtio_transport_reset_no_sock(t, skb, net); > > + (void)virtio_transport_reset_no_sock(t, skb, sock_net(sk)); > > kfree_skb(skb); > > break; > > } > > > > + return false; > > +} > > + > > +/* We are under the virtio-vsock's vsock->rx_lock or vhost-vsock's vq->mutex > > + * lock. > > + */ > > +void virtio_transport_recv_pkt(struct virtio_transport *t, > > + struct sk_buff *skb, struct net *net) > > +{ > > + struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb); > > + struct sockaddr_vm src, dst; > > + struct sock *sk; > > + bool free_pkt; > > + > > + vsock_addr_init(&src, le64_to_cpu(hdr->src_cid), > > + le32_to_cpu(hdr->src_port)); > > + vsock_addr_init(&dst, le64_to_cpu(hdr->dst_cid), > > + le32_to_cpu(hdr->dst_port)); > > + > > + trace_virtio_transport_recv_pkt(src.svm_cid, src.svm_port, > > + dst.svm_cid, dst.svm_port, > > + le32_to_cpu(hdr->len), > > + le16_to_cpu(hdr->type), > > + le16_to_cpu(hdr->op), > > + le32_to_cpu(hdr->flags), > > + le32_to_cpu(hdr->buf_alloc), > > + le32_to_cpu(hdr->fwd_cnt)); > > + > > + sk = virtio_transport_find_socket(skb, &src, &dst, net); > > + if (!sk) { > > + (void)virtio_transport_reset_no_sock(t, skb, net); > > + goto free_pkt; > > + } > > + > > + if (!skb_set_owner_sk_safe(skb, sk)) { > > + WARN_ONCE(1, "receiving vsock socket has sk_refcnt == 0\n"); > > + goto free_pkt; > > + } > > + > > + lock_sock(sk); > > + free_pkt = virtio_transport_recv_pkt_locked(t, skb, sk); > > release_sock(sk); > > > > /* Release refcnt obtained when we fetched this socket out of the > > * bound or connected list. > > */ > > sock_put(sk); > > + if (free_pkt) > > + kfree_skb(skb); > > return; > > > > free_pkt: > > -- > > 2.53.0 > > >