| Message ID | 20190717113030.163499-4-sgarzare@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | vsock/virtio: optimizations to increase the throughput | expand |
On Wed, Jul 17, 2019 at 01:30:28PM +0200, Stefano Garzarella wrote: > fwd_cnt and last_fwd_cnt are protected by rx_lock, so we should use > the same spinlock also if we are in the TX path. > > Move also buf_alloc under the same lock. > > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> Wait a second is this a bugfix? If it's used under the wrong lock won't values get corrupted? Won't traffic then stall or more data get to sent than credits? > --- > include/linux/virtio_vsock.h | 2 +- > net/vmw_vsock/virtio_transport_common.c | 4 ++-- > 2 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h > index 49fc9d20bc43..4c7781f4b29b 100644 > --- a/include/linux/virtio_vsock.h > +++ b/include/linux/virtio_vsock.h > @@ -35,7 +35,6 @@ struct virtio_vsock_sock { > > /* Protected by tx_lock */ > u32 tx_cnt; > - u32 buf_alloc; > u32 peer_fwd_cnt; > u32 peer_buf_alloc; > > @@ -43,6 +42,7 @@ struct virtio_vsock_sock { > u32 fwd_cnt; > u32 last_fwd_cnt; > u32 rx_bytes; > + u32 buf_alloc; > struct list_head rx_queue; > }; > > diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c > index a85559d4d974..34a2b42313b7 100644 > --- a/net/vmw_vsock/virtio_transport_common.c > +++ b/net/vmw_vsock/virtio_transport_common.c > @@ -210,11 +210,11 @@ static void virtio_transport_dec_rx_pkt(struct virtio_vsock_sock *vvs, > > void virtio_transport_inc_tx_pkt(struct virtio_vsock_sock *vvs, struct virtio_vsock_pkt *pkt) > { > - spin_lock_bh(&vvs->tx_lock); > + spin_lock_bh(&vvs->rx_lock); > vvs->last_fwd_cnt = vvs->fwd_cnt; > pkt->hdr.fwd_cnt = cpu_to_le32(vvs->fwd_cnt); > pkt->hdr.buf_alloc = cpu_to_le32(vvs->buf_alloc); > - spin_unlock_bh(&vvs->tx_lock); > + spin_unlock_bh(&vvs->rx_lock); > } > EXPORT_SYMBOL_GPL(virtio_transport_inc_tx_pkt); > > -- > 2.20.1
On Wed, Jul 17, 2019 at 4:51 PM Michael S. Tsirkin <mst@redhat.com> wrote: > > On Wed, Jul 17, 2019 at 01:30:28PM +0200, Stefano Garzarella wrote: > > fwd_cnt and last_fwd_cnt are protected by rx_lock, so we should use > > the same spinlock also if we are in the TX path. > > > > Move also buf_alloc under the same lock. > > > > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> > > Wait a second is this a bugfix? > If it's used under the wrong lock won't values get corrupted? > Won't traffic then stall or more data get to sent than > credits? Before this series, we only read vvs->fwd_cnt and vvs->buf_alloc in this function, but using a different lock than the one used to write them. I'm not sure if a corruption can happen, but if we want to avoid the lock, we should use an atomic operation or memory barriers. Since now we also need to update vvs->last_fwd_cnt, in order to limit the credit message, I decided to take the same lock used to protect vvs->fwd_cnt and vvs->last_fwd_cnt. Thanks, Stefano > > > --- > > include/linux/virtio_vsock.h | 2 +- > > net/vmw_vsock/virtio_transport_common.c | 4 ++-- > > 2 files changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h > > index 49fc9d20bc43..4c7781f4b29b 100644 > > --- a/include/linux/virtio_vsock.h > > +++ b/include/linux/virtio_vsock.h > > @@ -35,7 +35,6 @@ struct virtio_vsock_sock { > > > > /* Protected by tx_lock */ > > u32 tx_cnt; > > - u32 buf_alloc; > > u32 peer_fwd_cnt; > > u32 peer_buf_alloc; > > > > @@ -43,6 +42,7 @@ struct virtio_vsock_sock { > > u32 fwd_cnt; > > u32 last_fwd_cnt; > > u32 rx_bytes; > > + u32 buf_alloc; > > struct list_head rx_queue; > > }; > > > > diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c > > index a85559d4d974..34a2b42313b7 100644 > > --- a/net/vmw_vsock/virtio_transport_common.c > > +++ b/net/vmw_vsock/virtio_transport_common.c > > @@ -210,11 +210,11 @@ static void virtio_transport_dec_rx_pkt(struct virtio_vsock_sock *vvs, > > > > void virtio_transport_inc_tx_pkt(struct virtio_vsock_sock *vvs, struct virtio_vsock_pkt *pkt) > > { > > - spin_lock_bh(&vvs->tx_lock); > > + spin_lock_bh(&vvs->rx_lock); > > vvs->last_fwd_cnt = vvs->fwd_cnt; > > pkt->hdr.fwd_cnt = cpu_to_le32(vvs->fwd_cnt); > > pkt->hdr.buf_alloc = cpu_to_le32(vvs->buf_alloc); > > - spin_unlock_bh(&vvs->tx_lock); > > + spin_unlock_bh(&vvs->rx_lock); > > } > > EXPORT_SYMBOL_GPL(virtio_transport_inc_tx_pkt); > > > > -- > > 2.20.1
On Wed, Jul 17, 2019 at 01:30:28PM +0200, Stefano Garzarella wrote: > fwd_cnt and last_fwd_cnt are protected by rx_lock, so we should use > the same spinlock also if we are in the TX path. > > Move also buf_alloc under the same lock. > > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> > --- > include/linux/virtio_vsock.h | 2 +- > net/vmw_vsock/virtio_transport_common.c | 4 ++-- > 2 files changed, 3 insertions(+), 3 deletions(-) Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h index 49fc9d20bc43..4c7781f4b29b 100644 --- a/include/linux/virtio_vsock.h +++ b/include/linux/virtio_vsock.h @@ -35,7 +35,6 @@ struct virtio_vsock_sock { /* Protected by tx_lock */ u32 tx_cnt; - u32 buf_alloc; u32 peer_fwd_cnt; u32 peer_buf_alloc; @@ -43,6 +42,7 @@ struct virtio_vsock_sock { u32 fwd_cnt; u32 last_fwd_cnt; u32 rx_bytes; + u32 buf_alloc; struct list_head rx_queue; }; diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c index a85559d4d974..34a2b42313b7 100644 --- a/net/vmw_vsock/virtio_transport_common.c +++ b/net/vmw_vsock/virtio_transport_common.c @@ -210,11 +210,11 @@ static void virtio_transport_dec_rx_pkt(struct virtio_vsock_sock *vvs, void virtio_transport_inc_tx_pkt(struct virtio_vsock_sock *vvs, struct virtio_vsock_pkt *pkt) { - spin_lock_bh(&vvs->tx_lock); + spin_lock_bh(&vvs->rx_lock); vvs->last_fwd_cnt = vvs->fwd_cnt; pkt->hdr.fwd_cnt = cpu_to_le32(vvs->fwd_cnt); pkt->hdr.buf_alloc = cpu_to_le32(vvs->buf_alloc); - spin_unlock_bh(&vvs->tx_lock); + spin_unlock_bh(&vvs->rx_lock); } EXPORT_SYMBOL_GPL(virtio_transport_inc_tx_pkt);
fwd_cnt and last_fwd_cnt are protected by rx_lock, so we should use the same spinlock also if we are in the TX path. Move also buf_alloc under the same lock. Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> --- include/linux/virtio_vsock.h | 2 +- net/vmw_vsock/virtio_transport_common.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-)