Linux Virtualization - Mar 2023 - [RFC PATCH v5 2/2] virtio/vsock: check argument to avoid no effect call

On Wed, Mar 22, 2023 at 09:36:24PM +0300, Arseniy Krasnov
wrote:
>Both of these functions have no effect when input argument is 0, so to
>avoid useless spinlock access, check argument before it.
>
>Signed-off-by: Arseniy Krasnov <AVKrasnov at sberdevices.ru>
>---
> net/vmw_vsock/virtio_transport_common.c | 6 ++++++
> 1 file changed, 6 insertions(+)
Reviewed-by: Stefano Garzarella <sgarzare at redhat.com>
>
>diff --git a/net/vmw_vsock/virtio_transport_common.c
b/net/vmw_vsock/virtio_transport_common.c
>index 9e87c7d4d7cf..312658c176bd 100644
>--- a/net/vmw_vsock/virtio_transport_common.c
>+++ b/net/vmw_vsock/virtio_transport_common.c
>@@ -302,6 +302,9 @@ u32 virtio_transport_get_credit(struct virtio_vsock_sock
*vvs, u32 credit)
> {
> 	u32 ret;
>
>+	if (!credit)
>+		return 0;
>+
> 	spin_lock_bh(&vvs->tx_lock);
> 	ret = vvs->peer_buf_alloc - (vvs->tx_cnt - vvs->peer_fwd_cnt);
> 	if (ret > credit)
>@@ -315,6 +318,9 @@ EXPORT_SYMBOL_GPL(virtio_transport_get_credit);
>
> void virtio_transport_put_credit(struct virtio_vsock_sock *vvs, u32 credit)
> {
>+	if (!credit)
>+		return;
>+
> 	spin_lock_bh(&vvs->tx_lock);
> 	vvs->tx_cnt -= credit;
> 	spin_unlock_bh(&vvs->tx_lock);
>-- 
>2.25.1
>