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[82.53.134.98]) by smtp.gmail.com with ESMTPSA id o10-20020a05620a228a00b007441b675e81sm12893452qkh.22.2023.03.23.02.29.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Mar 2023 02:29:12 -0700 (PDT) Date: Thu, 23 Mar 2023 10:29:05 +0100 From: Stefano Garzarella To: Arseniy Krasnov Cc: Stefan Hajnoczi , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Bobby Eshleman , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@sberdevices.ru, oxffffaa@gmail.com Subject: Re: [RFC PATCH v5 2/2] virtio/vsock: check argument to avoid no effect call Message-ID: <20230323092905.fpsiiaca2ba2wug3@sgarzare-redhat> References: <50bb0210-1ed7-42fb-b5f6-8d97247209b5@sberdevices.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <50bb0210-1ed7-42fb-b5f6-8d97247209b5@sberdevices.ru> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 >--- > net/vmw_vsock/virtio_transport_common.c | 6 ++++++ > 1 file changed, 6 insertions(+) Reviewed-by: Stefano Garzarella > >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 >