From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DD5E5C433F5 for ; Thu, 6 Oct 2022 08:07:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230475AbiJFIG7 (ORCPT ); Thu, 6 Oct 2022 04:06:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229673AbiJFIG4 (ORCPT ); Thu, 6 Oct 2022 04:06:56 -0400 Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3F5522A406 for ; Thu, 6 Oct 2022 01:06:53 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R541e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046060;MF=liusong@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0VRPuuLR_1665043580; Received: from localhost(mailfrom:liusong@linux.alibaba.com fp:SMTPD_---0VRPuuLR_1665043580) by smtp.aliyun-inc.com; Thu, 06 Oct 2022 16:06:51 +0800 From: Liu Song To: mst@redhat.com, jasowang@redhat.com Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH] virtio_ring: remove unnecessary variables in virtqueue_add_packed Date: Thu, 6 Oct 2022 16:06:20 +0800 Message-Id: <1665043580-10009-1-git-send-email-liusong@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Liu Song Unlike "virtqueue_add_split", "descs_used" will only be equal to "total_sg" in the context of "virtqueue_add_packed", so it can be removed to reduce unnecessary operations. Signed-off-by: Liu Song --- drivers/virtio/virtio_ring.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 2e7689b..2f5b900 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -1353,7 +1353,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, struct vring_virtqueue *vq = to_vvq(_vq); struct vring_packed_desc *desc; struct scatterlist *sg; - unsigned int i, n, c, descs_used, err_idx; + unsigned int i, n, c, err_idx; __le16 head_flags, flags; u16 head, id, prev, curr, avail_used_flags; int err; @@ -1390,11 +1390,10 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, desc = vq->packed.vring.desc; i = head; - descs_used = total_sg; - if (unlikely(vq->vq.num_free < descs_used)) { + if (unlikely(vq->vq.num_free < total_sg)) { pr_debug("Can't add buf len %i - avail = %i\n", - descs_used, vq->vq.num_free); + total_sg, vq->vq.num_free); END_USE(vq); return -ENOSPC; } @@ -1445,14 +1444,14 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, vq->packed.avail_wrap_counter ^= 1; /* We're using some buffers from the free list. */ - vq->vq.num_free -= descs_used; + vq->vq.num_free -= total_sg; /* Update free pointer */ vq->packed.next_avail_idx = i; vq->free_head = curr; /* Store token. */ - vq->packed.desc_state[id].num = descs_used; + vq->packed.desc_state[id].num = total_sg; vq->packed.desc_state[id].data = data; vq->packed.desc_state[id].indir_desc = ctx; vq->packed.desc_state[id].last = prev; @@ -1464,7 +1463,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq, */ virtio_wmb(vq->weak_barriers); vq->packed.vring.desc[head].flags = head_flags; - vq->num_added += descs_used; + vq->num_added += total_sg; pr_debug("Added buffer head %i to %p\n", head, vq); END_USE(vq); -- 1.8.3.1