From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932387Ab3BSIF0 (ORCPT ); Tue, 19 Feb 2013 03:05:26 -0500 Received: from ozlabs.org ([203.10.76.45]:43659 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758240Ab3BSICs (ORCPT ); Tue, 19 Feb 2013 03:02:48 -0500 From: Rusty Russell To: Paolo Bonzini Cc: Rusty Russell , Asias He , "Michael S. Tsirkin" , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: [PATCH 07/16] virtio_ring: don't count elements twice for add_buf path. Date: Tue, 19 Feb 2013 18:26:25 +1030 Message-Id: <1361260594-601-8-git-send-email-rusty@rustcorp.com.au> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1361260594-601-1-git-send-email-rusty@rustcorp.com.au> References: <1361260594-601-1-git-send-email-rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Extract the post-counting code into virtqueue_add(), make both callers use it. Signed-off-by: Rusty Russell --- drivers/virtio/virtio_ring.c | 147 +++++++++++++++++++++++------------------- 1 file changed, 80 insertions(+), 67 deletions(-) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 27e31d3..c537385 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -163,69 +163,17 @@ static int vring_add_indirect(struct vring_virtqueue *vq, return head; } -/** - * virtqueue_add_buf - expose buffer to other end - * @vq: the struct virtqueue we're talking about. - * @sg: the description of the buffer(s). - * @out_num: the number of sg readable by other side - * @in_num: the number of sg which are writable (after readable ones) - * @data: the token identifying the buffer. - * @gfp: how to do memory allocations (if necessary). - * - * Caller must ensure we don't call this with other virtqueue operations - * at the same time (except where noted). - * - * Returns zero or a negative error (ie. ENOSPC, ENOMEM). - */ -int virtqueue_add_buf(struct virtqueue *_vq, - struct scatterlist sg[], - unsigned int out, - unsigned int in, - void *data, - gfp_t gfp) -{ - struct scatterlist *sgs[2]; - unsigned int i; - - sgs[0] = sg; - sgs[1] = sg + out; - - /* Workaround until callers pass well-formed sgs. */ - for (i = 0; i < out + in; i++) - sg_unmark_end(sg + i); - - sg_mark_end(sg + out + in - 1); - if (out && in) - sg_mark_end(sg + out - 1); - - return virtqueue_add_sgs(_vq, sgs, out ? 1 : 0, in ? 1 : 0, data, gfp); -} -EXPORT_SYMBOL_GPL(virtqueue_add_buf); - -/** - * virtqueue_add_sgs - expose buffers to other end - * @vq: the struct virtqueue we're talking about. - * @sgs: array of terminated scatterlists. - * @out_num: the number of scatterlists readable by other side - * @in_num: the number of scatterlists which are writable (after readable ones) - * @data: the token identifying the buffer. - * @gfp: how to do memory allocations (if necessary). - * - * Caller must ensure we don't call this with other virtqueue operations - * at the same time (except where noted). - * - * Returns zero or a negative error (ie. ENOSPC, ENOMEM). - */ -int virtqueue_add_sgs(struct virtqueue *_vq, - struct scatterlist *sgs[], - unsigned int out_sgs, - unsigned int in_sgs, - void *data, - gfp_t gfp) +static int virtqueue_add(struct virtqueue *_vq, + struct scatterlist *sgs[], + unsigned int total_sg, + unsigned int out_sgs, + unsigned int in_sgs, + void *data, + gfp_t gfp) { struct vring_virtqueue *vq = to_vvq(_vq); struct scatterlist *sg; - unsigned int i, n, avail, uninitialized_var(prev), total_sg; + unsigned int i, n, avail, uninitialized_var(prev); int head; START_USE(vq); @@ -245,13 +193,6 @@ int virtqueue_add_sgs(struct virtqueue *_vq, } #endif - /* Count them first. */ - for (i = total_sg = 0; i < out_sgs + in_sgs; i++) { - struct scatterlist *sg; - for (sg = sgs[i]; sg; sg = sg_next(sg)) - total_sg++; - } - /* If the host supports indirect descriptor tables, and we have multiple * buffers, then go indirect. FIXME: tune this threshold */ if (vq->indirect && total_sg > 1 && vq->vq.num_free) { @@ -329,6 +270,78 @@ add_head: return 0; } + +/** + * virtqueue_add_buf - expose buffer to other end + * @vq: the struct virtqueue we're talking about. + * @sg: the description of the buffer(s). + * @out_num: the number of sg readable by other side + * @in_num: the number of sg which are writable (after readable ones) + * @data: the token identifying the buffer. + * @gfp: how to do memory allocations (if necessary). + * + * Caller must ensure we don't call this with other virtqueue operations + * at the same time (except where noted). + * + * Returns zero or a negative error (ie. ENOSPC, ENOMEM). + */ +int virtqueue_add_buf(struct virtqueue *_vq, + struct scatterlist sg[], + unsigned int out, + unsigned int in, + void *data, + gfp_t gfp) +{ + struct scatterlist *sgs[2]; + unsigned int i; + + sgs[0] = sg; + sgs[1] = sg + out; + + /* Workaround until callers pass well-formed sgs. */ + for (i = 0; i < out + in; i++) + sg_unmark_end(sg + i); + + sg_mark_end(sg + out + in - 1); + if (out && in) + sg_mark_end(sg + out - 1); + + return virtqueue_add(_vq, sgs, out+in, out ? 1 : 0, in ? 1 : 0, + data, gfp); +} +EXPORT_SYMBOL_GPL(virtqueue_add_buf); + +/** + * virtqueue_add_sgs - expose buffers to other end + * @vq: the struct virtqueue we're talking about. + * @sgs: array of terminated scatterlists. + * @out_num: the number of scatterlists readable by other side + * @in_num: the number of scatterlists which are writable (after readable ones) + * @data: the token identifying the buffer. + * @gfp: how to do memory allocations (if necessary). + * + * Caller must ensure we don't call this with other virtqueue operations + * at the same time (except where noted). + * + * Returns zero or a negative error (ie. ENOSPC, ENOMEM). + */ +int virtqueue_add_sgs(struct virtqueue *_vq, + struct scatterlist *sgs[], + unsigned int out_sgs, + unsigned int in_sgs, + void *data, + gfp_t gfp) +{ + unsigned int i, total_sg; + + /* Count them first. */ + for (i = total_sg = 0; i < out_sgs + in_sgs; i++) { + struct scatterlist *sg; + for (sg = sgs[i]; sg; sg = sg_next(sg)) + total_sg++; + } + return virtqueue_add(_vq, sgs, total_sg, out_sgs, in_sgs, data, gfp); +} EXPORT_SYMBOL_GPL(virtqueue_add_sgs); /** -- 1.7.10.4