From patchwork Mon Sep 20 16:44:20 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Schoenebeck X-Patchwork-Id: 12506161 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6146C4332F for ; Mon, 20 Sep 2021 18:15:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BA9E460EE4 for ; Mon, 20 Sep 2021 18:15:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351352AbhITSRH (ORCPT ); Mon, 20 Sep 2021 14:17:07 -0400 Received: from lizzy.crudebyte.com ([91.194.90.13]:44745 "EHLO lizzy.crudebyte.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1376713AbhITSOU (ORCPT ); Mon, 20 Sep 2021 14:14:20 -0400 X-Greylist: delayed 3422 seconds by postgrey-1.27 at vger.kernel.org; Mon, 20 Sep 2021 14:12:11 EDT DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=lizzy; h=Cc:To:Subject:Date:From:References:In-Reply-To: Message-Id:Content-Type:Content-Transfer-Encoding:MIME-Version:Content-ID: Content-Description; bh=ePbeAywu/lY42TIL8si/nKq6WPM1V/jO+mL9Ww5/new=; b=MbwlD X4dDCdWuky707UY47kJQkOgqtqEUYEQnJmwp7/03ZtMNBzCeUEg59cBGkT+q+TKRTNNqH6Y+KsjFY ZKNm9h1o7JSKQQu9HpTXSGocK3sro9fFp9HsR9LoAPvU72ixDkjG2Xgf+cu4ZEdjx5nwkeNN0pwt5 2iZC9wm3jcOJ8E3Pdrx+3LR3B8RsLFYRfYBQBx7yQTNePujiPP7QAMzXpzlNWnUqD+H9risWMky3v Q97bnyBjEF29zs3gkP1isdrfbLxZg8eYqQaa9OuAqRMxeEkAAl1QTeA341kpgPJYy79NKERrz9aZD nkOgMWmMIZmq008e7NXQjvf7L6tBw==; Message-Id: <0a2c16b9acf580a679f38354b5d60a68c5fb6c99.1632156835.git.linux_oss@crudebyte.com> In-Reply-To: References: From: Christian Schoenebeck Date: Mon, 20 Sep 2021 18:44:20 +0200 Subject: [PATCH v2 7/7] 9p/trans_virtio: resize sg lists to whatever is possible To: v9fs-developer@lists.sourceforge.net Cc: netdev@vger.kernel.org, Dominique Martinet , Eric Van Hensbergen , Latchesar Ionkov , Greg Kurz , Vivek Goyal Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org Right now vq_sg_resize() used a lazy implementation following the all-or-nothing princible. So it either resized exactly to the requested new amount of sg lists, or it did not resize at all. The problem with this is if a user supplies a very large msize value, resize would simply fail and the user would stick to the default maximum msize supported by the virtio transport. To resolve this potential issue, change vq_sg_resize() to resize the passed sg list to whatever is possible on the machine. Signed-off-by: Christian Schoenebeck --- net/9p/trans_virtio.c | 65 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 55 insertions(+), 10 deletions(-) diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c index 4cb75f45aa15..b9bab7ed2768 100644 --- a/net/9p/trans_virtio.c +++ b/net/9p/trans_virtio.c @@ -205,24 +205,66 @@ static struct virtqueue_sg *vq_sg_alloc(unsigned int nsgl) * amount of lists * @_vq_sg: scatter/gather lists to be resized * @nsgl: new amount of scatter/gather lists + * + * Old scatter/gather lists are retained. Only growing the size is supported. + * If the requested amount cannot be satisfied, then lists are increased to + * whatever is possible. */ static int vq_sg_resize(struct virtqueue_sg **_vq_sg, unsigned int nsgl) { struct virtqueue_sg *vq_sg; + unsigned int i; + size_t sz; + int ret = 0; BUG_ON(!_vq_sg || !nsgl); vq_sg = *_vq_sg; + if (nsgl > VIRTQUEUE_SG_NSGL_MAX) + nsgl = VIRTQUEUE_SG_NSGL_MAX; if (vq_sg->nsgl == nsgl) return 0; + if (vq_sg->nsgl > nsgl) + return -ENOTSUPP; + + vq_sg = kzalloc(sizeof(struct virtqueue_sg) + + nsgl * sizeof(struct scatterlist *), + GFP_KERNEL); - /* lazy resize implementation for now */ - vq_sg = vq_sg_alloc(nsgl); if (!vq_sg) return -ENOMEM; - kfree(*_vq_sg); + /* copy over old scatter gather lists */ + sz = sizeof(struct virtqueue_sg) + + (*_vq_sg)->nsgl * sizeof(struct scatterlist *); + memcpy(vq_sg, *_vq_sg, sz); + + vq_sg->nsgl = nsgl; + + for (i = (*_vq_sg)->nsgl; i < nsgl; ++i) { + vq_sg->sgl[i] = kmalloc_array( + SG_MAX_SINGLE_ALLOC, sizeof(struct scatterlist), + GFP_KERNEL + ); + /* + * handle failed allocation as soft error, we take whatever + * we get + */ + if (!vq_sg->sgl[i]) { + ret = -ENOMEM; + vq_sg->nsgl = nsgl = i; + break; + } + sg_init_table(vq_sg->sgl[i], SG_MAX_SINGLE_ALLOC); + if (i) { + /* chain the lists */ + sg_chain(vq_sg->sgl[i - 1], SG_MAX_SINGLE_ALLOC, + vq_sg->sgl[i]); + } + } + sg_mark_end(&vq_sg->sgl[nsgl - 1][SG_MAX_SINGLE_ALLOC - 1]); + *_vq_sg = vq_sg; - return 0; + return ret; } /** @@ -839,13 +881,16 @@ p9_virtio_create(struct p9_client *client, const char *devname, char *args) if (nsgl > chan->vq_sg->nsgl) { /* * if resize fails, no big deal, then just - * continue with default msize instead + * continue with whatever we got */ - if (!vq_sg_resize(&chan->vq_sg, nsgl)) { - client->trans_maxsize = - PAGE_SIZE * - ((nsgl * SG_USER_PAGES_PER_LIST) - 3); - } + vq_sg_resize(&chan->vq_sg, nsgl); + /* + * actual allocation size might be less than + * requested, so use vq_sg->nsgl instead of nsgl + */ + client->trans_maxsize = + PAGE_SIZE * ((chan->vq_sg->nsgl * + SG_USER_PAGES_PER_LIST) - 3); } #endif /* CONFIG_ARCH_NO_SG_CHAIN */ }