From patchwork Mon Jul 12 13:26:44 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vasily Averin X-Patchwork-Id: 12371153 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=-17.3 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,URIBL_BLOCKED, USER_AGENT_SANE_1 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 06796C07E99 for ; Mon, 12 Jul 2021 13:26:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D8D2D61006 for ; Mon, 12 Jul 2021 13:26:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233028AbhGLN3h (ORCPT ); Mon, 12 Jul 2021 09:29:37 -0400 Received: from relay.sw.ru ([185.231.240.75]:49566 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231696AbhGLN3g (ORCPT ); Mon, 12 Jul 2021 09:29:36 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=virtuozzo.com; s=relay; h=Content-Type:MIME-Version:Date:Message-ID:Subject :From; bh=4xvvJxEFJ5BdiccDhVEn/6X1ajbfe8RaCWu9N5O1n48=; b=VY1gLHJ58pd3yGm3n+p Bad9BfbADwp1dhq1s1WZjymtyMHP+IlQbe99P8JdU4IafAYMoDMxHTZRIu8Z+iMXBRmy2R4aoKxzf le1+QtltnFVu7VDNBXAI5uV6qlBtkZN05SrqednvcgHrk7P0yZWDqJiZD/dt1P2ekWu1Ey50LYo=; Received: from [10.93.0.56] by relay.sw.ru with esmtp (Exim 4.94.2) (envelope-from ) id 1m2vxN-003iC0-7p; Mon, 12 Jul 2021 16:26:45 +0300 From: Vasily Averin Subject: [PATCH NET 1/7] skbuff: introduce pskb_realloc_headroom() To: "David S. Miller" , Hideaki YOSHIFUJI , David Ahern , Jakub Kicinski , Eric Dumazet Cc: netdev@vger.kernel.org, Joerg Reuter , Ralf Baechle , linux-hams@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , KP Singh , bpf@vger.kernel.org, linux-kernel@vger.kernel.org References: <74e90fba-df9f-5078-13de-41df54d2b257@virtuozzo.com> Message-ID: <8049e16b-3d7a-64c3-c948-ec504590a136@virtuozzo.com> Date: Mon, 12 Jul 2021 16:26:44 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org Unlike skb_realloc_headroom, new helper does not allocate a new skb if possible; copies skb->sk on new skb when as needed and frees original skb in case of failures. This helps to simplify ip[6]_finish_output2() and a few other similar cases. Signed-off-by: Vasily Averin --- include/linux/skbuff.h | 2 ++ net/core/skbuff.c | 41 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 43 insertions(+) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index dbf820a..381a219 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1174,6 +1174,8 @@ static inline struct sk_buff *__pskb_copy(struct sk_buff *skb, int headroom, int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail, gfp_t gfp_mask); struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom); +struct sk_buff *pskb_realloc_headroom(struct sk_buff *skb, + unsigned int headroom); struct sk_buff *skb_copy_expand(const struct sk_buff *skb, int newheadroom, int newtailroom, gfp_t priority); int __must_check skb_to_sgvec_nomark(struct sk_buff *skb, struct scatterlist *sg, diff --git a/net/core/skbuff.c b/net/core/skbuff.c index bbc3b4b..13cbe98 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1769,6 +1769,47 @@ struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom) EXPORT_SYMBOL(skb_realloc_headroom); /** + * pskb_realloc_headroom - reallocate header of &sk_buff + * @skb: buffer to reallocate + * @headroom: needed headroom + * + * Unlike skb_realloc_headroom, this one does not allocate a new skb + * if possible; copies skb->sk to new skb as needed + * and frees original scb in case of failures. + * + * It expect increased headroom, and generates warning otherwise. + */ + +struct sk_buff *pskb_realloc_headroom(struct sk_buff *skb, unsigned int headroom) +{ + int delta = headroom - skb_headroom(skb); + + if (WARN_ONCE(delta <= 0, "%s expect positive delta", __func__)) + return skb; + + /* pskb_expand_head() might crash, if skb is shared */ + if (skb_shared(skb)) { + struct sk_buff *nskb = skb_clone(skb, GFP_ATOMIC); + + if (likely(nskb)) { + if (skb->sk) + skb_set_owner_w(skb, skb->sk); + consume_skb(skb); + } else { + kfree(skb); + } + skb = nskb; + } + if (skb && + pskb_expand_head(skb, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) { + kfree(skb); + skb = NULL; + } + return skb; +} +EXPORT_SYMBOL(pskb_realloc_headroom); + +/** * skb_copy_expand - copy and expand sk_buff * @skb: buffer to copy * @newheadroom: new free bytes at head