From patchwork Tue Jul 13 20:57:53 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vasily Averin X-Patchwork-Id: 477322 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, USER_AGENT_SANE_1 autolearn=unavailable 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 F2946C07E96 for ; Tue, 13 Jul 2021 20:57:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D8B696115B for ; Tue, 13 Jul 2021 20:57:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235712AbhGMVAs (ORCPT ); Tue, 13 Jul 2021 17:00:48 -0400 Received: from relay.sw.ru ([185.231.240.75]:56684 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235570AbhGMVAq (ORCPT ); Tue, 13 Jul 2021 17:00:46 -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=wzD7p3eMscQSgryl/aNBA5sYqn+D84GYHaWrmA8jwMw=; b=yTpcUoq9HpBnTWTwb39 2vH3hZ8vDeWwIkIZPntvKC2/F9UNEKAl8bKI9/W66QzpWO7novbG/xioZUJkXoZj3VyAwAr7gcDre ZD53NHUeyKJ+CgHHlSwveDs9d0qZkHkltk+2KKsu+3fygQ5QT6Z0E1k6et7mNghTvXGrF6kza9A=; Received: from [10.93.0.56] by relay.sw.ru with esmtp (Exim 4.94.2) (envelope-from ) id 1m3PTW-003sYb-2W; Tue, 13 Jul 2021 23:57:54 +0300 From: Vasily Averin Subject: [PATCH NET v2 1/7] skbuff: introduce skb_expand_head() 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: <55c9e2ae-b060-baa2-460c-90eb3e9ded5c@virtuozzo.com> Message-ID: Date: Tue, 13 Jul 2021 23:57:53 +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 Like skb_realloc_headroom(), new helper increases headroom of specified skb. Unlike skb_realloc_headroom(), it 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 | 1 + net/core/skbuff.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 43 insertions(+) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index dbf820a..0003307 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1174,6 +1174,7 @@ 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 *skb_expand_head(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..a7997c2 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1769,6 +1769,48 @@ struct sk_buff *skb_realloc_headroom(struct sk_buff *skb, unsigned int headroom) EXPORT_SYMBOL(skb_realloc_headroom); /** + * skb_expand_head - 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 skb in case of failures. + * + * It expect increased headroom and generates warning otherwise. + */ + +struct sk_buff *skb_expand_head(struct sk_buff *skb, unsigned int headroom) +{ + int delta = headroom - skb_headroom(skb); + + if (WARN_ONCE(delta <= 0, + "%s is expecting an increase in the headroom", __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(nskb, skb->sk); + consume_skb(skb); + } else { + kfree_skb(skb); + } + skb = nskb; + } + if (skb && + pskb_expand_head(skb, SKB_DATA_ALIGN(delta), 0, GFP_ATOMIC)) { + kfree_skb(skb); + skb = NULL; + } + return skb; +} +EXPORT_SYMBOL(skb_expand_head); + +/** * skb_copy_expand - copy and expand sk_buff * @skb: buffer to copy * @newheadroom: new free bytes at head