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 X-Spam-Level: X-Spam-Status: No, score=-18.8 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,URIBL_BLOCKED, USER_AGENT_GIT 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 F033CC433E6 for ; Fri, 22 Jan 2021 14:23:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A8913230FC for ; Fri, 22 Jan 2021 14:23:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728596AbhAVOXV (ORCPT ); Fri, 22 Jan 2021 09:23:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:39308 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728563AbhAVOWy (ORCPT ); Fri, 22 Jan 2021 09:22:54 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 66F5823B6C; Fri, 22 Jan 2021 14:16:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1611325005; bh=WEE2pYAzXqt5jonheFeplys8motuV2yMEuaOr1evwKg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2Fd8ezHhc1oPF3R+/bJyezkY4an+PpymRzKThkw6PaASeTqrQVF4EK1WKKiU1MnIN 76JNYdvFs4cEGCyL9hqrV9P/fxd+fd3p2VOsZoBTrKj1TCJWX5SAI8fdYpNl2LdxFw b02608mhUWX85uw7hIX6MYK3PQDdYGBfg0mmvymU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Jason A. Donenfeld" , "David S. Miller" Subject: [PATCH 5.4 14/33] net: introduce skb_list_walk_safe for skb segment walking Date: Fri, 22 Jan 2021 15:12:30 +0100 Message-Id: <20210122135734.153685343@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210122135733.565501039@linuxfoundation.org> References: <20210122135733.565501039@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Jason A. Donenfeld commit dcfea72e79b0aa7a057c8f6024169d86a1bbc84b upstream. As part of the continual effort to remove direct usage of skb->next and skb->prev, this patch adds a helper for iterating through the singly-linked variant of skb lists, which are used for lists of GSO packet. The name "skb_list_..." has been chosen to match the existing function, "kfree_skb_list, which also operates on these singly-linked lists, and the "..._walk_safe" part is the same idiom as elsewhere in the kernel. This patch removes the helper from wireguard and puts it into linux/skbuff.h, while making it a bit more robust for general usage. In particular, parenthesis are added around the macro argument usage, and it now accounts for trying to iterate through an already-null skb pointer, which will simply run the iteration zero times. This latter enhancement means it can be used to replace both do { ... } while and while (...) open-coded idioms. This should take care of these three possible usages, which match all current methods of iterations. skb_list_walk_safe(segs, skb, next) { ... } skb_list_walk_safe(skb, skb, next) { ... } skb_list_walk_safe(segs, skb, segs) { ... } Gcc appears to generate efficient code for each of these. Signed-off-by: Jason A. Donenfeld Signed-off-by: David S. Miller [ Just the skbuff.h changes for backporting - gregkh] Signed-off-by: Greg Kroah-Hartman --- include/linux/skbuff.h | 5 +++++ 1 file changed, 5 insertions(+) --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1480,6 +1480,11 @@ static inline void skb_mark_not_on_list( skb->next = NULL; } +/* Iterate through singly-linked GSO fragments of an skb. */ +#define skb_list_walk_safe(first, skb, next) \ + for ((skb) = (first), (next) = (skb) ? (skb)->next : NULL; (skb); \ + (skb) = (next), (next) = (skb) ? (skb)->next : NULL) + static inline void skb_list_del_init(struct sk_buff *skb) { __list_del_entry(&skb->list);