{"id":2223696,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2223696/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260416013101.221555-13-pablo@netfilter.org/","project":{"id":26,"url":"http://patchwork.ozlabs.org/api/1.1/projects/26/?format=json","name":"Netfilter Development","link_name":"netfilter-devel","list_id":"netfilter-devel.vger.kernel.org","list_email":"netfilter-devel@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null},"msgid":"<20260416013101.221555-13-pablo@netfilter.org>","date":"2026-04-16T01:30:59","name":"[net,12/14] rculist: add list_splice_rcu() for private lists","commit_ref":null,"pull_url":null,"state":"superseded","archived":true,"hash":"3ab9ef6053b3ca1d8f1c87534bae5b7f60ab9f0a","submitter":{"id":1315,"url":"http://patchwork.ozlabs.org/api/1.1/people/1315/?format=json","name":"Pablo Neira Ayuso","email":"pablo@netfilter.org"},"delegate":{"id":11902,"url":"http://patchwork.ozlabs.org/api/1.1/users/11902/?format=json","username":"strlen","first_name":"Florian","last_name":"Westphal","email":"fw@strlen.de"},"mbox":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260416013101.221555-13-pablo@netfilter.org/mbox/","series":[{"id":500063,"url":"http://patchwork.ozlabs.org/api/1.1/series/500063/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/list/?series=500063","date":"2026-04-16T01:30:47","name":"[net,01/14] netfilter: nft_fwd_netdev: use recursion counter in neigh egress path","version":1,"mbox":"http://patchwork.ozlabs.org/series/500063/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2223696/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2223696/checks/","tags":{},"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","netfilter-devel@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=netfilter.org header.i=@netfilter.org\n header.a=rsa-sha256 header.s=2025 header.b=VvpAxH/f;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.105.105.114; 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a=rsa-sha256; c=relaxed/relaxed; d=netfilter.org;\n\ts=2025; t=1776303084;\n\tbh=o8VaDYQ2e6Gez2TNQ38DdiCZe12qY8iiXBtviqCYhfM=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=VvpAxH/f5VO88hsLsKMhxVylzpxFNG4EgBo1X6GMgeiICHiB3XVvh5zuBlDkVQpt/\n\t R2pkX7MjEdrNbKlLO6LL6/1C0mGbG9op8otvsQVeL3FGji4VgUdxEGo/gjFmvEXm5O\n\t L42x9SFlcmMlBFScdPYXQ4JLGrbUL1DTp98Dm4QZ5dGj232Qim8kthY2fZj0eXKbMO\n\t WTx3J1MoGlfhKMWXhtsZDTj1GS3XskqfektLRNxDgY+2m4s3FtSIg1GpSGZFyVCZIP\n\t 3YQiBJIs+ckwWR+CkblQYJcoO3hJWgUMmn6r9J5RjFm/N5bNJ4dGJ/MjkwahOg3Z5y\n\t A6HXrYxmNOomw==","From":"Pablo Neira Ayuso ","To":"netfilter-devel@vger.kernel.org","Cc":"davem@davemloft.net,\n\tnetdev@vger.kernel.org,\n\tkuba@kernel.org,\n\tpabeni@redhat.com,\n\tedumazet@google.com,\n\tfw@strlen.de,\n\thorms@kernel.org","Subject":"[PATCH net 12/14] rculist: add list_splice_rcu() for private lists","Date":"Thu, 16 Apr 2026 03:30:59 +0200","Message-ID":"<20260416013101.221555-13-pablo@netfilter.org>","X-Mailer":"git-send-email 2.47.3","In-Reply-To":"<20260416013101.221555-1-pablo@netfilter.org>","References":"<20260416013101.221555-1-pablo@netfilter.org>","Precedence":"bulk","X-Mailing-List":"netfilter-devel@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit"},"content":"This patch adds a helper function, list_splice_rcu(), to safely splice\na private (non-RCU-protected) list into an RCU-protected list.\n\nThe function ensures that only the pointer visible to RCU readers\n(prev->next) is updated using rcu_assign_pointer(), while the rest of\nthe list manipulations are performed with regular assignments, as the\nsource list is private and not visible to concurrent RCU readers.\n\nThis is useful for moving elements from a private list into a global\nRCU-protected list, ensuring safe publication for RCU readers.\nSubsystems with some sort of batching mechanism from userspace can\nbenefit from this new function.\n\nThe function __list_splice_rcu() has been added for clarity and to\nfollow the same pattern as in the existing list_splice*() interfaces,\nwhere there is a check to ensure that the list to splice is not\nempty. Note that __list_splice_rcu() has no documentation for this\nreason.\n\nReviewed-by: Paul E. McKenney \nSigned-off-by: Pablo Neira Ayuso \n---\n include/linux/rculist.h | 29 +++++++++++++++++++++++++++++\n 1 file changed, 29 insertions(+)","diff":"diff --git a/include/linux/rculist.h b/include/linux/rculist.h\nindex 2abba7552605..e3bc44225692 100644\n--- a/include/linux/rculist.h\n+++ b/include/linux/rculist.h\n@@ -261,6 +261,35 @@ static inline void list_replace_rcu(struct list_head *old,\n \told->prev = LIST_POISON2;\n }\n \n+static inline void __list_splice_rcu(struct list_head *list,\n+\t\t\t\t struct list_head *prev,\n+\t\t\t\t struct list_head *next)\n+{\n+\tstruct list_head *first = list->next;\n+\tstruct list_head *last = list->prev;\n+\n+\tlast->next = next;\n+\tfirst->prev = prev;\n+\tnext->prev = last;\n+\trcu_assign_pointer(list_next_rcu(prev), first);\n+}\n+\n+/**\n+ * list_splice_rcu - splice a non-RCU list into an RCU-protected list,\n+ * designed for stacks.\n+ * @list:\tthe non RCU-protected list to splice\n+ * @head:\tthe place in the existing RCU-protected list to splice\n+ *\n+ * The list pointed to by @head can be RCU-read traversed concurrently with\n+ * this function.\n+ */\n+static inline void list_splice_rcu(struct list_head *list,\n+\t\t\t\t struct list_head *head)\n+{\n+\tif (!list_empty(list))\n+\t\t__list_splice_rcu(list, head, head->next);\n+}\n+\n /**\n * __list_splice_init_rcu - join an RCU-protected list into an existing list.\n * @list:\tthe RCU-protected list to splice\n","prefixes":["net","12/14"]}