{"id":2229490,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2229490/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260428095840.51961-4-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":"<20260428095840.51961-4-pablo@netfilter.org>","date":"2026-04-28T09:58:34","name":"[net,3/8] rculist: add list_splice_rcu() for private lists","commit_ref":null,"pull_url":null,"state":"new","archived":false,"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":null,"mbox":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260428095840.51961-4-pablo@netfilter.org/mbox/","series":[{"id":501814,"url":"http://patchwork.ozlabs.org/api/1.1/series/501814/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/list/?series=501814","date":"2026-04-28T09:58:32","name":"[net,1/8] netfilter: arp_tables: fix IEEE1394 ARP payload parsing","version":1,"mbox":"http://patchwork.ozlabs.org/series/501814/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2229490/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2229490/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=fQmg0tJT;\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=1777370330;\n\tbh=o8VaDYQ2e6Gez2TNQ38DdiCZe12qY8iiXBtviqCYhfM=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=fQmg0tJTiJ1473/d1QqWqmKexDbCFEzRV/wECPiqWPtrGEHLoYtMNqdOJPW2NxS18\n\t Z5v8LmgD8EID4HrXkIj3Py+J6IMn7dNPr6Gsoxnp+DXj3NySOokaBBssbBVH96zrdD\n\t 2mFUy5TomTUwHOsxW9n3PZm0oOMfk1yw9PzjZ0ksyIsQ2IFX7yXID6B8QRVAPI9wo5\n\t gCiTdiQ+vPoeeMcO2Qok5o8VMSfeIE7btikOenZZXCWagIfp4YYMFT2oyU7nB1YjlK\n\t XOdDHUXD/IHdtHscYN+ZDeNyqtCnb7pv17wFzddO+3WYiITXpTyPgGFTB9MU5Zf6Hn\n\t cGRywNkIoIBJQ==","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 3/8] rculist: add list_splice_rcu() for private lists","Date":"Tue, 28 Apr 2026 11:58:34 +0200","Message-ID":"<20260428095840.51961-4-pablo@netfilter.org>","X-Mailer":"git-send-email 2.47.3","In-Reply-To":"<20260428095840.51961-1-pablo@netfilter.org>","References":"<20260428095840.51961-1-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","3/8"]}