From nobody Thu Dec 18 15:23:06 2025 Received: from m15.mail.163.com (m15.mail.163.com [45.254.50.220]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0AC453BB50; Thu, 20 Jun 2024 08:55:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.254.50.220 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718873710; cv=none; b=mfXaDD3deuzvwC7SjjXiL3hO5opBd76Bpwna4H82wY5pvuFNTRPROIjuiXC9dN5HaxGy9B5iRW3gzR+e3m6Z5wkn1aNW5G/ih8207MvgaDnMuKgtIcSoH7bqhjBzE8FEtt9W1hxQ3zUSSldc77QSl996aqo5X9BeUHpWb+O2Aw4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718873710; c=relaxed/simple; bh=jHWt+oS0pQA+C3uyXiXZ+VQ20jbeR+O/U+jRyfrwnbM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=p3zmlRAZyfxshK8ehpQFNBgPkMPjob0PSZYiwnkpbGxxHX+FG4I7GtU6ikPEUv28/MkBMJkfjAQpaEXvJx1JwK8pDgzu81nqvRUObAFCpvNfYQD8mkpF0Dltz6nUBQXxvo06TcO1TIWwk+tDH5Ba5RFCxAS4hAbZxsKjK8yBaYo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=EVQqJgvM; arc=none smtp.client-ip=45.254.50.220 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="EVQqJgvM" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-Id:MIME-Version; bh=P+H56 2k2vggjvg30NvL8+mRhFD6CP57Wnu7B+p9noDY=; b=EVQqJgvM9XACxbAJMl/nN Hy/AdSnGvjwIU0FL9ioSHHjT0l1CF4GJpBWGJg+nXUk74XIT2Qi42UyMCZAJDLkN nsQJr+hFCj7en5ac+BlfwYrgqw+8XPO33iTqVQVv9vePqx1uijrH6d6Tm72S6YQw Y6iGSqAXJT52SORmoZxeeU= Received: from localhost (unknown [101.132.132.191]) by gzga-smtp-mta-g0-1 (Coremail) with SMTP id _____wDnLzzU7XNmxZGiDw--.17631S2; Thu, 20 Jun 2024 16:52:36 +0800 (CST) From: Xavier To: longman@redhat.com, mkoutny@suse.com Cc: lizefan.x@bytedance.com, tj@kernel.org, hannes@cmpxchg.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Xavier Subject: [PATCH v4 v4 1/2] Union-Find: add a new module in kernel library Date: Thu, 20 Jun 2024 16:52:32 +0800 Message-Id: <20240620085233.205690-2-xavier_qy@163.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240620085233.205690-1-xavier_qy@163.com> References: <20240603123101.590760-1-ghostxavier@sina.com> <20240620085233.205690-1-xavier_qy@163.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: _____wDnLzzU7XNmxZGiDw--.17631S2 X-Coremail-Antispam: 1Uf129KBjvJXoWxJF4UZFWDtr48Gry7tr1xGrg_yoW5KF48pF 45GryfCrs7Jry7Cr9akFWFyw4Sva1rGrWUuFWxGw4rArn5tr10qF1qvryFyrn3Jr4xCFW7 XF4agr13CrWUJ3DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07U7kucUUUUU= X-CM-SenderInfo: 50dyxvpubt5qqrwthudrp/1tbiZRYEEGXAmg963AAAsx Content-Type: text/plain; charset="utf-8" This patch implements a union-find data structure in the kernel library, which includes operations for allocating nodes, freeing nodes, finding the root of a node, and merging two nodes. Signed-off-by: Xavier --- MAINTAINERS | 7 +++++++ include/linux/union_find.h | 30 ++++++++++++++++++++++++++++++ lib/Makefile | 2 +- lib/union_find.c | 38 ++++++++++++++++++++++++++++++++++++++ 4 files changed, 76 insertions(+), 1 deletion(-) create mode 100644 include/linux/union_find.h create mode 100644 lib/union_find.c diff --git a/MAINTAINERS b/MAINTAINERS index d6c90161c7..602d8c6f42 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -23054,6 +23054,13 @@ F: drivers/cdrom/cdrom.c F: include/linux/cdrom.h F: include/uapi/linux/cdrom.h =20 +UNION-FIND +M: Xavier +L: linux-kernel@vger.kernel.org +S: Maintained +F: include/linux/union_find.h +F: lib/union_find.c + UNIVERSAL FLASH STORAGE HOST CONTROLLER DRIVER R: Alim Akhtar R: Avri Altman diff --git a/include/linux/union_find.h b/include/linux/union_find.h new file mode 100644 index 0000000000..67e9f62bb3 --- /dev/null +++ b/include/linux/union_find.h @@ -0,0 +1,30 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __LINUX_UNION_FIND_H +#define __LINUX_UNION_FIND_H +#include + +/* Define a union-find node struct */ +struct uf_node { + struct uf_node *parent; + unsigned int rank; +}; + +/* Allocate nodes and initialize to 0 */ +static inline struct uf_node *uf_nodes_alloc(unsigned int node_num) +{ + return kzalloc(sizeof(struct uf_node) * node_num, GFP_KERNEL); +} + +/* Free nodes*/ +static inline void uf_nodes_free(struct uf_node *nodes) +{ + kfree(nodes); +} + +/* find the root of a node*/ +struct uf_node *uf_find(struct uf_node *node); + +/* Merge two intersecting nodes */ +void uf_union(struct uf_node *node1, struct uf_node *node2); + +#endif /*__LINUX_UNION_FIND_H*/ diff --git a/lib/Makefile b/lib/Makefile index 3b17690456..e1769e6f03 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -34,7 +34,7 @@ lib-y :=3D ctype.o string.o vsprintf.o cmdline.o \ is_single_threaded.o plist.o decompress.o kobject_uevent.o \ earlycpio.o seq_buf.o siphash.o dec_and_lock.o \ nmi_backtrace.o win_minmax.o memcat_p.o \ - buildid.o objpool.o + buildid.o objpool.o union_find.o =20 lib-$(CONFIG_PRINTK) +=3D dump_stack.o lib-$(CONFIG_SMP) +=3D cpumask.o diff --git a/lib/union_find.c b/lib/union_find.c new file mode 100644 index 0000000000..2f77bae1ca --- /dev/null +++ b/lib/union_find.c @@ -0,0 +1,38 @@ +// SPDX-License-Identifier: GPL-2.0 +#include + +struct uf_node *uf_find(struct uf_node *node) +{ + struct uf_node *parent; + + if (!node->parent) { + node->parent =3D node; + return node; + } + + /*Find the root node and perform path compression at the same time*/ + while (node->parent !=3D node) { + parent =3D node->parent; + node->parent =3D parent->parent; + node =3D parent; + } + return node; +} + +/*Function to merge two sets, using union by rank*/ +void uf_union(struct uf_node *node1, struct uf_node *node2) +{ + struct uf_node *root1 =3D uf_find(node1); + struct uf_node *root2 =3D uf_find(node2); + + if (root1 !=3D root2) { + if (root1->rank < root2->rank) { + root1->parent =3D root2; + } else if (root1->rank > root2->rank) { + root2->parent =3D root1; + } else { + root2->parent =3D root1; + root1->rank++; + } + } +} --=20 2.45.2