From nobody Sun Dec 14 06:31:53 2025 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 07B492EFDB5; Wed, 13 Aug 2025 08:43:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755074614; cv=none; b=Tu3pXPStnXtbUGp4OCh4CsZwiStQqkTpm5H3Xh2eM5SGxo1OZGD7+U4fmmZZK5bhRErkmC3KtBG0OnwNIbpHHVS9/KOB2QhovGhyZF7JjxbPzXknzMmNf2JavNL7ycx1WUQlX3rRUbMb5W8yIRKxuruM3HxeCoo8aD4Su35iAf8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755074614; c=relaxed/simple; bh=RGt1tIYft6crFMNv5et40pBjMR6KEN1WAn93iGLySJg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=FL5e3YUW5ImcWQqdvOEWt2QqojdPJzHAUcd+PIKOXjumMr0tfbIKtI0oB8JdWwMO+ICFuX5L4QX+IVsCh/GFFQ4UsODMcm7128j6gpjLhzD2VVXUp49SpKCCH7kfmbs3bP36vFvGoPlfBBixsi2JaDY+KZS3x+OYjzczhNiEIwE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.235]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4c222n5p22zYQvJF; Wed, 13 Aug 2025 16:43:29 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 671831A0EFC; Wed, 13 Aug 2025 16:43:28 +0800 (CST) Received: from hulk-vt.huawei.com (unknown [10.67.174.121]) by APP4 (Coremail) with SMTP id gCh0CgBHDg8qUJxoaYwdDg--.28644S3; Wed, 13 Aug 2025 16:43:28 +0800 (CST) From: Chen Ridong To: tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com, longman@redhat.com Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, lujialin4@huawei.com, chenridong@huawei.com, christophe.jaillet@wanadoo.fr Subject: [-next v2 1/4] cpuset: remove redundant CS_ONLINE flag Date: Wed, 13 Aug 2025 08:29:01 +0000 Message-Id: <20250813082904.1091651-2-chenridong@huaweicloud.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250813082904.1091651-1-chenridong@huaweicloud.com> References: <20250813082904.1091651-1-chenridong@huaweicloud.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: gCh0CgBHDg8qUJxoaYwdDg--.28644S3 X-Coremail-Antispam: 1UD129KBjvJXoWxXF1xGFyxtFyxAw4DAr48Crg_yoW5tw1kpF 1DCFyUKw45GF17CaykG34qq34fKw4fZa4UKF1rK3s5AFyayFya9F1kZ345JFyUAFWkCrWU AF4SvrWY93W8trJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9Kb4IE77IF4wAFF20E14v26ryj6rWUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUGw A2048vs2IY020Ec7CjxVAFwI0_JFI_Gr1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v2 6rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMc Ij6xIIjxv20xvE14v26r106r15McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_ Jr0_Gr1lF7xvr2IYc2Ij64vIr41lc7CjxVAaw2AFwI0_Jw0_GFyl42xK82IYc2Ij64vIr4 1l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK 67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI 8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0xvE42xK8VAv wI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14 v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjxUFID7UUUUU X-CM-SenderInfo: hfkh02xlgr0w46kxt4xhlfz01xgou0bp/ Content-Type: text/plain; charset="utf-8" From: Chen Ridong The CS_ONLINE flag was introduced prior to the CSS_ONLINE flag in the cpuset subsystem. Currently, the flag setting sequence is as follows: 1. cpuset_css_online() sets CS_ONLINE 2. css->flags gets CSS_ONLINE set ... 3. cgroup->kill_css sets CSS_DYING 4. cpuset_css_offline() clears CS_ONLINE 5. css->flags clears CSS_ONLINE The is_cpuset_online() check currently occurs between steps 1 and 3. However, it would be equally safe to perform this check between steps 2 and 3, as CSS_ONLINE provides the same synchronization guarantee as CS_ONLINE. Since CS_ONLINE is redundant with CSS_ONLINE and provides no additional synchronization benefits, we can safely remove it to simplify the code. Signed-off-by: Chen Ridong Acked-by: Waiman Long --- include/linux/cgroup.h | 5 +++++ kernel/cgroup/cpuset-internal.h | 3 +-- kernel/cgroup/cpuset.c | 4 +--- 3 files changed, 7 insertions(+), 5 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index b18fb5fcb38e..ae73dbb19165 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -354,6 +354,11 @@ static inline bool css_is_dying(struct cgroup_subsys_s= tate *css) return css->flags & CSS_DYING; } =20 +static inline bool css_is_online(struct cgroup_subsys_state *css) +{ + return css->flags & CSS_ONLINE; +} + static inline bool css_is_self(struct cgroup_subsys_state *css) { if (css =3D=3D &css->cgroup->self) { diff --git a/kernel/cgroup/cpuset-internal.h b/kernel/cgroup/cpuset-interna= l.h index 383963e28ac6..75b3aef39231 100644 --- a/kernel/cgroup/cpuset-internal.h +++ b/kernel/cgroup/cpuset-internal.h @@ -38,7 +38,6 @@ enum prs_errcode { =20 /* bits in struct cpuset flags field */ typedef enum { - CS_ONLINE, CS_CPU_EXCLUSIVE, CS_MEM_EXCLUSIVE, CS_MEM_HARDWALL, @@ -202,7 +201,7 @@ static inline struct cpuset *parent_cs(struct cpuset *c= s) /* convenient tests for these bits */ static inline bool is_cpuset_online(struct cpuset *cs) { - return test_bit(CS_ONLINE, &cs->flags) && !css_is_dying(&cs->css); + return css_is_online(&cs->css) && !css_is_dying(&cs->css); } =20 static inline int is_cpu_exclusive(const struct cpuset *cs) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 27adb04df675..3466ebbf1016 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -207,7 +207,7 @@ static inline void notify_partition_change(struct cpuse= t *cs, int old_prs) * parallel, we may leave an offline CPU in cpu_allowed or some other mask= s. */ static struct cpuset top_cpuset =3D { - .flags =3D BIT(CS_ONLINE) | BIT(CS_CPU_EXCLUSIVE) | + .flags =3D BIT(CS_CPU_EXCLUSIVE) | BIT(CS_MEM_EXCLUSIVE) | BIT(CS_SCHED_LOAD_BALANCE), .partition_root_state =3D PRS_ROOT, .relax_domain_level =3D -1, @@ -3496,7 +3496,6 @@ static int cpuset_css_online(struct cgroup_subsys_sta= te *css) cpus_read_lock(); mutex_lock(&cpuset_mutex); =20 - set_bit(CS_ONLINE, &cs->flags); if (is_spread_page(parent)) set_bit(CS_SPREAD_PAGE, &cs->flags); if (is_spread_slab(parent)) @@ -3571,7 +3570,6 @@ static void cpuset_css_offline(struct cgroup_subsys_s= tate *css) cpuset_update_flag(CS_SCHED_LOAD_BALANCE, cs, 0); =20 cpuset_dec(); - clear_bit(CS_ONLINE, &cs->flags); =20 mutex_unlock(&cpuset_mutex); cpus_read_unlock(); --=20 2.34.1