From nobody Sun Dec 14 07:58:07 2025 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (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 7A23226A1A8; Fri, 8 Aug 2025 09:39:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754645986; cv=none; b=eFRNlG70v7x+vtUsqgK1EGg6imFswOR3/Fp5Y5VkK4fbF/P1qd1aovjhsf3XHrycyoHfyn9YX/WmyCVuXSCvj3OGdXYuBC/n4SYn0AUXTVpQXkwWhAt+bKxVtxKbnPmJTAX3GfShWKiwBEo+dmPjGYQKiqz/7GQ7YVY39pN4GWI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754645986; c=relaxed/simple; bh=pgxmGpjnHnFyN7uX4DglrytT1ogOQKsOseVKGgGQJqQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=PmqXsM9nHc/tpDAeH61XZu3r6xB69mgDBNoBrz9K05rjfVjHSvFBEwO134BxEDbc/U3+UpMIKoPqjsxBgpOlEwjEclA/uPLt2pWYOGc+zHP7gx13Q3buz9AK2tQbPPULuRmGi7NUA9BykJSYdLQaHv4NJnCni5fJtBUYVIiOkyA= 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=45.249.212.56 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 [172.19.163.216]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4byzWx6dXdzKHMsQ; Fri, 8 Aug 2025 17:39:41 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.75]) by mail.maildlp.com (Postfix) with ESMTP id 0DF941A1C1C; Fri, 8 Aug 2025 17:39:41 +0800 (CST) Received: from hulk-vt.huawei.com (unknown [10.67.174.121]) by APP2 (Coremail) with SMTP id Syh0CgCXo7XPxZVooOS_Cw--.51716S3; Fri, 08 Aug 2025 17:39:40 +0800 (CST) From: Chen Ridong To: tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com, longman@redhat.com, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, lujialin4@huawei.com, chenridong@huawei.com Subject: [PATCH -next 1/4] cpuset: remove redundant CS_ONLINE flag Date: Fri, 8 Aug 2025 09:25:12 +0000 Message-Id: <20250808092515.764820-2-chenridong@huaweicloud.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250808092515.764820-1-chenridong@huaweicloud.com> References: <20250808092515.764820-1-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: Syh0CgCXo7XPxZVooOS_Cw--.51716S3 X-Coremail-Antispam: 1UD129KBjvJXoWxXF1xGFyxtFyxAw4DAr48Crg_yoW5tF4UpF 1DCFyUKw45G3W7CaykG3yqq34fKws3Z3WUKFyrK3s5AF1ayFya9F1kZ345JFyYyFWkCrWU AF4SvrWY9a48trJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUPFb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUGw A2048vs2IY020Ec7CjxVAFwI0_Gr0_Xr1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v2 6rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMc Ij6xIIjxv20xvE14v26r106r15McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_ Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lc7CjxVAaw2AFwI 0_GFv_Wryl42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG 67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r4a6rW5MI IYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E 14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJV W8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjxUV89N UUUUU 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 f74d04429a29..cf7cd2255265 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, @@ -3498,7 +3498,6 @@ 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)) @@ -3573,7 +3572,6 @@ 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