From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 3502412F585; Tue, 7 Jul 2026 00:12:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783383165; cv=none; b=cerGs/xFwpBUiqOxDXmwr0WoORNjbi8s7xqeuh+S2rk0q9uZGRImThnQn7ENGsSkVakUjJmK2ETu+La8LdFx7EVIcV6yFH+rU90ARgM4o+ArryBGf4VMXqiFzTL2m514aw82KhHWp1XWKbe/Ofw1TGNNpoJ6lnGqmemii2qfIuk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783383165; c=relaxed/simple; bh=EYiTLnL/VOrj9Hui++HPnrkVHgZJYLA1wUI1sSFqEqA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CSijmZ2zadmG3DKAYRFRpfVVU+oe6AKgq4KLaILcSHurXCpq0LRbqXexo0q5MZ4c8pLvzcYAL1ZP5+0t+fx5qv2pWYnVeFdIfE0y7RdqdJxyPUbWH8uKublP7acDOpFWreecYNq+2qthNtx0Qy+6YOIVtFUtN7yghmCcwQJpDRE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IzZQ/1WI; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="IzZQ/1WI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E89791F00A3E; Tue, 7 Jul 2026 00:12:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783383163; bh=HkSVFm9i9P6wZTWoh9Ff39LL9m40rgrKdiAxf5P8MzU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=IzZQ/1WI0v+KmIxm3f3CuYCf9C35eq/qCF7FajtTrHZIr3D8snifvKDgBNulApkSF YW3L+hoE3jrmAG/WjpAmsJtXsvX61DbKgE421RNmgVijW1zcgayUqKixkM/a5Tg6ng 4BeiHn91uJN3TSscY7UdvFM9461sULY+BowYsNWP2URO3rkn8Y43inlpf/stMTOwQ/ BslcDDv4dd12osdQnONgl3m723EwvMuFEDY94yiu4driEnOcExT9HYsG4fatPiTKA2 EAJfZoJMd00zC6rlFFyuCz4BmxX62VJYsa23ZiL3f4BVFWvjN+UQqIc16jVQb8TDbe Ehd5Ynu2wnCuw== From: Tejun Heo To: David Vernet , Andrea Righi , Changwoo Min Cc: sched-ext@lists.linux.dev, Emil Tsalapatis , linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH v3 sched_ext/for-7.3 13/36] sched_ext: Defer scx_sched kobj sysfs add into the enable workfns Date: Mon, 6 Jul 2026 14:12:06 -1000 Message-ID: <20260707001229.1410929-14-tj@kernel.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260707001229.1410929-1-tj@kernel.org> References: <20260707001229.1410929-1-tj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Split kobject_init_and_add() in scx_alloc_and_add_sched(): only kobject_init() runs there. A new scx_sched_sysfs_add() helper does kobject_add() (and creates sub_kset when the scheduler implements ops.sub_attach), called by both enable workfns once @sch is linked and its sysfs-visible state is initialized. Prep so a future caps attribute can rely on @sch being fully built by the time it's sysfs-visible. Add early enough that a stall later in enable still leaves sysfs inspectable. Signed-off-by: Tejun Heo --- kernel/sched/ext/ext.c | 73 +++++++++++++++++++++++-------------- kernel/sched/ext/internal.h | 1 + kernel/sched/ext/sub.c | 8 +++- 3 files changed, 53 insertions(+), 29 deletions(-) diff --git a/kernel/sched/ext/ext.c b/kernel/sched/ext/ext.c index 4e48ef16bdab..340d1cf3630c 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -5696,7 +5696,9 @@ static void scx_root_disable(struct scx_sched *sch) if (sch->sub_kset) kobject_del(&sch->sub_kset->kobj); #endif - kobject_del(&sch->kobj); + /* not added if enable failed before scx_sched_sysfs_add() */ + if (sch->kobj.state_in_sysfs) + kobject_del(&sch->kobj); free_kick_syncs(); @@ -6413,36 +6415,15 @@ struct scx_sched *scx_alloc_and_add_sched(struct scx_enable_cmd *cmd, * disable. Released in scx_sched_free_rcu_work(). */ kobject_get(&parent->kobj); - ret = kobject_init_and_add(&sch->kobj, &scx_ktype, - &parent->sub_kset->kobj, - "sub-%llu", cgroup_id(cgrp)); - } else { - ret = kobject_init_and_add(&sch->kobj, &scx_ktype, NULL, "root"); - } - - if (ret < 0) { - RCU_INIT_POINTER(ops->priv, NULL); - kobject_put(&sch->kobj); - return ERR_PTR(ret); - } - - if (ops->sub_attach) { - sch->sub_kset = kset_create_and_add("sub", NULL, &sch->kobj); - if (!sch->sub_kset) { - RCU_INIT_POINTER(ops->priv, NULL); - kobject_put(&sch->kobj); - return ERR_PTR(-ENOMEM); - } - } -#else /* CONFIG_EXT_SUB_SCHED */ - ret = kobject_init_and_add(&sch->kobj, &scx_ktype, NULL, "root"); - if (ret < 0) { - RCU_INIT_POINTER(ops->priv, NULL); - kobject_put(&sch->kobj); - return ERR_PTR(ret); } #endif /* CONFIG_EXT_SUB_SCHED */ + /* + * Init the kobj but don't add to sysfs yet. The enable path calls + * scx_sched_sysfs_add() once @sch's sysfs-visible state is initialized. + */ + kobject_init(&sch->kobj, &scx_ktype); + /* * Consume the arena_map ref bpf_scx_reg_cid() took. Defer to here so * earlier failure paths leave cmd->arena_map set and bpf_scx_reg_cid @@ -6500,6 +6481,36 @@ struct scx_sched *scx_alloc_and_add_sched(struct scx_enable_cmd *cmd, return ERR_PTR(ret); } +/* + * Add @sch's kobject to sysfs, and create its sub_kset if the scheduler + * implements ops.sub_attach. Called by the enable workfns once @sch's + * sysfs-visible state is initialized. + */ +int scx_sched_sysfs_add(struct scx_sched *sch) +{ +#ifdef CONFIG_EXT_SUB_SCHED + struct scx_sched *parent = scx_parent(sch); + int ret; + + if (parent) + ret = kobject_add(&sch->kobj, &parent->sub_kset->kobj, + "sub-%llu", cgroup_id(sch_cgroup(sch))); + else + ret = kobject_add(&sch->kobj, NULL, "root"); + if (ret < 0) + return ret; + + if (sch->ops.sub_attach) { + sch->sub_kset = kset_create_and_add("sub", NULL, &sch->kobj); + if (!sch->sub_kset) + return -ENOMEM; + } + return 0; +#else + return kobject_add(&sch->kobj, NULL, "root"); +#endif +} + static int check_hotplug_seq(struct scx_sched *sch, const struct sched_ext_ops *ops) { @@ -6722,6 +6733,12 @@ static void scx_root_enable_workfn(struct kthread_work *work) sch->exit_info->flags |= SCX_EFLAG_INITIALIZED; } + ret = scx_sched_sysfs_add(sch); + if (ret) { + cpus_read_unlock(); + goto err_disable; + } + for (i = SCX_OPI_CPU_HOTPLUG_BEGIN; i < SCX_OPI_CPU_HOTPLUG_END; i++) if (((void (**)(void))ops)[i]) set_bit(i, sch->has_op); diff --git a/kernel/sched/ext/internal.h b/kernel/sched/ext/internal.h index a02aad5c0338..61a9230265cd 100644 --- a/kernel/sched/ext/internal.h +++ b/kernel/sched/ext/internal.h @@ -1690,6 +1690,7 @@ struct scx_sched *scx_alloc_and_add_sched(struct scx_enable_cmd *cmd, struct cgroup *cgrp, struct scx_sched *parent); int scx_validate_ops(struct scx_sched *sch, const struct sched_ext_ops *ops); +int scx_sched_sysfs_add(struct scx_sched *sch); extern raw_spinlock_t scx_sched_lock; extern struct mutex scx_enable_mutex; diff --git a/kernel/sched/ext/sub.c b/kernel/sched/ext/sub.c index 050420427273..e94a415ee10a 100644 --- a/kernel/sched/ext/sub.c +++ b/kernel/sched/ext/sub.c @@ -270,7 +270,9 @@ void scx_sub_disable(struct scx_sched *sch) SCX_CALL_OP(sch, exit, NULL, sch->exit_info); if (sch->sub_kset) kobject_del(&sch->sub_kset->kobj); - kobject_del(&sch->kobj); + /* not added if enable failed before scx_sched_sysfs_add() */ + if (sch->kobj.state_in_sysfs) + kobject_del(&sch->kobj); } /* verify that a scheduler can be attached to @cgrp and return the parent */ @@ -363,6 +365,10 @@ void scx_sub_enable_workfn(struct kthread_work *work) if (ret) goto err_disable; + ret = scx_sched_sysfs_add(sch); + if (ret) + goto err_disable; + if (sch->level >= SCX_SUB_MAX_DEPTH) { scx_error(sch, "max nesting depth %d violated", SCX_SUB_MAX_DEPTH); -- 2.54.0