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 1A5CE3F5BE5; Wed, 8 Jul 2026 21:24:46 +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=1783545888; cv=none; b=K/7Do47GP2zfaTizk710jSaBvg0kFEFSipYYAHxeqCY9kmNJ5+U08QjSdAIB+SsWr+gg65l9RC+IJ3GUVC2sKUvQNVrgmxfLDa3Idt/CygO78E8ZRujQM5nFq6BsheAEauAr/W/1PIjU4BzG9TIMRngtf8LlRADiffvMIfQJosY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783545888; c=relaxed/simple; bh=qPQX27uE5+pCYac79oM/sK6PeVtvrf3lGZasWaQW8m4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GrsG1SCkhBSEaOzY/pIHjj3thqd5q0T8o0MIEGIDar+ahFRKm6UJsOhDJhh9PASOxnxJY2vLXuAZRHulhKYoggVQvD/OT7ctp3MXs6f6eoeVscumT6C2bAJUYwfRmsO5lrojdp0d9BeVCTCzKkLy4cGXsBdEQYEMTal/fHgY0Mk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GuDJRCTF; 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="GuDJRCTF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AE7151F00ACA; Wed, 8 Jul 2026 21:24:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783545885; bh=Lbc+TgH0SgQI+N3JrbFyn59mTDEnq8nZTMwBtViDvT4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=GuDJRCTFHuNgaBuxtvo05tVjNsA7T4jQ2vo3IKjlJWn8/eehuY2sTWSV+3dTJK/Zl oYziAMxKABmY0whfwPdjwKGVXasChxYBnqv01USBLCiDgWhkj1wlHJi+4rD6J+SLxC kDDLfU8GI7XT20uw40t5n2wOdrmbQNAfXfz4vt3ydYBjKRM5sNcGwtO1+BSHXB9yr1 +NopIqSu/PqgkADGw59WKuudvcxbPIG7VdPTSapPUwvhQcpnKvbXwY83quHyJhUBFP 9Zfdrgxca7/5wHY9qLWNRutmtYtNkj3rIZgart1+ihz8/Rz/FhQmEMqaPHVfcWfDFe DX/X4+CpTH8Cw== 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 v4 sched_ext/for-7.3 14/40] sched_ext: Defer scx_sched kobj sysfs add into the enable workfns Date: Wed, 8 Jul 2026 11:24:03 -1000 Message-ID: <20260708212429.3405787-15-tj@kernel.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260708212429.3405787-1-tj@kernel.org> References: <20260708212429.3405787-1-tj@kernel.org> Precedence: bulk X-Mailing-List: sched-ext@lists.linux.dev 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 93cd66b1a0e0..1a8d62efb5c5 100644 --- a/kernel/sched/ext/ext.c +++ b/kernel/sched/ext/ext.c @@ -5698,7 +5698,9 @@ 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(); @@ -6415,36 +6417,15 @@ 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 @@ -6502,6 +6483,36 @@ 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) { @@ -6724,6 +6735,12 @@ 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 ce76ae141e0a..9855a9a4e709 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