From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1C81E3B531C; Wed, 21 Jan 2026 23:11:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769037109; cv=none; b=TvOIBJ7U7CaFazsTVZN50R1STWh0ja5G+r7HMP7hpPg6SO1S+og+31P+SsO7//17MLClxLVd4QW7ossssNNJmlxq5e3/M8iu06IPEqQ0c+BJOmFP119N91ASucj05lSC0n/wV1Tlg7sl08oMPMSMP6ukbkUO6K9XWe2ppwE1grI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769037109; c=relaxed/simple; bh=B26XvVYwHwuA6dvKdNc4FFEC6SpD4rQPwa5McMm3bo0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qp+VCwPaHaSX1780Xre9USvv5s6bzpM+0FkPxgnFfSn+FFzSRpxCGSIBfEalPoTriocSAvwPlaf1toBXc4wDv0UcajCqsHAgNSVtHocCc+crg5aQKKqi5ZJzIz9i2aNO60wmJsfS4QgUNbrpSX0RJTgFjbq1m0oFRlYLsWuBm9k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=POYqfcWc; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="POYqfcWc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96B15C16AAE; Wed, 21 Jan 2026 23:11:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769037107; bh=B26XvVYwHwuA6dvKdNc4FFEC6SpD4rQPwa5McMm3bo0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=POYqfcWcToDq3qZCFtLXGjRK0z5EVvlqCIe7WBJtbYzdJy++eXzAR6xgDtvD9RsS1 3wUn4zcL/awfAR5cAeQ5x9bnT9KoUH0SaTZz7rt7fq4z8YzwbWYmBEA5/pMmkw7eXp pHayWCNMykRNvk3iN5HRPIQs42SKiRwiy7uCnWrzAGeYNFh92G6GxtR75Tzr2aBkfQ ooHrDp28wENzfphIEheeypYhPxJpgQ+9csd9vJZw/cClidn5Apur5f1czL6d6LjxXq Y2KW1d9qaUTs9jFACY/q6YbMxu09phlmqOVUlETf1hpu+RHgZ96bshaTain0A/VsVE CgRTG7ve++uFg== From: Tejun Heo To: linux-kernel@vger.kernel.org, sched-ext@lists.linux.dev Cc: void@manifault.com, andrea.righi@linux.dev, changwoo@igalia.com, emil@etsalapatis.com, Tejun Heo Subject: [PATCH 06/34] sched_ext: Reorganize enable/disable path for multi-scheduler support Date: Wed, 21 Jan 2026 13:11:12 -1000 Message-ID: <20260121231140.832332-7-tj@kernel.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260121231140.832332-1-tj@kernel.org> References: <20260121231140.832332-1-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 In preparation for multiple scheduler support, reorganize the enable and disable paths to make scheduler instances explicit. Extract scx_root_disable() from scx_disable_workfn(). Rename scx_enable() to scx_root_enable(). Change scx_disable() to take @sch parameter and only queue disable_work if scx_claim_exit() succeeds for consistency. Move exit_kind validation into scx_claim_exit(). The sysrq handler now prints a message when no scheduler is loaded. These changes don't materially affect user-visible behavior. Signed-off-by: Tejun Heo --- kernel/sched/ext.c | 73 ++++++++++++++++++++++++++-------------------- 1 file changed, 41 insertions(+), 32 deletions(-) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index e61af4b0961c..c501ce2ca5f2 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -3094,8 +3094,8 @@ void sched_ext_dead(struct task_struct *p) raw_spin_unlock_irqrestore(&scx_tasks_lock, flags); /* - * @p is off scx_tasks and wholly ours. scx_enable()'s READY -> ENABLED - * transitions can't race us. Disable ops for @p. + * @p is off scx_tasks and wholly ours. scx_root_enable()'s READY -> + * ENABLED transitions can't race us. Disable ops for @p. */ if (scx_get_task_state(p) != SCX_TASK_NONE) { struct rq_flags rf; @@ -4246,24 +4246,12 @@ static void free_kick_syncs(void) } } -static void scx_disable_workfn(struct kthread_work *work) +static void scx_root_disable(struct scx_sched *sch) { - struct scx_sched *sch = container_of(work, struct scx_sched, disable_work); struct scx_exit_info *ei = sch->exit_info; struct scx_task_iter sti; struct task_struct *p; - int kind, cpu; - - kind = atomic_read(&sch->exit_kind); - while (true) { - if (kind == SCX_EXIT_DONE) /* already disabled? */ - return; - WARN_ON_ONCE(kind == SCX_EXIT_NONE); - if (atomic_try_cmpxchg(&sch->exit_kind, &kind, SCX_EXIT_DONE)) - break; - } - ei->kind = kind; - ei->reason = scx_exit_reason(ei->kind); + int cpu; /* guarantee forward progress by bypassing scx_ops */ scx_bypass(true); @@ -4398,6 +4386,9 @@ static bool scx_claim_exit(struct scx_sched *sch, enum scx_exit_kind kind) { int none = SCX_EXIT_NONE; + if (WARN_ON_ONCE(kind == SCX_EXIT_NONE || kind == SCX_EXIT_DONE)) + kind = SCX_EXIT_ERROR; + if (!atomic_try_cmpxchg(&sch->exit_kind, &none, kind)) return false; @@ -4410,20 +4401,30 @@ static bool scx_claim_exit(struct scx_sched *sch, enum scx_exit_kind kind) return true; } -static void scx_disable(enum scx_exit_kind kind) +static void scx_disable_workfn(struct kthread_work *work) { - struct scx_sched *sch; + struct scx_sched *sch = container_of(work, struct scx_sched, disable_work); + struct scx_exit_info *ei = sch->exit_info; + int kind; - if (WARN_ON_ONCE(kind == SCX_EXIT_NONE || kind == SCX_EXIT_DONE)) - kind = SCX_EXIT_ERROR; + kind = atomic_read(&sch->exit_kind); + while (true) { + if (kind == SCX_EXIT_DONE) /* already disabled? */ + return; + WARN_ON_ONCE(kind == SCX_EXIT_NONE); + if (atomic_try_cmpxchg(&sch->exit_kind, &kind, SCX_EXIT_DONE)) + break; + } + ei->kind = kind; + ei->reason = scx_exit_reason(ei->kind); - rcu_read_lock(); - sch = rcu_dereference(scx_root); - if (sch) { - scx_claim_exit(sch, kind); + scx_root_disable(sch); +} + +static void scx_disable(struct scx_sched *sch, enum scx_exit_kind kind) +{ + if (scx_claim_exit(sch, kind)) kthread_queue_work(sch->helper, &sch->disable_work); - } - rcu_read_unlock(); } static void dump_newline(struct seq_buf *s) @@ -4927,13 +4928,13 @@ static int validate_ops(struct scx_sched *sch, const struct sched_ext_ops *ops) return 0; } -static int scx_enable(struct sched_ext_ops *ops, struct bpf_link *link) +static s32 scx_root_enable(struct sched_ext_ops *ops, struct bpf_link *link) { struct scx_sched *sch; struct scx_task_iter sti; struct task_struct *p; unsigned long timeout; - int i, cpu, ret; + s32 i, cpu, ret; if (!cpumask_equal(housekeeping_cpumask(HK_TYPE_DOMAIN), cpu_possible_mask)) { @@ -5180,7 +5181,7 @@ static int scx_enable(struct sched_ext_ops *ops, struct bpf_link *link) * Flush scx_disable_work to ensure that error is reported before init * completion. sch's base reference will be put by bpf_scx_unreg(). */ - scx_error(sch, "scx_enable() failed (%d)", ret); + scx_error(sch, "scx_root_enable() failed (%d)", ret); kthread_flush_work(&sch->disable_work); return 0; } @@ -5312,7 +5313,7 @@ static int bpf_scx_check_member(const struct btf_type *t, static int bpf_scx_reg(void *kdata, struct bpf_link *link) { - return scx_enable(kdata, link); + return scx_root_enable(kdata, link); } static void bpf_scx_unreg(void *kdata, struct bpf_link *link) @@ -5320,7 +5321,7 @@ static void bpf_scx_unreg(void *kdata, struct bpf_link *link) struct sched_ext_ops *ops = kdata; struct scx_sched *sch = ops->priv; - scx_disable(SCX_EXIT_UNREG); + scx_disable(sch, SCX_EXIT_UNREG); kthread_flush_work(&sch->disable_work); kobject_put(&sch->kobj); } @@ -5448,7 +5449,15 @@ static struct bpf_struct_ops bpf_sched_ext_ops = { static void sysrq_handle_sched_ext_reset(u8 key) { - scx_disable(SCX_EXIT_SYSRQ); + struct scx_sched *sch; + + rcu_read_lock(); + sch = rcu_dereference(scx_root); + if (likely(sch)) + scx_disable(sch, SCX_EXIT_SYSRQ); + else + pr_info("sched_ext: BPF schedulers not loaded\n"); + rcu_read_unlock(); } static const struct sysrq_key_op sysrq_sched_ext_reset_op = { -- 2.52.0