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 6D0AF39A046; Wed, 4 Mar 2026 22:01:26 +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=1772661687; cv=none; b=HHSjscfnCWEmylXo/5kLpYPYjFChExZl0p3cT1LVy6hHkb2A0V/d5W6EHqGVkZjM7wcNQ+cQQMlwB0ya/Q2MuOvK28AjW2Puzu1qgWFhrlHFVh+9NzKyz+FA+xLdYv+aZ3SZxvlAkOeuwp6K0RSJtVm2oXzfsVRWhyazqKSkaMw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772661687; c=relaxed/simple; bh=gujlPOKoSu8uUNdDQ8vI3Kj+wgIL8N4jV5+5n7MW9Es=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AqnD1yd4VrLSDUOVo8anNsm0T26OKI45TGf8HB1jhoC3kxld0mHaMKsBJ8435RfTSOJe7fNYroHdQLv0hwtp2t8qFmF6A9TgiYmzXO/kDsEBaYdrcoSqVHsCDL25bsbYm/kxcgwpJ9gG53D473lFdA+VflFvT5byciKLXZ9gMp8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=huAQ4LCv; 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="huAQ4LCv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 95B84C4CEF7; Wed, 4 Mar 2026 22:01:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772661686; bh=gujlPOKoSu8uUNdDQ8vI3Kj+wgIL8N4jV5+5n7MW9Es=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=huAQ4LCvmi9xlaESUMK9b+wcv9tf6EJ8vjGl0tFwGi5qA6IO5J07WXcY3wORMIP7V UxmhTH91BUy1DzeBlT/juy0na9HDz+hTZC4RVbKr3eTyraRRnj7CAObwGhdl1zA4fH rMFAe8G5OTzKn/cBM5yFecFXEZp1C8myc+azAAn3hlawdzI5sBwT1pVZ4BOOjp4XJA bAQLw0yh/898alGVS5enpJ3QAVTYLq3yMTxHQ9zggmFUcgD0BqM0iy6EU0JBhNB7Vu ONs9i+40AemAUwbHa5yoR8k+ytveN5xlstqdr36bJdxVB/coimaNsFjqgFUtjpFTmi QTiJHrdO7TFDQ== From: Tejun Heo To: linux-kernel@vger.kernel.org, sched-ext@lists.linux.dev Cc: void@manifault.com, arighi@nvidia.com, changwoo@igalia.com, emil@etsalapatis.com, Tejun Heo Subject: [PATCH 06/34] sched_ext: Reorganize enable/disable path for multi-scheduler support Date: Wed, 4 Mar 2026 12:00:51 -1000 Message-ID: <20260304220119.4095551-7-tj@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260304220119.4095551-1-tj@kernel.org> References: <20260304220119.4095551-1-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 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_workfn() to scx_root_enable_workfn(). 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. v2: Keep scx_enable() name as-is and only rename the workfn to scx_root_enable_workfn(). Change scx_enable() return type to s32. Signed-off-by: Tejun Heo --- kernel/sched/ext.c | 78 +++++++++++++++++++++++++--------------------- 1 file changed, 43 insertions(+), 35 deletions(-) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index d1f7de05da04..f1d946749e54 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -3267,8 +3267,8 @@ 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; @@ -4430,24 +4430,12 @@ 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); @@ -4591,6 +4579,9 @@ static bool scx_claim_exit(struct scx_sched *sch, enum scx_exit_kind kind) lockdep_assert_preemption_disabled(); + 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; @@ -4603,21 +4594,31 @@ 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) { - guard(preempt)(); - scx_claim_exit(sch, kind); + scx_root_disable(sch); +} + +static void scx_disable(struct scx_sched *sch, enum scx_exit_kind kind) +{ + guard(preempt)(); + 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) @@ -5135,10 +5136,9 @@ struct scx_enable_cmd { int ret; }; -static void scx_enable_workfn(struct kthread_work *work) +static void scx_root_enable_workfn(struct kthread_work *work) { - struct scx_enable_cmd *cmd = - container_of(work, struct scx_enable_cmd, work); + struct scx_enable_cmd *cmd = container_of(work, struct scx_enable_cmd, work); struct sched_ext_ops *ops = cmd->ops; struct scx_sched *sch; struct scx_task_iter sti; @@ -5387,12 +5387,12 @@ static void scx_enable_workfn(struct kthread_work *work) * 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); cmd->ret = 0; } -static int scx_enable(struct sched_ext_ops *ops, struct bpf_link *link) +static s32 scx_enable(struct sched_ext_ops *ops, struct bpf_link *link) { static struct kthread_worker *helper; static DEFINE_MUTEX(helper_mutex); @@ -5418,7 +5418,7 @@ static int scx_enable(struct sched_ext_ops *ops, struct bpf_link *link) mutex_unlock(&helper_mutex); } - kthread_init_work(&cmd.work, scx_enable_workfn); + kthread_init_work(&cmd.work, scx_root_enable_workfn); cmd.ops = ops; kthread_queue_work(READ_ONCE(helper), &cmd.work); @@ -5561,7 +5561,7 @@ 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); } @@ -5689,7 +5689,15 @@ 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 = { -- 2.53.0