From nobody Fri Oct 3 08:51:12 2025 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 7045A2EC573 for ; Wed, 3 Sep 2025 21:23:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756934619; cv=none; b=MFiqulw2A6z9969l1iGB5tZiSplRPovSHpZcil762ev4KLcQV30xgwxCzWINNucM0lKYiNztcZ4orfvKVJxny04FBIjzlZBPJrhJpAuo1nwLHjATHKoEZ1C5q1ojTj8fma2masyOYL3LDrOsYpjUEVT00LkJgfqRVrejKUPdrgo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756934619; c=relaxed/simple; bh=ElRvS8XUhRJeZToccc++Fe/3u4yPQ0/w/ug2DD+z+Xg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=VuJ9memuufg6UmlozL29eVm1KKBeFWvO1wjYEDiU6erdMJpg213Wf9GdqIjonJu+kvu0Kv8GaN4RiGA8Tgp0jHU7s9QfV18X9KOIy1UUv0Zp3uXUmwUJTBLMW3JrxZCnYXF9MLZJkDWYf7kAvl3ZuIhqFzIckw/PEED7v55afds= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7E0421CE0; Wed, 3 Sep 2025 14:23:28 -0700 (PDT) Received: from e127648.arm.com (unknown [10.57.93.203]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 044C23F694; Wed, 3 Sep 2025 14:23:34 -0700 (PDT) From: Christian Loehle To: tj@kernel.org, arighi@nvidia.com, void@manifault.com Cc: linux-kernel@vger.kernel.org, sched-ext@lists.linux.dev, changwoo@igalia.com, hodgesd@meta.com, mingo@redhat.com, peterz@infradead.org, jake@hillion.co.uk, Christian Loehle Subject: [PATCH v7 3/3] sched_ext: deprecation warn for scx_bpf_cpu_rq() Date: Wed, 3 Sep 2025 22:23:11 +0100 Message-Id: <20250903212311.369697-4-christian.loehle@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250903212311.369697-1-christian.loehle@arm.com> References: <20250903212311.369697-1-christian.loehle@arm.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 Content-Type: text/plain; charset="utf-8" scx_bpf_cpu_rq() works on an unlocked rq which generally isn't safe. For the common use-cases scx_bpf_locked_rq() and scx_bpf_cpu_curr() work, so add a deprecation warning to scx_bpf_cpu_rq() so it can eventually be removed. Signed-off-by: Christian Loehle --- kernel/sched/ext.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 6ea81b6a6b2d..1a0afdf5fcf5 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -873,6 +873,7 @@ struct scx_sched { struct scx_event_stats __percpu *event_stats_cpu; =20 bool warned_zero_slice; + bool warned_deprecated_rq; =20 atomic_t exit_kind; struct scx_exit_info *exit_info; @@ -7424,9 +7425,18 @@ __bpf_kfunc s32 scx_bpf_task_cpu(const struct task_s= truct *p) */ __bpf_kfunc struct rq *scx_bpf_cpu_rq(s32 cpu) { + struct scx_sched *sch =3D scx_root; + if (!kf_cpu_valid(cpu, NULL)) return NULL; =20 + if (!sch->warned_deprecated_rq) { + printk_deferred(KERN_WARNING "sched_ext: %s() is deprecated; " + "use scx_bpf_locked_rq() when holding rq lock " + "or scx_bpf_cpu_curr() to read remote curr safely.\n", __func__); + sch->warned_deprecated_rq =3D true; + } + return cpu_rq(cpu); } =20 --=20 2.34.1