From nobody Tue Feb 10 18:21:17 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3FB94246798 for ; Tue, 5 Aug 2025 11:10:58 +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=1754392259; cv=none; b=RMFgG/Kmsh7AVsToduHgUyPQLgYKstv/li9dGI8T1LDCxnCIPznIt4kFHPa2ZyXciHJUazRxYcl0d2yQndwGBf53uxjphe/+6SDyIy7gldcl+YNWK7jfz9XyqxijisYk01fmQOqmMaLqjvC1k43cnawubga3IVye9Cf4Yo7nXtk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754392259; c=relaxed/simple; bh=PUDAo6grH9DktBE1Hai0CoaFv7psRNK9cyOz30Tu3Uo=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=BJQSfETnaoWgjBRbgQfUYUpVr834pFfpfkOOT8XJ/LsLJ6NFaUYDrzi1NB371OORn0hMDiIIT1CUZtZoBycPmUC0LI9kaqNRkBxAfgcMK58yN7tcKKC0MvScZfe+OB3vFTE4dWrUHDaXAxaxdKaoinWlPm6vGyjzGb2OSXeg+Bc= 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 7880B113E; Tue, 5 Aug 2025 04:10:49 -0700 (PDT) Received: from e127648.cambridge.arm.com (e127648.arm.com [10.1.27.68]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 650F63F673; Tue, 5 Aug 2025 04:10:55 -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, Christian Loehle Subject: [PATCH v3 3/3] sched_ext: Guarantee rq lock on scx_bpf_cpu_rq() Date: Tue, 5 Aug 2025 12:10:36 +0100 Message-Id: <20250805111036.130121-4-christian.loehle@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250805111036.130121-1-christian.loehle@arm.com> References: <20250805111036.130121-1-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" Most fields in scx_bpf_cpu_rq() assume that its rq_lock is held. Furthermore they become meaningless without rq lock, too. Only return scx_bpf_cpu_rq() if we hold rq lock of that rq. All upstream scx schedulers can be converted into the new scx_bpf_task_acquire_remote_curr() instead. Signed-off-by: Christian Loehle --- kernel/sched/ext.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 3e2fa0b1eb57..a66cf654f33e 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -7420,10 +7420,20 @@ __bpf_kfunc s32 scx_bpf_task_cpu(const struct task_= struct *p) */ __bpf_kfunc struct rq *scx_bpf_cpu_rq(s32 cpu) { + struct rq *rq; + if (!kf_cpu_valid(cpu, NULL)) return NULL; =20 - return cpu_rq(cpu); + preempt_disable(); + rq =3D cpu_rq(cpu); + if (rq !=3D scx_locked_rq()) { + scx_kf_error("Accessing not locked rq %d", cpu); + rq =3D NULL; + } + preempt_enable(); + + return rq; } =20 /** --=20 2.34.1