From nobody Sun Oct 5 16:29:40 2025 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5813F26E71C for ; Fri, 1 Aug 2025 14:18:02 +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=1754057883; cv=none; b=C26dvybJ3VoDSryTLUtI3MXLpXoGiW7YkT1V+eO9SzQD/lI0SLSL11QGavSVv3Jvm8Z+ah7THPwLAvsuIVt8XNs7gKBtsib4x78RZIeX9VOKgvoituBkYzQPWHK+ICiAwEXEomH6idP43sXVfAo9QxKqB/u9QXjHSdlQvl9H4yE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754057883; c=relaxed/simple; bh=Ym6ERqnzHQoUR3s3jCQ9RI780xASY9USRgCsxRkOzoA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=nPZK6V0ZIu2P27ve+C0H8SAARgsJgnhNz0SV4DNifFzRWLEOAKHU6zrCPVaY93DmiALrvsKvTrs+p2jMjWTvHPX/lD2dEn4PE0p/j506Yvyjnqa6tGho4F6Nr3UcKxf/69HbPQixLVWiBJd3dHeFTCSehc9vo0KR3rR2i+XizcA= 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 A66981515; Fri, 1 Aug 2025 07:17:53 -0700 (PDT) Received: from e127648.cambridge.arm.com (e127648.arm.com [10.1.27.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D0AA43F673; Fri, 1 Aug 2025 07:17:59 -0700 (PDT) From: Christian Loehle To: christian.loehle@arm.com, linux-kernel@vger.kernel.org, sched-ext@lists.linux.dev, tj@kernel.org, void@manifault.com, arighi@nvidia.com Cc: mingo@redhat.com, peterz@infradead.org Subject: [PATCH 3/3] sched_ext: Guarantee rq lock on scx_bpf_cpu_rq() Date: Fri, 1 Aug 2025 15:17:41 +0100 Message-Id: <20250801141741.355059-4-christian.loehle@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250801141741.355059-1-christian.loehle@arm.com> References: <20250801141741.355059-1-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() when we hold rq lock of that rq. All upstream scx schedulers can be converted into the new scx_bpf_remote_curr() instead. Signed-off-by: Christian Loehle --- kernel/sched/ext.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 92e66bb0b5f2..627df3088fd0 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -7425,7 +7425,7 @@ __bpf_kfunc s32 scx_bpf_task_cpu(const struct task_st= ruct *p) } =20 /** - * scx_bpf_cpu_rq - Fetch the rq of a CPU + * scx_bpf_cpu_rq - Fetch the rq of a CPU if its rq lock is currently held * @cpu: CPU of the rq */ __bpf_kfunc struct rq *scx_bpf_cpu_rq(s32 cpu) @@ -7433,7 +7433,7 @@ __bpf_kfunc struct rq *scx_bpf_cpu_rq(s32 cpu) if (!kf_cpu_valid(cpu, NULL)) return NULL; =20 - return cpu_rq(cpu); + return this_cpu_read(locked_rq) =3D=3D cpu_rq(cpu) ? cpu_rq(cpu) : NULL; } =20 /** --=20 2.34.1