From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 34A6E371899; Mon, 17 Aug 2026 17:53:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786989214; cv=none; b=uCrOrXLsE28pMHp8xBBS9OUHa6N2YlQWFrZ1+LzLD3+rQMNrTyEBs12mgH07N4GxPKqs/Eyijfm0/nTlRPecogPOOrYligQnawlp8OEZXUerp8TujMw8mjVTnA7V/5e7SkFsNEzgqYQmwPdeF72VpD6x2hf9eGMovMPSOtzyZ8g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786989214; c=relaxed/simple; bh=Is2j2wghblK9QFPxNZVuRhmCR40Pohscow1rlbmEAJI=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References; b=GmSGDHB5KKy+7WijqQ6STMkK/+xEbkvVNRtU1NZ3992i8a5L87zrEzmYT47sdn7ZiB6RwheRsZMNFkpgM4QQAMbCNkDaVchYgFWqqIYi1RorIZvNCbiPGotlaVb/dJ265baT83RqIQasWKYb6L6D4NAt5wCob7ut3U5bx8iTxJY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OxSN5Qq9; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="OxSN5Qq9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 180741F000E9; Mon, 17 Aug 2026 17:53:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786989211; bh=Is2j2wghblK9QFPxNZVuRhmCR40Pohscow1rlbmEAJI=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=OxSN5Qq9D2k7dSiFvlnPsHFt2RHus/erXehAfpna+RAynE/MqSJOa6BwCO2DLsfBy qV+WiyNivg0ycBJPnmHVWKTraoT5KuXJjSMNpsglaDaR7YfoJp8o/GYQ3COlfeeazd 5/lj/h31qjzhq2KDmeZv7Zowjp0GBA0D9uVob84dx9pc6W+uTb5YvuJncV0K2Zduy6 aIX8wAvvdSC33d/l1KW8EkVXqQcrda2Mm9w8+htYz7udmZgM9ZDIj6+SiIlN06qpF2 8WaobnNObNUBulaSfAtyuF4F8NuT7HdEInH386eKRenUsbep/d7qC4ww2OMR7/Tux1 Sr2immTn7WH4w== Date: Mon, 17 Aug 2026 07:53:30 -1000 Message-ID: <9ffe41fba1d0462a27443e95c5e3e03b@kernel.org> From: Tejun Heo To: Changwoo Min Cc: void@manifault.com, arighi@nvidia.com, emil@etsalapatis.com, kernel-dev@igalia.com, sched-ext@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH] sched_ext: allow ops.cgroup_set_bandwidth() to be sleepable In-Reply-To: <20260817170941.668571-1-changwoo@igalia.com> References: <20260817170941.668571-1-changwoo@igalia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Hello, On Tue, Aug 18, 2026 at 02:09:41AM +0900, Changwoo Min wrote: > +/* > + * Capability marker for userspace. The sleepable allowance for > + * ops.cgroup_set_bandwidth() (see bpf_scx_check_member()) is a verifier > + * property with no other symbol a scheduler can probe, so this no-op function > + * exists solely so its presence in the kernel's BTF can be detected. It has no > + * callers; __used keeps it from being optimized away. > + */ > +__used void scx_cgroup_set_bandwidth_may_sleep(void) {} __used only prevents the compiler from dropping the function. With CONFIG_LD_DEAD_CODE_DATA_ELIMINATION, the linker can still garbage collect its section, so please add __retain too (cf. __bpf_kfunc). Also, we'll likely accumulate more of these markers over time, so let's give them a shared prefix - scx_compat_marker_ or something like that - and collect them in one place, maybe towards the end of ext.c next to the module init code. Thanks. -- tejun