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 D60282C21FD; Wed, 19 Aug 2026 20:43:52 +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=1787172233; cv=none; b=hNmPP2jRqarOi1425wW8pRZ4UaG7BsYfVXxZeTLkotr49ddsuGV2EEYNSDhokmf152fAv10blYJj9dh/B1HlEFbctr54G4BWkrTRNC8w12DYmSPOel9HjPl4fZLwza+QezegbgiSUvb9H9e0vrX4c+Sy6yjmLqqfmdGpuUBSqZA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787172233; c=relaxed/simple; bh=Fid7AxH9uI6nvxUFpdzYl7i92YyXJIdOCxhlEymPNPE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qWcKftuH2WVZYQL7qiYeXZqsGVXXJiREV1PjXVjheqJk3LsVqEncll4Bh/rVtoqPUYQ6GuvDLdXzvOs0V05ciL5YJI90Lb8kCVU11caWYILklgwl/wsPnunQz7eZgUK1yOZBmU/Qt3fdE40gfr6wfD08bQGZV4kMRYV1PYd2sxI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HYfNASxW; 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="HYfNASxW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61BB71F000E9; Wed, 19 Aug 2026 20:43:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787172232; bh=9PLl4id7OxDfMv9esI2Tn9DhkQb0PtEscSkhXUWvpuI=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=HYfNASxW583tyR26TIXYW6Vm4HWHwbeqgtgcTYRALVVsnxaLyC2WTlWtZOBv/zRi3 CU/We1yx51+muTOGLm1Ohoq7F2UU6m24gM62dwNFHT2bzRH27gxDAqFANaLlbspgtq 5F/0/EMuwhwtmC0+MvXsl7SURZjfK/DZv6vj6udq1+Mn9SnN4OWo0skGa0LNaXnmBT Bp7/hE4rJ2uAgarqLPXuG7jpDBGgcfyA6G977Ujk5xxX0cIoEGWSJ6+3kzNB2uTU3G b/WByGAFtjeHNKcL03eJxa1+Ie153RDmcBZizzOfqO8Z0mqP0rVYzhFa1by8On2/qn zXDHVKf5kXSdQ== Date: Wed, 19 Aug 2026 10:43:51 -1000 From: Tejun Heo To: Ziyang Men Cc: kernel-team@meta.com, Jens Axboe , Josef Bacik , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Shuah Khan , Johannes Weiner , Michal =?iso-8859-1?Q?Koutn=FD?= , Roman Gushchin , Shakeel Butt , JP Kobryn , Mykola Lysenko , linux-block@vger.kernel.org, bpf@vger.kernel.org, cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/2] block: add BPF kfuncs to read blkcg io.stat Message-ID: References: <20260817214205.723267-1-ziyang.meme@gmail.com> <20260817214205.723267-2-ziyang.meme@gmail.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hello, On Tue, Aug 18, 2026 at 04:01:58PM -0700, Ziyang Men wrote: > On Tue, Aug 18, 2026 at 12:42:54PM -1000, Tejun Heo wrote: > > On Tue, Aug 18, 2026 at 03:31:29PM -0700, Ziyang Men wrote: > > > Ok I will add the casts bpf_get_blkcg() and bpf_put_blkcg(), and remove the > > > check of css->ss in above functoins. > > > > RCU_PROTECTED is probably better than get/put(). > > Yes we can make the blkcg* RCU_PROTECTED but then the bpf_blkcg_flush_stats() > needs to take the @cgroup* since it is SLEEPABLE. Does this work for you? Do we really need that function? css_rstat_flush() is already exposed and css can already be obtained, right? blkcg_fill_root_iostat() is just accessing system-wide bdev stats, which you probably don't need to begin with or if necessary just access through bdevs. Thanks. -- tejun