From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 A3CA7374DE; Thu, 9 Nov 2023 21:19:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="FoVjHHH1" Received: from mail-pl1-x62f.google.com (mail-pl1-x62f.google.com [IPv6:2607:f8b0:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0382BD65; Thu, 9 Nov 2023 13:19:46 -0800 (PST) Received: by mail-pl1-x62f.google.com with SMTP id d9443c01a7336-1cc53d0030fso11789475ad.0; Thu, 09 Nov 2023 13:19:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1699564785; x=1700169585; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=LX5y+iaQf1po/cv20bnKPKtRsqD9RuKdrMysiV1f6ro=; b=FoVjHHH1klIiYgtnhoCJf1sqt5xXSeo5yPmWRszEwIMdSwpN6ivUh17YGwRji/kiJt QduPjTTh3o52yPnpvtgDsGeMLYRej4DOYd0fN/lzcgmH9VDNDtQsvCPKfvfFGI8OKiFn 54yp2OAfpHW3v9bRx3DTMAaxJzIC/tkVM+xpqqnN1NIIvN507EAVPRbeES6OIcJRauiq uIpEG9bQfpDe1uXKAfx3H3gos0pSG+JIXn5U3UzK03XydiVbN+BauvD7bPKNHy7V4zkF 7GsLdLp1hxXc5kqnjs7JMm42o/2eV2uBmMArT7gqt5k89ZgVOWy6MG5WR+GY/hGai4od CkdA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1699564785; x=1700169585; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=LX5y+iaQf1po/cv20bnKPKtRsqD9RuKdrMysiV1f6ro=; b=rRKFV3TqiK7TBotvUbQDbJeyya0R1gY3ByNdiliJcNRsZh36NOefDeWE1ehPxhR6Rn s1VyxVHIKuPMcAdbpG3hF9pANS1qoeDvaSbtGOrzQmajPg+8k6jWgcwyVJYnLSe2+bum 79J4zM/IZuIzHh1xwJRsiAhCSybogpwpXzQIZo1RL/tXUSiKT+kp6TThwW3esVxyUhgx FfkVJIosJE6/9hvvqER9OYC0SKVpd08uWU0cGPv75964YXR3ixDHBtBFjJYqiiasgk10 ZyXeIPjnJ6tTnL/ROC3FIfiuCNhBvXc7PSuNQlcsbGAKJPEyn2SEOYgTIZZeWYdBhwzX qB0g== X-Gm-Message-State: AOJu0YxE0GN741eh2Zj7LZVMCH0cVHSdI/tWOst9CsKiHTRf5NAFTwEE 6Rwc62ch2NJPg1rng5hjbLs= X-Google-Smtp-Source: AGHT+IHHX6YpvE/k0cKYCEO0LlxVWGgM4jCuwPYoingJbCsdNuakGtzXA04rcGaVT2NFvbci1EJsGg== X-Received: by 2002:a17:903:120d:b0:1bc:1e17:6d70 with SMTP id l13-20020a170903120d00b001bc1e176d70mr637433plh.24.1699564785332; Thu, 09 Nov 2023 13:19:45 -0800 (PST) Received: from localhost ([2620:10d:c090:400::4:7384]) by smtp.gmail.com with ESMTPSA id j24-20020a170902759800b001c62b9a51a4sm3936632pll.239.2023.11.09.13.19.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Nov 2023 13:19:44 -0800 (PST) Sender: Tejun Heo Date: Thu, 9 Nov 2023 11:19:43 -1000 From: Tejun Heo To: Yafang Shao Cc: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, lizefan.x@bytedance.com, hannes@cmpxchg.org, yosryahmed@google.com, mkoutny@suse.com, sinquersw@gmail.com, longman@redhat.com, cgroups@vger.kernel.org, bpf@vger.kernel.org, oliver.sang@intel.com Subject: Re: [PATCH v3 bpf-next 02/11] cgroup: Make operations on the cgroup root_list RCU safe Message-ID: References: <20231029061438.4215-1-laoar.shao@gmail.com> <20231029061438.4215-3-laoar.shao@gmail.com> Precedence: bulk X-Mailing-List: cgroups@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: <20231029061438.4215-3-laoar.shao@gmail.com> On Sun, Oct 29, 2023 at 06:14:29AM +0000, Yafang Shao wrote: > At present, when we perform operations on the cgroup root_list, we must > hold the cgroup_mutex, which is a relatively heavyweight lock. In reality, > we can make operations on this list RCU-safe, eliminating the need to hold > the cgroup_mutex during traversal. Modifications to the list only occur in > the cgroup root setup and destroy paths, which should be infrequent in a > production environment. In contrast, traversal may occur frequently. > Therefore, making it RCU-safe would be beneficial. > > Signed-off-by: Yafang Shao Acked-by: Tejun Heo Thanks. -- tejun