From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E726B2110; Sat, 19 Jul 2025 00:28:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752884882; cv=none; b=BIkY2cQdughOch89ZDUv0NnYveS7o8wmJ1vnfHnaePEH95KyXrcsrepsX+Mc/L9CWp7zKgyBJj9cyEPF33vBxFnIeFoFObwxpJd4CW1bsm6og186Qt+bzQIfHqpr2ljJMDp72ThF7smvdCTxn/aL1J8xjNFrn8RAXHpst81nl0c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752884882; c=relaxed/simple; bh=peO+H93Yb/AoZJd5yCIfu7Ot2DeGqz3/MglVOEZqKMM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=d4AMoRLkiyzin+7PA7wnzZWLvWAi9t65W+pm7UrIJWx1EvSmB0xiNxoZGuJrUeVV1O26ykgPuQjXh5Q8Hg4nZvJEbYZuieKqaG9oxoCkmqITzAt+e6CqS23llxxl6B+YpARt9rqNeuaRr0nIOTupfuQ0K47U0d7s6mJqGSYWBmw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sKL3fdR1; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="sKL3fdR1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6FE9EC4CEEB; Sat, 19 Jul 2025 00:28:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752884881; bh=peO+H93Yb/AoZJd5yCIfu7Ot2DeGqz3/MglVOEZqKMM=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=sKL3fdR1R4cmxwCN00/UVjbPE4Cl3Z8LKwDFzJ8tnymTVkonASALvc57OyLC1mrDc 5E5VE0zfvDzrF3sO5o3T0Xs0zuFacGgVv9liHmWh8lWDGKhTuzM0ccleODxk7wOTmS uelwupa6Ow/D9XguTIC999WFeF5uU7NZ6OD5cIzLU6EVZC0JXUSva2zbMH29Tk8UVU RcNBktos6AEgOIskgM+/ACqu4K1QHmE32b70pGYZcfWbiAJYzcl+Zp2/lSduNg/zd8 glM+zEBFOz/C1cIcbHV2LOpvSwcUkxF+zsUcMLQpffuBYyGlyXWYi7reja9Vw+2p/i 5LXZBhTCQhx5g== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id EB72ECE0D3A; Fri, 18 Jul 2025 17:28:00 -0700 (PDT) Date: Fri, 18 Jul 2025 17:28:00 -0700 From: "Paul E. McKenney" To: Steven Rostedt Cc: Mathieu Desnoyers , Sebastian Andrzej Siewior , Boqun Feng , linux-rt-devel@lists.linux.dev, rcu@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Frederic Weisbecker , Joel Fernandes , Josh Triplett , Lai Jiangshan , Masami Hiramatsu , Neeraj Upadhyay , Thomas Gleixner , Uladzislau Rezki , Zqiang , bpf@vger.kernel.org Subject: Re: [RFC PATCH 1/2] rcu: Add rcu_read_lock_notrace() Message-ID: <3cecf6c9-b2ee-4f34-9d1b-ca4cfb8e56a7@paulmck-laptop> Reply-To: paulmck@kernel.org References: <29b5c215-7006-4b27-ae12-c983657465e1@efficios.com> <512331d8-fdb4-4dc1-8d9b-34cc35ba48a5@paulmck-laptop> <16dd7f3c-1c0f-4dfd-bfee-4c07ec844b72@paulmck-laptop> <20250716110922.0dadc4ec@batman.local.home> <895b48bd-d51e-4439-b5e0-0cddcc17a142@paulmck-laptop> Precedence: bulk X-Mailing-List: linux-trace-kernel@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! This is version 2 of a patch series introducing SRCU-fast to the __DECLARE_TRACE() in place of the current preemption disabling. This change enable preemption of BPF programs attached to tracepoints in in, as is required for runtime use of BPF in real-time systems. The patches are as follows: 1. Move rcu_is_watching() checks to srcu_read_{,un}lock_fast(). 2. Add srcu_read_lock_fast_notrace() and srcu_read_unlock_fast_notrace(). 3. Add guards for notrace variants of SRCU-fast readers. 4. Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast. Changes since RFC version: o RFC patch 6/4 has been pulled into the shared RCU tree: e88c632a8698 ("srcu: Add guards for SRCU-fast readers") o RFC patch 5/4 (which removed the now-unnecessary special boot-time avoidance of SRCU) has been folded into patch 4/4 shown above, as suggested by Steven Rostedt. Thanx, Paul ------------------------------------------------------------------------ b/include/linux/srcu.h | 4 ++++ b/include/linux/srcutree.h | 2 -- b/include/linux/tracepoint.h | 6 ++++-- b/kernel/tracepoint.c | 21 ++++++++++++++++++++- include/linux/srcu.h | 30 ++++++++++++++++++++++++++++++ 5 files changed, 58 insertions(+), 5 deletions(-)