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 647BD2D3EEE; Wed, 5 Nov 2025 20:31:01 +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=1762374661; cv=none; b=uZNk0PjFL70ktYAy71uTIoz+qp97yajCZnSgKLGsbxy1DYX2s8lRo/sO8F6GBEzNliFUH1GgKimLnE8tIkX/JwRyz84ncVDlYjlx/H8js4tByns/OoQc6HCsRvDXlF4pwqrJMOCatkqpUll6FtDWXlkYbbauTi4xzCf5pSutWRI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762374661; c=relaxed/simple; bh=sxQuvX/WV2W1bappBx9oI1NpveSp6sJBwxr5rH6PSHs=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition; b=g+7Q2t2lNwYjD1NONfTMeUC+ftqd2rfH2mt2eKJjQ8HmXfS6qkl9driKHxQUIiR15lDGROBKwVL6gpMB5xwpq/9Jsl8zlE8kt2Kwx+6btUu718surHEWuhnZJCAsfytcv9wTLVv8xCWzXsWTCAFCAf3XbiWujaWZIO1+ntOPzY4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eZiEwVyJ; 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="eZiEwVyJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F1793C4CEF5; Wed, 5 Nov 2025 20:31:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1762374661; bh=sxQuvX/WV2W1bappBx9oI1NpveSp6sJBwxr5rH6PSHs=; h=Date:From:To:Cc:Subject:Reply-To:From; b=eZiEwVyJDTEyCYZxAevGrmcfmMuYYrdwYUHIH+XfO8mjWvZ6o4Mbt53hHFLvUrOZT XiZxA74KrN/Fvsx1PmJjXFOt/hx8f6G0vlBC2owXZWLQL/R9lExCV47bTBW8dJ+D6v T7ApQI0d7oRjfwyHZbGIcuumUDylDFiR0nny1wIHKrsrrI1P1TSieTCYgotbiCVDuk 9XFMcdkooAYtZA/RxmkaIXkESNiXLKcySYH39w7l2MgrxNqPBiX/vYdTUs49U5CbaI FwyGGpykJfAjCy59XjiUFH3UBcKIvxmQnHmtOKKfwW8642P/ZoVKalM9VkyVuLIE9h xSZiiDsvdvYdg== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 058F5CE0B94; Wed, 5 Nov 2025 12:31:00 -0800 (PST) Date: Wed, 5 Nov 2025 12:31:00 -0800 From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org Subject: [PATCH v2 0/16] SRCU updates for v6.19 Message-ID: Reply-To: paulmck@kernel.org Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hello! This series creates an srcu_expedite_current() function that allows after-the-fact expediting of SRCU grace periods, adds a DEFINE_SRCU_FAST() that further speeds things up by removing a conditional branch from srcu_read_lock_fast*(), updates documentation, uses SRCU-fast to guard event traces in PREEMPT_RT kernel (thus making such kernels safe for event tracing), adds srcu_read_{,un}lock_fast_updown() functions that are compatible with srcu_down_read() and srcu_up_read(), but do not permit use in NMI handlers (to permit further optimization of SRCU-fast readers by relieving them of the need to deal with irq/softirq/NMI handlers with unbalanced lock/unlock calls), and optimizes SRCU-fast-updown for large ARM servers that use LSE. It is expected that this optimization will be obsoleted by some arm64 architecture-specific work: https://lore.kernel.org/all/aQU7l-qMKJTx4znJ@arm.com/ The patches are as follows: 1. Permit Tiny SRCU srcu_read_unlock() with interrupts disabled. 2. Create an srcu_expedite_current() function. 3. Test srcu_expedite_current(). 4. Create a DEFINE_SRCU_FAST(). 5. Make grace-period determination use ssp->srcu_reader_flavor. 6. Exercise DEFINE_STATIC_SRCU_FAST() and init_srcu_struct_fast(). 7. Require special srcu_struct define/init for SRCU-fast readers. 8. Make SRCU-fast readers enforce use of SRCU-fast definition/init. 9. Update for SRCU-fast definitions and initialization. 10. Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast. 11. Mark diagnostic functions as notrace. 12. Add SRCU_READ_FLAVOR_FAST_UPDOWN CPP macro. 13. Permit negative kvm.sh --kconfig numberic arguments. 14. Create an SRCU-fast-updown API. 15. Optimize SRCU-fast-updown for arm64. 16. Make srcu{,d}_torture_init() announce the SRCU type. Changes since v1: o Merge addition and testing of SRCU-fast-updown for bisectability. https://lore.kernel.org/all/082fb8ba-91b8-448e-a472-195eb7b282fd@paulmck-laptop/ Many of these patches were previously associated with another series that re-implemented RCU tasks trace in terms of SRCU-fast. This work is being deferred pending resolution of the ARM LSE situation on the one hand or full debugging of the all-too-clever workaround optimization on the other. ;-) https://lore.kernel.org/all/7fa58961-2dce-4e08-8174-1d1cc592210f@paulmck-laptop/ Thanx, Paul ------------------------------------------------------------------------ b/Documentation/RCU/Design/Requirements/Requirements.rst | 33 +-- b/Documentation/RCU/checklist.rst | 12 - b/Documentation/RCU/whatisRCU.rst | 3 b/include/linux/notifier.h | 2 b/include/linux/srcu.h | 16 + b/include/linux/srcutiny.h | 1 b/include/linux/srcutree.h | 8 b/include/linux/tracepoint.h | 45 ++-- b/include/trace/perf.h | 4 b/include/trace/trace_events.h | 4 b/kernel/rcu/rcutorture.c | 12 + b/kernel/rcu/srcutiny.c | 13 - b/kernel/rcu/srcutree.c | 58 +++++ b/kernel/rcu/tree.c | 2 b/kernel/rcu/update.c | 8 b/kernel/tracepoint.c | 21 +- b/tools/testing/selftests/rcutorture/bin/kvm.sh | 2 include/linux/srcu.h | 133 ++++++++++--- include/linux/srcutiny.h | 30 ++ include/linux/srcutree.h | 152 +++++++++++---- kernel/rcu/rcutorture.c | 84 ++++++-- kernel/rcu/srcutree.c | 78 +++++++ 22 files changed, 575 insertions(+), 146 deletions(-)