From patchwork Fri Mar 24 00:19:21 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 13186187 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4DF90C6FD1C for ; Fri, 24 Mar 2023 00:19:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231161AbjCXATr (ORCPT ); Thu, 23 Mar 2023 20:19:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57752 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229917AbjCXATq (ORCPT ); Thu, 23 Mar 2023 20:19:46 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1FA8E2DE4A; Thu, 23 Mar 2023 17:19:42 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 9660D62920; Fri, 24 Mar 2023 00:19:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED9A0C433D2; Fri, 24 Mar 2023 00:19:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1679617181; bh=NfvU5usTkW6B5h8S2WMilLDlOwDmJEkpL6G4bgxR4N4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nP3/V17kUQWQO1UOGwccGf/h74BiIzZMw0wXVLx8lRLykGQ2lnft1/BUCKGbJ/HlR mBKW5xOJ3+Cca3vQMBS3TtZQ7ePFFNIFk+HKoH/DYvX2QdI1hSUqraHM7DRfET66r3 c+AdrN8d/V8b3kqwfyYeOJL93sqrVOFrVLWsag/KHddUMXDTVCYmAhxlYnmKcuAHuy m7FzAYmSgBc/TMpq4/2lmMKNI1y4W3Knf6utQvm6RBvZHW073radP024xKkPzHTZKL CBReo9bfi1XsuD5DFtXWJ97WAZsYDrlcb/GQ5N80NzoiZtxzPqgu/rVBuCDPZENwNp EqCwPeMoDziGQ== Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id 8B7841540338; Thu, 23 Mar 2023 17:19:40 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org, hch@lst.de, "Paul E. McKenney" Subject: [PATCH RFC rcu 02/19] srcu: Use static init for statically allocated in-module srcu_struct Date: Thu, 23 Mar 2023 17:19:21 -0700 Message-Id: <20230324001938.3443499-2-paulmck@kernel.org> X-Mailer: git-send-email 2.40.0.rc2 In-Reply-To: <3db82572-f156-4a5d-b711-841aa28bd996@paulmck-laptop> References: <3db82572-f156-4a5d-b711-841aa28bd996@paulmck-laptop> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org Further shrinking the srcu_struct structure is eased by requiring that in-module srcu_struct structures rely more heavily on static initialization. In particular, this preserves the property that a module-load-time srcu_struct initialization can fail only due to memory-allocation failure of the per-CPU srcu_data structures. It might also slightly improve robustness by keeping the number of memory allocations that must succeed down percpu_alloc() call. This is in preparation for splitting an srcu_usage structure out of the srcu_struct structure. [ paulmck: Fold in qiang1.zhang@intel.com feedback. ] Signed-off-by: Paul E. McKenney Cc: Christoph Hellwig --- include/linux/srcutree.h | 19 ++++++++++++++----- kernel/rcu/srcutree.c | 19 +++++++++++++------ 2 files changed, 27 insertions(+), 11 deletions(-) diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h index ac8af12f93b3..428480152375 100644 --- a/include/linux/srcutree.h +++ b/include/linux/srcutree.h @@ -121,15 +121,24 @@ struct srcu_struct { #define SRCU_STATE_SCAN1 1 #define SRCU_STATE_SCAN2 2 -#define __SRCU_STRUCT_INIT(name, pcpu_name) \ -{ \ - .sda = &pcpu_name, \ +#define __SRCU_STRUCT_INIT_COMMON(name) \ .lock = __SPIN_LOCK_UNLOCKED(name.lock), \ .srcu_gp_seq_needed = -1UL, \ .work = __DELAYED_WORK_INITIALIZER(name.work, NULL, 0), \ - __SRCU_DEP_MAP_INIT(name) \ + __SRCU_DEP_MAP_INIT(name) + +#define __SRCU_STRUCT_INIT_MODULE(name) \ +{ \ + __SRCU_STRUCT_INIT_COMMON(name) \ } +#define __SRCU_STRUCT_INIT(name, pcpu_name) \ +{ \ + .sda = &pcpu_name, \ + __SRCU_STRUCT_INIT_COMMON(name) \ +} + + /* * Define and initialize a srcu struct at build time. * Do -not- call init_srcu_struct() nor cleanup_srcu_struct() on it. @@ -151,7 +160,7 @@ struct srcu_struct { */ #ifdef MODULE # define __DEFINE_SRCU(name, is_static) \ - is_static struct srcu_struct name; \ + is_static struct srcu_struct name = __SRCU_STRUCT_INIT_MODULE(name); \ extern struct srcu_struct * const __srcu_struct_##name; \ struct srcu_struct * const __srcu_struct_##name \ __section("___srcu_struct_ptrs") = &name diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index cd46fe063e50..7a6d9452a5d0 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -1895,13 +1895,14 @@ void __init srcu_init(void) static int srcu_module_coming(struct module *mod) { int i; + struct srcu_struct *ssp; struct srcu_struct **sspp = mod->srcu_struct_ptrs; - int ret; for (i = 0; i < mod->num_srcu_structs; i++) { - ret = init_srcu_struct(*(sspp++)); - if (WARN_ON_ONCE(ret)) - return ret; + ssp = *(sspp++); + ssp->sda = alloc_percpu(struct srcu_data); + if (WARN_ON_ONCE(!ssp->sda)) + return -ENOMEM; } return 0; } @@ -1910,10 +1911,16 @@ static int srcu_module_coming(struct module *mod) static void srcu_module_going(struct module *mod) { int i; + struct srcu_struct *ssp; struct srcu_struct **sspp = mod->srcu_struct_ptrs; - for (i = 0; i < mod->num_srcu_structs; i++) - cleanup_srcu_struct(*(sspp++)); + for (i = 0; i < mod->num_srcu_structs; i++) { + ssp = *(sspp++); + if (!rcu_seq_state(smp_load_acquire(&ssp->srcu_sup->srcu_gp_seq_needed)) && + !WARN_ON_ONCE(!ssp->srcu_sup->sda_is_static)) + cleanup_srcu_struct(ssp); + free_percpu(ssp->sda); + } } /* Handle one module, either coming or going. */