From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7263EC2BA19 for ; Wed, 15 Apr 2020 22:27:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4ED66206E9 for ; Wed, 15 Apr 2020 22:27:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ogbq48oE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731962AbgDOW1L (ORCPT ); Wed, 15 Apr 2020 18:27:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56708 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1727993AbgDOW1H (ORCPT ); Wed, 15 Apr 2020 18:27:07 -0400 Received: from mail-wm1-x341.google.com (mail-wm1-x341.google.com [IPv6:2a00:1450:4864:20::341]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7D283C061A0C; Wed, 15 Apr 2020 15:27:07 -0700 (PDT) Received: by mail-wm1-x341.google.com with SMTP id z6so2067572wml.2; Wed, 15 Apr 2020 15:27:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=zg3ob5dFIHsdWUyPt1RU43xeZYyJjlIPkOiX/f8YR84=; b=ogbq48oEXKMvuX6Wqc6V76/Y7aYtAhaE3UxZLBIRfJWjqKTFOGiMRkVg03+/9opHA0 Nq6JVFRzLkJTSiWD4gAsFBQEX7eFyrNMHD7B3XftHASOHKXdIzeVyv4D7j69sC1bLwIe aPFXb+CYlnhKrsIqHb2AXECHd6qlZ4mH4rZ4cEhZQ9ZnNOHzycXeSdFC0KuJMtcuhINR UO5jtzUV+dpWuVz/6KV/c6mIHKpGO8vTqMFIxRaN5d9gy+mtTGct+2KDKgvJQCCs3Fvy QpYmYrE3jVGqaF+PyeEh8uOYzopcs35jPRrF1Ac2l3N3RQDta9L8/ERN881JxIBhXm0X OBhw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=zg3ob5dFIHsdWUyPt1RU43xeZYyJjlIPkOiX/f8YR84=; b=scLId3iEV3u4iyy+5md9kBsHOJ168jni7pinyGawwapuGY7VQd1qehZ6J60gshiRxP faWnpUndNbTLQV6c1MgglQwU/JpuavQjAa1YgbJ0yNlIF0um+UH+AMBkNUVyOR2ukL9N sLasdSeelGafspvuRHnNEgsH4PvslZ0mikxadN2A3csW1+qlgMyiNgnB6sTPROijglkE 9XA8DprLrv9Pw3qjcBlzsrvdd7qDX2A1OCyDISRhBNUn5dy+sMpDUt1gSA9Au9ju525i p12JOYkcX709CEfpf5NBnXQD0i3T/uYLh2qOEnjrVfnjfqrtGytnBj+pTzQuwYfx40Ln 8RUQ== X-Gm-Message-State: AGi0PuZ8ddYhVP8nHyBafBbSUZMFy26owqzRU4XahPfz7xQ1GNq8eh7m VQ8IBzAYumBzD+zdxUxWiQ8= X-Google-Smtp-Source: APiQypJ4nk4y/NIUuy7cNNsNj4JyK9eMcuHuy+sY0Q3j/CR3sPw4tKyyX94iSUliU+33fV8kivTCDw== X-Received: by 2002:a1c:1d4b:: with SMTP id d72mr1421501wmd.19.1586989626211; Wed, 15 Apr 2020 15:27:06 -0700 (PDT) Received: from localhost ([185.92.221.13]) by smtp.gmail.com with ESMTPSA id b4sm20105151wrv.42.2020.04.15.15.27.05 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Wed, 15 Apr 2020 15:27:05 -0700 (PDT) From: Wei Yang To: paulmck@kernel.org, josh@joshtriplett.org Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org, Wei Yang Subject: [PATCH] rcu: init and destroy rcu_synchronize when necessary Date: Wed, 15 Apr 2020 22:26:55 +0000 Message-Id: <20200415222655.9006-1-richard.weiyang@gmail.com> X-Mailer: git-send-email 2.11.0 Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org We would skip the rcu_synchronize if it is a duplicate call back function. This is not necessary to init and destroy for them. Signed-off-by: Wei Yang --- kernel/rcu/update.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index 6c4b862f57d6..91e44b527aad 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -353,13 +353,14 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array, might_sleep(); continue; } - init_rcu_head_on_stack(&rs_array[i].head); - init_completion(&rs_array[i].completion); for (j = 0; j < i; j++) if (crcu_array[j] == crcu_array[i]) break; - if (j == i) + if (j == i) { + init_rcu_head_on_stack(&rs_array[i].head); + init_completion(&rs_array[i].completion); (crcu_array[i])(&rs_array[i].head, wakeme_after_rcu); + } } /* Wait for all callbacks to be invoked. */ @@ -370,9 +371,10 @@ void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array, for (j = 0; j < i; j++) if (crcu_array[j] == crcu_array[i]) break; - if (j == i) + if (j == i) { wait_for_completion(&rs_array[i].completion); - destroy_rcu_head_on_stack(&rs_array[i].head); + destroy_rcu_head_on_stack(&rs_array[i].head); + } } } EXPORT_SYMBOL_GPL(__wait_rcu_gp); -- 2.23.0