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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 81FC6FC6195 for ; Fri, 8 Nov 2019 16:09:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 577D92178F for ; Fri, 8 Nov 2019 16:09:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573229371; bh=XONYQsEoNe8yVWiybJpTIylgaGizvlUWWexXaABvNxg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=m3mKd+nvGPW6qT+BlZHMpE+fSywvJl6alYs/AGADTSZ3nVhVwZDap64iajxEurWdU 6AlwZTU3AVJF5pziU1BCcX/fRIhPzTVJJh1Nit6kmne2+wmjzOU/iUM1RRdM9YtZjB 6Z/8IOrsodjontS/4vxjyL7WEofZHZ+rEpAgU1kg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728172AbfKHQJa (ORCPT ); Fri, 8 Nov 2019 11:09:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:55252 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727959AbfKHQJ2 (ORCPT ); Fri, 8 Nov 2019 11:09:28 -0500 Received: from lenoir.home (lfbn-ncy-1-150-155.w83-194.abo.wanadoo.fr [83.194.232.155]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 407D721D82; Fri, 8 Nov 2019 16:09:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573229368; bh=XONYQsEoNe8yVWiybJpTIylgaGizvlUWWexXaABvNxg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=w+0a+rZoGK8baZ8RtUPEP5dXwYAdacH2bRiwraNRRrUHJFMoybLuxEviHRV2Zj3On 3/zIrpKqMcQiZYiPwj0VJ3LUvkVxE+Q25JIDk59LkQ7Y4POga029VnZXbAzHSw1hEP YYqIF3oaDNjcr2sztFERCk/Me38178YwL7g2lo9c= From: Frederic Weisbecker To: Peter Zijlstra , Ingo Molnar Cc: LKML , Frederic Weisbecker , "Paul E . McKenney" , Thomas Gleixner Subject: [PATCH 3/4] irq_work: Slightly simplify IRQ_WORK_PENDING clearing Date: Fri, 8 Nov 2019 17:08:57 +0100 Message-Id: <20191108160858.31665-4-frederic@kernel.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191108160858.31665-1-frederic@kernel.org> References: <20191108160858.31665-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Instead of fetching the value of flags and perform an xchg() to clear a bit, just use atomic_fetch_andnot() that is more suitable to do that job in one operation while keeping the full ordering. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Ingo Molnar --- kernel/irq_work.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/kernel/irq_work.c b/kernel/irq_work.c index 255454a48346..49c53f80a13a 100644 --- a/kernel/irq_work.c +++ b/kernel/irq_work.c @@ -34,7 +34,7 @@ static bool irq_work_claim(struct irq_work *work) oflags = atomic_fetch_or(IRQ_WORK_CLAIMED, &work->flags); /* * If the work is already pending, no need to raise the IPI. - * The pairing atomic_xchg() in irq_work_run() makes sure + * The pairing atomic_fetch_andnot() in irq_work_run() makes sure * everything we did before is visible. */ if (oflags & IRQ_WORK_PENDING) @@ -135,7 +135,6 @@ static void irq_work_run_list(struct llist_head *list) { struct irq_work *work, *tmp; struct llist_node *llnode; - int flags; BUG_ON(!irqs_disabled()); @@ -144,6 +143,7 @@ static void irq_work_run_list(struct llist_head *list) llnode = llist_del_all(list); llist_for_each_entry_safe(work, tmp, llnode, llnode) { + int flags; /* * Clear the PENDING bit, after this point the @work * can be re-used. @@ -151,8 +151,7 @@ static void irq_work_run_list(struct llist_head *list) * to claim that work don't rely on us to handle their data * while we are in the middle of the func. */ - flags = atomic_read(&work->flags) & ~IRQ_WORK_PENDING; - atomic_xchg(&work->flags, flags); + flags = atomic_fetch_andnot(IRQ_WORK_PENDING, &work->flags); work->func(work); /* -- 2.23.0