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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 62AC3C433EF for ; Fri, 22 Apr 2022 09:56:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1446302AbiDVJ7j (ORCPT ); Fri, 22 Apr 2022 05:59:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40054 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1446285AbiDVJ7i (ORCPT ); Fri, 22 Apr 2022 05:59:38 -0400 Received: from mail-pg1-x531.google.com (mail-pg1-x531.google.com [IPv6:2607:f8b0:4864:20::531]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 24CCE53B6C; Fri, 22 Apr 2022 02:56:45 -0700 (PDT) Received: by mail-pg1-x531.google.com with SMTP id k14so6994112pga.0; Fri, 22 Apr 2022 02:56:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=4z0DG/HTGjm0nnHIhD5v7rm7s7fXaigHD/5btxNfFCk=; b=KnDr5TtxaHLKB/6Qy7Jus6MHdsRi3aLqIG52gWYCLtsuQRIqYzvx6Btesrkh3ECEup wGS/yAONCHvSgQ1oTRV8kD3YvcmnArQdgDHvS1dolRqJQUgOWk7Wh4TbgoyFgDcuAsiR Ngms1Go/S44idIyo9RpPsk+o/nKEx1glBalAJx1FKoJtlMB0cC4XZ2MBSPeIPNr90EHI Uorxsu0oEyBLI2/tXqHBZizkgSjM2JJ2vFtvjy6Ww/o+p8xT3bBI8uTe7Gkto/93uCxZ Mmi94sEXjiuNrwen4hbeGYAxRcTdPHQ8EiMAwVShwSfN4R4D4yXremQvuHHAgIiZt+FX ohoQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=4z0DG/HTGjm0nnHIhD5v7rm7s7fXaigHD/5btxNfFCk=; b=aM/eASQ9z3SK1uFdh09kNSgbFyuNaF8kD80S3DqPOBNfDJ9ogQsfTo2lIOxLBTVU9B wBB84lLDM6FabChKBAhQ54beAMUFe1YgUi4i1C+oORuUf6+QlDRaoA8GmnrlA1gPzqcF jMhFqdOwpt+IVwOXaV/hAtXVZKx+dIbV1ey2Sqr0W6K+AKH0uzukefh9YgXKo6PcFIO1 6MwjuFLgEKM3CEf3BJWaQAmbcNy+bh8vnl0dkeEL4rQ7MWhOty30yjWYy3XmuShBTY3O k/U08y1uu2QYXyRVgzw84zla1RaASLmYTQiuiKEW2++5pYY0ad7r9CNpCMgXNODcIs38 It/g== X-Gm-Message-State: AOAM533Jryq8rVbjKz+uwpkSIJVvLTUmxDPRr4czCrLj/Ulq2Qh2XLsD bD6+9IDWivzfEH5GhcVYxQ== X-Google-Smtp-Source: ABdhPJymP25I1AQXQk1+BZt3KKsq69o66XmBVh4Uoc2nQ2OVFQLlErCTqoeUB+sho6sq2LWimXe3XQ== X-Received: by 2002:a63:780f:0:b0:386:5d6f:2153 with SMTP id t15-20020a63780f000000b003865d6f2153mr3150837pgc.555.1650621404650; Fri, 22 Apr 2022 02:56:44 -0700 (PDT) Received: from piliu.users.ipa.redhat.com ([209.132.188.80]) by smtp.gmail.com with ESMTPSA id c139-20020a624e91000000b005060cdff4ffsm1995538pfb.129.2022.04.22.02.56.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Apr 2022 02:56:44 -0700 (PDT) Date: Fri, 22 Apr 2022 17:56:37 +0800 From: Pingfan Liu To: Heiko Carstens Cc: linux-s390@vger.kernel.org, Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/9] s390/irq: utilize RCU instead of irq_lock_sparse() in show_msi_interrupt() Message-ID: References: <20220420140521.45361-1-kernelfans@gmail.com> <20220420140521.45361-5-kernelfans@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 21, 2022 at 01:42:59PM +0200, Heiko Carstens wrote: > On Thu, Apr 21, 2022 at 11:36:17AM +0800, Pingfan Liu wrote: > > Oops. You are right. What about using rcu_read_lock() directly? > > > > > > diff --git a/arch/s390/kernel/irq.c b/arch/s390/kernel/irq.c > > index 3033f616e256..45393919fe61 100644 > > --- a/arch/s390/kernel/irq.c > > +++ b/arch/s390/kernel/irq.c > > @@ -205,7 +205,7 @@ static void show_msi_interrupt(struct seq_file *p, int irq) > > unsigned long flags; > > int cpu; > > > > - irq_lock_sparse(); > > + rcu_read_lock(); > > desc = irq_to_desc(irq); > > if (!desc) > > goto out; > > @@ -224,7 +224,7 @@ static void show_msi_interrupt(struct seq_file *p, int irq) > > seq_putc(p, '\n'); > > raw_spin_unlock_irqrestore(&desc->lock, flags); > > out: > > - irq_unlock_sparse(); > > + rcu_read_unlock(); > > That looks like it should work. Please resend and also add a reference > to commit 74bdf7815dfb ("genirq: Speedup show_interrupts()") which > explains why this works. Thanks for your review. I will follow up with V2. Regards, Pingfan