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 ADDBCC433FE for ; Thu, 21 Apr 2022 11:43:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1388912AbiDULqC (ORCPT ); Thu, 21 Apr 2022 07:46:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37382 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231417AbiDULqA (ORCPT ); Thu, 21 Apr 2022 07:46:00 -0400 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 073E124970; Thu, 21 Apr 2022 04:43:11 -0700 (PDT) Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 23LApW8b015963; Thu, 21 Apr 2022 11:43:08 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=pp1; bh=TzGKmzTfoWC4Y0zsxNAxppY+uyfM7GYUC04vAB1rd30=; b=cE9hS4wMOxRbC2rkgBNrghCrP6JTr+0QCWugGBQ3P8Ri1UHZ50mtdWL7moM3xOH9TXAi bsJMV5BoFUjPjCKb3lASWgN8QzTU+icrxwugEPdpAadxV+PfRVIJPRKoSUFFx6o7SOCw 7MNZEP6ox44b6xHhkLh2t8uQWTmHgvErlLbRnkSIruF90RCp8ymd26EraCJOa+eZgc4O ktZ8FVFe/bKgaEkMheIQIs6OePNa0u13CqR2R3vpeVvoXP4JztAxhp17JXJJtYdWCPU7 lxsCUm0twu6T9r9/HxL4Pk8unu8EnGdyZUdXmT/7Sc6bQ4jANqfDsHNnWCaqy1+qVRq1 UQ== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 3fjm2hwra9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 21 Apr 2022 11:43:07 +0000 Received: from m0098410.ppops.net (m0098410.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 23LBfaa8019440; Thu, 21 Apr 2022 11:43:07 GMT Received: from ppma03fra.de.ibm.com (6b.4a.5195.ip4.static.sl-reverse.com [149.81.74.107]) by mx0a-001b2d01.pphosted.com with ESMTP id 3fjm2hwr9u-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 21 Apr 2022 11:43:07 +0000 Received: from pps.filterd (ppma03fra.de.ibm.com [127.0.0.1]) by ppma03fra.de.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 23LBdM2J010792; Thu, 21 Apr 2022 11:43:04 GMT Received: from b06avi18878370.portsmouth.uk.ibm.com (b06avi18878370.portsmouth.uk.ibm.com [9.149.26.194]) by ppma03fra.de.ibm.com with ESMTP id 3ffne9661e-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 21 Apr 2022 11:43:04 +0000 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 23LBhCGh36176138 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 21 Apr 2022 11:43:12 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D2215A405B; Thu, 21 Apr 2022 11:43:00 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 769F9A4054; Thu, 21 Apr 2022 11:43:00 +0000 (GMT) Received: from osiris (unknown [9.145.171.214]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Thu, 21 Apr 2022 11:43:00 +0000 (GMT) Date: Thu, 21 Apr 2022 13:42:59 +0200 From: Heiko Carstens To: Pingfan Liu 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: X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 3F7MHwimN9XDr0Fjcvlxl_oqztMIHWGt X-Proofpoint-ORIG-GUID: 56pkuxdQk7Sa1pIH7iXTODD4VGEdVR9Z X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.858,Hydra:6.0.486,FMLib:17.11.64.514 definitions=2022-04-20_06,2022-04-21_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 clxscore=1015 lowpriorityscore=0 adultscore=0 suspectscore=0 mlxlogscore=598 spamscore=0 bulkscore=0 phishscore=0 malwarescore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2202240000 definitions=main-2204210064 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.