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=-14.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=unavailable 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 C0EE6C433E0 for ; Fri, 5 Mar 2021 07:07:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8F233601FA for ; Fri, 5 Mar 2021 07:07:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229526AbhCEHH5 (ORCPT ); Fri, 5 Mar 2021 02:07:57 -0500 Received: from m12-15.163.com ([220.181.12.15]:36099 "EHLO m12-15.163.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229446AbhCEHH4 (ORCPT ); Fri, 5 Mar 2021 02:07:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=Date:From:Subject:Message-ID:MIME-Version; bh=1CrzQ K1FiZQ6UWshLPUj3+3c3rlvZ+x61jdocF6Jma8=; b=Inac1/PdOL9Oi2sDMH0WD uOHyrLIK+aIUzdARMwf9vqeP7SOGpcj6EplN2U0F0JT65LhLE55uleZF+8CAywvh Iqi86yjKeIZfuD4M/Ry+gs7+lsR+S/M6mSGbHEV72O9Zq3CQGwHRi+ON63cHLcVc Fxa8dNZCQijfkmZuo3iibQ= Received: from localhost (unknown [119.137.55.151]) by smtp11 (Coremail) with SMTP id D8CowAC3vhKx10Fgj6uHDw--.63S2; Fri, 05 Mar 2021 15:03:22 +0800 (CST) Date: Fri, 5 Mar 2021 15:03:25 +0800 From: angkery To: Christophe Leroy Cc: mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, drt@linux.ibm.com, ljp@linux.ibm.com, sukadev@linux.ibm.com, davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Junlin Yang Subject: Re: [PATCH] ibmvnic: remove excessive irqsave Message-ID: <20210305150325.0000286b.angkery@163.com> In-Reply-To: <67215668-0850-a0f3-06e1-49db590b8fcc@csgroup.eu> References: <20210305014350.1460-1-angkery@163.com> <67215668-0850-a0f3-06e1-49db590b8fcc@csgroup.eu> Organization: yulong X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset=GB18030 Content-Transfer-Encoding: 8bit X-CM-TRANSID: D8CowAC3vhKx10Fgj6uHDw--.63S2 X-Coremail-Antispam: 1Uf129KBjvJXoWxJryfXrW5Jr1DGrWxuw45ZFb_yoW8trWkpF srWFy3C3Wvqr1jgwsrXw10yFsrC3yDtry8WrykC3Wfuas8Zr1Fqr1rKFy29FWDJ3yfKan0 yF15Z3s3ZFn8C3DanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07UzKZXUUUUU= X-Originating-IP: [119.137.55.151] X-CM-SenderInfo: 5dqjyvlu16il2tof0z/1tbiLQFMI1SIlLiOnAABsg Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 5 Mar 2021 06:49:14 +0100 Christophe Leroy wrote: > Le 05/03/2021 à 02:43, angkery a écrit : > > From: Junlin Yang > > > > ibmvnic_remove locks multiple spinlocks while disabling interrupts: > > spin_lock_irqsave(&adapter->state_lock, flags); > > spin_lock_irqsave(&adapter->rwi_lock, flags); > > > > there is no need for the second irqsave,since interrupts are > > disabled at that point, so remove the second irqsave: > > The problème is not that there is no need. The problem is a lot more > serious: As reported by coccinella, the second _irqsave() overwrites > the value saved in 'flags' by the first _irqsave, therefore when the > second _irqrestore comes, the value in 'flags' is not valid, the > value saved by the first _irqsave has been lost. This likely leads to > IRQs remaining disabled, which is _THE_ problem really. > Thank you for explaining the real problem. I will update the commit information with your description. > > spin_lock_irqsave(&adapter->state_lock, flags); > > spin_lock(&adapter->rwi_lock); > > > > Generated by: ./scripts/coccinelle/locks/flags.cocci > > ./drivers/net/ethernet/ibm/ibmvnic.c:5413:1-18: > > ERROR: nested lock+irqsave that reuses flags from line 5404. > > > > Signed-off-by: Junlin Yang > > --- > > drivers/net/ethernet/ibm/ibmvnic.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/net/ethernet/ibm/ibmvnic.c > > b/drivers/net/ethernet/ibm/ibmvnic.c index 2464c8a..a52668d 100644 > > --- a/drivers/net/ethernet/ibm/ibmvnic.c > > +++ b/drivers/net/ethernet/ibm/ibmvnic.c > > @@ -5408,9 +5408,9 @@ static void ibmvnic_remove(struct vio_dev > > *dev) > > * after setting state, so __ibmvnic_reset() which is > > called > > * from the flush_work() below, can make progress. > > */ > > - spin_lock_irqsave(&adapter->rwi_lock, flags); > > + spin_lock(&adapter->rwi_lock); > > adapter->state = VNIC_REMOVING; > > - spin_unlock_irqrestore(&adapter->rwi_lock, flags); > > + spin_unlock(&adapter->rwi_lock); > > > > spin_unlock_irqrestore(&adapter->state_lock, flags); > > > >