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 1B232C433EF for ; Thu, 31 Mar 2022 04:10:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229955AbiCaELs (ORCPT ); Thu, 31 Mar 2022 00:11:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50816 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229965AbiCaELJ (ORCPT ); Thu, 31 Mar 2022 00:11:09 -0400 Received: from out30-42.freemail.mail.aliyun.com (out30-42.freemail.mail.aliyun.com [115.124.30.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0A9FB14A6D7 for ; Wed, 30 Mar 2022 20:44:18 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R851e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04395;MF=joseph.qi@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0V8gzrDQ_1648697185; Received: from 30.225.24.67(mailfrom:joseph.qi@linux.alibaba.com fp:SMTPD_---0V8gzrDQ_1648697185) by smtp.aliyun-inc.com(127.0.0.1); Thu, 31 Mar 2022 11:26:27 +0800 Message-ID: Date: Thu, 31 Mar 2022 11:26:25 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH RESEND] uio/uio_pci_generic: Introduce refcnt on open/release Content-Language: en-US To: Yao Hongbo , mst@redhat.com, gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, alikernel-developer@linux.alibaba.com References: <1648693432-129409-1-git-send-email-yaohongbo@linux.alibaba.com> From: Joseph Qi In-Reply-To: <1648693432-129409-1-git-send-email-yaohongbo@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/31/22 10:23 AM, Yao Hongbo wrote: > If two userspace programs both open the PCI UIO fd, when one > of the program exits uncleanly, the other will cause IO hang > due to bus-mastering disabled. > > It's a common usage for spdk/dpdk to use UIO. So, introduce refcnt > to avoid such problems. > > Fixes: 865a11f("uio/uio_pci_generic: Disable bus-mastering on release") Fixes commit id should be 12 abbrev instead. Thanks, Joseph > Reported-by: Xiu Yang > Signed-off-by: Yao Hongbo > --- > drivers/uio/uio_pci_generic.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/drivers/uio/uio_pci_generic.c b/drivers/uio/uio_pci_generic.c > index e03f9b5..8add2cf 100644 > --- a/drivers/uio/uio_pci_generic.c > +++ b/drivers/uio/uio_pci_generic.c > @@ -31,6 +31,7 @@ > struct uio_pci_generic_dev { > struct uio_info info; > struct pci_dev *pdev; > + atomic_t refcnt; > }; > > static inline struct uio_pci_generic_dev * > @@ -39,6 +40,14 @@ struct uio_pci_generic_dev { > return container_of(info, struct uio_pci_generic_dev, info); > } > > +static int open(struct uio_info *info, struct inode *inode) > +{ > + struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info); > + > + atomic_inc(&gdev->refcnt); > + return 0; > +} > + > static int release(struct uio_info *info, struct inode *inode) > { > struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info); > @@ -51,7 +60,9 @@ static int release(struct uio_info *info, struct inode *inode) >  * Note that there's a non-zero chance doing this will wedge the device >  * at least until reset. > */ > - pci_clear_master(gdev->pdev); > + if (atomic_dec_and_test(&gdev->refcnt)) > + pci_clear_master(gdev->pdev); > + > return 0; > } > > @@ -92,8 +103,11 @@ static int probe(struct pci_dev *pdev, > > gdev->info.name = "uio_pci_generic"; > gdev->info.version = DRIVER_VERSION; > + gdev->info.open = open; > gdev->info.release = release; > gdev->pdev = pdev; > + atomic_set(&gdev->refcnt, 0); > + > if (pdev->irq && (pdev->irq != IRQ_NOTCONNECTED)) { > gdev->info.irq = pdev->irq; > gdev->info.irq_flags = IRQF_SHARED;