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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 CD7C4C010CF for ; Tue, 5 Nov 2019 12:15:20 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 93A0722480 for ; Tue, 5 Nov 2019 12:15:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 93A0722480 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=8bytes.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 625F916E1; Tue, 5 Nov 2019 12:15:20 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 555DA16E0 for ; Tue, 5 Nov 2019 12:15:18 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from theia.8bytes.org (8bytes.org [81.169.241.247]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id BDEE35D0 for ; Tue, 5 Nov 2019 12:15:17 +0000 (UTC) Received: by theia.8bytes.org (Postfix, from userid 1000) id 1DCFD450; Tue, 5 Nov 2019 13:15:15 +0100 (CET) Date: Tue, 5 Nov 2019 13:15:08 +0100 From: Joerg Roedel To: Will Deacon Subject: Re: [PATCH 5/7] iommu/arm-smmu-v3: Allow building as a module Message-ID: <20191105121508.GA3479@8bytes.org> References: <20191030145112.19738-1-will@kernel.org> <20191030145112.19738-6-will@kernel.org> <20191030193148.GA8432@8bytes.org> <20191031154247.GB28061@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191031154247.GB28061@willie-the-truck> User-Agent: Mutt/1.10.1 (2018-07-13) Cc: Bjorn Helgaas , iommu@lists.linux-foundation.org, Robin Murphy , linux-kernel@vger.kernel.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org Hi Will, On Thu, Oct 31, 2019 at 03:42:47PM +0000, Will Deacon wrote: > Generally, I think unloading the IOMMU driver module while there are > active users is a pretty bad idea, much like unbinding the driver via > /sys in the same situation would also be fairly daft. However, I *think* > the code in __device_release_driver() tries to deal with this by > iterating over the active consumers and ->remove()ing them first. > > I'm without hardware access at the moment, so I haven't been able to > test this myself. We could nobble the module_exit() hook, but there's > still the "force unload" option depending on the .config. Okay, but besides the force-unload case, can we prevent accidential unloading by taking a reference to the module in add_device() and release it in remove_device()? Regards, Joerg _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu