From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELvVOUAsc1Y8vQE46Rzc0hTQzytPsDQ8XSawRjulXmHpJyfmXkEjG/ape4pEqsRdqJAK5jEk ARC-Seal: i=1; a=rsa-sha256; t=1521030207; cv=none; d=google.com; s=arc-20160816; b=YuTNAn9EidtxMwBLGTGoyDAmIb3RVtNJbDPLghNObyZfLhGLABulGKbaNzRPz2yJM+ v2eKw1+5/QeH7zVUtWB/ZLr7HeTzscyWArGniiHjZwrdxa7HxDluT869mNzdODKhwOJm MZ7UGXP76fwbYd7hsslj4mDlHJSQyjAJTOvFir0f9Z7kMVr9kDdwmyqp4jGQSOa7lrYk 0apJdzCDJzFYdnxLrKcUNngTJNP+iYlT0OkRsavUNFfc2UhSlaHSLPqENeNASlVFkAQB QVIUzmL7BC97ASlTnN8+H2Oh2vkib5+aA4G/6gHYTRSLxkMUgkNYM4rOT2QkJqVTTw6c OhAQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:arc-authentication-results; bh=L8c/dMpmms8975xyJXkag4epgiZND1RVlFaKIMdzqeM=; b=BtpDvHtl4roUr1iiW+35PkypHhCMMvWW8ZX6xtglVl9+5whLaS4YvholCDS93fkOKW f3KwdjGde0RE6SX2Wmf4c/lE5wUdMlkLWDZHL0UDBSK76+/mhyuWLiu+ttBd7zOsMZpP 151GnCob+DHKn+RqHzxxY/gIuzQqkgX8kVIoX0+7J5sXYkdRco/lNudGLSATc0OSiHCh EnG1uA/DEkF8wyBpHx0VtJgcPXLmeDMJ7tuSeEao8TrQR0p+e9voYO5ALRZZg/4cf+Jb RZKMhkpYoZqriC+fy8mOXfB14AWGsvqSsyKqfqx+EbPlk3s6VCJEfMTCWjiNprDB9yZg vaYA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of foo00@h08.hostsharing.net designates 83.223.90.240 as permitted sender) smtp.mailfrom=foo00@h08.hostsharing.net Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of foo00@h08.hostsharing.net designates 83.223.90.240 as permitted sender) smtp.mailfrom=foo00@h08.hostsharing.net Date: Wed, 14 Mar 2018 13:23:26 +0100 From: Lukas Wunner To: "Rafael J. Wysocki" Cc: Tomasz Figa , Vivek Gautam , Joerg Roedel , Rob Herring , Robin Murphy , "open list:IOMMU DRIVERS" , devicetree@vger.kernel.org, Linux Kernel Mailing List , Mark Rutland , Will Deacon , Rob Clark , Sricharan R , Marek Szyprowski , Archit Taneja , linux-arm-msm , Greg Kroah-Hartman Subject: Re: [PATCH v9 1/5] driver core: Find an existing link between two devices Message-ID: <20180314122326.GA19651@wunner.de> References: <20180313085534.11650-1-vivek.gautam@codeaurora.org> <2217404.A2W3Iek6du@aspire.rjw.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2217404.A2W3Iek6du@aspire.rjw.lan> User-Agent: Mutt/1.5.23 (2014-03-12) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1594812129788829883?= X-GMAIL-MSGID: =?utf-8?q?1594915771167446877?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Wed, Mar 14, 2018 at 12:12:05PM +0100, Rafael J. Wysocki wrote: > On Tuesday, March 13, 2018 12:23:34 PM CET Tomasz Figa wrote: > > On Tue, Mar 13, 2018 at 7:34 PM, Vivek Gautam wrote: > > > On Tue, Mar 13, 2018 at 3:45 PM, Tomasz Figa wrote: > > >> On Tue, Mar 13, 2018 at 5:55 PM, Vivek Gautam wrote: > > >>> The lists managing the device-links can be traversed to > > >>> find the link between two devices. The device_link_add() APIs > > >>> does traverse these lists to check if there's already a link > > >>> setup between the two devices. > > >>> So, add a new APIs, device_link_find(), to find an existing > > >>> device link between two devices - suppliers and consumers. > > >> > > >> I'm wondering if this API would be useful for anything else that the > > >> problem we're trying to solve with deleting links without storing them > > >> anywhere. Perhaps a device_link_del_dev(consumer, supplier) would be a > > >> better alternative? > > > > > > Yea, that sounds simpler i think. Will add this API instead of > > > find_link(). Thanks. > > > > Perhaps let's wait for a moment to see if there are other opinions. :) > > > > Rafael, Lucas, any thoughts? > > It is not clear to me what the device_link_del_dev(consumer, supplier) > would do. The point appears to be that the pointer to the device_link need not be stored somewhere for later deletion. The newly added function would check if a device link exists and delete it if so. However I don't understand why storing the pointer would be a problem? Also, would using DL_FLAG_AUTOREMOVE avoid the need for the additional function? Thanks, Lukas