From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Subject: [RFC] dmaengine: bcm2835: Avoid GFP_KERNEL in device_prep_slave_sg From: Vinod Koul Message-Id: <20190423051109.GE28103@vkoul-mobl> Date: Tue, 23 Apr 2019 10:41:09 +0530 To: Stefan Wahren Cc: Dan Williams , Florian Fainelli , Ray Jui , Scott Branden , Eric Anholt , bcm-kernel-feedback-list@broadcom.com, Aaro Koskinen , Lukas Wunner , Florian Kauer , Martin Sperl , dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rpi-kernel@lists.infradead.org List-ID: T24gMDEtMDQtMTksIDIwOjM4LCBTdGVmYW4gV2FocmVuIHdyb3RlOgo+IFRoZSBjb21taXQgYWYx OWI3Y2U3NmJhICgibW1jOiBiY20yODM1OiBBdm9pZCBwb3NzaWJsZSByYWNlcyBvbgo+IGRhdGEg cmVxdWVzdHMiKSBpbnRyb2R1Y2VzIGEgcG9zc2libGUgY2lyY3VsYXIgbG9ja2luZyBkZXBlbmRl bmN5LAo+IHdoaWNoIGlzIHRyaWdnZXJlZCBieSBzd2FwcGluZyB0byB0aGUgc2Rob3N0IGludGVy ZmFjZS4KPiAKPiBTbyBpbnN0ZWFkIG9mIHJlaW50cm9kdWNlIHRoZSByYWNlIGNvbmRpdGlvbiBh Z2Fpbiwgd2UgY291bGQgYWxzbwo+IGF2b2lkIHRoaXMgc2l0dWF0aW9uIGJ5IHVzaW5nIEdGUF9O T1dBSVQgZm9yIHRoZSBhbGxvY2F0aW9uIG9mIHRoZQo+IERNQSBidWZmZXIgZGVzY3JpcHRvcnMu CgpBcHBsaWVkLCB0aGFua3MK 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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH,USER_AGENT_MUTT autolearn=ham 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 7A02BC10F14 for ; Tue, 23 Apr 2019 05:11:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 48A43214AE for ; Tue, 23 Apr 2019 05:11:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555996276; bh=jND5KBLA5hl7G9qH/rxqX/MJ4O60Ms3M5+zk7ebnDkg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=ywlu1JacKMhxpy6co5YAxgPTPfNKFUpZzItpBKTuHzdeMZHWwKmVKQyrk4ytYg/js hBcvD6e9C0cmHd/m4T1/Vm1gBy1rEg8aTtc8pDE+sCKq3utdJDjVbvnIA0OvAlZHWR Oe0UVdlhCY1H7EbToWD+9ds4rLnwCDVteiAVQUnE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726004AbfDWFLP (ORCPT ); Tue, 23 Apr 2019 01:11:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:59612 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725882AbfDWFLP (ORCPT ); Tue, 23 Apr 2019 01:11:15 -0400 Received: from localhost (unknown [171.76.113.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7B26D20811; Tue, 23 Apr 2019 05:11:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555996275; bh=jND5KBLA5hl7G9qH/rxqX/MJ4O60Ms3M5+zk7ebnDkg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=PAZvKbIZ2SpdTByeFNvRwsCXmBltB9TQhyXqeN/RPB2CrjkzFPcKNyFGH2NHTSQ2N 6pGO6ovHEXFvLsRMVsGliWNZgwKKqS+PJJJ8Cif9dSr4UnW7n0H9K838khUkQd7oVS 5HWeL3Ty26HnZyYLqmUoEOfZSa2wwEHXml07309w= Date: Tue, 23 Apr 2019 10:41:09 +0530 From: Vinod Koul To: Stefan Wahren Cc: Dan Williams , Florian Fainelli , Ray Jui , Scott Branden , Eric Anholt , bcm-kernel-feedback-list@broadcom.com, Aaro Koskinen , Lukas Wunner , Florian Kauer , Martin Sperl , dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rpi-kernel@lists.infradead.org Subject: Re: [PATCH RFC] dmaengine: bcm2835: Avoid GFP_KERNEL in device_prep_slave_sg Message-ID: <20190423051109.GE28103@vkoul-mobl> References: <1554143899-4124-1-git-send-email-stefan.wahren@i2se.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline In-Reply-To: <1554143899-4124-1-git-send-email-stefan.wahren@i2se.com> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: dmaengine-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org Message-ID: <20190423051109.MBoL_qIxOJXgzykYhGnPRDZ6XM9EQuqadbXMN6I5XZQ@z> On 01-04-19, 20:38, Stefan Wahren wrote: > The commit af19b7ce76ba ("mmc: bcm2835: Avoid possible races on > data requests") introduces a possible circular locking dependency, > which is triggered by swapping to the sdhost interface. > > So instead of reintroduce the race condition again, we could also > avoid this situation by using GFP_NOWAIT for the allocation of the > DMA buffer descriptors. Applied, thanks -- ~Vinod