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=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS 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 E349CC43441 for ; Fri, 23 Nov 2018 14:39:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A9563206B2 for ; Fri, 23 Nov 2018 14:39:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="ahBtdCAm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A9563206B2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2440047AbeKXBYG (ORCPT ); Fri, 23 Nov 2018 20:24:06 -0500 Received: from perceval.ideasonboard.com ([213.167.242.64]:43106 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2436868AbeKXBYG (ORCPT ); Fri, 23 Nov 2018 20:24:06 -0500 Received: from avalon.localnet (dfj612ybrt5fhg77mgycy-3.rev.dnainternet.fi [IPv6:2001:14ba:21f5:5b00:2e86:4862:ef6a:2804]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id E2E1158E; Fri, 23 Nov 2018 15:39:38 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1542983979; bh=o9/7zYKUZaT0x8iW1PMeteaD9MEdQeIEArRj3YzsDug=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ahBtdCAmmLz9On2p/QT6tI3YTgmmYyPUDHxChmsv6gfh9toBe9fbDhaNmbYiDcTH9 /vztrINAll9IS1G0/+KsdpCmwPwPledIorIH7zunaCXkstCw6V9PcuqQ2QqLoMti/4 +uX4mNA7oyUXxRVs1ykETsbiLFsigT4yn0kFDY00= From: Laurent Pinchart To: Nicholas Mc Guire Cc: Tomi Valkeinen , David Airlie , Sebastian Reichel , Peter Ujfalusi , "Andrew F. Davis" , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/omap: dss: do not allow devm_kasprintf() to fail Date: Fri, 23 Nov 2018 16:39:59 +0200 Message-ID: <3550363.0Jm6vJdJjr@avalon> Organization: Ideas on Board Oy In-Reply-To: <1542974495-12387-1-git-send-email-hofrat@osadl.org> References: <1542974495-12387-1-git-send-email-hofrat@osadl.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Nicholas, On Friday, 23 November 2018 14:01:35 EET Nicholas Mc Guire wrote: > omapdss_display_init() is called by multiple drivers and does not expect > a return value so without changing all call-sites the low-probability > failure of devm_kasprintf() can not be reported up the call stack. As > the amount allocated here is very small (<= 16 bytes) and it is an > initialization function that most likely will be called during system > initialization it should be OK to use __GFP_NOFAIL here to prevent > devm_kasprintf() from returning NULL. > > Signed-off-by: Nicholas Mc Guire > Fixes: 36c61ae2b755 ("drm/omap: dss: Remove display ordering from > dss/display.c") > --- > > Problem located with experimental coccinelle script > > While the use of __GFP_NOFAIL is to be limited (small infrequent > allocations) this case does seems suitable as it is rare and small > (initialization) .As all the current drivers using > omapdss_display_init() currently seem not to initialize dssdev->name > prior to calling omapdss_display_init() and the unlikely failure > case can not be reasonably responded (returns void) not allowing > a allocation failure here should be acceptable. Given that my plan is to eventually drop omapdss_display_init(), this looks fine to me. Acked-by: Laurent Pinchart > Patch was compile tested with: omap2plus_defconfig (implies OMAP_DSS_BASE=m) > > Patch is against 4.20-rc3 (localversion-next is next-20181123) > > drivers/gpu/drm/omapdrm/dss/display.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/omapdrm/dss/display.c > b/drivers/gpu/drm/omapdrm/dss/display.c index 34b2a4e..7dbe874 100644 > --- a/drivers/gpu/drm/omapdrm/dss/display.c > +++ b/drivers/gpu/drm/omapdrm/dss/display.c > @@ -45,7 +45,8 @@ void omapdss_display_init(struct omap_dss_device *dssdev) > of_property_read_string(dssdev->dev->of_node, "label", &dssdev->name); > > if (dssdev->name == NULL) > - dssdev->name = devm_kasprintf(dssdev->dev, GFP_KERNEL, > + dssdev->name = devm_kasprintf(dssdev->dev, > + GFP_KERNEL | __GFP_NOFAIL, > "display%u", id); > } > EXPORT_SYMBOL_GPL(omapdss_display_init); -- Regards, Laurent Pinchart