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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C329FC433FE for ; Mon, 7 Nov 2022 15:56:48 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 40D4910E432; Mon, 7 Nov 2022 15:56:47 +0000 (UTC) Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by gabe.freedesktop.org (Postfix) with ESMTPS id A136410E438 for ; Mon, 7 Nov 2022 15:56:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1667836603; x=1699372603; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=p+x7JSU3SOxlwX4TBBBHg1OTJgpF1kYj6OZkGlbsb4A=; b=FKscAI8+tAf5oPrwf5dzpe4JrFbCvr41OmWWmOKF8E8B7vaOwlheaukl +7UlNax7tMJUt2/l9O7LHbrPPTfwctRafqlvhWUI0z19RDO9FUjmWD2EU Xh3QkwSc6VHzk6usym9mhOoCg0GIFt+Hqv29c8OGy8Sg7rE1JFO9OOKOg 9bnpmBcCw87i+NLFqUirwMx+pITsX1aVPFLDkeGAu5RGzF0OF2fnj17CJ 5bzMnMK/p2dUyBpoa+5IXyXbzjcczeBgCePM14QeGpvBDM+xUHvPRT0ey TGoJTGrfjssf7If3inYbdzvDL6q6DjrLml82dSgfJB1aW+nh/bo0BccyH w==; X-IronPort-AV: E=McAfee;i="6500,9779,10524"; a="308067595" X-IronPort-AV: E=Sophos;i="5.96,145,1665471600"; d="scan'208";a="308067595" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Nov 2022 07:56:42 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10524"; a="810881641" X-IronPort-AV: E=Sophos;i="5.96,145,1665471600"; d="scan'208";a="810881641" Received: from stinkpipe.fi.intel.com (HELO stinkbox) ([10.237.72.191]) by orsmga005.jf.intel.com with SMTP; 07 Nov 2022 07:56:37 -0800 Received: by stinkbox (sSMTP sendmail emulation); Mon, 07 Nov 2022 17:56:36 +0200 Date: Mon, 7 Nov 2022 17:56:36 +0200 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Stanislaw Gruszka Subject: Re: [PATCH RESEND] drm: fix crash in drm_minor_alloc_release Message-ID: References: <20221107144500.3692212-1-stanislaw.gruszka@linux.intel.com> <20221107154041.GA3600973@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20221107154041.GA3600973@linux.intel.com> X-Patchwork-Hint: comment X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: dri-devel@lists.freedesktop.org, Thomas Zimmermann , Jacek Lawrynowicz Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mon, Nov 07, 2022 at 04:40:41PM +0100, Stanislaw Gruszka wrote: > On Mon, Nov 07, 2022 at 05:10:48PM +0200, Ville Syrjälä wrote: > > On Mon, Nov 07, 2022 at 03:45:00PM +0100, Stanislaw Gruszka wrote: > > > index 8214a0b1ab7f..e3a1243dd2ae 100644 > > > --- a/drivers/gpu/drm/drm_drv.c > > > +++ b/drivers/gpu/drm/drm_drv.c > > > @@ -102,7 +102,8 @@ static void drm_minor_alloc_release(struct drm_device *dev, void *data) > > > > > > WARN_ON(dev != minor->dev); > > > > > > - put_device(minor->kdev); > > > + if (!IS_ERR(minor->kdev)) > > > + put_device(minor->kdev); > > > > Assigning error pointers into things is a terrible idea. > > IMO the correct fix would be to not return some > > half-constructed garbage from drm_minor_alloc(). > > So basically should at least partically revert > > commit f96306f9892b ("drm: manage drm_minor cleanup with drmm_") > > I would prefer to not change any ordering or remove drmm_* stuff, since > as pointed to above commit message, things are tricky there. Looks to me that it's only tricky because of drmm. Without that it was totally clear what was happening. I think if the managed stuff is making stuff more tricky then it has failed its purpose. > > I think assigning NULL to minor->kdev should be fine: > > if (IS_ERR(minor->kdev)) { > r = PTR_ERR(minor->kdev); > minor->kdev = NULL; > return r; > } > > put_device() in drm_minor_alloc_release() will cope nicely with it. > > Regards > Stanislaw -- Ville Syrjälä Intel