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=-8.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,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 54179C4360F for ; Wed, 3 Apr 2019 07:22:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2029F21473 for ; Wed, 3 Apr 2019 07:22:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="LO9+0mIR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728635AbfDCHWP (ORCPT ); Wed, 3 Apr 2019 03:22:15 -0400 Received: from mail-ed1-f67.google.com ([209.85.208.67]:37669 "EHLO mail-ed1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725936AbfDCHWP (ORCPT ); Wed, 3 Apr 2019 03:22:15 -0400 Received: by mail-ed1-f67.google.com with SMTP id v21so131432edq.4 for ; Wed, 03 Apr 2019 00:22:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=sender:date:from:to:cc:subject:message-id:mail-followup-to :references:mime-version:content-disposition:in-reply-to:user-agent; bh=zonT63YgWKVIcQgjVqQN83lDjmhEgLXdo5gkBXtDGoc=; b=LO9+0mIRo6XD9pKea+Ac019ifHrKkisgu9rQbzObgcBzeFWzj76Ix6oLzr2NxFnXbx kOmy6m+VTgMOVLkF5pRi5Em8EhQeWDVWcVR/37oybmjIdU0uASqZ/pIAoBtqD8w8Tavp 81eyYOuukuujl7TCyAgNfaIVjLDC/7Po0CTAs= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :mail-followup-to:references:mime-version:content-disposition :in-reply-to:user-agent; bh=zonT63YgWKVIcQgjVqQN83lDjmhEgLXdo5gkBXtDGoc=; b=jI7vJSaM9awu690Mb2PRkf3UcwCF4J9h8aKdZOTS9hbg4q4K22J+io/auYCRp5FdXS YeewWOW+nxitd8IPnm6bswxOEOkI2tg7IM2bj70Q/0S4NiYOarQpnqrU/YEqoHlfli1Q qDHGiw+O5F4fr/5hP1dRafbIYTml863Udk0KeQ6Wbu1AT8hDw4N8YYMtQ2BtHz4r8Mfs UKDT10ccOHittv05DsWPTS0DwQQOA+ULpgMSI+4O70FlSSKvxQ7u/wtUW6tqpTPa3sHU QZb13ZiI9D/hr55CZ1pPQ1AFuq/OMNdajPhMp+/HN94zbwPRE3HqvlKsi/tuE5BJGXqv cwog== X-Gm-Message-State: APjAAAXxdE5sXBU7mtJL6X4tnR1dRFhoG5ri7ViNzngYVDo3MzvTOwbI IW/N0QgyEE13tP0Igi0dS5yEww== X-Google-Smtp-Source: APXvYqwRUNI4jHd35HSLabIGBMHJnlo3PLCLNK9+J4jx2Spj40+1ae3JsaCcKe9lZNCsDJcbNCcj1A== X-Received: by 2002:a50:a4db:: with SMTP id x27mr29212169edb.120.1554276133669; Wed, 03 Apr 2019 00:22:13 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:569e:0:3106:d637:d723:e855]) by smtp.gmail.com with ESMTPSA id k5sm394006ejv.83.2019.04.03.00.22.12 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 03 Apr 2019 00:22:12 -0700 (PDT) Date: Wed, 3 Apr 2019 09:22:10 +0200 From: Daniel Vetter To: Philipp Zabel Cc: Michael Grzeschik , airlied@linux.ie, gregkh@linuxfoundation.org, kernel@pengutronix.de, rafael@kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux@armlinux.org.uk Subject: Re: [PATCH 1/3] ipuv3-crtc: add remove action for devres data Message-ID: <20190403072210.GP2665@phenom.ffwll.local> Mail-Followup-To: Philipp Zabel , Michael Grzeschik , airlied@linux.ie, gregkh@linuxfoundation.org, kernel@pengutronix.de, rafael@kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, linux@armlinux.org.uk References: <0687f68004b28ed3a364b06a9eb64e2e@agner.ch> <20190402134904.588-1-m.grzeschik@pengutronix.de> <20190402134904.588-2-m.grzeschik@pengutronix.de> <1554220163.2338.2.camel@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1554220163.2338.2.camel@pengutronix.de> X-Operating-System: Linux phenom 4.19.0-1-amd64 User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 02, 2019 at 05:49:23PM +0200, Philipp Zabel wrote: > Hi Michael, > > On Tue, 2019-04-02 at 15:49 +0200, Michael Grzeschik wrote: > > The destroy function in drm_mode_config_cleanup will remove the objects > > in ipu-drm-core by calling its destroy functions if the bind function > > fails. The drm_crtc is also part of the devres allocated ipu_crtc > > object. The ipu_crtc object will already be cleaned up if the bind for > > the crtc fails. This leads drm_crtc_cleanup try to clean already freed > > memory. > > > > We fix this issue by adding the devres action ipu_crtc_remove_head which > > will remove its head from the objects in ipu-drm-core which then never > > calls its destroy function anymore. > > > > Signed-off-by: Michael Grzeschik > > --- > > drivers/gpu/drm/imx/ipuv3-crtc.c | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/drivers/gpu/drm/imx/ipuv3-crtc.c b/drivers/gpu/drm/imx/ipuv3-crtc.c > > index ec3602ebbc1cd..fa1ee33a43d77 100644 > > --- a/drivers/gpu/drm/imx/ipuv3-crtc.c > > +++ b/drivers/gpu/drm/imx/ipuv3-crtc.c > > @@ -429,6 +429,14 @@ static int ipu_crtc_init(struct ipu_crtc *ipu_crtc, > > return ret; > > } > > > > +static void ipu_crtc_remove_head(void *data) > > +{ > > + struct ipu_crtc *ipu_crtc = data; > > + struct drm_crtc *crtc = &ipu_crtc->base; > > + > > + list_del(&crtc->head); > > I don't think reaching into drm_crtc internals like this is going to be > robust. Currently, this is either missing the rest of drm_crtc_cleanup, > or it will crash if drm_crtc_init_with_planes hasn't been called yet. > > I think you could call devm_add_action with a function that calls > drm_crtc_cleanup after drm_crtc_init_with_planes in ipu_crtc_init. > > Alternatively, the ipu_crtc allocation could be changed to kzalloc. It > would then have to freed manually in the drm_crtc_funcs->destroy > callback. Dirty secret of devm: You can't use it for any drm_ structure, because the lifetimes of those do not match the lifetimes of the underlying device. We'd need to tie the lifetimes of drm objects to drm_device. Noralf has some patches to move that forward. We'd need something like drm_dev_kzalloc which releases memory when drm_device is freed. Agreed that digging even deeper into the devm deadend is not a good idea. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch