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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 C1A30C43217 for ; Tue, 14 Sep 2021 21:15:25 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 6AF9E61178 for ; Tue, 14 Sep 2021 21:15:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 6AF9E61178 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id DBD776E825; Tue, 14 Sep 2021 21:15:23 +0000 (UTC) Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by gabe.freedesktop.org (Postfix) with ESMTPS id 20F466E824; Tue, 14 Sep 2021 21:15:22 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10107"; a="222175013" X-IronPort-AV: E=Sophos;i="5.85,292,1624345200"; d="scan'208";a="222175013" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Sep 2021 14:15:21 -0700 X-IronPort-AV: E=Sophos;i="5.85,292,1624345200"; d="scan'208";a="508312014" Received: from jons-linux-dev-box.fm.intel.com (HELO jons-linux-dev-box) ([10.1.27.20]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Sep 2021 14:15:21 -0700 Date: Tue, 14 Sep 2021 14:10:22 -0700 From: Matthew Brost To: Daniel Vetter Cc: Dave Airlie , Intel Graphics Development , dri-devel , john.c.harrison@intel.com Subject: Re: [Intel-gfx] [PATCH 1/5] drm/i915: Do not define vma on stack Message-ID: <20210914211022.GA15442@jons-linux-dev-box> References: <20210914044933.22932-1-matthew.brost@intel.com> <20210914044933.22932-2-matthew.brost@intel.com> <20210914153656.GA23874@jons-linux-dev-box> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) 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: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Tue, Sep 14, 2021 at 10:05:03PM +0200, Daniel Vetter wrote: > On Tue, Sep 14, 2021 at 08:36:56AM -0700, Matthew Brost wrote: > > On Tue, Sep 14, 2021 at 03:04:59PM +1000, Dave Airlie wrote: > > > On Tue, 14 Sept 2021 at 14:55, Matthew Brost wrote: > > > > > > > > From: Venkata Sandeep Dhanalakota > > > > > > > > Defining vma on stack can cause stack overflow, if > > > > vma gets populated with new fields. > > > > > > Is there some higher level locking stopping that from getting trashed? > > > or a guarantee that uc_fw_bind_ggtt is only entered by one thread at a > > > time? > > > > > > > I believe this function is only called during driver load (inherently > > one thread) or during a GT reset (protected by reset mutex) so at most 1 > > thread can be executing this code at once, thus it is safe to use a > > global dummy vma in this function. > > This kind of stuff must be documented in kerneldoc comments. Please use > the inline struct member format. > Forgot to include kerneldoc for this new field, will add. > Also please document the other fields in that struct, cant hurt :-) I'll see what I can do but I didn't write this code and may not fully understand all the fields off hand. Matt > -Daniel > > > > > Matt > > > > > Dave. > > > > > > > > > > > Cc: Daniele Ceraolo Spurio > > > > Cc: Tvrtko Ursulin > > > > Signed-off-by: Venkata Sandeep Dhanalakota > > > > Signed-off-by: Matthew Brost > > > > Reviewed-by: Matthew Brost > > > > --- > > > > drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c | 18 +++++++++--------- > > > > drivers/gpu/drm/i915/gt/uc/intel_uc_fw.h | 2 ++ > > > > 2 files changed, 11 insertions(+), 9 deletions(-) > > > > > > > > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c > > > > index 3a16d08608a5..f632dbd32b42 100644 > > > > --- a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c > > > > +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c > > > > @@ -413,20 +413,20 @@ static void uc_fw_bind_ggtt(struct intel_uc_fw *uc_fw) > > > > { > > > > struct drm_i915_gem_object *obj = uc_fw->obj; > > > > struct i915_ggtt *ggtt = __uc_fw_to_gt(uc_fw)->ggtt; > > > > - struct i915_vma dummy = { > > > > - .node.start = uc_fw_ggtt_offset(uc_fw), > > > > - .node.size = obj->base.size, > > > > - .pages = obj->mm.pages, > > > > - .vm = &ggtt->vm, > > > > - }; > > > > + struct i915_vma *dummy = &uc_fw->dummy; > > > > + > > > > + dummy->node.start = uc_fw_ggtt_offset(uc_fw); > > > > + dummy->node.size = obj->base.size; > > > > + dummy->pages = obj->mm.pages; > > > > + dummy->vm = &ggtt->vm; > > > > > > > > GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj)); > > > > - GEM_BUG_ON(dummy.node.size > ggtt->uc_fw.size); > > > > + GEM_BUG_ON(dummy->node.size > ggtt->uc_fw.size); > > > > > > > > /* uc_fw->obj cache domains were not controlled across suspend */ > > > > - drm_clflush_sg(dummy.pages); > > > > + drm_clflush_sg(dummy->pages); > > > > > > > > - ggtt->vm.insert_entries(&ggtt->vm, &dummy, I915_CACHE_NONE, 0); > > > > + ggtt->vm.insert_entries(&ggtt->vm, dummy, I915_CACHE_NONE, 0); > > > > } > > > > > > > > static void uc_fw_unbind_ggtt(struct intel_uc_fw *uc_fw) > > > > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.h b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.h > > > > index 99bb1fe1af66..693cc0ebcd63 100644 > > > > --- a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.h > > > > +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.h > > > > @@ -10,6 +10,7 @@ > > > > #include "intel_uc_fw_abi.h" > > > > #include "intel_device_info.h" > > > > #include "i915_gem.h" > > > > +#include "i915_vma.h" > > > > > > > > struct drm_printer; > > > > struct drm_i915_private; > > > > @@ -75,6 +76,7 @@ struct intel_uc_fw { > > > > bool user_overridden; > > > > size_t size; > > > > struct drm_i915_gem_object *obj; > > > > + struct i915_vma dummy; > > > > > > > > /* > > > > * The firmware build process will generate a version header file with major and > > > > -- > > > > 2.32.0 > > > > > > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch