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[2620:137:e000::1:20]) by mx.google.com with ESMTP id b13-20020a056402350d00b004739d471e12si33738258edd.280.2023.01.04.09.58.14; Wed, 04 Jan 2023 09:58:28 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@inria.fr header.s=dc header.b=QQY9ert9; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=inria.fr Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239912AbjADRvn (ORCPT + 56 others); Wed, 4 Jan 2023 12:51:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229441AbjADRvl (ORCPT ); Wed, 4 Jan 2023 12:51:41 -0500 Received: from mail2-relais-roc.national.inria.fr (mail2-relais-roc.national.inria.fr [192.134.164.83]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3FA7F2BE9 for ; Wed, 4 Jan 2023 09:51:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=inria.fr; s=dc; h=date:from:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=jPIOICMJamB8Q+k5NZeaoYSyd6m7DdgJ938P616hzCc=; b=QQY9ert9138tBSipHgPuDLMcAPtLB2fm0L8B1JdP2te+pSz0p6WnxmEG NEiFbSoMLo6aFvP12O7CnxGlwplm4rRSIdzsWz3xRrXnZ+fMbZZfSkS/A djFmMTCati7ETdLEiovvya0zvAuiEQZ1lv5PB/sQ5Ei1MGpIcZcyhYA/c U=; Authentication-Results: mail2-relais-roc.national.inria.fr; dkim=none (message not signed) header.i=none; spf=SoftFail smtp.mailfrom=julia.lawall@inria.fr; dmarc=fail (p=none dis=none) d=inria.fr X-IronPort-AV: E=Sophos;i="5.96,300,1665439200"; d="scan'208";a="85986134" Received: from 214.123.68.85.rev.sfr.net (HELO hadrien) ([85.68.123.214]) by mail2-relais-roc.national.inria.fr with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Jan 2023 18:51:38 +0100 Date: Wed, 4 Jan 2023 18:51:37 +0100 (CET) From: Julia Lawall X-X-Sender: jll@hadrien To: Deepak R Varma cc: Rodrigo Vivi , Nicolai Stange , Julia Lawall , Jani Nikula , Joonas Lahtinen , Tvrtko Ursulin , David Airlie , Daniel Vetter , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Saurabh Singh Sengar , Praveen Kumar Subject: Re: [PATCH] drm/i915/fbc: Avoid full proxy f_ops for FBC debug attributes In-Reply-To: Message-ID: References: User-Agent: Alpine 2.22 (DEB 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 3 Jan 2023, Deepak R Varma wrote: > On Wed, Dec 28, 2022 at 06:18:12AM -0500, Rodrigo Vivi wrote: > > On Tue, Dec 27, 2022 at 11:36:13PM +0530, Deepak R Varma wrote: > > > On Tue, Dec 27, 2022 at 12:13:56PM -0500, Rodrigo Vivi wrote: > > > > On Tue, Dec 27, 2022 at 01:30:53PM +0530, Deepak R Varma wrote: > > > > > Using DEFINE_SIMPLE_ATTRIBUTE macro with the debugfs_create_file() > > > > > function adds the overhead of introducing a proxy file operation > > > > > functions to wrap the original read/write inside file removal protection > > > > > functions. This adds significant overhead in terms of introducing and > > > > > managing the proxy factory file operations structure and function > > > > > wrapping at runtime. > > > > > As a replacement, a combination of DEFINE_DEBUGFS_ATTRIBUTE macro paired > > > > > with debugfs_create_file_unsafe() is suggested to be used instead. The > > > > > DEFINE_DEBUGFS_ATTRIBUTE utilises debugfs_file_get() and > > > > > debugfs_file_put() wrappers to protect the original read and write > > > > > function calls for the debug attributes. There is no need for any > > > > > runtime proxy file operations to be managed by the debugfs core. > > > > > > > > > > This Change is reported by the debugfs_simple_attr.cocci Coccinelle > > > > > semantic patch. > > > > > > > > I just checked here with > > > > $ make coccicheck M=drivers/gpu/drm/i915/ MODE=context COCCI=./scripts/coccinelle/api/debugfs/debugfs_simple_attr.cocci > > > > > > Hello Rodrigo, > > > Thank you so much for your review and feedback on the patch proposal. > > > > > > > > > > > The part reported by the this script is the s/SIMPLE/DEBUGFS > > > > but the change to the unsafe option is not. > > > > > > If you look at the original commit of this coccinelle file, it calls out the > > > need for pairing debugfs_create_file_unsafe() as well. Please review this > > > > > > commitID: 5103068eaca2: ("debugfs, coccinelle: check for obsolete DEFINE_SIMPLE_ATTRIBUTE() usage") > > > > +Nicolai and Julia. > > > > It looks like coccinelle got right the > > - DEFINE_SIMPLE_ATTRIBUTE(dsa_fops, dsa_get, dsa_set, dsa_fmt); > > + DEFINE_DEBUGFS_ATTRIBUTE(dsa_fops, dsa_get, dsa_set, dsa_fmt); > > > > but it failed badly on > > - debugfs_create_file(name, mode, parent, data, &dsa_fops) > > + debugfs_create_file_unsafe(name, mode, parent, data, &dsa_fops) > > > > > > > > Based on my review of the code, the functions debugfs_create_file() and > > > debugfs_create_file_unsafe(), both internally call __debugfs_create_file(). > > > However, they pass debugfs_full_proxy_file_operations and > > > debugfs_open_proxy_file_operations respectively to it. The former represents the > > > full proxy factory, where as the later one is lightweight open proxy > > > implementation of the file operations structure. > > > > > > > > > > > This commit message is not explaining why the unsafe is the suggested > > > > or who suggested it. > > > > > > If you find the response above accurate, I will include these details about > > > the _unsafe() function in my commit message in v2. > > > > > > > > > > > If you remove the unsafe part feel free to resend adding: > > > > > > Please confirm you still believe switching to _unsafe() is not necessary. > > > > Based on the coccinelle commit it looks like you are right, but cocinelle > > just failed to detect the case. Let's see what Nicolai and Julia respond > > before we move with any patch here. > > Hello Nicolai and Julia, > Can you please review this proposed patch and the feedback comments from Rodrigo > please? I'm not an expert on this issue. If the semantic patch needs to change in some way, I would be happy to take any improvements. julia > > Thank you, > ./drv > > > > > > > > > > > > > > Reviewed-by: Rodrigo Vivi > > > > (to both patches, this and the drrs one. > > > > > > > > Also, it looks like you could contribute with other 2 patches: > > > > drivers/gpu/drm/i915/pxp/intel_pxp_debugfs.c:64:0-23: WARNING: pxp_terminate_fops should be defined with DEFINE_DEBUGFS_ATTRIBUTE > > > > drivers/gpu/drm/i915/gvt/debugfs.c:150:0-23: WARNING: vgpu_scan_nonprivbb_fops should be defined with DEFINE_DEBUGFS_ATTRIBUTE > > > > > > Yes, these are on my list. Was waiting for a feedback on the first submission > > > before I send more similar patches. > > > > > > Appreciate your time and the feedback. > > > > > > > > > Regards, > > > ./drv > > > > > > > > > > > > > > > > > Signed-off-by: Deepak R Varma > > > > > --- > > > > > drivers/gpu/drm/i915/display/intel_fbc.c | 12 ++++++------ > > > > > 1 file changed, 6 insertions(+), 6 deletions(-) > > > > > > > > > > diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c > > > > > index b5ee5ea0d010..4b481e2f908b 100644 > > > > > --- a/drivers/gpu/drm/i915/display/intel_fbc.c > > > > > +++ b/drivers/gpu/drm/i915/display/intel_fbc.c > > > > > @@ -1809,10 +1809,10 @@ static int intel_fbc_debugfs_false_color_set(void *data, u64 val) > > > > > return 0; > > > > > } > > > > > > > > > > -DEFINE_SIMPLE_ATTRIBUTE(intel_fbc_debugfs_false_color_fops, > > > > > - intel_fbc_debugfs_false_color_get, > > > > > - intel_fbc_debugfs_false_color_set, > > > > > - "%llu\n"); > > > > > +DEFINE_DEBUGFS_ATTRIBUTE(intel_fbc_debugfs_false_color_fops, > > > > > + intel_fbc_debugfs_false_color_get, > > > > > + intel_fbc_debugfs_false_color_set, > > > > > + "%llu\n"); > > > > > > > > > > static void intel_fbc_debugfs_add(struct intel_fbc *fbc, > > > > > struct dentry *parent) > > > > > @@ -1821,8 +1821,8 @@ static void intel_fbc_debugfs_add(struct intel_fbc *fbc, > > > > > fbc, &intel_fbc_debugfs_status_fops); > > > > > > > > > > if (fbc->funcs->set_false_color) > > > > > - debugfs_create_file("i915_fbc_false_color", 0644, parent, > > > > > - fbc, &intel_fbc_debugfs_false_color_fops); > > > > > + debugfs_create_file_unsafe("i915_fbc_false_color", 0644, parent, > > > > > + fbc, &intel_fbc_debugfs_false_color_fops); > > > > > } > > > > > > > > > > void intel_fbc_crtc_debugfs_add(struct intel_crtc *crtc) > > > > > -- > > > > > 2.34.1 > > > > > > > > > > > > > > > > > > > > > > > > > >