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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BC542C433F5 for ; Thu, 31 Mar 2022 09:34:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234124AbiCaJgc (ORCPT ); Thu, 31 Mar 2022 05:36:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37962 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232507AbiCaJgc (ORCPT ); Thu, 31 Mar 2022 05:36:32 -0400 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5111AA94CC; Thu, 31 Mar 2022 02:34:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1648719284; x=1680255284; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=accBRYHMBah+nI3IJi8qJ4uZB9q5SYI8c2Q9UFYLYpM=; b=FusmpTAnv2tpVOI6CLesc9XUYI2qpOfiEntKFji0LQvUwc6GVZsiCOi/ sO8YdaM8r1Kn2zb0BHlAfPC/x6Aq4HPJB+EA+Fby6H9Lg2wpSLMg3wEbr CJUqXktOWIArnXDoGYolpBxmCUuqiy/vbSSR7VJNaX+uhaXMIfw8yd0f5 4m2PNTwEHc17jVso327ylRPznOARGW+k5jiS6l4STwLLmI7KiVwrckUB+ idiZpaPIqaQk3JpKljBUSwDoGdQlcoJT//xEWZ5YaPAwhmUZg/5x34ZAN zTSO5UaREhJDW6QIy72va64nvGaG72FsTuIe8U6EdjDIYiHDfWGUNOEOe A==; X-IronPort-AV: E=McAfee;i="6200,9189,10302"; a="247279389" X-IronPort-AV: E=Sophos;i="5.90,224,1643702400"; d="scan'208";a="247279389" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Mar 2022 02:34:43 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.90,224,1643702400"; d="scan'208";a="695424720" Received: from kuha.fi.intel.com ([10.237.72.185]) by fmsmga001.fm.intel.com with SMTP; 31 Mar 2022 02:34:39 -0700 Received: by kuha.fi.intel.com (sSMTP sendmail emulation); Thu, 31 Mar 2022 12:34:38 +0300 Date: Thu, 31 Mar 2022 12:34:38 +0300 From: Heikki Krogerus To: Takashi Iwai Cc: Won Chung , Jaroslav Kysela , Takashi Iwai , Mika Westerberg , Benson Leung , Prashant Malani , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2] sound/hda: Add NULL check to component match callback function Message-ID: References: <20220330211913.2068108-1-wonchung@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Thu, Mar 31, 2022 at 11:28:20AM +0200, Takashi Iwai wrote: > On Thu, 31 Mar 2022 11:25:43 +0200, > Heikki Krogerus wrote: > > > > On Thu, Mar 31, 2022 at 11:12:55AM +0200, Takashi Iwai wrote: > > > > > > - if (!strcmp(dev->driver->name, "i915") && > > > > > > + if (dev->driver && !strcmp(dev->driver->name, "i915") && > > > > > > > > > > Can NULL dev->driver be really seen? I thought the components are > > > > > added by the drivers, hence they ought to have the driver field set. > > > > > But there can be corner cases I overlooked. > > > > > > > > > > > > > > > thanks, > > > > > > > > > > Takashi > > > > > > > > Hi Takashi, > > > > > > > > When I try using component_add in a different driver (usb4 in my > > > > case), I think dev->driver here is NULL because the i915 drivers do > > > > not have their component master fully bound when this new component is > > > > registered. When I test it, it seems to be causing a crash. > > > > > > Hm, from where component_add*() is called? Basically dev->driver must > > > be already set before the corresponding driver gets bound at > > > __driver_probe_deviec(). So, if the device is added to component from > > > the corresponding driver's probe, dev->driver must be non-NULL. > > > > The code that declares a device as component does not have to be the > > driver of that device. > > > > In our case the components are USB ports, and they are devices that > > are actually never bind to any drivers: drivers/usb/core/port.c > > OK, that's what I wanted to know. It'd be helpful if it's more > clearly mentioned in the commit log. Agree. > BTW, the same problem must be seen in MEI drivers, too. Wasn't there a patch for those too? I lost track... thanks, -- heikki