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 B0ED9C433EF for ; Thu, 31 Mar 2022 09:29:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234194AbiCaJbC (ORCPT ); Thu, 31 Mar 2022 05:31:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37646 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234088AbiCaJan (ORCPT ); Thu, 31 Mar 2022 05:30:43 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4446719FF57; Thu, 31 Mar 2022 02:28:22 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id DAA9421A94; Thu, 31 Mar 2022 09:28:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1648718900; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=XFYfyrwVmalPRCaJIXRo5qf+pa6Yt4e0di4LG/QUdCY=; b=cb1k+h93A36MO7riwd/Qq76x5i0lu0S4SLrdnMiGjNy696815AcLMhqNGXrMIn9ftssWqL fJXw7j/A7irFO3EatIsZLuM2bziydIhKhAJtvHjC3ARMQDsPLuPIKfCSxY8Zd0Z6iHhN8z i4CoOSECGpnDo/pwJ6IKuaj/yLDwRCY= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1648718900; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=XFYfyrwVmalPRCaJIXRo5qf+pa6Yt4e0di4LG/QUdCY=; b=06BUBuFtLxd3hjLa9h9D7KiBDTs6H9WhKtnqH6kUGCJzhStFZggmmFG6ObPFZGr53Y+lWL nwF2aEcRxDD/AGBQ== Received: from alsa1.suse.de (alsa1.suse.de [10.160.4.42]) by relay2.suse.de (Postfix) with ESMTP id C7434A3B94; Thu, 31 Mar 2022 09:28:20 +0000 (UTC) Date: Thu, 31 Mar 2022 11:28:20 +0200 Message-ID: From: Takashi Iwai To: Heikki Krogerus Cc: Takashi Iwai , 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 In-Reply-To: References: <20220330211913.2068108-1-wonchung@google.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. BTW, the same problem must be seen in MEI drivers, too. Takashi