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 65E9FC433EF for ; Fri, 29 Apr 2022 07:54:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1355273AbiD2H5d (ORCPT ); Fri, 29 Apr 2022 03:57:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44792 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355277AbiD2H5c (ORCPT ); Fri, 29 Apr 2022 03:57:32 -0400 Received: from mail-wr1-x432.google.com (mail-wr1-x432.google.com [IPv6:2a00:1450:4864:20::432]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CE294BC860 for ; Fri, 29 Apr 2022 00:54:14 -0700 (PDT) Received: by mail-wr1-x432.google.com with SMTP id e2so9660857wrh.7 for ; Fri, 29 Apr 2022 00:54:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=date:from:to:cc:subject:message-id:mail-followup-to:references :mime-version:content-disposition:in-reply-to; bh=m3+VWI4CFopJUrW0W/J3jbhF0AMueeAVUj1oVXfQZW4=; b=VvC9PUR/NSQ5SiqLBxcYHp2n5sEVkcB1hOTRiJAgpvc+JKWkhDbUIzZNNl8RJibkZV /g1PVHR/EFVZlUukYcYazjIxauAp5+9oA1eZAkV+Wh1T8TrZTfoRjZsMJBjaJbwiDJ58 D92D+gCOXFepnW+TC8Qgz0XnLd5Si1ncBuwVA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id :mail-followup-to:references:mime-version:content-disposition :in-reply-to; bh=m3+VWI4CFopJUrW0W/J3jbhF0AMueeAVUj1oVXfQZW4=; b=3w+BliRoOzLb1oDg9hn4abdDrsd/b2aj+ZViTaKmTm5hNw2LXXq91km/pT91A32RHB o4q4Qs5D5wa/yEOliAkdGMjhNKMcfITXbPoymPiANcMxQFPwq/Liq+iwQs66LHehSFPE E3iOLlolauBHd2GD3I9+f3mAttI0UnpbY99l8KgfIoSiAirKQBYZtqEl/XrMV5Em8Su2 0cvAFsHcW1Rgks9ZVMmLFqaWc/MENluw4k7D0ESbmxP3VIohV59UO9lbBvvhg46aPhPL MDDOikgQkpRk238XNkS7KEnpefMBTKZjfYlZW4rGaj2ifJD8k9hxWblI5rqwsP60Qaak URYQ== X-Gm-Message-State: AOAM530V6ILN/FsOxtzbCVOh3B63I+oO4jmoL67r2lRlfrH0wMCakOip /iQb7WhFV7+djt7AkGqqV6Z9Aw== X-Google-Smtp-Source: ABdhPJzALWE3X8Qp/b8LblTfj7IKWnFrmVWN4YU90qP7Bd5sPq3nkT1cduO0/x5y7t876IyYGeVW8A== X-Received: by 2002:a05:6000:1ac9:b0:20a:f6a1:811c with SMTP id i9-20020a0560001ac900b0020af6a1811cmr6005839wry.100.1651218853362; Fri, 29 Apr 2022 00:54:13 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id c66-20020a1c3545000000b00393fc022e03sm1952641wma.12.2022.04.29.00.54.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 Apr 2022 00:54:12 -0700 (PDT) Date: Fri, 29 Apr 2022 09:54:10 +0200 From: Daniel Vetter To: Mauro Carvalho Chehab , Greg KH Cc: Luis Chamberlain , mauro.chehab@intel.com, Kai Vehmanen , Lucas De Marchi , Pierre-Louis Bossart , dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org, Daniel Vetter , David Airlie , Dan Williams Subject: Re: [PATCH 1/2] module: add a function to add module references Message-ID: Mail-Followup-To: Mauro Carvalho Chehab , Greg KH , Luis Chamberlain , mauro.chehab@intel.com, Kai Vehmanen , Lucas De Marchi , Pierre-Louis Bossart , dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org, David Airlie , Dan Williams References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Operating-System: Linux phenom 5.10.0-8-amd64 Precedence: bulk List-ID: On Fri, Apr 29, 2022 at 07:31:15AM +0100, Mauro Carvalho Chehab wrote: > Sometimes, device drivers are bound using indirect references, > which is not visible when looking at /proc/modules or lsmod. > > Add a function to allow setting up module references for such > cases. > > Reviewed-by: Dan Williams > Signed-off-by: Mauro Carvalho Chehab This sounds like duct tape at the wrong level. We should have a device_link connecting these devices, and maybe device_link internally needs to make sure the respective driver modules stay around for long enough too. But open-coding this all over the place into every driver that has some kind of cross-driver dependency sounds terrible. Or maybe the bug is that the snd driver keeps accessing the hw/component side when that is just plain gone. Iirc there's still fundamental issues there on the sound side of things, which have been attempted to paper over by timeouts and stuff like that in the past instead of enforcing a hard link between the snd and i915 side. Adding Greg for device model questions like this. -Daniel > --- > > See [PATCH 0/2] at: https://lore.kernel.org/all/cover.1651212016.git.mchehab@kernel.org/ > > include/linux/module.h | 7 +++++++ > kernel/module/main.c | 31 +++++++++++++++++++++++++++++++ > 2 files changed, 38 insertions(+) > > diff --git a/include/linux/module.h b/include/linux/module.h > index 46d4d5f2516e..be74f807e41d 100644 > --- a/include/linux/module.h > +++ b/include/linux/module.h > @@ -596,6 +596,8 @@ static inline bool within_module(unsigned long addr, const struct module *mod) > /* Search for module by name: must be in a RCU-sched critical section. */ > struct module *find_module(const char *name); > > +int module_add_named_dependency(const char *name, struct module *this); > + > /* Returns 0 and fills in value, defined and namebuf, or -ERANGE if > symnum out of range. */ > int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type, > @@ -772,6 +774,11 @@ static inline int lookup_module_symbol_attrs(unsigned long addr, unsigned long * > return -ERANGE; > } > > +static inline int module_add_named_dependency(const char *name, struct module *this) > +{ > + return 0; > +} > + > static inline int module_get_kallsym(unsigned int symnum, unsigned long *value, > char *type, char *name, > char *module_name, int *exported) > diff --git a/kernel/module/main.c b/kernel/module/main.c > index 05a42d8fcd7a..dbd577ccc38c 100644 > --- a/kernel/module/main.c > +++ b/kernel/module/main.c > @@ -631,6 +631,37 @@ static int ref_module(struct module *a, struct module *b) > return 0; > } > > +int module_add_named_dependency(const char *name, struct module *this) > +{ > + struct module *mod; > + int ret; > + > + if (!name || !this || !this->name) { > + return -EINVAL; > + } > + > + mutex_lock(&module_mutex); > + mod = find_module(name); > + if (!mod) { > + ret = -EINVAL; > + goto ret; > + } > + > + ret = ref_module(this, mod); > + if (ret) > + goto ret; > + > +#ifdef CONFIG_MODULE_UNLOAD > + ret = sysfs_create_link(mod->holders_dir, > + &this->mkobj.kobj, this->name); > +#endif > + > +ret: > + mutex_unlock(&module_mutex); > + return ret; > +} > +EXPORT_SYMBOL_GPL(module_add_named_dependency); > + > /* Clear the unload stuff of the module. */ > static void module_unload_free(struct module *mod) > { > -- > 2.35.1 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch