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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 86418C433F5 for ; Fri, 29 Apr 2022 07:54:20 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 2954710FAF2; Fri, 29 Apr 2022 07:54:16 +0000 (UTC) Received: from mail-wr1-x42b.google.com (mail-wr1-x42b.google.com [IPv6:2a00:1450:4864:20::42b]) by gabe.freedesktop.org (Postfix) with ESMTPS id 04AB410FAE5 for ; Fri, 29 Apr 2022 07:54:14 +0000 (UTC) Received: by mail-wr1-x42b.google.com with SMTP id x18so9709330wrc.0 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=gTY9FEwcrjVPx7XKhk9WxiGJbMxJf6tTvK+kXGTqWJfiZYb67ZAjtDnh4DWXETb0q2 DMf9+wEdt4oPjGydvjp6tBHpKwzqr5v3/Gx5dw2hIwDXnI5yGGxlCZtps2pnbS2MarMx CXWg+1P2uZcJhfNXjF4/reHLuoSuAHNDXFYz40lsduFCxso7PzwXMWrNNjs4j2AkigYg at8YjEVFmG0N1Hdcum/DKhR53MYYEjhFfU8oDyz6F/Y1DfztrYNSGdc1cLAnVmb21uxM VZGn5+g5h8OxrN9EZh2mmDC2CWQGN9HwZ0pEKTeMDfTU3XSPhbE+cwfSIwXEHSiUIc14 c60Q== X-Gm-Message-State: AOAM5323LFS75D0j2smWbeF1oUNb0MjBiq3oWpSBZbQhBJ+Wz9PJ8BrW ilmG6OI2ua9tdD641ZZvNESAZw== 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 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 Subject: Re: [Intel-gfx] [PATCH 1/2] module: add a function to add module references X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kai Vehmanen , intel-gfx@lists.freedesktop.org, Lucas De Marchi , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, David Airlie , Luis Chamberlain , mauro.chehab@intel.com, Dan Williams , linux-modules@vger.kernel.org, Pierre-Louis Bossart Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" 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